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52826846 | 1 | .\" -*- nroff -*- |
e43d0cda NB |
2 | .\" Copyright Neil Brown and others. |
3 | .\" This program is free software; you can redistribute it and/or modify | |
4 | .\" it under the terms of the GNU General Public License as published by | |
5 | .\" the Free Software Foundation; either version 2 of the License, or | |
6 | .\" (at your option) any later version. | |
7 | .\" See file COPYING in distribution for details. | |
e30ca260 | 8 | .TH MDADM 8 "" v4.2 |
52826846 | 9 | .SH NAME |
9a9dab36 | 10 | mdadm \- manage MD devices |
cd29a5c8 | 11 | .I aka |
93e790af | 12 | Linux Software RAID |
cd29a5c8 | 13 | |
52826846 NB |
14 | .SH SYNOPSIS |
15 | ||
e0d19036 | 16 | .BI mdadm " [mode] <raiddevice> [options] <component-devices>" |
52826846 | 17 | |
2ae555c3 | 18 | .SH DESCRIPTION |
52826846 | 19 | RAID devices are virtual devices created from two or more |
e0fe762a | 20 | real block devices. This allows multiple devices (typically disk |
35cc5be4 | 21 | drives or partitions thereof) to be combined into a single device to |
cd29a5c8 | 22 | hold (for example) a single filesystem. |
2d465520 | 23 | Some RAID levels include redundancy and so can survive some degree of |
cd29a5c8 NB |
24 | device failure. |
25 | ||
2d465520 NB |
26 | Linux Software RAID devices are implemented through the md (Multiple |
27 | Devices) device driver. | |
cd29a5c8 NB |
28 | |
29 | Currently, Linux supports | |
30 | .B LINEAR | |
31 | md devices, | |
32 | .B RAID0 | |
33 | (striping), | |
34 | .B RAID1 | |
35 | (mirroring), | |
d013a55e NB |
36 | .BR RAID4 , |
37 | .BR RAID5 , | |
98c6faba | 38 | .BR RAID6 , |
1a7dfc35 | 39 | .BR RAID10 , |
b5e64645 | 40 | .BR MULTIPATH , |
90c8d668 | 41 | .BR FAULTY , |
cd29a5c8 | 42 | and |
90c8d668 | 43 | .BR CONTAINER . |
d013a55e | 44 | |
a9d69660 NB |
45 | .B MULTIPATH |
46 | is not a Software RAID mechanism, but does involve | |
93e790af | 47 | multiple devices: |
d013a55e | 48 | each device is a path to one common physical storage device. |
9652457e N |
49 | New installations should not use md/multipath as it is not well |
50 | supported and has no ongoing development. Use the Device Mapper based | |
51 | multipath-tools instead. | |
d013a55e | 52 | |
a9d69660 NB |
53 | .B FAULTY |
54 | is also not true RAID, and it only involves one device. It | |
b5e64645 | 55 | provides a layer over a true device that can be used to inject faults. |
52826846 | 56 | |
4cce4069 | 57 | .B CONTAINER |
8fd8d9c4 N |
58 | is different again. A |
59 | .B CONTAINER | |
60 | is a collection of devices that are | |
90c8d668 N |
61 | managed as a set. This is similar to the set of devices connected to |
62 | a hardware RAID controller. The set of devices may contain a number | |
9652457e | 63 | of different RAID arrays each utilising some (or all) of the blocks from a |
90c8d668 | 64 | number of the devices in the set. For example, two devices in a 5-device set |
9652457e | 65 | might form a RAID1 using the whole devices. The remaining three might |
90c8d668 N |
66 | have a RAID5 over the first half of each device, and a RAID0 over the |
67 | second half. | |
68 | ||
8fd8d9c4 N |
69 | With a |
70 | .BR CONTAINER , | |
71 | there is one set of metadata that describes all of | |
72 | the arrays in the container. So when | |
73 | .I mdadm | |
74 | creates a | |
75 | .B CONTAINER | |
9652457e N |
76 | device, the device just represents the metadata. Other normal arrays (RAID1 |
77 | etc) can be created inside the container. | |
52826846 NB |
78 | |
79 | .SH MODES | |
8382f19b | 80 | mdadm has several major modes of operation: |
cd29a5c8 NB |
81 | .TP |
82 | .B Assemble | |
93e790af | 83 | Assemble the components of a previously created |
e0fe762a | 84 | array into an active array. Components can be explicitly given |
2ae555c3 | 85 | or can be searched for. |
51ac42e3 | 86 | .I mdadm |
cd29a5c8 NB |
87 | checks that the components |
88 | do form a bona fide array, and can, on request, fiddle superblock | |
89 | information so as to assemble a faulty array. | |
90 | ||
91 | .TP | |
92 | .B Build | |
e0fe762a | 93 | Build an array that doesn't have per-device metadata (superblocks). For these |
a9d69660 NB |
94 | sorts of arrays, |
95 | .I mdadm | |
96 | cannot differentiate between initial creation and subsequent assembly | |
97 | of an array. It also cannot perform any checks that appropriate | |
93e790af | 98 | components have been requested. Because of this, the |
a9d69660 NB |
99 | .B Build |
100 | mode should only be used together with a complete understanding of | |
101 | what you are doing. | |
cd29a5c8 NB |
102 | |
103 | .TP | |
104 | .B Create | |
e0fe762a N |
105 | Create a new array with per-device metadata (superblocks). |
106 | Appropriate metadata is written to each device, and then the array | |
107 | comprising those devices is activated. A 'resync' process is started | |
108 | to make sure that the array is consistent (e.g. both sides of a mirror | |
109 | contain the same data) but the content of the device is left otherwise | |
110 | untouched. | |
111 | The array can be used as soon as it has been created. There is no | |
112 | need to wait for the initial resync to finish. | |
cd29a5c8 | 113 | |
cd29a5c8 NB |
114 | .TP |
115 | .B "Follow or Monitor" | |
5787fa49 | 116 | Monitor one or more md devices and act on any state changes. This is |
e0fe762a N |
117 | only meaningful for RAID1, 4, 5, 6, 10 or multipath arrays, as |
118 | only these have interesting state. RAID0 or Linear never have | |
98c6faba | 119 | missing, spare, or failed drives, so there is nothing to monitor. |
5787fa49 | 120 | |
dd0781e5 NB |
121 | .TP |
122 | .B "Grow" | |
123 | Grow (or shrink) an array, or otherwise reshape it in some way. | |
124 | Currently supported growth options including changing the active size | |
c64881d7 N |
125 | of component devices and changing the number of active devices in |
126 | Linear and RAID levels 0/1/4/5/6, | |
127 | changing the RAID level between 0, 1, 5, and 6, and between 0 and 10, | |
17790db6 | 128 | changing the chunk size and layout for RAID 0,4,5,6,10 as well as adding or |
860f11ed | 129 | removing a write-intent bitmap and changing the array's consistency policy. |
cd29a5c8 | 130 | |
8382f19b NB |
131 | .TP |
132 | .B "Incremental Assembly" | |
133 | Add a single device to an appropriate array. If the addition of the | |
134 | device makes the array runnable, the array will be started. | |
135 | This provides a convenient interface to a | |
136 | .I hot-plug | |
137 | system. As each device is detected, | |
138 | .I mdadm | |
139 | has a chance to include it in some array as appropriate. | |
29ba4804 N |
140 | Optionally, when the |
141 | .I \-\-fail | |
142 | flag is passed in we will remove the device from any active array | |
143 | instead of adding it. | |
9652457e | 144 | |
8fd8d9c4 N |
145 | If a |
146 | .B CONTAINER | |
147 | is passed to | |
148 | .I mdadm | |
149 | in this mode, then any arrays within that container will be assembled | |
150 | and started. | |
8382f19b | 151 | |
2ae555c3 NB |
152 | .TP |
153 | .B Manage | |
154 | This is for doing things to specific components of an array such as | |
155 | adding new spares and removing faulty devices. | |
156 | ||
157 | .TP | |
158 | .B Misc | |
159 | This is an 'everything else' mode that supports operations on active | |
160 | arrays, operations on component devices such as erasing old superblocks, and | |
161 | information gathering operations. | |
e43d0cda NB |
162 | .\"This mode allows operations on independent devices such as examine MD |
163 | .\"superblocks, erasing old superblocks and stopping active arrays. | |
2ae555c3 | 164 | |
1f48664b NB |
165 | .TP |
166 | .B Auto-detect | |
167 | This mode does not act on a specific device or array, but rather it | |
168 | requests the Linux Kernel to activate any auto-detected arrays. | |
52826846 NB |
169 | .SH OPTIONS |
170 | ||
2ae555c3 | 171 | .SH Options for selecting a mode are: |
52826846 | 172 | |
cd29a5c8 | 173 | .TP |
7e23fc43 | 174 | .BR \-A ", " \-\-assemble |
2d465520 | 175 | Assemble a pre-existing array. |
52826846 | 176 | |
cd29a5c8 | 177 | .TP |
7e23fc43 | 178 | .BR \-B ", " \-\-build |
cd29a5c8 | 179 | Build a legacy array without superblocks. |
52826846 | 180 | |
cd29a5c8 | 181 | .TP |
7e23fc43 | 182 | .BR \-C ", " \-\-create |
cd29a5c8 | 183 | Create a new array. |
52826846 | 184 | |
cd29a5c8 | 185 | .TP |
7e23fc43 | 186 | .BR \-F ", " \-\-follow ", " \-\-monitor |
cd29a5c8 NB |
187 | Select |
188 | .B Monitor | |
189 | mode. | |
52826846 | 190 | |
dd0781e5 | 191 | .TP |
7e23fc43 | 192 | .BR \-G ", " \-\-grow |
dd0781e5 | 193 | Change the size or shape of an active array. |
8382f19b NB |
194 | |
195 | .TP | |
1f48664b | 196 | .BR \-I ", " \-\-incremental |
29ba4804 | 197 | Add/remove a single device to/from an appropriate array, and possibly start the array. |
8382f19b | 198 | |
1f48664b NB |
199 | .TP |
200 | .B \-\-auto-detect | |
201 | Request that the kernel starts any auto-detected arrays. This can only | |
202 | work if | |
203 | .I md | |
204 | is compiled into the kernel \(em not if it is a module. | |
205 | Arrays can be auto-detected by the kernel if all the components are in | |
206 | primary MS-DOS partitions with partition type | |
e0fe762a N |
207 | .BR FD , |
208 | and all use v0.90 metadata. | |
1f48664b NB |
209 | In-kernel autodetect is not recommended for new installations. Using |
210 | .I mdadm | |
211 | to detect and assemble arrays \(em possibly in an | |
212 | .I initrd | |
213 | \(em is substantially more flexible and should be preferred. | |
214 | ||
2ae555c3 NB |
215 | .P |
216 | If a device is given before any options, or if the first option is | |
4a984120 | 217 | one of |
7e23fc43 | 218 | .BR \-\-add , |
f33a71f1 N |
219 | .BR \-\-re\-add , |
220 | .BR \-\-add\-spare , | |
7e23fc43 | 221 | .BR \-\-fail , |
7e23fc43 | 222 | .BR \-\-remove , |
70c55e36 N |
223 | or |
224 | .BR \-\-replace , | |
e0fe762a | 225 | then the MANAGE mode is assumed. |
2ae555c3 NB |
226 | Anything other than these will cause the |
227 | .B Misc | |
228 | mode to be assumed. | |
dd0781e5 | 229 | |
2ae555c3 | 230 | .SH Options that are not mode-specific are: |
e793c2e5 | 231 | |
cd29a5c8 | 232 | .TP |
7e23fc43 | 233 | .BR \-h ", " \-\-help |
a9d69660 | 234 | Display general help message or, after one of the above options, a |
93e790af | 235 | mode-specific help message. |
56eedc1a NB |
236 | |
237 | .TP | |
7e23fc43 | 238 | .B \-\-help\-options |
56eedc1a NB |
239 | Display more detailed help about command line parsing and some commonly |
240 | used options. | |
52826846 | 241 | |
cd29a5c8 | 242 | .TP |
7e23fc43 | 243 | .BR \-V ", " \-\-version |
9a9dab36 | 244 | Print version information for mdadm. |
52826846 | 245 | |
cd29a5c8 | 246 | .TP |
7e23fc43 | 247 | .BR \-v ", " \-\-verbose |
22892d56 NB |
248 | Be more verbose about what is happening. This can be used twice to be |
249 | extra-verbose. | |
a9d69660 | 250 | The extra verbosity currently only affects |
7e23fc43 | 251 | .B \-\-detail \-\-scan |
22892d56 | 252 | and |
7e23fc43 | 253 | .BR "\-\-examine \-\-scan" . |
52826846 | 254 | |
dab6685f | 255 | .TP |
7e23fc43 | 256 | .BR \-q ", " \-\-quiet |
dab6685f | 257 | Avoid printing purely informative messages. With this, |
51ac42e3 | 258 | .I mdadm |
dab6685f NB |
259 | will be silent unless there is something really important to report. |
260 | ||
08ca2adf | 261 | |
e0d19036 | 262 | .TP |
7e23fc43 | 263 | .BR \-f ", " \-\-force |
93e790af | 264 | Be more forceful about certain operations. See the various modes for |
e0d19036 NB |
265 | the exact meaning of this option in different contexts. |
266 | ||
267 | .TP | |
7e23fc43 | 268 | .BR \-c ", " \-\-config= |
9dc70cbc N |
269 | Specify the config file or directory. Default is to use |
270 | .B /etc/mdadm.conf | |
271 | and | |
272 | .BR /etc/mdadm.conf.d , | |
273 | or if those are missing then | |
274 | .B /etc/mdadm/mdadm.conf | |
275 | and | |
276 | .BR /etc/mdadm/mdadm.conf.d . | |
5787fa49 | 277 | If the config file given is |
93e790af | 278 | .B "partitions" |
5787fa49 NB |
279 | then nothing will be read, but |
280 | .I mdadm | |
281 | will act as though the config file contained exactly | |
9dc70cbc N |
282 | .br |
283 | .B " DEVICE partitions containers" | |
284 | .br | |
5787fa49 NB |
285 | and will read |
286 | .B /proc/partitions | |
8fd8d9c4 N |
287 | to find a list of devices to scan, and |
288 | .B /proc/mdstat | |
289 | to find a list of containers to examine. | |
d013a55e | 290 | If the word |
93e790af | 291 | .B "none" |
d013a55e NB |
292 | is given for the config file, then |
293 | .I mdadm | |
294 | will act as though the config file were empty. | |
e0d19036 | 295 | |
9dc70cbc N |
296 | If the name given is of a directory, then |
297 | .I mdadm | |
298 | will collect all the files contained in the directory with a name ending | |
299 | in | |
300 | .BR .conf , | |
301 | sort them lexically, and process all of those files as config files. | |
302 | ||
e0d19036 | 303 | .TP |
7e23fc43 | 304 | .BR \-s ", " \-\-scan |
93e790af | 305 | Scan config file or |
e0d19036 NB |
306 | .B /proc/mdstat |
307 | for missing information. | |
308 | In general, this option gives | |
51ac42e3 | 309 | .I mdadm |
93e790af SW |
310 | permission to get any missing information (like component devices, |
311 | array devices, array identities, and alert destination) from the | |
312 | configuration file (see previous option); | |
313 | one exception is MISC mode when using | |
7e23fc43 | 314 | .B \-\-detail |
e0d19036 | 315 | or |
93e790af | 316 | .B \-\-stop, |
e0d19036 | 317 | in which case |
7e23fc43 | 318 | .B \-\-scan |
e0d19036 NB |
319 | says to get a list of array devices from |
320 | .BR /proc/mdstat . | |
321 | ||
570c0542 | 322 | .TP |
d16c7af6 | 323 | .BR \-e ", " \-\-metadata= |
e0fe762a | 324 | Declare the style of RAID metadata (superblock) to be used. The |
26f467a9 | 325 | default is {DEFAULT_METADATA} for |
7e23fc43 | 326 | .BR \-\-create , |
53e8b987 | 327 | and to guess for other operations. |
2790ffe3 GB |
328 | The default can be overridden by setting the |
329 | .B metadata | |
330 | value for the | |
331 | .B CREATE | |
332 | keyword in | |
333 | .BR mdadm.conf . | |
570c0542 NB |
334 | |
335 | Options are: | |
336 | .RS | |
26f467a9 | 337 | .ie '{DEFAULT_METADATA}'0.90' |
338 | .IP "0, 0.90, default" | |
339 | .el | |
7d5c3964 | 340 | .IP "0, 0.90" |
570c0542 | 341 | Use the original 0.90 format superblock. This format limits arrays to |
93e790af | 342 | 28 component devices and limits component devices of levels 1 and |
cd19c0cf JR |
343 | greater to 2 terabytes. It is also possible for there to be confusion |
344 | about whether the superblock applies to a whole device or just the | |
345 | last partition, if that partition starts on a 64K boundary. | |
26f467a9 | 346 | .ie '{DEFAULT_METADATA}'0.90' |
347 | .IP "1, 1.0, 1.1, 1.2" | |
348 | .el | |
7d5c3964 | 349 | .IP "1, 1.0, 1.1, 1.2 default" |
cd19c0cf JR |
350 | Use the new version-1 format superblock. This has fewer restrictions. |
351 | It can easily be moved between hosts with different endian-ness, and a | |
352 | recovery operation can be checkpointed and restarted. The different | |
353 | sub-versions store the superblock at different locations on the | |
354 | device, either at the end (for 1.0), at the start (for 1.1) or 4K from | |
7050aa3f N |
355 | the start (for 1.2). "1" is equivalent to "1.2" (the commonly |
356 | preferred 1.x format). | |
26f467a9 | 357 | 'if '{DEFAULT_METADATA}'1.2' "default" is equivalent to "1.2". |
8fd8d9c4 | 358 | .IP ddf |
e0fe762a N |
359 | Use the "Industry Standard" DDF (Disk Data Format) format defined by |
360 | SNIA. | |
361 | When creating a DDF array a | |
8fd8d9c4 N |
362 | .B CONTAINER |
363 | will be created, and normal arrays can be created in that container. | |
364 | .IP imsm | |
4cce4069 | 365 | Use the Intel(R) Matrix Storage Manager metadata format. This creates a |
8fd8d9c4 | 366 | .B CONTAINER |
4cce4069 DW |
367 | which is managed in a similar manner to DDF, and is supported by an |
368 | option-rom on some platforms: | |
369 | .IP | |
bcf40dbb | 370 | .B https://www.intel.com/content/www/us/en/support/products/122484/memory-and-storage/ssd-software/intel-virtual-raid-on-cpu-intel-vroc.html |
4cce4069 | 371 | .PP |
570c0542 NB |
372 | .RE |
373 | ||
41a3b72a | 374 | .TP |
7e23fc43 | 375 | .B \-\-homehost= |
35cc5be4 | 376 | This will override any |
41a3b72a | 377 | .B HOMEHOST |
93e790af | 378 | setting in the config file and provides the identity of the host which |
41a3b72a NB |
379 | should be considered the home for any arrays. |
380 | ||
381 | When creating an array, the | |
382 | .B homehost | |
e0fe762a | 383 | will be recorded in the metadata. For version-1 superblocks, it will |
93e790af | 384 | be prefixed to the array name. For version-0.90 superblocks, part of |
41a3b72a NB |
385 | the SHA1 hash of the hostname will be stored in the later half of the |
386 | UUID. | |
387 | ||
388 | When reporting information about an array, any array which is tagged | |
389 | for the given homehost will be reported as such. | |
390 | ||
391 | When using Auto-Assemble, only arrays tagged for the given homehost | |
0ac91628 | 392 | will be allowed to use 'local' names (i.e. not ending in '_' followed |
e0fe762a N |
393 | by a digit string). See below under |
394 | .BR "Auto Assembly" . | |
41a3b72a | 395 | |
49325eac N |
396 | The special name "\fBany\fP" can be used as a wild card. If an array |
397 | is created with | |
398 | .B --homehost=any | |
399 | then the name "\fBany\fP" will be stored in the array and it can be | |
400 | assembled in the same way on any host. If an array is assembled with | |
401 | this option, then the homehost recorded on the array will be ignored. | |
402 | ||
c2ecf5f6 N |
403 | .TP |
404 | .B \-\-prefer= | |
405 | When | |
406 | .I mdadm | |
407 | needs to print the name for a device it normally finds the name in | |
408 | .B /dev | |
409 | which refers to the device and is shortest. When a path component is | |
410 | given with | |
411 | .B \-\-prefer | |
412 | .I mdadm | |
413 | will prefer a longer name if it contains that component. For example | |
414 | .B \-\-prefer=by-uuid | |
415 | will prefer a name in a subdirectory of | |
416 | .B /dev | |
417 | called | |
418 | .BR by-uuid . | |
419 | ||
420 | This functionality is currently only provided by | |
421 | .B \-\-detail | |
422 | and | |
423 | .BR \-\-monitor . | |
424 | ||
7716570e GJ |
425 | .TP |
426 | .B \-\-home\-cluster= | |
427 | specifies the cluster name for the md device. The md device can be assembled | |
428 | only on the cluster which matches the name specified. If this option is not | |
429 | provided, mdadm tries to detect the cluster name automatically. | |
430 | ||
2ae555c3 NB |
431 | .SH For create, build, or grow: |
432 | ||
433 | .TP | |
7e23fc43 | 434 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
435 | Specify the number of active devices in the array. This, plus the |
436 | number of spare devices (see below) must equal the number of | |
437 | .I component-devices | |
438 | (including "\fBmissing\fP" devices) | |
439 | that are listed on the command line for | |
e0fe762a | 440 | .BR \-\-create . |
2ae555c3 NB |
441 | Setting a value of 1 is probably |
442 | a mistake and so requires that | |
7e23fc43 | 443 | .B \-\-force |
2ae555c3 | 444 | be specified first. A value of 1 will then be allowed for linear, |
e0fe762a | 445 | multipath, RAID0 and RAID1. It is never allowed for RAID4, RAID5 or RAID6. |
2ae555c3 NB |
446 | .br |
447 | This number can only be changed using | |
7e23fc43 | 448 | .B \-\-grow |
e0fe762a N |
449 | for RAID1, RAID4, RAID5 and RAID6 arrays, and only on kernels which provide |
450 | the necessary support. | |
2ae555c3 NB |
451 | |
452 | .TP | |
7e23fc43 | 453 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
454 | Specify the number of spare (eXtra) devices in the initial array. |
455 | Spares can also be added | |
456 | and removed later. The number of component devices listed | |
e0fe762a | 457 | on the command line must equal the number of RAID devices plus the |
2ae555c3 NB |
458 | number of spare devices. |
459 | ||
2ae555c3 | 460 | .TP |
7e23fc43 | 461 | .BR \-z ", " \-\-size= |
fea026b4 MK |
462 | Amount (in Kilobytes) of space to use from each drive in RAID levels 1/4/5/6/10 |
463 | and for RAID 0 on external metadata. | |
2ae555c3 NB |
464 | This must be a multiple of the chunk size, and must leave about 128Kb |
465 | of space at the end of the drive for the RAID superblock. | |
466 | If this is not specified | |
467 | (as it normally is not) the smallest drive (or partition) sets the | |
468 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
469 | issued. | |
470 | ||
42e641ab KT |
471 | A suffix of 'K', 'M', 'G' or 'T' can be given to indicate Kilobytes, |
472 | Megabytes, Gigabytes or Terabytes respectively. | |
36fad8ec | 473 | |
9ab6e80a N |
474 | Sometimes a replacement drive can be a little smaller than the |
475 | original drives though this should be minimised by IDEMA standards. | |
476 | Such a replacement drive will be rejected by | |
477 | .IR md . | |
478 | To guard against this it can be useful to set the initial size | |
479 | slightly smaller than the smaller device with the aim that it will | |
480 | still be larger than any replacement. | |
481 | ||
fea026b4 MK |
482 | This option can be used with |
483 | .B \-\-create | |
484 | for determining initial size of an array. For external metadata, | |
485 | it can be used on a volume, but not on a container itself. | |
486 | Setting initial size of | |
487 | .B RAID 0 | |
488 | array is only valid for external metadata. | |
489 | ||
2ae555c3 | 490 | This value can be set with |
7e23fc43 | 491 | .B \-\-grow |
fea026b4 | 492 | for RAID level 1/4/5/6/10 though |
4431efeb | 493 | DDF arrays may not be able to support this. |
fea026b4 | 494 | RAID 0 array size cannot be changed. |
9ab6e80a N |
495 | If the array was created with a size smaller than the currently |
496 | active drives, the extra space can be accessed using | |
7e23fc43 | 497 | .BR \-\-grow . |
2ae555c3 NB |
498 | The size can be given as |
499 | .B max | |
500 | which means to choose the largest size that fits on all current drives. | |
52826846 | 501 | |
c26d78fe N |
502 | Before reducing the size of the array (with |
503 | .BR "\-\-grow \-\-size=" ) | |
504 | you should make sure that space isn't needed. If the device holds a | |
505 | filesystem, you would need to resize the filesystem to use less space. | |
506 | ||
507 | After reducing the array size you should check that the data stored in | |
508 | the device is still available. If the device holds a filesystem, then | |
509 | an 'fsck' of the filesystem is a minimum requirement. If there are | |
510 | problems the array can be made bigger again with no loss with another | |
511 | .B "\-\-grow \-\-size=" | |
512 | command. | |
513 | ||
f24e2d6c | 514 | .TP |
c26d78fe | 515 | .BR \-Z ", " \-\-array\-size= |
f24e2d6c N |
516 | This is only meaningful with |
517 | .B \-\-grow | |
36fad8ec | 518 | and its effect is not persistent: when the array is stopped and |
f24e2d6c N |
519 | restarted the default array size will be restored. |
520 | ||
521 | Setting the array-size causes the array to appear smaller to programs | |
522 | that access the data. This is particularly needed before reshaping an | |
523 | array so that it will be smaller. As the reshape is not reversible, | |
524 | but setting the size with | |
525 | .B \-\-array-size | |
526 | is, it is required that the array size is reduced as appropriate | |
527 | before the number of devices in the array is reduced. | |
528 | ||
c26d78fe N |
529 | Before reducing the size of the array you should make sure that space |
530 | isn't needed. If the device holds a filesystem, you would need to | |
531 | resize the filesystem to use less space. | |
532 | ||
533 | After reducing the array size you should check that the data stored in | |
534 | the device is still available. If the device holds a filesystem, then | |
535 | an 'fsck' of the filesystem is a minimum requirement. If there are | |
536 | problems the array can be made bigger again with no loss with another | |
537 | .B "\-\-grow \-\-array\-size=" | |
538 | command. | |
539 | ||
42e641ab KT |
540 | A suffix of 'K', 'M', 'G' or 'T' can be given to indicate Kilobytes, |
541 | Megabytes, Gigabytes or Terabytes respectively. | |
36fad8ec N |
542 | A value of |
543 | .B max | |
544 | restores the apparent size of the array to be whatever the real | |
545 | amount of available space is. | |
546 | ||
e39c76b9 ZL |
547 | Clustered arrays do not support this parameter yet. |
548 | ||
cd29a5c8 | 549 | .TP |
7e23fc43 | 550 | .BR \-c ", " \-\-chunk= |
95b55f18 | 551 | Specify chunk size of kilobytes. The default when creating an |
5f175898 | 552 | array is 512KB. To ensure compatibility with earlier versions, the |
422da715 | 553 | default when building an array with no persistent metadata is 64KB. |
e0fe762a | 554 | This is only meaningful for RAID0, RAID4, RAID5, RAID6, and RAID10. |
52826846 | 555 | |
a252c078 N |
556 | RAID4, RAID5, RAID6, and RAID10 require the chunk size to be a power |
557 | of 2. In any case it must be a multiple of 4KB. | |
558 | ||
42e641ab KT |
559 | A suffix of 'K', 'M', 'G' or 'T' can be given to indicate Kilobytes, |
560 | Megabytes, Gigabytes or Terabytes respectively. | |
36fad8ec | 561 | |
cd29a5c8 | 562 | .TP |
7e23fc43 | 563 | .BR \-\-rounding= |
e0fe762a N |
564 | Specify rounding factor for a Linear array. The size of each |
565 | component will be rounded down to a multiple of this size. | |
566 | This is a synonym for | |
567 | .B \-\-chunk | |
568 | but highlights the different meaning for Linear as compared to other | |
5f175898 N |
569 | RAID levels. The default is 64K if a kernel earlier than 2.6.16 is in |
570 | use, and is 0K (i.e. no rounding) in later kernels. | |
52826846 | 571 | |
cd29a5c8 | 572 | .TP |
7e23fc43 | 573 | .BR \-l ", " \-\-level= |
e0fe762a | 574 | Set RAID level. When used with |
7e23fc43 | 575 | .BR \-\-create , |
98c6faba | 576 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
8fd8d9c4 N |
577 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container. |
578 | Obviously some of these are synonymous. | |
579 | ||
580 | When a | |
581 | .B CONTAINER | |
582 | metadata type is requested, only the | |
583 | .B container | |
584 | level is permitted, and it does not need to be explicitly given. | |
aa88f531 NB |
585 | |
586 | When used with | |
7e23fc43 | 587 | .BR \-\-build , |
a9d69660 | 588 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 589 | |
fd547b50 N |
590 | Can be used with |
591 | .B \-\-grow | |
592 | to change the RAID level in some cases. See LEVEL CHANGES below. | |
2ae555c3 | 593 | |
cd29a5c8 | 594 | .TP |
7e23fc43 | 595 | .BR \-p ", " \-\-layout= |
f24e2d6c N |
596 | This option configures the fine details of data layout for RAID5, RAID6, |
597 | and RAID10 arrays, and controls the failure modes for | |
1a7dfc35 | 598 | .IR faulty . |
329dfc28 N |
599 | It can also be used for working around a kernel bug with RAID0, but generally |
600 | doesn't need to be used explicitly. | |
1a7dfc35 | 601 | |
e0fe762a | 602 | The layout of the RAID5 parity block can be one of |
7e23fc43 PS |
603 | .BR left\-asymmetric , |
604 | .BR left\-symmetric , | |
605 | .BR right\-asymmetric , | |
606 | .BR right\-symmetric , | |
53e8b987 PS |
607 | .BR la ", " ra ", " ls ", " rs . |
608 | The default is | |
7e23fc43 | 609 | .BR left\-symmetric . |
52826846 | 610 | |
cd19c0cf | 611 | It is also possible to cause RAID5 to use a RAID4-like layout by |
e0fe762a N |
612 | choosing |
613 | .BR parity\-first , | |
614 | or | |
615 | .BR parity\-last . | |
616 | ||
617 | Finally for RAID5 there are DDF\-compatible layouts, | |
618 | .BR ddf\-zero\-restart , | |
619 | .BR ddf\-N\-restart , | |
620 | and | |
621 | .BR ddf\-N\-continue . | |
622 | ||
623 | These same layouts are available for RAID6. There are also 4 layouts | |
624 | that will provide an intermediate stage for converting between RAID5 | |
625 | and RAID6. These provide a layout which is identical to the | |
626 | corresponding RAID5 layout on the first N\-1 devices, and has the 'Q' | |
627 | syndrome (the second 'parity' block used by RAID6) on the last device. | |
628 | These layouts are: | |
629 | .BR left\-symmetric\-6 , | |
630 | .BR right\-symmetric\-6 , | |
631 | .BR left\-asymmetric\-6 , | |
632 | .BR right\-asymmetric\-6 , | |
633 | and | |
10adfe9a | 634 | .BR parity\-first\-6 . |
e0fe762a | 635 | |
93e790af SW |
636 | When setting the failure mode for level |
637 | .I faulty, | |
1a7dfc35 | 638 | the options are: |
7e23fc43 PS |
639 | .BR write\-transient ", " wt , |
640 | .BR read\-transient ", " rt , | |
641 | .BR write\-persistent ", " wp , | |
642 | .BR read\-persistent ", " rp , | |
643 | .BR write\-all , | |
644 | .BR read\-fixable ", " rf , | |
53e8b987 | 645 | .BR clear ", " flush ", " none . |
b5e64645 | 646 | |
93e790af | 647 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
648 | between fault generation. Without a number, the fault is generated |
649 | once on the first relevant request. With a number, the fault will be | |
93e790af | 650 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
651 | every time the period elapses. |
652 | ||
653 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 654 | .B \-\-grow |
53e8b987 | 655 | option to set subsequent failure modes. |
b5e64645 NB |
656 | |
657 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 658 | and "flush" will clear any persistent faults. |
b5e64645 | 659 | |
329dfc28 | 660 | The layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 661 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 662 | |
93e790af | 663 | .I 'n' |
e0fe762a | 664 | signals 'near' copies. Multiple copies of one data block are at |
b578481c NB |
665 | similar offsets in different devices. |
666 | ||
93e790af | 667 | .I 'o' |
b578481c NB |
668 | signals 'offset' copies. Rather than the chunks being duplicated |
669 | within a stripe, whole stripes are duplicated but are rotated by one | |
670 | device so duplicate blocks are on different devices. Thus subsequent | |
671 | copies of a block are in the next drive, and are one chunk further | |
672 | down. | |
673 | ||
93e790af | 674 | .I 'f' |
1a7dfc35 | 675 | signals 'far' copies |
93e790af | 676 | (multiple copies have very different offsets). |
e0fe762a | 677 | See md(4) for more detail about 'near', 'offset', and 'far'. |
1a7dfc35 NB |
678 | |
679 | The number is the number of copies of each datablock. 2 is normal, 3 | |
680 | can be useful. This number can be at most equal to the number of | |
681 | devices in the array. It does not need to divide evenly into that | |
682 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
683 | with an odd number of devices). | |
684 | ||
329dfc28 N |
685 | A bug introduced in Linux 3.14 means that RAID0 arrays |
686 | .B "with devices of differing sizes" | |
687 | started using a different layout. This could lead to | |
688 | data corruption. Since Linux 5.4 (and various stable releases that received | |
689 | backports), the kernel will not accept such an array unless | |
690 | a layout is explictly set. It can be set to | |
691 | .RB ' original ' | |
692 | or | |
693 | .RB ' alternate '. | |
694 | When creating a new array, | |
695 | .I mdadm | |
696 | will select | |
697 | .RB ' original ' | |
698 | by default, so the layout does not normally need to be set. | |
699 | An array created for either | |
700 | .RB ' original ' | |
701 | or | |
702 | .RB ' alternate ' | |
703 | will not be recognized by an (unpatched) kernel prior to 5.4. To create | |
704 | a RAID0 array with devices of differing sizes that can be used on an | |
705 | older kernel, you can set the layout to | |
706 | .RB ' dangerous '. | |
707 | This will use whichever layout the running kernel supports, so the data | |
708 | on the array may become corrupt when changing kernel from pre-3.14 to a | |
709 | later kernel. | |
710 | ||
f24e2d6c N |
711 | When an array is converted between RAID5 and RAID6 an intermediate |
712 | RAID6 layout is used in which the second parity block (Q) is always on | |
713 | the last device. To convert a RAID5 to RAID6 and leave it in this new | |
714 | layout (which does not require re-striping) use | |
715 | .BR \-\-layout=preserve . | |
716 | This will try to avoid any restriping. | |
717 | ||
718 | The converse of this is | |
719 | .B \-\-layout=normalise | |
720 | which will change a non-standard RAID6 layout into a more standard | |
721 | arrangement. | |
722 | ||
cd29a5c8 | 723 | .TP |
7e23fc43 | 724 | .BR \-\-parity= |
53e8b987 | 725 | same as |
7e23fc43 | 726 | .B \-\-layout |
53e8b987 | 727 | (thus explaining the p of |
7e23fc43 | 728 | .BR \-p ). |
52826846 | 729 | |
e793c2e5 | 730 | .TP |
7e23fc43 | 731 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 732 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 733 | exist unless |
7e23fc43 | 734 | .B \-\-force |
53e8b987 | 735 | is also given. The same file should be provided |
2ae555c3 | 736 | when assembling the array. If the word |
93e790af | 737 | .B "internal" |
2ae555c3 NB |
738 | is given, then the bitmap is stored with the metadata on the array, |
739 | and so is replicated on all devices. If the word | |
93e790af | 740 | .B "none" |
2ae555c3 | 741 | is given with |
7e23fc43 | 742 | .B \-\-grow |
95a05b37 GJ |
743 | mode, then any bitmap that is present is removed. If the word |
744 | .B "clustered" | |
745 | is given, the array is created for a clustered environment. One bitmap | |
746 | is created for each node as defined by the | |
747 | .B \-\-nodes | |
748 | parameter and are stored internally. | |
e793c2e5 | 749 | |
2ae555c3 NB |
750 | To help catch typing errors, the filename must contain at least one |
751 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
752 | ||
753 | Note: external bitmaps are only known to work on ext2 and ext3. | |
754 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 755 | |
748952f7 N |
756 | When creating an array on devices which are 100G or larger, |
757 | .I mdadm | |
758 | automatically adds an internal bitmap as it will usually be | |
759 | beneficial. This can be suppressed with | |
5308f117 AP |
760 | .B "\-\-bitmap=none" |
761 | or by selecting a different consistency policy with | |
762 | .BR \-\-consistency\-policy . | |
748952f7 | 763 | |
cd29a5c8 | 764 | .TP |
7e23fc43 | 765 | .BR \-\-bitmap\-chunk= |
e0fe762a | 766 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
767 | Kilobytes of storage. |
768 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 769 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
770 | When using an |
771 | .B internal | |
b8ab2a50 N |
772 | bitmap, the chunksize defaults to 64Meg, or larger if necessary to |
773 | fit the bitmap into the available space. | |
5787fa49 | 774 | |
42e641ab KT |
775 | A suffix of 'K', 'M', 'G' or 'T' can be given to indicate Kilobytes, |
776 | Megabytes, Gigabytes or Terabytes respectively. | |
36fad8ec | 777 | |
cd29a5c8 | 778 | .TP |
7e23fc43 | 779 | .BR \-W ", " \-\-write\-mostly |
e0fe762a | 780 | subsequent devices listed in a |
7e23fc43 PS |
781 | .BR \-\-build , |
782 | .BR \-\-create , | |
2ae555c3 | 783 | or |
7e23fc43 | 784 | .B \-\-add |
71574efb | 785 | command will be flagged as 'write\-mostly'. This is valid for RAID1 |
2ae555c3 NB |
786 | only and means that the 'md' driver will avoid reading from these |
787 | devices if at all possible. This can be useful if mirroring over a | |
788 | slow link. | |
52826846 | 789 | |
2ae555c3 | 790 | .TP |
7e23fc43 | 791 | .BR \-\-write\-behind= |
2ae555c3 | 792 | Specify that write-behind mode should be enabled (valid for RAID1 |
e0fe762a N |
793 | only). If an argument is specified, it will set the maximum number |
794 | of outstanding writes allowed. The default value is 256. | |
2ae555c3 NB |
795 | A write-intent bitmap is required in order to use write-behind |
796 | mode, and write-behind is only attempted on drives marked as | |
797 | .IR write-mostly . | |
dd0781e5 | 798 | |
71574efb N |
799 | .TP |
800 | .BR \-\-failfast | |
801 | subsequent devices listed in a | |
802 | .B \-\-create | |
803 | or | |
804 | .B \-\-add | |
805 | command will be flagged as 'failfast'. This is valid for RAID1 and | |
806 | RAID10 only. IO requests to these devices will be encouraged to fail | |
807 | quickly rather than cause long delays due to error handling. Also no | |
808 | attempt is made to repair a read error on these devices. | |
809 | ||
810 | If an array becomes degraded so that the 'failfast' device is the only | |
811 | usable device, the 'failfast' flag will then be ignored and extended | |
812 | delays will be preferred to complete failure. | |
813 | ||
814 | The 'failfast' flag is appropriate for storage arrays which have a | |
815 | low probability of true failure, but which may sometimes | |
816 | cause unacceptable delays due to internal maintenance functions. | |
817 | ||
dd0781e5 | 818 | .TP |
7e23fc43 | 819 | .BR \-\-assume\-clean |
dd0781e5 NB |
820 | Tell |
821 | .I mdadm | |
47d79ef8 NB |
822 | that the array pre-existed and is known to be clean. It can be useful |
823 | when trying to recover from a major failure as you can be sure that no | |
824 | data will be affected unless you actually write to the array. It can | |
825 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 826 | initial resync, however this practice \(em while normally safe \(em is not |
e0fe762a | 827 | recommended. Use this only if you really know what you are doing. |
6acad481 ME |
828 | .IP |
829 | When the devices that will be part of a new array were filled | |
830 | with zeros before creation the operator knows the array is | |
831 | actually clean. If that is the case, such as after running | |
832 | badblocks, this argument can be used to tell mdadm the | |
833 | facts the operator knows. | |
ce52f92f N |
834 | .IP |
835 | When an array is resized to a larger size with | |
836 | .B "\-\-grow \-\-size=" | |
837 | the new space is normally resynced in that same way that the whole | |
6cbf8fb8 | 838 | array is resynced at creation. From Linux version 3.0, |
ce52f92f N |
839 | .B \-\-assume\-clean |
840 | can be used with that command to avoid the automatic resync. | |
dd0781e5 | 841 | |
2ae555c3 | 842 | .TP |
7e23fc43 | 843 | .BR \-\-backup\-file= |
53e8b987 | 844 | This is needed when |
7e23fc43 | 845 | .B \-\-grow |
cd19c0cf JR |
846 | is used to increase the number of raid-devices in a RAID5 or RAID6 if |
847 | there are no spare devices available, or to shrink, change RAID level | |
848 | or layout. See the GROW MODE section below on RAID\-DEVICES CHANGES. | |
849 | The file must be stored on a separate device, not on the RAID array | |
850 | being reshaped. | |
2ae555c3 | 851 | |
40c9a66a N |
852 | .TP |
853 | .B \-\-data\-offset= | |
854 | Arrays with 1.x metadata can leave a gap between the start of the | |
855 | device and the start of array data. This gap can be used for various | |
856 | metadata. The start of data is known as the | |
857 | .IR data\-offset . | |
858 | Normally an appropriate data offset is computed automatically. | |
859 | However it can be useful to set it explicitly such as when re-creating | |
860 | an array which was originally created using a different version of | |
861 | .I mdadm | |
862 | which computed a different offset. | |
863 | ||
864 | Setting the offset explicitly over-rides the default. The value given | |
42e641ab KT |
865 | is in Kilobytes unless a suffix of 'K', 'M', 'G' or 'T' is used to explicitly |
866 | indicate Kilobytes, Megabytes, Gigabytes or Terabytes respectively. | |
40c9a66a N |
867 | |
868 | Since Linux 3.4, | |
869 | .B \-\-data\-offset | |
870 | can also be used with | |
871 | .B --grow | |
872 | for some RAID levels (initially on RAID10). This allows the | |
72ca9bcf | 873 | data\-offset to be changed as part of the reshape process. When the |
40c9a66a N |
874 | data offset is changed, no backup file is required as the difference |
875 | in offsets is used to provide the same functionality. | |
876 | ||
877 | When the new offset is earlier than the old offset, the number of | |
878 | devices in the array cannot shrink. When it is after the old offset, | |
879 | the number of devices in the array cannot increase. | |
880 | ||
72ca9bcf N |
881 | When creating an array, |
882 | .B \-\-data\-offset | |
883 | can be specified as | |
884 | .BR variable . | |
885 | In the case each member device is expected to have a offset appended | |
886 | to the name, separated by a colon. This makes it possible to recreate | |
887 | exactly an array which has varying data offsets (as can happen when | |
888 | different versions of | |
889 | .I mdadm | |
890 | are used to add different devices). | |
891 | ||
f211a137 AK |
892 | .TP |
893 | .BR \-\-continue | |
894 | This option is complementary to the | |
895 | .B \-\-freeze-reshape | |
896 | option for assembly. It is needed when | |
897 | .B \-\-grow | |
898 | operation is interrupted and it is not restarted automatically due to | |
899 | .B \-\-freeze-reshape | |
900 | usage during array assembly. This option is used together with | |
901 | .BR \-G | |
902 | , ( | |
903 | .BR \-\-grow | |
904 | ) command and device for a pending reshape to be continued. | |
905 | All parameters required for reshape continuation will be read from array metadata. | |
906 | If initial | |
907 | .BR \-\-grow | |
908 | command had required | |
909 | .BR \-\-backup\-file= | |
910 | option to be set, continuation option will require to have exactly the same | |
911 | backup file given as well. | |
912 | .IP | |
913 | Any other parameter passed together with | |
914 | .BR \-\-continue | |
915 | option will be ignored. | |
916 | ||
947fd4dd | 917 | .TP |
7e23fc43 | 918 | .BR \-N ", " \-\-name= |
947fd4dd NB |
919 | Set a |
920 | .B name | |
921 | for the array. This is currently only effective when creating an | |
e0fe762a N |
922 | array with a version-1 superblock, or an array in a DDF container. |
923 | The name is a simple textual string that can be used to identify array | |
924 | components when assembling. If name is needed but not specified, it | |
925 | is taken from the basename of the device that is being created. | |
926 | e.g. when creating | |
927 | .I /dev/md/home | |
928 | the | |
929 | .B name | |
930 | will default to | |
931 | .IR home . | |
947fd4dd | 932 | |
dd0781e5 | 933 | .TP |
7e23fc43 | 934 | .BR \-R ", " \-\-run |
dd0781e5 NB |
935 | Insist that |
936 | .I mdadm | |
937 | run the array, even if some of the components | |
938 | appear to be active in another array or filesystem. Normally | |
939 | .I mdadm | |
940 | will ask for confirmation before including such components in an | |
941 | array. This option causes that question to be suppressed. | |
942 | ||
943 | .TP | |
7e23fc43 | 944 | .BR \-f ", " \-\-force |
dd0781e5 NB |
945 | Insist that |
946 | .I mdadm | |
947 | accept the geometry and layout specified without question. Normally | |
948 | .I mdadm | |
949 | will not allow creation of an array with only one device, and will try | |
e0fe762a | 950 | to create a RAID5 array with one missing drive (as this makes the |
dd0781e5 | 951 | initial resync work faster). With |
7e23fc43 | 952 | .BR \-\-force , |
dd0781e5 NB |
953 | .I mdadm |
954 | will not try to be so clever. | |
955 | ||
0ea8f5b1 N |
956 | .TP |
957 | .BR \-o ", " \-\-readonly | |
958 | Start the array | |
959 | .B read only | |
960 | rather than read-write as normal. No writes will be allowed to the | |
8a70632f ZL |
961 | array, and no resync, recovery, or reshape will be started. It works with |
962 | Create, Assemble, Manage and Misc mode. | |
0ea8f5b1 | 963 | |
dd0781e5 | 964 | .TP |
257c1dc2 N |
965 | .BR \-a ", " "\-\-auto{=yes,md,mdp,part,p}{NN}" |
966 | Instruct mdadm how to create the device file if needed, possibly allocating | |
48f7b27a | 967 | an unused minor number. "md" causes a non-partitionable array |
257c1dc2 N |
968 | to be used (though since Linux 2.6.28, these array devices are in fact |
969 | partitionable). "mdp", "part" or "p" causes a partitionable array (2.6 and | |
2ae555c3 | 970 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 971 | a 'standard' format, and the type and minor number will be determined |
257c1dc2 N |
972 | from this. With mdadm 3.0, device creation is normally left up to |
973 | .I udev | |
974 | so this option is unlikely to be needed. | |
975 | See DEVICE NAMES below. | |
48f7b27a | 976 | |
a9d69660 | 977 | The argument can also come immediately after |
7e23fc43 | 978 | "\-a". e.g. "\-ap". |
dd0781e5 | 979 | |
53e8b987 | 980 | If |
7e23fc43 | 981 | .B \-\-auto |
53e8b987 | 982 | is not given on the command line or in the config file, then |
75723446 | 983 | the default will be |
7e23fc43 | 984 | .BR \-\-auto=yes . |
75723446 | 985 | |
1337546d | 986 | If |
7e23fc43 | 987 | .B \-\-scan |
1337546d NB |
988 | is also given, then any |
989 | .I auto= | |
35cc5be4 | 990 | entries in the config file will override the |
7e23fc43 | 991 | .B \-\-auto |
1337546d NB |
992 | instruction given on the command line. |
993 | ||
dd0781e5 NB |
994 | For partitionable arrays, |
995 | .I mdadm | |
996 | will create the device file for the whole array and for the first 4 | |
997 | partitions. A different number of partitions can be specified at the | |
998 | end of this option (e.g. | |
7e23fc43 | 999 | .BR \-\-auto=p7 ). |
2ae555c3 | 1000 | If the device name ends with a digit, the partition names add a 'p', |
e0fe762a N |
1001 | and a number, e.g. |
1002 | .IR /dev/md/home1p3 . | |
1003 | If there is no trailing digit, then the partition names just have a | |
1004 | number added, e.g. | |
1005 | .IR /dev/md/scratch3 . | |
dd0781e5 | 1006 | |
48f7b27a NB |
1007 | If the md device name is in a 'standard' format as described in DEVICE |
1008 | NAMES, then it will be created, if necessary, with the appropriate | |
e0fe762a N |
1009 | device number based on that name. If the device name is not in one of these |
1010 | formats, then a unused device number will be allocated. The device | |
48f7b27a NB |
1011 | number will be considered unused if there is no active array for that |
1012 | number, and there is no entry in /dev for that number and with a | |
e0fe762a | 1013 | non-standard name. Names that are not in 'standard' format are only |
8fd8d9c4 N |
1014 | allowed in "/dev/md/". |
1015 | ||
3c7efacb NK |
1016 | This is meaningful with |
1017 | .B \-\-create | |
1018 | or | |
1019 | .BR \-\-build . | |
1020 | ||
3c7efacb NK |
1021 | .TP |
1022 | .BR \-a ", " "\-\-add" | |
1023 | This option can be used in Grow mode in two cases. | |
1024 | ||
1025 | If the target array is a Linear array, then | |
1026 | .B \-\-add | |
1027 | can be used to add one or more devices to the array. They | |
1028 | are simply catenated on to the end of the array. Once added, the | |
1029 | devices cannot be removed. | |
1030 | ||
1031 | If the | |
1032 | .B \-\-raid\-disks | |
1033 | option is being used to increase the number of devices in an array, | |
1034 | then | |
1035 | .B \-\-add | |
1036 | can be used to add some extra devices to be included in the array. | |
1037 | In most cases this is not needed as the extra devices can be added as | |
1038 | spares first, and then the number of raid-disks can be changed. | |
1039 | However for RAID0, it is not possible to add spares. So to increase | |
1040 | the number of devices in a RAID0, it is necessary to set the new | |
1041 | number of devices, and to add the new devices, in the same command. | |
1042 | ||
529e2aa5 GJ |
1043 | .TP |
1044 | .BR \-\-nodes | |
1045 | Only works when the array is for clustered environment. It specifies | |
1046 | the maximum number of nodes in the cluster that will use this device | |
1047 | simultaneously. If not specified, this defaults to 4. | |
1048 | ||
28d74446 SL |
1049 | .TP |
1050 | .BR \-\-write-journal | |
1051 | Specify journal device for the RAID-4/5/6 array. The journal device | |
1052 | should be a SSD with reasonable lifetime. | |
1053 | ||
d64c2283 ZL |
1054 | .TP |
1055 | .BR \-\-symlinks | |
1056 | Auto creation of symlinks in /dev to /dev/md, option --symlinks must | |
1057 | be 'no' or 'yes' and work with --create and --build. | |
1058 | ||
5308f117 AP |
1059 | .TP |
1060 | .BR \-k ", " \-\-consistency\-policy= | |
1061 | Specify how the array maintains consistency in case of unexpected shutdown. | |
1062 | Only relevant for RAID levels with redundancy. | |
1063 | Currently supported options are: | |
1064 | .RS | |
1065 | ||
1066 | .TP | |
1067 | .B resync | |
1068 | Full resync is performed and all redundancy is regenerated when the array is | |
1069 | started after unclean shutdown. | |
1070 | ||
1071 | .TP | |
1072 | .B bitmap | |
1073 | Resync assisted by a write-intent bitmap. Implicitly selected when using | |
1074 | .BR \-\-bitmap . | |
1075 | ||
1076 | .TP | |
1077 | .B journal | |
1078 | For RAID levels 4/5/6, journal device is used to log transactions and replay | |
1079 | after unclean shutdown. Implicitly selected when using | |
1080 | .BR \-\-write\-journal . | |
1081 | ||
1082 | .TP | |
1083 | .B ppl | |
1084 | For RAID5 only, Partial Parity Log is used to close the write hole and | |
1085 | eliminate resync. PPL is stored in the metadata region of RAID member drives, | |
1086 | no additional journal drive is needed. | |
860f11ed AP |
1087 | |
1088 | .PP | |
1089 | Can be used with \-\-grow to change the consistency policy of an active array | |
1090 | in some cases. See CONSISTENCY POLICY CHANGES below. | |
5308f117 AP |
1091 | .RE |
1092 | ||
28d74446 | 1093 | |
52826846 NB |
1094 | .SH For assemble: |
1095 | ||
cd29a5c8 | 1096 | .TP |
7e23fc43 | 1097 | .BR \-u ", " \-\-uuid= |
e0fe762a | 1098 | uuid of array to assemble. Devices which don't have this uuid are |
cd29a5c8 NB |
1099 | excluded |
1100 | ||
1101 | .TP | |
7e23fc43 | 1102 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
1103 | Minor number of device that array was created for. Devices which |
1104 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 1105 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
1106 | the array is later assembled as /dev/md2. |
1107 | ||
d013a55e | 1108 | Giving the literal word "dev" for |
7e23fc43 | 1109 | .B \-\-super\-minor |
d013a55e NB |
1110 | will cause |
1111 | .I mdadm | |
1112 | to use the minor number of the md device that is being assembled. | |
1113 | e.g. when assembling | |
1114 | .BR /dev/md0 , | |
51ac42e3 | 1115 | .B \-\-super\-minor=dev |
d013a55e NB |
1116 | will look for super blocks with a minor number of 0. |
1117 | ||
e0fe762a N |
1118 | .B \-\-super\-minor |
1119 | is only relevant for v0.90 metadata, and should not normally be used. | |
1120 | Using | |
1121 | .B \-\-uuid | |
1122 | is much safer. | |
1123 | ||
947fd4dd | 1124 | .TP |
7e23fc43 | 1125 | .BR \-N ", " \-\-name= |
947fd4dd | 1126 | Specify the name of the array to assemble. This must be the name |
624920bb | 1127 | that was specified when creating the array. It must either match |
93e790af | 1128 | the name stored in the superblock exactly, or it must match |
41a3b72a | 1129 | with the current |
624920bb | 1130 | .I homehost |
93e790af | 1131 | prefixed to the start of the given name. |
947fd4dd | 1132 | |
cd29a5c8 | 1133 | .TP |
7e23fc43 | 1134 | .BR \-f ", " \-\-force |
e0fe762a N |
1135 | Assemble the array even if the metadata on some devices appears to be |
1136 | out-of-date. If | |
1137 | .I mdadm | |
1138 | cannot find enough working devices to start the array, but can find | |
1139 | some devices that are recorded as having failed, then it will mark | |
92a647c8 MT |
1140 | those devices as working so that the array can be started. This works only for |
1141 | native. For external metadata it allows to start dirty degraded RAID 4, 5, 6. | |
e0fe762a N |
1142 | An array which requires |
1143 | .B \-\-force | |
1144 | to be started may contain data corruption. Use it carefully. | |
52826846 | 1145 | |
cd29a5c8 | 1146 | .TP |
7e23fc43 | 1147 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
1148 | Attempt to start the array even if fewer drives were given than were |
1149 | present last time the array was active. Normally if not all the | |
1150 | expected drives are found and | |
7e23fc43 | 1151 | .B \-\-scan |
cd29a5c8 NB |
1152 | is not used, then the array will be assembled but not started. |
1153 | With | |
7e23fc43 | 1154 | .B \-\-run |
cd29a5c8 | 1155 | an attempt will be made to start it anyway. |
52826846 | 1156 | |
b8a8ccf9 | 1157 | .TP |
7e23fc43 | 1158 | .B \-\-no\-degraded |
b8a8ccf9 | 1159 | This is the reverse of |
7e23fc43 | 1160 | .B \-\-run |
93e790af | 1161 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 1162 | are present. This is only needed with |
93e790af SW |
1163 | .B \-\-scan, |
1164 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
1165 | not as reliable as you would like. |
1166 | ||
dd0781e5 | 1167 | .TP |
7e23fc43 | 1168 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
1169 | See this option under Create and Build options. |
1170 | ||
e793c2e5 | 1171 | .TP |
7e23fc43 | 1172 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
1173 | Specify the bitmap file that was given when the array was created. If |
1174 | an array has an | |
1175 | .B internal | |
1176 | bitmap, there is no need to specify this when assembling the array. | |
1177 | ||
1178 | .TP | |
7e23fc43 | 1179 | .BR \-\-backup\-file= |
2ae555c3 | 1180 | If |
7e23fc43 | 1181 | .B \-\-backup\-file |
87f26d14 N |
1182 | was used while reshaping an array (e.g. changing number of devices or |
1183 | chunk size) and the system crashed during the critical section, then the same | |
7e23fc43 | 1184 | .B \-\-backup\-file |
53e8b987 | 1185 | must be presented to |
7e23fc43 | 1186 | .B \-\-assemble |
cd19c0cf JR |
1187 | to allow possibly corrupted data to be restored, and the reshape |
1188 | to be completed. | |
e793c2e5 | 1189 | |
87f26d14 N |
1190 | .TP |
1191 | .BR \-\-invalid\-backup | |
1192 | If the file needed for the above option is not available for any | |
1193 | reason an empty file can be given together with this option to | |
1194 | indicate that the backup file is invalid. In this case the data that | |
1195 | was being rearranged at the time of the crash could be irrecoverably | |
1196 | lost, but the rest of the array may still be recoverable. This option | |
1197 | should only be used as a last resort if there is no way to recover the | |
1198 | backup file. | |
1199 | ||
1200 | ||
5787fa49 | 1201 | .TP |
7e23fc43 | 1202 | .BR \-U ", " \-\-update= |
5787fa49 | 1203 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
1204 | argument given to this flag can be one of |
1205 | .BR sparc2.2 , | |
1206 | .BR summaries , | |
7d99579f | 1207 | .BR uuid , |
c4f12c13 | 1208 | .BR name , |
7e6e839a | 1209 | .BR nodes , |
0237e0ca | 1210 | .BR homehost , |
0aa2f15b | 1211 | .BR home-cluster , |
e5329c37 | 1212 | .BR resync , |
586ed405 | 1213 | .BR byteorder , |
bee8ec56 | 1214 | .BR devicesize , |
5a31170d | 1215 | .BR no\-bitmap , |
688e99a7 | 1216 | .BR bbl , |
47120ad5 | 1217 | .BR no\-bbl , |
e6e9dd3f AP |
1218 | .BR ppl , |
1219 | .BR no\-ppl , | |
027c099f N |
1220 | .BR layout\-original , |
1221 | .BR layout\-alternate , | |
97b51a2c | 1222 | .BR layout\-unspecified , |
afa368f4 | 1223 | .BR metadata , |
5787fa49 | 1224 | or |
7e23fc43 | 1225 | .BR super\-minor . |
5787fa49 NB |
1226 | |
1227 | The | |
1228 | .B sparc2.2 | |
7d99579f | 1229 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
1230 | machine running a patched 2.2 Linux kernel. This kernel got the |
1231 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 1232 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
1233 | option to |
1234 | .I mdadm | |
1235 | to see what effect this would have. | |
1236 | ||
1237 | The | |
7e23fc43 | 1238 | .B super\-minor |
5787fa49 | 1239 | option will update the |
2ae555c3 | 1240 | .B "preferred minor" |
5787fa49 | 1241 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
1242 | assembled. |
1243 | This can be useful if | |
7e23fc43 | 1244 | .B \-\-examine |
45c073c9 | 1245 | reports a different "Preferred Minor" to |
7e23fc43 | 1246 | .BR \-\-detail . |
45c073c9 | 1247 | In some cases this update will be performed automatically |
e0fe762a | 1248 | by the kernel driver. In particular the update happens automatically |
45c073c9 NB |
1249 | at the first write to an array with redundancy (RAID level 1 or |
1250 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 1251 | |
7d99579f NB |
1252 | The |
1253 | .B uuid | |
1254 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 1255 | .B \-\-uuid |
53e8b987 | 1256 | option that UUID will be used as a new UUID and will |
7d99579f NB |
1257 | .B NOT |
1258 | be used to help identify the devices in the array. | |
53e8b987 | 1259 | If no |
7e23fc43 | 1260 | .B \-\-uuid |
53e8b987 | 1261 | is given, a random UUID is chosen. |
7d99579f | 1262 | |
c4f12c13 NB |
1263 | The |
1264 | .B name | |
1265 | option will change the | |
1266 | .I name | |
b3774a48 GJ |
1267 | of the array as stored in the superblock. This is only supported for |
1268 | version-1 superblocks. | |
7e6e839a GJ |
1269 | |
1270 | The | |
1271 | .B nodes | |
1272 | option will change the | |
1273 | .I nodes | |
b3774a48 GJ |
1274 | of the array as stored in the bitmap superblock. This option only |
1275 | works for a clustered environment. | |
c4f12c13 | 1276 | |
0237e0ca NB |
1277 | The |
1278 | .B homehost | |
1279 | option will change the | |
1280 | .I homehost | |
1281 | as recorded in the superblock. For version-0 superblocks, this is the | |
1282 | same as updating the UUID. | |
1283 | For version-1 superblocks, this involves updating the name. | |
1284 | ||
0aa2f15b GJ |
1285 | The |
1286 | .B home\-cluster | |
1287 | option will change the cluster name as recorded in the superblock and | |
1288 | bitmap. This option only works for clustered environment. | |
1289 | ||
e5329c37 NB |
1290 | The |
1291 | .B resync | |
1292 | option will cause the array to be marked | |
1293 | .I dirty | |
e0fe762a N |
1294 | meaning that any redundancy in the array (e.g. parity for RAID5, |
1295 | copies for RAID1) may be incorrect. This will cause the RAID system | |
e5329c37 NB |
1296 | to perform a "resync" pass to make sure that all redundant information |
1297 | is correct. | |
1298 | ||
586ed405 NB |
1299 | The |
1300 | .B byteorder | |
1301 | option allows arrays to be moved between machines with different | |
4224685f N |
1302 | byte-order, such as from a big-endian machine like a Sparc or some |
1303 | MIPS machines, to a little-endian x86_64 machine. | |
2ae555c3 | 1304 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 1305 | .B "\-\-update=byteorder" |
586ed405 NB |
1306 | will cause |
1307 | .I mdadm | |
1308 | to expect superblocks to have their byteorder reversed, and will | |
1309 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 1310 | with original (Version 0.90) superblocks. |
586ed405 | 1311 | |
feb716e9 NB |
1312 | The |
1313 | .B summaries | |
e0fe762a | 1314 | option will correct the summaries in the superblock. That is the |
feb716e9 | 1315 | counts of total, working, active, failed, and spare devices. |
5787fa49 | 1316 | |
bee8ec56 NB |
1317 | The |
1318 | .B devicesize | |
5a31170d | 1319 | option will rarely be of use. It applies to version 1.1 and 1.2 metadata |
bee8ec56 NB |
1320 | only (where the metadata is at the start of the device) and is only |
1321 | useful when the component device has changed size (typically become | |
1322 | larger). The version 1 metadata records the amount of the device that | |
1323 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
1324 | array becomes larger, the metadata will still be visible, but the | |
1325 | extra space will not. In this case it might be useful to assemble the | |
1326 | array with | |
7e23fc43 | 1327 | .BR \-\-update=devicesize . |
bee8ec56 NB |
1328 | This will cause |
1329 | .I mdadm | |
1330 | to determine the maximum usable amount of space on each device and | |
1331 | update the relevant field in the metadata. | |
1332 | ||
afa368f4 N |
1333 | The |
1334 | .B metadata | |
1335 | option only works on v0.90 metadata arrays and will convert them to | |
1336 | v1.0 metadata. The array must not be dirty (i.e. it must not need a | |
1337 | sync) and it must not have a write-intent bitmap. | |
1338 | ||
1339 | The old metadata will remain on the devices, but will appear older | |
1340 | than the new metadata and so will usually be ignored. The old metadata | |
1341 | (or indeed the new metadata) can be removed by giving the appropriate | |
1342 | .B \-\-metadata= | |
1343 | option to | |
1344 | .BR \-\-zero\-superblock . | |
1345 | ||
5a31170d N |
1346 | The |
1347 | .B no\-bitmap | |
1348 | option can be used when an array has an internal bitmap which is | |
1349 | corrupt in some way so that assembling the array normally fails. It | |
1350 | will cause any internal bitmap to be ignored. | |
1351 | ||
688e99a7 N |
1352 | The |
1353 | .B bbl | |
1354 | option will reserve space in each device for a bad block list. This | |
1355 | will be 4K in size and positioned near the end of any free space | |
1356 | between the superblock and the data. | |
1357 | ||
1358 | The | |
1359 | .B no\-bbl | |
1360 | option will cause any reservation of space for a bad block list to be | |
1361 | removed. If the bad block list contains entries, this will fail, as | |
1362 | removing the list could cause data corruption. | |
1363 | ||
e6e9dd3f AP |
1364 | The |
1365 | .B ppl | |
1366 | option will enable PPL for a RAID5 array and reserve space for PPL on each | |
1367 | device. There must be enough free space between the data and superblock and a | |
1368 | write-intent bitmap or journal must not be used. | |
1369 | ||
1370 | The | |
1371 | .B no\-ppl | |
1372 | option will disable PPL in the superblock. | |
1373 | ||
027c099f N |
1374 | The |
1375 | .B layout\-original | |
1376 | and | |
1377 | .B layout\-alternate | |
97b51a2c N |
1378 | options are for RAID0 arrays with non-uniform devices size that were in |
1379 | use before Linux 5.4. If the array was being used with Linux 3.13 or | |
1380 | earlier, then to assemble the array on a new kernel, | |
027c099f N |
1381 | .B \-\-update=layout\-original |
1382 | must be given. If the array was created and used with a kernel from Linux 3.14 to | |
1383 | Linux 5.3, then | |
1384 | .B \-\-update=layout\-alternate | |
1385 | must be given. This only needs to be given once. Subsequent assembly of the array | |
1386 | will happen normally. | |
1387 | For more information, see | |
1388 | .IR md (4). | |
1389 | ||
97b51a2c N |
1390 | The |
1391 | .B layout\-unspecified | |
1392 | option reverts the effect of | |
1393 | .B layout\-orignal | |
1394 | or | |
1395 | .B layout\-alternate | |
1396 | and allows the array to be again used on a kernel prior to Linux 5.3. | |
1397 | This option should be used with great caution. | |
1398 | ||
afd0a969 AK |
1399 | .TP |
1400 | .BR \-\-freeze\-reshape | |
1401 | Option is intended to be used in start-up scripts during initrd boot phase. | |
1402 | When array under reshape is assembled during initrd phase, this option | |
1403 | stops reshape after reshape critical section is being restored. This happens | |
1404 | before file system pivot operation and avoids loss of file system context. | |
1405 | Losing file system context would cause reshape to be broken. | |
1406 | ||
a6482415 N |
1407 | Reshape can be continued later using the |
1408 | .B \-\-continue | |
1409 | option for the grow command. | |
afd0a969 | 1410 | |
d64c2283 ZL |
1411 | .TP |
1412 | .BR \-\-symlinks | |
1413 | See this option under Create and Build options. | |
1414 | ||
e0d19036 | 1415 | .SH For Manage mode: |
52826846 | 1416 | |
3d5279b0 N |
1417 | .TP |
1418 | .BR \-t ", " \-\-test | |
1419 | Unless a more serious error occurred, | |
1420 | .I mdadm | |
1421 | will exit with a status of 2 if no changes were made to the array and | |
1422 | 0 if at least one change was made. | |
1423 | This can be useful when an indirect specifier such as | |
1424 | .BR missing , | |
1425 | .B detached | |
1426 | or | |
1427 | .B faulty | |
1428 | is used in requesting an operation on the array. | |
1429 | .B \-\-test | |
1430 | will report failure if these specifiers didn't find any match. | |
1431 | ||
cd29a5c8 | 1432 | .TP |
7e23fc43 | 1433 | .BR \-a ", " \-\-add |
3d5279b0 N |
1434 | hot-add listed devices. |
1435 | If a device appears to have recently been part of the array | |
342460cb | 1436 | (possibly it failed or was removed) the device is re\-added as described |
3d5279b0 N |
1437 | in the next point. |
1438 | If that fails or the device was never part of the array, the device is | |
1439 | added as a hot-spare. | |
1440 | If the array is degraded, it will immediately start to rebuild data | |
1441 | onto that spare. | |
1442 | ||
1443 | Note that this and the following options are only meaningful on array | |
1444 | with redundancy. They don't apply to RAID0 or Linear. | |
52826846 | 1445 | |
fe80f49b | 1446 | .TP |
7e23fc43 | 1447 | .BR \-\-re\-add |
eae6b036 | 1448 | re\-add a device that was previously removed from an array. |
3d5279b0 N |
1449 | If the metadata on the device reports that it is a member of the |
1450 | array, and the slot that it used is still vacant, then the device will | |
1451 | be added back to the array in the same position. This will normally | |
1452 | cause the data for that device to be recovered. However based on the | |
1453 | event count on the device, the recovery may only require sections that | |
1454 | are flagged a write-intent bitmap to be recovered or may not require | |
1455 | any recovery at all. | |
1456 | ||
1457 | When used on an array that has no metadata (i.e. it was built with | |
1458 | .BR \-\-build) | |
1459 | it will be assumed that bitmap-based recovery is enough to make the | |
1460 | device fully consistent with the array. | |
fe80f49b | 1461 | |
688e99a7 | 1462 | When used with v1.x metadata, |
833bb0f8 N |
1463 | .B \-\-re\-add |
1464 | can be accompanied by | |
688e99a7 N |
1465 | .BR \-\-update=devicesize , |
1466 | .BR \-\-update=bbl ", or" | |
1467 | .BR \-\-update=no\-bbl . | |
1468 | See the description of these option when used in Assemble mode for an | |
1469 | explanation of their use. | |
833bb0f8 | 1470 | |
a4e13010 N |
1471 | If the device name given is |
1472 | .B missing | |
262e3b7f N |
1473 | then |
1474 | .I mdadm | |
1475 | will try to find any device that looks like it should be | |
a4e13010 N |
1476 | part of the array but isn't and will try to re\-add all such devices. |
1477 | ||
262e3b7f N |
1478 | If the device name given is |
1479 | .B faulty | |
1480 | then | |
1481 | .I mdadm | |
1482 | will find all devices in the array that are marked | |
1483 | .BR faulty , | |
1484 | remove them and attempt to immediately re\-add them. This can be | |
1485 | useful if you are certain that the reason for failure has been | |
1486 | resolved. | |
1487 | ||
f33a71f1 N |
1488 | .TP |
1489 | .B \-\-add\-spare | |
1490 | Add a device as a spare. This is similar to | |
1491 | .B \-\-add | |
1492 | except that it does not attempt | |
1493 | .B \-\-re\-add | |
1494 | first. The device will be added as a spare even if it looks like it | |
1495 | could be an recent member of the array. | |
1496 | ||
cd29a5c8 | 1497 | .TP |
7e23fc43 | 1498 | .BR \-r ", " \-\-remove |
2d465520 | 1499 | remove listed devices. They must not be active. i.e. they should |
64a78416 N |
1500 | be failed or spare devices. |
1501 | ||
1502 | As well as the name of a device file | |
b80da661 NB |
1503 | (e.g. |
1504 | .BR /dev/sda1 ) | |
1505 | the words | |
64a78416 | 1506 | .BR failed , |
b80da661 | 1507 | .B detached |
64a78416 N |
1508 | and names like |
1509 | .B set-A | |
b80da661 NB |
1510 | can be given to |
1511 | .BR \-\-remove . | |
1512 | The first causes all failed device to be removed. The second causes | |
93e790af | 1513 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
1514 | returns |
1515 | .BR ENXIO ) | |
64a78416 N |
1516 | to be removed. |
1517 | The third will remove a set as describe below under | |
1518 | .BR \-\-fail . | |
52826846 | 1519 | |
cd29a5c8 | 1520 | .TP |
7e23fc43 | 1521 | .BR \-f ", " \-\-fail |
70c55e36 | 1522 | Mark listed devices as faulty. |
b80da661 NB |
1523 | As well as the name of a device file, the word |
1524 | .B detached | |
64a78416 N |
1525 | or a set name like |
1526 | .B set\-A | |
1527 | can be given. The former will cause any device that has been detached from | |
b80da661 | 1528 | the system to be marked as failed. It can then be removed. |
52826846 | 1529 | |
64a78416 N |
1530 | For RAID10 arrays where the number of copies evenly divides the number |
1531 | of devices, the devices can be conceptually divided into sets where | |
1532 | each set contains a single complete copy of the data on the array. | |
1533 | Sometimes a RAID10 array will be configured so that these sets are on | |
1534 | separate controllers. In this case all the devices in one set can be | |
1535 | failed by giving a name like | |
1536 | .B set\-A | |
1537 | or | |
1538 | .B set\-B | |
1539 | to | |
1540 | .BR \-\-fail . | |
1541 | The appropriate set names are reported by | |
1542 | .BR \-\-detail . | |
1543 | ||
cd29a5c8 | 1544 | .TP |
7e23fc43 | 1545 | .BR \-\-set\-faulty |
53e8b987 | 1546 | same as |
7e23fc43 | 1547 | .BR \-\-fail . |
52826846 | 1548 | |
70c55e36 N |
1549 | .TP |
1550 | .B \-\-replace | |
1551 | Mark listed devices as requiring replacement. As soon as a spare is | |
1552 | available, it will be rebuilt and will replace the marked device. | |
1553 | This is similar to marking a device as faulty, but the device remains | |
1554 | in service during the recovery process to increase resilience against | |
1555 | multiple failures. When the replacement process finishes, the | |
1556 | replaced device will be marked as faulty. | |
1557 | ||
1558 | .TP | |
1559 | .B \-\-with | |
1560 | This can follow a list of | |
1561 | .B \-\-replace | |
1562 | devices. The devices listed after | |
1563 | .B \-\-with | |
1564 | will be preferentially used to replace the devices listed after | |
1565 | .BR \-\-replace . | |
1566 | These device must already be spare devices in the array. | |
1567 | ||
b3d31955 N |
1568 | .TP |
1569 | .BR \-\-write\-mostly | |
a4e13010 | 1570 | Subsequent devices that are added or re\-added will have the 'write-mostly' |
e0fe762a | 1571 | flag set. This is only valid for RAID1 and means that the 'md' driver |
b3d31955 N |
1572 | will avoid reading from these devices if possible. |
1573 | .TP | |
1574 | .BR \-\-readwrite | |
a4e13010 | 1575 | Subsequent devices that are added or re\-added will have the 'write-mostly' |
b3d31955 | 1576 | flag cleared. |
4de90913 GJ |
1577 | .TP |
1578 | .BR \-\-cluster\-confirm | |
1579 | Confirm the existence of the device. This is issued in response to an \-\-add | |
1580 | request by a node in a cluster. When a node adds a device it sends a message | |
1581 | to all nodes in the cluster to look for a device with a UUID. This translates | |
1582 | to a udev notification with the UUID of the device to be added and the slot | |
1583 | number. The receiving node must acknowledge this message | |
1584 | with \-\-cluster\-confirm. Valid arguments are <slot>:<devicename> in case | |
1585 | the device is found or <slot>:missing in case the device is not found. | |
b3d31955 | 1586 | |
ff3c881f SL |
1587 | .TP |
1588 | .BR \-\-add-journal | |
3373d49f SL |
1589 | Add journal to an existing array, or recreate journal for RAID-4/5/6 array |
1590 | that lost a journal device. To avoid interrupting on-going write opertions, | |
ff3c881f SL |
1591 | .B \-\-add-journal |
1592 | only works for array in Read-Only state. | |
1593 | ||
71574efb N |
1594 | .TP |
1595 | .BR \-\-failfast | |
1596 | Subsequent devices that are added or re\-added will have | |
1597 | the 'failfast' flag set. This is only valid for RAID1 and RAID10 and | |
1598 | means that the 'md' driver will avoid long timeouts on error handling | |
1599 | where possible. | |
1600 | .TP | |
1601 | .BR \-\-nofailfast | |
1602 | Subsequent devices that are re\-added will be re\-added without | |
1603 | the 'failfast' flag set. | |
1604 | ||
2ae555c3 | 1605 | .P |
e0fe762a | 1606 | Each of these options requires that the first device listed is the array |
93e790af | 1607 | to be acted upon, and the remainder are component devices to be added, |
e0fe762a | 1608 | removed, marked as faulty, etc. Several different operations can be |
2ae555c3 NB |
1609 | specified for different devices, e.g. |
1610 | .in +5 | |
7e23fc43 | 1611 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
1612 | .in -5 |
1613 | Each operation applies to all devices listed until the next | |
93e790af | 1614 | operation. |
2ae555c3 NB |
1615 | |
1616 | If an array is using a write-intent bitmap, then devices which have | |
a4e13010 | 1617 | been removed can be re\-added in a way that avoids a full |
93e790af | 1618 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
1619 | since the device was removed. For arrays with persistent metadata |
1620 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 1621 | .B \-\-build |
2ae555c3 | 1622 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 1623 | .BR \-\-re\-add . |
2ae555c3 NB |
1624 | |
1625 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
1626 | use, i.e. that must be spares or failed devices. To remove an active |
1627 | device, it must first be marked as | |
1628 | .B faulty. | |
2ae555c3 NB |
1629 | |
1630 | .SH For Misc mode: | |
1631 | ||
1632 | .TP | |
7e23fc43 | 1633 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
1634 | Examine a device to see |
1635 | (1) if it is an md device and (2) if it is a component of an md | |
1636 | array. | |
1637 | Information about what is discovered is presented. | |
1638 | ||
1639 | .TP | |
7e23fc43 | 1640 | .BR \-D ", " \-\-detail |
e0fe762a | 1641 | Print details of one or more md devices. |
5787fa49 | 1642 | |
4cce4069 DW |
1643 | .TP |
1644 | .BR \-\-detail\-platform | |
e0fe762a | 1645 | Print details of the platform's RAID capabilities (firmware / hardware |
9eafa1de MN |
1646 | topology) for a given metadata format. If used without argument, mdadm |
1647 | will scan all controllers looking for their capabilities. Otherwise, mdadm | |
1648 | will only look at the controller specified by the argument in form of an | |
1649 | absolute filepath or a link, e.g. | |
1650 | .IR /sys/devices/pci0000:00/0000:00:1f.2 . | |
4cce4069 | 1651 | |
54bad364 KS |
1652 | .TP |
1653 | .BR \-Y ", " \-\-export | |
1654 | When used with | |
9ca39acb N |
1655 | .BR \-\-detail , |
1656 | .BR \-\-detail-platform , | |
0d726f17 | 1657 | .BR \-\-examine , |
9ca39acb N |
1658 | or |
1659 | .B \-\-incremental | |
54bad364 KS |
1660 | output will be formatted as |
1661 | .B key=value | |
1662 | pairs for easy import into the environment. | |
1663 | ||
9ca39acb N |
1664 | With |
1665 | .B \-\-incremental | |
1666 | The value | |
1667 | .B MD_STARTED | |
1668 | indicates whether an array was started | |
1669 | .RB ( yes ) | |
1670 | or not, which may include a reason | |
1671 | .RB ( unsafe ", " nothing ", " no ). | |
1672 | Also the value | |
1673 | .B MD_FOREIGN | |
1674 | indicates if the array is expected on this host | |
1675 | .RB ( no ), | |
1676 | or seems to be from elsewhere | |
1677 | .RB ( yes ). | |
1678 | ||
2ae555c3 | 1679 | .TP |
7e23fc43 | 1680 | .BR \-E ", " \-\-examine |
e0fe762a N |
1681 | Print contents of the metadata stored on the named device(s). |
1682 | Note the contrast between | |
1683 | .B \-\-examine | |
1684 | and | |
1685 | .BR \-\-detail . | |
1686 | .B \-\-examine | |
1687 | applies to devices which are components of an array, while | |
1688 | .B \-\-detail | |
1689 | applies to a whole array which is currently active. | |
5787fa49 | 1690 | .TP |
7e23fc43 | 1691 | .B \-\-sparc2.2 |
e0fe762a N |
1692 | If an array was created on a SPARC machine with a 2.2 Linux kernel |
1693 | patched with RAID support, the superblock will have been created | |
1694 | incorrectly, or at least incompatibly with 2.4 and later kernels. | |
1695 | Using the | |
7e23fc43 | 1696 | .B \-\-sparc2.2 |
5787fa49 | 1697 | flag with |
7e23fc43 | 1698 | .B \-\-examine |
5787fa49 NB |
1699 | will fix the superblock before displaying it. If this appears to do |
1700 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 1701 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 1702 | |
2ae555c3 | 1703 | .TP |
7e23fc43 | 1704 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 1705 | Report information about a bitmap file. |
01d9299c | 1706 | The argument is either an external bitmap file or an array component |
e0fe762a N |
1707 | in case of an internal bitmap. Note that running this on an array |
1708 | device (e.g. | |
1709 | .BR /dev/md0 ) | |
1710 | does not report the bitmap for that array. | |
e0d19036 | 1711 | |
6d388a88 N |
1712 | .TP |
1713 | .B \-\-examine\-badblocks | |
1714 | List the bad-blocks recorded for the device, if a bad-blocks list has | |
5f418455 | 1715 | been configured. Currently only |
6d388a88 | 1716 | .B 1.x |
5f418455 MT |
1717 | and |
1718 | .B IMSM | |
1719 | metadata support bad-blocks lists. | |
6d388a88 | 1720 | |
74db60b0 N |
1721 | .TP |
1722 | .BI \-\-dump= directory | |
1723 | .TP | |
1724 | .BI \-\-restore= directory | |
1725 | Save metadata from lists devices, or restore metadata to listed devices. | |
1726 | ||
cd29a5c8 | 1727 | .TP |
7e23fc43 | 1728 | .BR \-R ", " \-\-run |
e0fe762a N |
1729 | start a partially assembled array. If |
1730 | .B \-\-assemble | |
1731 | did not find enough devices to fully start the array, it might leaving | |
1732 | it partially assembled. If you wish, you can then use | |
1733 | .B \-\-run | |
1734 | to start the array in degraded mode. | |
52826846 | 1735 | |
cd29a5c8 | 1736 | .TP |
7e23fc43 | 1737 | .BR \-S ", " \-\-stop |
cd29a5c8 | 1738 | deactivate array, releasing all resources. |
52826846 | 1739 | |
cd29a5c8 | 1740 | .TP |
7e23fc43 | 1741 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 1742 | mark array as readonly. |
52826846 | 1743 | |
cd29a5c8 | 1744 | .TP |
7e23fc43 | 1745 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 1746 | mark array as readwrite. |
52826846 | 1747 | |
e0d19036 | 1748 | .TP |
7e23fc43 | 1749 | .B \-\-zero\-superblock |
e0d19036 | 1750 | If the device contains a valid md superblock, the block is |
35cc5be4 | 1751 | overwritten with zeros. With |
7e23fc43 | 1752 | .B \-\-force |
35cc5be4 | 1753 | the block where the superblock would be is overwritten even if it |
e0d19036 | 1754 | doesn't appear to be valid. |
52826846 | 1755 | |
b2a613dd ZL |
1756 | .B Note: |
1757 | Be careful to call \-\-zero\-superblock with clustered raid, make sure | |
1758 | array isn't used or assembled in other cluster node before execute it. | |
1759 | ||
33414a01 DW |
1760 | .TP |
1761 | .B \-\-kill\-subarray= | |
1762 | If the device is a container and the argument to \-\-kill\-subarray | |
1763 | specifies an inactive subarray in the container, then the subarray is | |
1764 | deleted. Deleting all subarrays will leave an 'empty-container' or | |
afa368f4 N |
1765 | spare superblock on the drives. See |
1766 | .B \-\-zero\-superblock | |
1767 | for completely | |
33414a01 DW |
1768 | removing a superblock. Note that some formats depend on the subarray |
1769 | index for generating a UUID, this command will fail if it would change | |
1770 | the UUID of an active subarray. | |
1771 | ||
aa534678 DW |
1772 | .TP |
1773 | .B \-\-update\-subarray= | |
1774 | If the device is a container and the argument to \-\-update\-subarray | |
1775 | specifies a subarray in the container, then attempt to update the given | |
1776 | superblock field in the subarray. See below in | |
1777 | .B MISC MODE | |
1778 | for details. | |
1779 | ||
feb716e9 | 1780 | .TP |
7e23fc43 | 1781 | .BR \-t ", " \-\-test |
feb716e9 | 1782 | When used with |
7e23fc43 | 1783 | .BR \-\-detail , |
feb716e9 NB |
1784 | the exit status of |
1785 | .I mdadm | |
e0fe762a N |
1786 | is set to reflect the status of the device. See below in |
1787 | .B MISC MODE | |
1788 | for details. | |
feb716e9 | 1789 | |
b90c0e9a | 1790 | .TP |
7e23fc43 | 1791 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1792 | For each md device given, wait for any resync, recovery, or reshape |
1793 | activity to finish before returning. | |
1794 | .I mdadm | |
1795 | will return with success if it actually waited for every device | |
1796 | listed, otherwise it will return failure. | |
1797 | ||
1770662b DW |
1798 | .TP |
1799 | .BR \-\-wait\-clean | |
fabbfd48 DW |
1800 | For each md device given, or each device in /proc/mdstat if |
1801 | .B \-\-scan | |
1802 | is given, arrange for the array to be marked clean as soon as possible. | |
7146ec6a DW |
1803 | .I mdadm |
1804 | will return with success if the array uses external metadata and we | |
1805 | successfully waited. For native arrays this returns immediately as the | |
6a0ee6a0 DW |
1806 | kernel handles dirty-clean transitions at shutdown. No action is taken |
1807 | if safe-mode handling is disabled. | |
1770662b | 1808 | |
a740cf64 N |
1809 | .TP |
1810 | .B \-\-action= | |
1811 | Set the "sync_action" for all md devices given to one of | |
1812 | .BR idle , | |
1813 | .BR frozen , | |
1814 | .BR check , | |
1815 | .BR repair . | |
1816 | Setting to | |
1817 | .B idle | |
1818 | will abort any currently running action though some actions will | |
1819 | automatically restart. | |
1820 | Setting to | |
1821 | .B frozen | |
1822 | will abort any current action and ensure no other action starts | |
1823 | automatically. | |
1824 | ||
1825 | Details of | |
1826 | .B check | |
1827 | and | |
1828 | .B repair | |
1829 | can be found it | |
1830 | .IR md (4) | |
1831 | under | |
1832 | .BR "SCRUBBING AND MISMATCHES" . | |
1833 | ||
8382f19b NB |
1834 | .SH For Incremental Assembly mode: |
1835 | .TP | |
7e23fc43 | 1836 | .BR \-\-rebuild\-map ", " \-r |
8382f19b | 1837 | Rebuild the map file |
96fd06ed | 1838 | .RB ( {MAP_PATH} ) |
8382f19b NB |
1839 | that |
1840 | .I mdadm | |
1841 | uses to help track which arrays are currently being assembled. | |
1842 | ||
1843 | .TP | |
7e23fc43 | 1844 | .BR \-\-run ", " \-R |
8382f19b NB |
1845 | Run any array assembled as soon as a minimal number of devices are |
1846 | available, rather than waiting until all expected devices are present. | |
1847 | ||
1848 | .TP | |
7e23fc43 | 1849 | .BR \-\-scan ", " \-s |
8382f19b | 1850 | Only meaningful with |
7e23fc43 | 1851 | .B \-R |
8382f19b NB |
1852 | this will scan the |
1853 | .B map | |
1854 | file for arrays that are being incrementally assembled and will try to | |
1855 | start any that are not already started. If any such array is listed | |
1856 | in | |
1857 | .B mdadm.conf | |
1858 | as requiring an external bitmap, that bitmap will be attached first. | |
1859 | ||
29ba4804 N |
1860 | .TP |
1861 | .BR \-\-fail ", " \-f | |
1862 | This allows the hot-plug system to remove devices that have fully disappeared | |
1863 | from the kernel. It will first fail and then remove the device from any | |
1864 | array it belongs to. | |
1865 | The device name given should be a kernel device name such as "sda", | |
1866 | not a name in | |
1867 | .IR /dev . | |
1868 | ||
210597d1 PC |
1869 | .TP |
1870 | .BR \-\-path= | |
87eb4fab N |
1871 | Only used with \-\-fail. The 'path' given will be recorded so that if |
1872 | a new device appears at the same location it can be automatically | |
1873 | added to the same array. This allows the failed device to be | |
1874 | automatically replaced by a new device without metadata if it appears | |
1875 | at specified path. This option is normally only set by a | |
1876 | .I udev | |
1877 | script. | |
210597d1 | 1878 | |
e0d19036 NB |
1879 | .SH For Monitor mode: |
1880 | .TP | |
7e23fc43 | 1881 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1882 | Give a mail address to send alerts to. |
1883 | ||
1884 | .TP | |
7e23fc43 | 1885 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1886 | Give a program to be run whenever an event is detected. |
1887 | ||
773135f5 | 1888 | .TP |
7e23fc43 | 1889 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1890 | Cause all events to be reported through 'syslog'. The messages have |
1891 | facility of 'daemon' and varying priorities. | |
1892 | ||
e0d19036 | 1893 | .TP |
7e23fc43 | 1894 | .BR \-d ", " \-\-delay |
e0d19036 | 1895 | Give a delay in seconds. |
51ac42e3 | 1896 | .I mdadm |
e0d19036 | 1897 | polls the md arrays and then waits this many seconds before polling |
e0fe762a N |
1898 | again. The default is 60 seconds. Since 2.6.16, there is no need to |
1899 | reduce this as the kernel alerts | |
1900 | .I mdadm | |
1901 | immediately when there is any change. | |
e0d19036 | 1902 | |
9a36a9b7 ZB |
1903 | .TP |
1904 | .BR \-r ", " \-\-increment | |
1905 | Give a percentage increment. | |
1906 | .I mdadm | |
1907 | will generate RebuildNN events with the given percentage increment. | |
1908 | ||
d013a55e | 1909 | .TP |
7e23fc43 | 1910 | .BR \-f ", " \-\-daemonise |
d013a55e | 1911 | Tell |
51ac42e3 | 1912 | .I mdadm |
d013a55e | 1913 | to run as a background daemon if it decides to monitor anything. This |
e0fe762a | 1914 | causes it to fork and run in the child, and to disconnect from the |
d013a55e NB |
1915 | terminal. The process id of the child is written to stdout. |
1916 | This is useful with | |
7e23fc43 | 1917 | .B \-\-scan |
d013a55e NB |
1918 | which will only continue monitoring if a mail address or alert program |
1919 | is found in the config file. | |
1920 | ||
b5e64645 | 1921 | .TP |
7e23fc43 | 1922 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1923 | When |
51ac42e3 | 1924 | .I mdadm |
b5e64645 NB |
1925 | is running in daemon mode, write the pid of the daemon process to |
1926 | the specified file, instead of printing it on standard output. | |
1927 | ||
aa88f531 | 1928 | .TP |
7e23fc43 | 1929 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1930 | Check arrays only once. This will generate |
1931 | .B NewArray | |
1932 | events and more significantly | |
1933 | .B DegradedArray | |
a9d69660 NB |
1934 | and |
1935 | .B SparesMissing | |
aa88f531 NB |
1936 | events. Running |
1937 | .in +5 | |
7e23fc43 | 1938 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1939 | .in -5 |
1940 | from a cron script will ensure regular notification of any degraded arrays. | |
1941 | ||
98c6faba | 1942 | .TP |
7e23fc43 | 1943 | .BR \-t ", " \-\-test |
98c6faba NB |
1944 | Generate a |
1945 | .B TestMessage | |
1946 | alert for every array found at startup. This alert gets mailed and | |
1947 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1948 | message do get through successfully. |
98c6faba | 1949 | |
210597d1 PC |
1950 | .TP |
1951 | .BR \-\-no\-sharing | |
87eb4fab | 1952 | This inhibits the functionality for moving spares between arrays. |
210597d1 PC |
1953 | Only one monitoring process started with |
1954 | .B \-\-scan | |
87eb4fab N |
1955 | but without this flag is allowed, otherwise the two could interfere |
1956 | with each other. | |
210597d1 | 1957 | |
e0d19036 | 1958 | .SH ASSEMBLE MODE |
52826846 | 1959 | |
cd29a5c8 NB |
1960 | .HP 12 |
1961 | Usage: | |
7e23fc43 | 1962 | .B mdadm \-\-assemble |
5787fa49 NB |
1963 | .I md-device options-and-component-devices... |
1964 | .HP 12 | |
1965 | Usage: | |
7e23fc43 | 1966 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1967 | .I md-devices-and-options... |
cd29a5c8 NB |
1968 | .HP 12 |
1969 | Usage: | |
7e23fc43 | 1970 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1971 | .I options... |
52826846 | 1972 | |
cd29a5c8 | 1973 | .PP |
e0fe762a | 1974 | This usage assembles one or more RAID arrays from pre-existing components. |
9a9dab36 | 1975 | For each array, mdadm needs to know the md device, the identity of the |
e0fe762a | 1976 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1977 | |
5787fa49 | 1978 | In the first usage example (without the |
7e23fc43 | 1979 | .BR \-\-scan ) |
5787fa49 NB |
1980 | the first device given is the md device. |
1981 | In the second usage example, all devices listed are treated as md | |
1982 | devices and assembly is attempted. | |
1983 | In the third (where no devices are listed) all md devices that are | |
cb77f620 | 1984 | listed in the configuration file are assembled. If no arrays are |
e0fe762a N |
1985 | described by the configuration file, then any arrays that |
1986 | can be found on unused devices will be assembled. | |
52826846 | 1987 | |
d013a55e | 1988 | If precisely one device is listed, but |
7e23fc43 | 1989 | .B \-\-scan |
dd0781e5 | 1990 | is not given, then |
d013a55e NB |
1991 | .I mdadm |
1992 | acts as though | |
7e23fc43 | 1993 | .B \-\-scan |
93e790af | 1994 | was given and identity information is extracted from the configuration file. |
d013a55e | 1995 | |
2ae555c3 | 1996 | The identity can be given with the |
7e23fc43 | 1997 | .B \-\-uuid |
e0fe762a N |
1998 | option, the |
1999 | .B \-\-name | |
2000 | option, or the | |
7e23fc43 | 2001 | .B \-\-super\-minor |
93e790af SW |
2002 | option, will be taken from the md-device record in the config file, or |
2003 | will be taken from the super block of the first component-device | |
2004 | listed on the command line. | |
52826846 | 2005 | |
2ae555c3 | 2006 | Devices can be given on the |
7e23fc43 | 2007 | .B \-\-assemble |
e0fe762a | 2008 | command line or in the config file. Only devices which have an md |
5787fa49 NB |
2009 | superblock which contains the right identity will be considered for |
2010 | any array. | |
52826846 | 2011 | |
2ae555c3 | 2012 | The config file is only used if explicitly named with |
7e23fc43 | 2013 | .B \-\-config |
d013a55e | 2014 | or requested with (a possibly implicit) |
7e23fc43 | 2015 | .BR \-\-scan . |
52826846 | 2016 | In the later case, |
9a9dab36 | 2017 | .B /etc/mdadm.conf |
8fd8d9c4 N |
2018 | or |
2019 | .B /etc/mdadm/mdadm.conf | |
52826846 NB |
2020 | is used. |
2021 | ||
2ae555c3 | 2022 | If |
7e23fc43 | 2023 | .B \-\-scan |
cd29a5c8 NB |
2024 | is not given, then the config file will only be used to find the |
2025 | identity of md arrays. | |
52826846 | 2026 | |
2d465520 | 2027 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 2028 | .B \-\-scan |
e0fe762a N |
2029 | is not given and not all expected drives were listed, then the array |
2030 | is not started (to guard against usage errors). To insist that the | |
2031 | array be started in this case (as may work for RAID1, 4, 5, 6, or 10), | |
2032 | give the | |
7e23fc43 | 2033 | .B \-\-run |
cd29a5c8 | 2034 | flag. |
52826846 | 2035 | |
e0fe762a N |
2036 | If |
2037 | .I udev | |
2038 | is active, | |
2039 | .I mdadm | |
2040 | does not create any entries in | |
dd0781e5 | 2041 | .B /dev |
e0fe762a N |
2042 | but leaves that to |
2043 | .IR udev . | |
2044 | It does record information in | |
96fd06ed | 2045 | .B {MAP_PATH} |
e0fe762a N |
2046 | which will allow |
2047 | .I udev | |
2048 | to choose the correct name. | |
dd0781e5 | 2049 | |
e0fe762a N |
2050 | If |
2051 | .I mdadm | |
2052 | detects that udev is not configured, it will create the devices in | |
2053 | .B /dev | |
2054 | itself. | |
dd0781e5 | 2055 | |
e0fe762a N |
2056 | In Linux kernels prior to version 2.6.28 there were two distinctly |
2057 | different types of md devices that could be created: one that could be | |
2058 | partitioned using standard partitioning tools and one that could not. | |
2059 | Since 2.6.28 that distinction is no longer relevant as both type of | |
2060 | devices can be partitioned. | |
2061 | .I mdadm | |
2062 | will normally create the type that originally could not be partitioned | |
2063 | as it has a well defined major number (9). | |
dd0781e5 | 2064 | |
e0fe762a N |
2065 | Prior to 2.6.28, it is important that mdadm chooses the correct type |
2066 | of array device to use. This can be controlled with the | |
2067 | .B \-\-auto | |
2068 | option. In particular, a value of "mdp" or "part" or "p" tells mdadm | |
2069 | to use a partitionable device rather than the default. | |
dd0781e5 | 2070 | |
e0fe762a N |
2071 | In the no-udev case, the value given to |
2072 | .B \-\-auto | |
2073 | can be suffixed by a number. This tells | |
2074 | .I mdadm | |
2075 | to create that number of partition devices rather than the default of 4. | |
dd0781e5 | 2076 | |
e0fe762a | 2077 | The value given to |
7e23fc43 | 2078 | .B \-\-auto |
e0fe762a N |
2079 | can also be given in the configuration file as a word starting |
2080 | .B auto= | |
2081 | on the ARRAY line for the relevant array. | |
52826846 | 2082 | |
41a3b72a NB |
2083 | .SS Auto Assembly |
2084 | When | |
7e23fc43 | 2085 | .B \-\-assemble |
41a3b72a | 2086 | is used with |
7e23fc43 | 2087 | .B \-\-scan |
41a3b72a NB |
2088 | and no devices are listed, |
2089 | .I mdadm | |
2090 | will first attempt to assemble all the arrays listed in the config | |
2091 | file. | |
2092 | ||
cb77f620 | 2093 | If no arrays are listed in the config (other than those marked |
e0fe762a N |
2094 | .BR <ignore> ) |
2095 | it will look through the available devices for possible arrays and | |
2096 | will try to assemble anything that it finds. Arrays which are tagged | |
2097 | as belonging to the given homehost will be assembled and started | |
2098 | normally. Arrays which do not obviously belong to this host are given | |
2099 | names that are expected not to conflict with anything local, and are | |
2100 | started "read-auto" so that nothing is written to any device until the | |
2101 | array is written to. i.e. automatic resync etc is delayed. | |
41a3b72a NB |
2102 | |
2103 | If | |
2104 | .I mdadm | |
2105 | finds a consistent set of devices that look like they should comprise | |
2106 | an array, and if the superblock is tagged as belonging to the given | |
2107 | home host, it will automatically choose a device name and try to | |
2108 | assemble the array. If the array uses version-0.90 metadata, then the | |
2109 | .B minor | |
2110 | number as recorded in the superblock is used to create a name in | |
2111 | .B /dev/md/ | |
2112 | so for example | |
2113 | .BR /dev/md/3 . | |
2114 | If the array uses version-1 metadata, then the | |
2115 | .B name | |
2116 | from the superblock is used to similarly create a name in | |
e0fe762a | 2117 | .B /dev/md/ |
93e790af | 2118 | (the name will have any 'host' prefix stripped first). |
41a3b72a | 2119 | |
c64ba03a N |
2120 | This behaviour can be modified by the |
2121 | .I AUTO | |
2122 | line in the | |
2123 | .I mdadm.conf | |
2124 | configuration file. This line can indicate that specific metadata | |
2125 | type should, or should not, be automatically assembled. If an array | |
2126 | is found which is not listed in | |
2127 | .I mdadm.conf | |
2128 | and has a metadata format that is denied by the | |
2129 | .I AUTO | |
2130 | line, then it will not be assembled. | |
2131 | The | |
2132 | .I AUTO | |
2133 | line can also request that all arrays identified as being for this | |
2134 | homehost should be assembled regardless of their metadata type. | |
2135 | See | |
2136 | .IR mdadm.conf (5) | |
2137 | for further details. | |
2138 | ||
246cebdb AK |
2139 | Note: Auto assembly cannot be used for assembling and activating some |
2140 | arrays which are undergoing reshape. In particular as the | |
2141 | .B backup\-file | |
2142 | cannot be given, any reshape which requires a backup-file to continue | |
2143 | cannot be started by auto assembly. An array which is growing to more | |
2144 | devices and has passed the critical section can be assembled using | |
2145 | auto-assembly. | |
41a3b72a | 2146 | |
cd29a5c8 | 2147 | .SH BUILD MODE |
52826846 | 2148 | |
cd29a5c8 NB |
2149 | .HP 12 |
2150 | Usage: | |
7e23fc43 | 2151 | .B mdadm \-\-build |
93e790af | 2152 | .I md-device |
7e23fc43 PS |
2153 | .BI \-\-chunk= X |
2154 | .BI \-\-level= Y | |
2155 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
2156 | .I devices |
2157 | ||
2158 | .PP | |
2ae555c3 | 2159 | This usage is similar to |
7e23fc43 | 2160 | .BR \-\-create . |
e0fe762a | 2161 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 2162 | these arrays there is no difference between initially creating the array and |
52826846 NB |
2163 | subsequently assembling the array, except that hopefully there is useful |
2164 | data there in the second case. | |
2165 | ||
e0fe762a N |
2166 | The level may raid0, linear, raid1, raid10, multipath, or faulty, or |
2167 | one of their synonyms. All devices must be listed and the array will | |
2168 | be started once complete. It will often be appropriate to use | |
2169 | .B \-\-assume\-clean | |
2170 | with levels raid1 or raid10. | |
cd29a5c8 NB |
2171 | |
2172 | .SH CREATE MODE | |
2173 | ||
2174 | .HP 12 | |
2175 | Usage: | |
7e23fc43 | 2176 | .B mdadm \-\-create |
93e790af | 2177 | .I md-device |
7e23fc43 PS |
2178 | .BI \-\-chunk= X |
2179 | .BI \-\-level= Y | |
cd29a5c8 | 2180 | .br |
7e23fc43 | 2181 | .BI \-\-raid\-devices= Z |
e0fe762a | 2182 | .I devices |
cd29a5c8 NB |
2183 | |
2184 | .PP | |
2185 | This usage will initialise a new md array, associate some devices with | |
2186 | it, and activate the array. | |
2187 | ||
e0fe762a N |
2188 | The named device will normally not exist when |
2189 | .I "mdadm \-\-create" | |
2190 | is run, but will be created by | |
2191 | .I udev | |
2192 | once the array becomes active. | |
dd0781e5 | 2193 | |
ced5fa8b BK |
2194 | The max length md-device name is limited to 32 characters. |
2195 | Different metadata types have more strict limitation | |
2196 | (like IMSM where only 16 characters are allowed). | |
2197 | For that reason, long name could be truncated or rejected, it depends on metadata policy. | |
2198 | ||
e0fe762a N |
2199 | As devices are added, they are checked to see if they contain RAID |
2200 | superblocks or filesystems. They are also checked to see if the variance in | |
cd29a5c8 NB |
2201 | device size exceeds 1%. |
2202 | ||
2203 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 2204 | the presence of a |
7e23fc43 | 2205 | .B \-\-run |
cd29a5c8 NB |
2206 | can override this caution. |
2207 | ||
2d465520 | 2208 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 2209 | give the word "\fBmissing\fP" |
2d465520 | 2210 | in place of a device name. This will cause |
51ac42e3 | 2211 | .I mdadm |
2d465520 NB |
2212 | to leave the corresponding slot in the array empty. |
2213 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 2214 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
2215 | For a RAID1 array, only one real device needs to be given. All of the |
2216 | others can be | |
d013a55e | 2217 | "\fBmissing\fP". |
2d465520 | 2218 | |
feb716e9 | 2219 | When creating a RAID5 array, |
51ac42e3 | 2220 | .I mdadm |
feb716e9 | 2221 | will automatically create a degraded array with an extra spare drive. |
e0fe762a N |
2222 | This is because building the spare into a degraded array is in general |
2223 | faster than resyncing the parity on a non-degraded, but not clean, | |
2224 | array. This feature can be overridden with the | |
7e23fc43 | 2225 | .B \-\-force |
feb716e9 NB |
2226 | option. |
2227 | ||
0ee4da98 | 2228 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
2229 | required. |
2230 | If this is not given with the | |
7e23fc43 | 2231 | .B \-\-name |
41a3b72a NB |
2232 | option, |
2233 | .I mdadm | |
0ee4da98 | 2234 | will choose a name based on the last component of the name of the |
41a3b72a NB |
2235 | device being created. So if |
2236 | .B /dev/md3 | |
2237 | is being created, then the name | |
2238 | .B 3 | |
2239 | will be chosen. | |
2240 | If | |
2241 | .B /dev/md/home | |
2242 | is being created, then the name | |
2243 | .B home | |
2244 | will be used. | |
2245 | ||
e0fe762a N |
2246 | When creating a partition based array, using |
2247 | .I mdadm | |
2248 | with version-1.x metadata, the partition type should be set to | |
e0f31f50 | 2249 | .B 0xDA |
e0fe762a | 2250 | (non fs-data). This type selection allows for greater precision since |
e0f31f50 PC |
2251 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], |
2252 | might create problems in the event of array recovery through a live cdrom. | |
2253 | ||
3d3dd91e NB |
2254 | A new array will normally get a randomly assigned 128bit UUID which is |
2255 | very likely to be unique. If you have a specific need, you can choose | |
2256 | a UUID for the array by giving the | |
7e23fc43 | 2257 | .B \-\-uuid= |
3d3dd91e NB |
2258 | option. Be warned that creating two arrays with the same UUID is a |
2259 | recipe for disaster. Also, using | |
7e23fc43 | 2260 | .B \-\-uuid= |
3d3dd91e | 2261 | when creating a v0.90 array will silently override any |
7e23fc43 | 2262 | .B \-\-homehost= |
3d3dd91e | 2263 | setting. |
e43d0cda NB |
2264 | .\"If the |
2265 | .\".B \-\-size | |
2266 | .\"option is given, it is not necessary to list any component-devices in this command. | |
2267 | .\"They can be added later, before a | |
2268 | .\".B \-\-run. | |
2269 | .\"If no | |
2270 | .\".B \-\-size | |
2271 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 2272 | |
748952f7 N |
2273 | If the array type supports a write-intent bitmap, and if the devices |
2274 | in the array exceed 100G is size, an internal write-intent bitmap | |
2275 | will automatically be added unless some other option is explicitly | |
2276 | requested with the | |
2277 | .B \-\-bitmap | |
5308f117 AP |
2278 | option or a different consistency policy is selected with the |
2279 | .B \-\-consistency\-policy | |
2280 | option. In any case space for a bitmap will be reserved so that one | |
2281 | can be added later with | |
748952f7 N |
2282 | .BR "\-\-grow \-\-bitmap=internal" . |
2283 | ||
8fac4a54 TM |
2284 | If the metadata type supports it (currently only 1.x and IMSM metadata), |
2285 | space will be allocated to store a bad block list. This allows a modest | |
bf95d0f3 N |
2286 | number of bad blocks to be recorded, allowing the drive to remain in |
2287 | service while only partially functional. | |
2288 | ||
8fd8d9c4 N |
2289 | When creating an array within a |
2290 | .B CONTAINER | |
2291 | .I mdadm | |
2292 | can be given either the list of devices to use, or simply the name of | |
2293 | the container. The former case gives control over which devices in | |
2294 | the container will be used for the array. The latter case allows | |
2295 | .I mdadm | |
2296 | to automatically choose which devices to use based on how much spare | |
2297 | space is available. | |
2298 | ||
53e8b987 | 2299 | The General Management options that are valid with |
7e23fc43 | 2300 | .B \-\-create |
53e8b987 | 2301 | are: |
cd29a5c8 | 2302 | .TP |
7e23fc43 | 2303 | .B \-\-run |
dd0781e5 | 2304 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
2305 | be in use. |
2306 | ||
2307 | .TP | |
7e23fc43 | 2308 | .B \-\-readonly |
8a70632f | 2309 | start the array in readonly mode. |
52826846 | 2310 | |
e0d19036 | 2311 | .SH MANAGE MODE |
cd29a5c8 NB |
2312 | .HP 12 |
2313 | Usage: | |
e0d19036 NB |
2314 | .B mdadm |
2315 | .I device | |
2316 | .I options... devices... | |
cd29a5c8 NB |
2317 | .PP |
2318 | ||
e0d19036 NB |
2319 | This usage will allow individual devices in an array to be failed, |
2320 | removed or added. It is possible to perform multiple operations with | |
e0fe762a | 2321 | on command. For example: |
e0d19036 | 2322 | .br |
7e23fc43 | 2323 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
2324 | .br |
2325 | will firstly mark | |
2326 | .B /dev/hda1 | |
2327 | as faulty in | |
2328 | .B /dev/md0 | |
2329 | and will then remove it from the array and finally add it back | |
2d465520 | 2330 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 2331 | command. |
e0d19036 | 2332 | |
e0fe762a N |
2333 | When a device is added to an active array, mdadm checks to see if it |
2334 | has metadata on it which suggests that it was recently a member of the | |
a4e13010 | 2335 | array. If it does, it tries to "re\-add" the device. If there have |
e0fe762a N |
2336 | been no changes since the device was removed, or if the array has a |
2337 | write-intent bitmap which has recorded whatever changes there were, | |
2338 | then the device will immediately become a full member of the array and | |
2339 | those differences recorded in the bitmap will be resolved. | |
2340 | ||
e0d19036 NB |
2341 | .SH MISC MODE |
2342 | .HP 12 | |
2343 | Usage: | |
9a9dab36 | 2344 | .B mdadm |
e0d19036 | 2345 | .I options ... |
e0fe762a | 2346 | .I devices ... |
e0d19036 | 2347 | .PP |
cd29a5c8 | 2348 | |
b5e64645 | 2349 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
2350 | operate on distinct devices. The operations are: |
2351 | .TP | |
962a108f | 2352 | .B \-\-query |
e0d19036 NB |
2353 | The device is examined to see if it is |
2354 | (1) an active md array, or | |
2355 | (2) a component of an md array. | |
2356 | The information discovered is reported. | |
2357 | ||
2358 | .TP | |
962a108f | 2359 | .B \-\-detail |
2d465520 | 2360 | The device should be an active md device. |
e0fe762a | 2361 | .B mdadm |
2d465520 | 2362 | will display a detailed description of the array. |
7e23fc43 | 2363 | .B \-\-brief |
2d465520 | 2364 | or |
7e23fc43 | 2365 | .B \-\-scan |
2d465520 | 2366 | will cause the output to be less detailed and the format to be |
e0d19036 | 2367 | suitable for inclusion in |
87eb4fab | 2368 | .BR mdadm.conf . |
feb716e9 NB |
2369 | The exit status of |
2370 | .I mdadm | |
2371 | will normally be 0 unless | |
2372 | .I mdadm | |
93e790af | 2373 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 2374 | .B \-\-test |
feb716e9 NB |
2375 | option is given, then the exit status will be: |
2376 | .RS | |
2377 | .TP | |
2378 | 0 | |
2379 | The array is functioning normally. | |
2380 | .TP | |
2381 | 1 | |
2382 | The array has at least one failed device. | |
2383 | .TP | |
2384 | 2 | |
a77be586 | 2385 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
2386 | .TP |
2387 | 4 | |
2388 | There was an error while trying to get information about the device. | |
2389 | .RE | |
cd29a5c8 | 2390 | |
4cce4069 DW |
2391 | .TP |
2392 | .B \-\-detail\-platform | |
e0fe762a | 2393 | Print detail of the platform's RAID capabilities (firmware / hardware |
4cce4069 DW |
2394 | topology). If the metadata is specified with |
2395 | .B \-e | |
2396 | or | |
2397 | .B \-\-metadata= | |
2398 | then the return status will be: | |
2399 | .RS | |
2400 | .TP | |
2401 | 0 | |
2402 | metadata successfully enumerated its platform components on this system | |
2403 | .TP | |
2404 | 1 | |
2405 | metadata is platform independent | |
2406 | .TP | |
2407 | 2 | |
2408 | metadata failed to find its platform components on this system | |
2409 | .RE | |
2410 | ||
aa534678 DW |
2411 | .TP |
2412 | .B \-\-update\-subarray= | |
2413 | If the device is a container and the argument to \-\-update\-subarray | |
2414 | specifies a subarray in the container, then attempt to update the given | |
2415 | superblock field in the subarray. Similar to updating an array in | |
2416 | "assemble" mode, the field to update is selected by | |
2417 | .B \-U | |
2418 | or | |
2419 | .B \-\-update= | |
e6e9dd3f AP |
2420 | option. The supported options are |
2421 | .BR name , | |
dc95f821 JR |
2422 | .BR ppl , |
2423 | .BR no\-ppl , | |
2424 | .BR bitmap | |
e6e9dd3f | 2425 | and |
dc95f821 | 2426 | .BR no\-bitmap . |
aa534678 | 2427 | |
bcbb92d4 | 2428 | The |
aa534678 DW |
2429 | .B name |
2430 | option updates the subarray name in the metadata, it may not affect the | |
2431 | device node name or the device node symlink until the subarray is | |
bcbb92d4 | 2432 | re\-assembled. If updating |
aa534678 DW |
2433 | .B name |
2434 | would change the UUID of an active subarray this operation is blocked, | |
2435 | and the command will end in an error. | |
2436 | ||
e6e9dd3f AP |
2437 | The |
2438 | .B ppl | |
2439 | and | |
2440 | .B no\-ppl | |
2441 | options enable and disable PPL in the metadata. Currently supported only for | |
2442 | IMSM subarrays. | |
2443 | ||
dc95f821 JR |
2444 | The |
2445 | .B bitmap | |
2446 | and | |
2447 | .B no\-bitmap | |
2448 | options enable and disable write-intent bitmap in the metadata. Currently supported only for | |
2449 | IMSM subarrays. | |
2450 | ||
e0d19036 | 2451 | .TP |
962a108f | 2452 | .B \-\-examine |
2d465520 | 2453 | The device should be a component of an md array. |
51ac42e3 | 2454 | .I mdadm |
2d465520 | 2455 | will read the md superblock of the device and display the contents. |
e0d19036 | 2456 | If |
7e23fc43 | 2457 | .B \-\-brief |
93e790af | 2458 | or |
7e23fc43 | 2459 | .B \-\-scan |
93e790af | 2460 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
2461 | are grouped together and reported in a single entry suitable |
2462 | for inclusion in | |
87eb4fab | 2463 | .BR mdadm.conf . |
e0d19036 | 2464 | |
2d465520 | 2465 | Having |
7e23fc43 | 2466 | .B \-\-scan |
e0d19036 NB |
2467 | without listing any devices will cause all devices listed in the |
2468 | config file to be examined. | |
2469 | ||
74db60b0 N |
2470 | .TP |
2471 | .BI \-\-dump= directory | |
2472 | If the device contains RAID metadata, a file will be created in the | |
2473 | .I directory | |
2474 | and the metadata will be written to it. The file will be the same | |
2475 | size as the device and have the metadata written in the file at the | |
2476 | same locate that it exists in the device. However the file will be "sparse" so | |
2477 | that only those blocks containing metadata will be allocated. The | |
2478 | total space used will be small. | |
2479 | ||
2480 | The file name used in the | |
2481 | .I directory | |
2482 | will be the base name of the device. Further if any links appear in | |
2483 | .I /dev/disk/by-id | |
2484 | which point to the device, then hard links to the file will be created | |
2485 | in | |
2486 | .I directory | |
2487 | based on these | |
2488 | .I by-id | |
2489 | names. | |
2490 | ||
2491 | Multiple devices can be listed and their metadata will all be stored | |
2492 | in the one directory. | |
2493 | ||
2494 | .TP | |
2495 | .BI \-\-restore= directory | |
2496 | This is the reverse of | |
2497 | .BR \-\-dump . | |
2498 | .I mdadm | |
2499 | will locate a file in the directory that has a name appropriate for | |
2500 | the given device and will restore metadata from it. Names that match | |
2501 | .I /dev/disk/by-id | |
2502 | names are preferred, however if two of those refer to different files, | |
2503 | .I mdadm | |
2504 | will not choose between them but will abort the operation. | |
2505 | ||
2506 | If a file name is given instead of a | |
2507 | .I directory | |
2508 | then | |
2509 | .I mdadm | |
2510 | will restore from that file to a single device, always provided the | |
2511 | size of the file matches that of the device, and the file contains | |
2512 | valid metadata. | |
e0d19036 | 2513 | .TP |
962a108f | 2514 | .B \-\-stop |
98c6faba NB |
2515 | The devices should be active md arrays which will be deactivated, as |
2516 | long as they are not currently in use. | |
e0d19036 NB |
2517 | |
2518 | .TP | |
962a108f | 2519 | .B \-\-run |
e0d19036 NB |
2520 | This will fully activate a partially assembled md array. |
2521 | ||
2522 | .TP | |
962a108f | 2523 | .B \-\-readonly |
e0d19036 NB |
2524 | This will mark an active array as read-only, providing that it is |
2525 | not currently being used. | |
2526 | ||
2527 | .TP | |
962a108f | 2528 | .B \-\-readwrite |
e0d19036 NB |
2529 | This will change a |
2530 | .B readonly | |
2531 | array back to being read/write. | |
2532 | ||
2d465520 | 2533 | .TP |
962a108f | 2534 | .B \-\-scan |
2d465520 | 2535 | For all operations except |
7e23fc43 PS |
2536 | .BR \-\-examine , |
2537 | .B \-\-scan | |
2d465520 NB |
2538 | will cause the operation to be applied to all arrays listed in |
2539 | .BR /proc/mdstat . | |
2540 | For | |
7e23fc43 PS |
2541 | .BR \-\-examine, |
2542 | .B \-\-scan | |
2d465520 NB |
2543 | causes all devices listed in the config file to be examined. |
2544 | ||
a1331cc4 N |
2545 | .TP |
2546 | .BR \-b ", " \-\-brief | |
2547 | Be less verbose. This is used with | |
2548 | .B \-\-detail | |
2549 | and | |
2550 | .BR \-\-examine . | |
2551 | Using | |
2552 | .B \-\-brief | |
2553 | with | |
2554 | .B \-\-verbose | |
2555 | gives an intermediate level of verbosity. | |
2556 | ||
e0d19036 NB |
2557 | .SH MONITOR MODE |
2558 | ||
cd29a5c8 NB |
2559 | .HP 12 |
2560 | Usage: | |
7e23fc43 | 2561 | .B mdadm \-\-monitor |
e0d19036 NB |
2562 | .I options... devices... |
2563 | ||
cd29a5c8 | 2564 | .PP |
e0d19036 | 2565 | This usage causes |
51ac42e3 | 2566 | .I mdadm |
e0d19036 NB |
2567 | to periodically poll a number of md arrays and to report on any events |
2568 | noticed. | |
51ac42e3 | 2569 | .I mdadm |
e0d19036 NB |
2570 | will never exit once it decides that there are arrays to be checked, |
2571 | so it should normally be run in the background. | |
2572 | ||
2d465520 | 2573 | As well as reporting events, |
51ac42e3 | 2574 | .I mdadm |
2d465520 NB |
2575 | may move a spare drive from one array to another if they are in the |
2576 | same | |
2577 | .B spare-group | |
210597d1 PC |
2578 | or |
2579 | .B domain | |
a9d69660 | 2580 | and if the destination array has a failed drive but no spares. |
2d465520 | 2581 | |
e0d19036 | 2582 | If any devices are listed on the command line, |
51ac42e3 | 2583 | .I mdadm |
e0fe762a | 2584 | will only monitor those devices. Otherwise all arrays listed in the |
e0d19036 | 2585 | configuration file will be monitored. Further, if |
7e23fc43 | 2586 | .B \-\-scan |
e0d19036 NB |
2587 | is given, then any other md devices that appear in |
2588 | .B /proc/mdstat | |
2589 | will also be monitored. | |
2590 | ||
2591 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 2592 | These events are passed to a separate program (if specified) and may |
2d465520 | 2593 | be mailed to a given E-mail address. |
e0d19036 | 2594 | |
93e790af SW |
2595 | When passing events to a program, the program is run once for each event, |
2596 | and is given 2 or 3 command-line arguments: the first is the | |
2597 | name of the event (see below), the second is the name of the | |
bd526cee | 2598 | md device which is affected, and the third is the name of a related |
93e790af | 2599 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
2600 | |
2601 | If | |
7e23fc43 | 2602 | .B \-\-scan |
e0d19036 NB |
2603 | is given, then a program or an E-mail address must be specified on the |
2604 | command line or in the config file. If neither are available, then | |
51ac42e3 | 2605 | .I mdadm |
e0d19036 NB |
2606 | will not monitor anything. |
2607 | Without | |
93e790af | 2608 | .B \-\-scan, |
51ac42e3 | 2609 | .I mdadm |
2d465520 | 2610 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
2611 | no program or email is given, then each event is reported to |
2612 | .BR stdout . | |
cd29a5c8 | 2613 | |
e0d19036 NB |
2614 | The different events are: |
2615 | ||
2616 | .RS 4 | |
2617 | .TP | |
2618 | .B DeviceDisappeared | |
2d465520 | 2619 | An md array which previously was configured appears to no longer be |
773135f5 | 2620 | configured. (syslog priority: Critical) |
e0d19036 | 2621 | |
b8f72a62 NB |
2622 | If |
2623 | .I mdadm | |
2624 | was told to monitor an array which is RAID0 or Linear, then it will | |
2625 | report | |
2626 | .B DeviceDisappeared | |
2627 | with the extra information | |
2628 | .BR Wrong-Level . | |
2629 | This is because RAID0 and Linear do not support the device-failed, | |
2630 | hot-spare and resync operations which are monitored. | |
2631 | ||
e0d19036 NB |
2632 | .TP |
2633 | .B RebuildStarted | |
2ca20929 JC |
2634 | An md array started reconstruction (e.g. recovery, resync, reshape, |
2635 | check, repair). (syslog priority: Warning) | |
e0d19036 NB |
2636 | |
2637 | .TP | |
2638 | .BI Rebuild NN | |
2639 | Where | |
2640 | .I NN | |
9a36a9b7 ZB |
2641 | is a two-digit number (ie. 05, 48). This indicates that rebuild |
2642 | has passed that many percent of the total. The events are generated | |
2643 | with fixed increment since 0. Increment size may be specified with | |
2644 | a commandline option (default is 20). (syslog priority: Warning) | |
e0d19036 | 2645 | |
98c6faba NB |
2646 | .TP |
2647 | .B RebuildFinished | |
2648 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 2649 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 2650 | |
e0d19036 NB |
2651 | .TP |
2652 | .B Fail | |
773135f5 NB |
2653 | An active component device of an array has been marked as |
2654 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
2655 | |
2656 | .TP | |
2657 | .B FailSpare | |
2658 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 2659 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
2660 | |
2661 | .TP | |
2662 | .B SpareActive | |
2663 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 2664 | device has been successfully rebuilt and has been made active. |
773135f5 | 2665 | (syslog priority: Info) |
e0d19036 NB |
2666 | |
2667 | .TP | |
2668 | .B NewArray | |
2669 | A new md array has been detected in the | |
2670 | .B /proc/mdstat | |
e0fe762a | 2671 | file. (syslog priority: Info) |
e0d19036 | 2672 | |
aa88f531 NB |
2673 | .TP |
2674 | .B DegradedArray | |
2675 | A newly noticed array appears to be degraded. This message is not | |
2676 | generated when | |
2677 | .I mdadm | |
2678 | notices a drive failure which causes degradation, but only when | |
2679 | .I mdadm | |
2680 | notices that an array is degraded when it first sees the array. | |
93e790af | 2681 | (syslog priority: Critical) |
aa88f531 | 2682 | |
e0d19036 NB |
2683 | .TP |
2684 | .B MoveSpare | |
2685 | A spare drive has been moved from one array in a | |
2686 | .B spare-group | |
210597d1 PC |
2687 | or |
2688 | .B domain | |
e0d19036 | 2689 | to another to allow a failed drive to be replaced. |
773135f5 | 2690 | (syslog priority: Info) |
e0d19036 | 2691 | |
b8f72a62 NB |
2692 | .TP |
2693 | .B SparesMissing | |
2694 | If | |
2695 | .I mdadm | |
2696 | has been told, via the config file, that an array should have a certain | |
2697 | number of spare devices, and | |
2698 | .I mdadm | |
93e790af | 2699 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
2700 | array, it will report a |
2701 | .B SparesMissing | |
2702 | message. | |
d1732eeb | 2703 | (syslog priority: Warning) |
b8f72a62 | 2704 | |
98c6faba NB |
2705 | .TP |
2706 | .B TestMessage | |
2707 | An array was found at startup, and the | |
7e23fc43 | 2708 | .B \-\-test |
98c6faba | 2709 | flag was given. |
773135f5 | 2710 | (syslog priority: Info) |
e0d19036 NB |
2711 | .RE |
2712 | ||
2713 | Only | |
93e790af SW |
2714 | .B Fail, |
2715 | .B FailSpare, | |
2716 | .B DegradedArray, | |
2717 | .B SparesMissing | |
e0d19036 | 2718 | and |
98c6faba | 2719 | .B TestMessage |
e0d19036 | 2720 | cause Email to be sent. All events cause the program to be run. |
93e790af | 2721 | The program is run with two or three arguments: the event |
e0d19036 NB |
2722 | name, the array device and possibly a second device. |
2723 | ||
2724 | Each event has an associated array device (e.g. | |
2725 | .BR /dev/md1 ) | |
2726 | and possibly a second device. For | |
2727 | .BR Fail , | |
2728 | .BR FailSpare , | |
2729 | and | |
2730 | .B SpareActive | |
2731 | the second device is the relevant component device. | |
2732 | For | |
2733 | .B MoveSpare | |
2734 | the second device is the array that the spare was moved from. | |
2735 | ||
2736 | For | |
51ac42e3 | 2737 | .I mdadm |
e0d19036 | 2738 | to move spares from one array to another, the different arrays need to |
93e790af | 2739 | be labeled with the same |
e0d19036 | 2740 | .B spare-group |
210597d1 | 2741 | or the spares must be allowed to migrate through matching POLICY domains |
e0d19036 NB |
2742 | in the configuration file. The |
2743 | .B spare-group | |
93e790af | 2744 | name can be any string; it is only necessary that different spare |
2d465520 | 2745 | groups use different names. |
e0d19036 NB |
2746 | |
2747 | When | |
51ac42e3 | 2748 | .I mdadm |
93e790af | 2749 | detects that an array in a spare group has fewer active |
e0d19036 NB |
2750 | devices than necessary for the complete array, and has no spare |
2751 | devices, it will look for another array in the same spare group that | |
2752 | has a full complement of working drive and a spare. It will then | |
2753 | attempt to remove the spare from the second drive and add it to the | |
2754 | first. | |
2755 | If the removal succeeds but the adding fails, then it is added back to | |
2756 | the original array. | |
2757 | ||
210597d1 PC |
2758 | If the spare group for a degraded array is not defined, |
2759 | .I mdadm | |
2760 | will look at the rules of spare migration specified by POLICY lines in | |
87eb4fab | 2761 | .B mdadm.conf |
210597d1 PC |
2762 | and then follow similar steps as above if a matching spare is found. |
2763 | ||
dd0781e5 NB |
2764 | .SH GROW MODE |
2765 | The GROW mode is used for changing the size or shape of an active | |
2766 | array. | |
2767 | For this to work, the kernel must support the necessary change. | |
c64881d7 | 2768 | Various types of growth are being added during 2.6 development. |
dd0781e5 | 2769 | |
c64881d7 | 2770 | Currently the supported changes include |
dfd4d8ee | 2771 | .IP \(bu 4 |
c64881d7 | 2772 | change the "size" attribute for RAID1, RAID4, RAID5 and RAID6. |
dfd4d8ee | 2773 | .IP \(bu 4 |
c64881d7 N |
2774 | increase or decrease the "raid\-devices" attribute of RAID0, RAID1, RAID4, |
2775 | RAID5, and RAID6. | |
cb77f620 | 2776 | .IP \(bu 4 |
17790db6 | 2777 | change the chunk-size and layout of RAID0, RAID4, RAID5, RAID6 and RAID10. |
cb77f620 | 2778 | .IP \(bu 4 |
c64881d7 | 2779 | convert between RAID1 and RAID5, between RAID5 and RAID6, between |
cb77f620 | 2780 | RAID0, RAID4, and RAID5, and between RAID0 and RAID10 (in the near-2 mode). |
dfd4d8ee | 2781 | .IP \(bu 4 |
93e790af | 2782 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 2783 | remove a write-intent bitmap from such an array. |
860f11ed AP |
2784 | .IP \(bu 4 |
2785 | change the array's consistency policy. | |
dfd4d8ee | 2786 | .PP |
dd0781e5 | 2787 | |
9ab6e80a | 2788 | Using GROW on containers is currently supported only for Intel's IMSM |
c64881d7 N |
2789 | container format. The number of devices in a container can be |
2790 | increased - which affects all arrays in the container - or an array | |
2791 | in a container can be converted between levels where those levels are | |
2792 | supported by the container, and the conversion is on of those listed | |
4431efeb | 2793 | above. |
8fd8d9c4 | 2794 | |
0de8d44d | 2795 | .PP |
5a5b3a67 MZ |
2796 | Notes: |
2797 | .IP \(bu 4 | |
2798 | Intel's native checkpointing doesn't use | |
0de8d44d AK |
2799 | .B --backup-file |
2800 | option and it is transparent for assembly feature. | |
5a5b3a67 MZ |
2801 | .IP \(bu 4 |
2802 | Roaming between Windows(R) and Linux systems for IMSM metadata is not | |
2803 | supported during grow process. | |
2551061c CL |
2804 | .IP \(bu 4 |
2805 | When growing a raid0 device, the new component disk size (or external | |
2806 | backup size) should be larger than LCM(old, new) * chunk-size * 2, | |
2807 | where LCM() is the least common multiple of the old and new count of | |
2808 | component disks, and "* 2" comes from the fact that mdadm refuses to | |
2809 | use more than half of a spare device for backup space. | |
0de8d44d | 2810 | |
2ae555c3 | 2811 | .SS SIZE CHANGES |
c64881d7 | 2812 | Normally when an array is built the "size" is taken from the smallest |
dd0781e5 NB |
2813 | of the drives. If all the small drives in an arrays are, one at a |
2814 | time, removed and replaced with larger drives, then you could have an | |
2815 | array of large drives with only a small amount used. In this | |
2816 | situation, changing the "size" with "GROW" mode will allow the extra | |
2817 | space to start being used. If the size is increased in this way, a | |
2818 | "resync" process will start to make sure the new parts of the array | |
2819 | are synchronised. | |
2820 | ||
2821 | Note that when an array changes size, any filesystem that may be | |
cb77f620 | 2822 | stored in the array will not automatically grow or shrink to use or |
88b496c2 | 2823 | vacate the space. The |
666bba9b N |
2824 | filesystem will need to be explicitly told to use the extra space |
2825 | after growing, or to reduce its size | |
2826 | .B prior | |
2827 | to shrinking the array. | |
dd0781e5 | 2828 | |
e0fe762a N |
2829 | Also the size of an array cannot be changed while it has an active |
2830 | bitmap. If an array has a bitmap, it must be removed before the size | |
cb77f620 | 2831 | can be changed. Once the change is complete a new bitmap can be created. |
e0fe762a | 2832 | |
7fa9af4c ZL |
2833 | .PP |
2834 | Note: | |
2835 | .B "--grow --size" | |
2836 | is not yet supported for external file bitmap. | |
2837 | ||
e0fe762a | 2838 | .SS RAID\-DEVICES CHANGES |
2ae555c3 | 2839 | |
dd0781e5 NB |
2840 | A RAID1 array can work with any number of devices from 1 upwards |
2841 | (though 1 is not very useful). There may be times which you want to | |
2842 | increase or decrease the number of active devices. Note that this is | |
2843 | different to hot-add or hot-remove which changes the number of | |
2844 | inactive devices. | |
2845 | ||
2846 | When reducing the number of devices in a RAID1 array, the slots which | |
2847 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 2848 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
2849 | |
2850 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 2851 | present will be activated immediately. |
dd0781e5 | 2852 | |
f24e2d6c | 2853 | Changing the number of active devices in a RAID5 or RAID6 is much more |
2ae555c3 | 2854 | effort. Every block in the array will need to be read and written |
f24e2d6c | 2855 | back to a new location. From 2.6.17, the Linux Kernel is able to |
ca4f89a3 N |
2856 | increase the number of devices in a RAID5 safely, including restarting |
2857 | an interrupted "reshape". From 2.6.31, the Linux Kernel is able to | |
f24e2d6c N |
2858 | increase or decrease the number of devices in a RAID5 or RAID6. |
2859 | ||
c64881d7 N |
2860 | From 2.6.35, the Linux Kernel is able to convert a RAID0 in to a RAID4 |
2861 | or RAID5. | |
2862 | .I mdadm | |
2863 | uses this functionality and the ability to add | |
2864 | devices to a RAID4 to allow devices to be added to a RAID0. When | |
2865 | requested to do this, | |
2866 | .I mdadm | |
2867 | will convert the RAID0 to a RAID4, add the necessary disks and make | |
2868 | the reshape happen, and then convert the RAID4 back to RAID0. | |
2869 | ||
f24e2d6c N |
2870 | When decreasing the number of devices, the size of the array will also |
2871 | decrease. If there was data in the array, it could get destroyed and | |
666bba9b N |
2872 | this is not reversible, so you should firstly shrink the filesystem on |
2873 | the array to fit within the new size. To help prevent accidents, | |
f24e2d6c N |
2874 | .I mdadm |
2875 | requires that the size of the array be decreased first with | |
2876 | .BR "mdadm --grow --array-size" . | |
2877 | This is a reversible change which simply makes the end of the array | |
2878 | inaccessible. The integrity of any data can then be checked before | |
2879 | the non-reversible reduction in the number of devices is request. | |
2ae555c3 | 2880 | |
cd19c0cf JR |
2881 | When relocating the first few stripes on a RAID5 or RAID6, it is not |
2882 | possible to keep the data on disk completely consistent and | |
2883 | crash-proof. To provide the required safety, mdadm disables writes to | |
2884 | the array while this "critical section" is reshaped, and takes a | |
2885 | backup of the data that is in that section. For grows, this backup may be | |
2886 | stored in any spare devices that the array has, however it can also be | |
2887 | stored in a separate file specified with the | |
7e23fc43 | 2888 | .B \-\-backup\-file |
cd19c0cf JR |
2889 | option, and is required to be specified for shrinks, RAID level |
2890 | changes and layout changes. If this option is used, and the system | |
2891 | does crash during the critical period, the same file must be passed to | |
7e23fc43 | 2892 | .B \-\-assemble |
cd19c0cf JR |
2893 | to restore the backup and reassemble the array. When shrinking rather |
2894 | than growing the array, the reshape is done from the end towards the | |
2895 | beginning, so the "critical section" is at the end of the reshape. | |
2ae555c3 | 2896 | |
f24e2d6c N |
2897 | .SS LEVEL CHANGES |
2898 | ||
2899 | Changing the RAID level of any array happens instantaneously. However | |
cd19c0cf | 2900 | in the RAID5 to RAID6 case this requires a non-standard layout of the |
f24e2d6c | 2901 | RAID6 data, and in the RAID6 to RAID5 case that non-standard layout is |
cd19c0cf | 2902 | required before the change can be accomplished. So while the level |
f24e2d6c | 2903 | change is instant, the accompanying layout change can take quite a |
cd19c0cf JR |
2904 | long time. A |
2905 | .B \-\-backup\-file | |
2906 | is required. If the array is not simultaneously being grown or | |
2907 | shrunk, so that the array size will remain the same - for example, | |
2908 | reshaping a 3-drive RAID5 into a 4-drive RAID6 - the backup file will | |
2909 | be used not just for a "cricital section" but throughout the reshape | |
2910 | operation, as described below under LAYOUT CHANGES. | |
f24e2d6c N |
2911 | |
2912 | .SS CHUNK-SIZE AND LAYOUT CHANGES | |
2913 | ||
ec7d7cee | 2914 | Changing the chunk-size or layout without also changing the number of |
f24e2d6c N |
2915 | devices as the same time will involve re-writing all blocks in-place. |
2916 | To ensure against data loss in the case of a crash, a | |
2917 | .B --backup-file | |
2918 | must be provided for these changes. Small sections of the array will | |
cd19c0cf JR |
2919 | be copied to the backup file while they are being rearranged. This |
2920 | means that all the data is copied twice, once to the backup and once | |
2921 | to the new layout on the array, so this type of reshape will go very | |
2922 | slowly. | |
f24e2d6c N |
2923 | |
2924 | If the reshape is interrupted for any reason, this backup file must be | |
cd19c0cf | 2925 | made available to |
f24e2d6c N |
2926 | .B "mdadm --assemble" |
2927 | so the array can be reassembled. Consequently the file cannot be | |
2928 | stored on the device being reshaped. | |
2929 | ||
2930 | ||
2ae555c3 NB |
2931 | .SS BITMAP CHANGES |
2932 | ||
2933 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 2934 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b | 2935 | can be added. Note that if you add a bitmap stored in a file which is |
e0fe762a | 2936 | in a filesystem that is on the RAID array being affected, the system |
fe80f49b NB |
2937 | will deadlock. The bitmap must be on a separate filesystem. |
2938 | ||
860f11ed AP |
2939 | .SS CONSISTENCY POLICY CHANGES |
2940 | ||
2941 | The consistency policy of an active array can be changed by using the | |
2942 | .B \-\-consistency\-policy | |
2943 | option in Grow mode. Currently this works only for the | |
2944 | .B ppl | |
2945 | and | |
2946 | .B resync | |
2947 | policies and allows to enable or disable the RAID5 Partial Parity Log (PPL). | |
2948 | ||
8382f19b NB |
2949 | .SH INCREMENTAL MODE |
2950 | ||
2951 | .HP 12 | |
2952 | Usage: | |
7e23fc43 PS |
2953 | .B mdadm \-\-incremental |
2954 | .RB [ \-\-run ] | |
2955 | .RB [ \-\-quiet ] | |
8382f19b | 2956 | .I component-device |
b11fe74d | 2957 | .RI [ optional-aliases-for-device ] |
8382f19b NB |
2958 | .HP 12 |
2959 | Usage: | |
29ba4804 N |
2960 | .B mdadm \-\-incremental \-\-fail |
2961 | .I component-device | |
2962 | .HP 12 | |
2963 | Usage: | |
7e6140e6 | 2964 | .B mdadm \-\-incremental \-\-rebuild\-map |
8382f19b NB |
2965 | .HP 12 |
2966 | Usage: | |
7e23fc43 | 2967 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b | 2968 | |
8382f19b NB |
2969 | .PP |
2970 | This mode is designed to be used in conjunction with a device | |
2971 | discovery system. As devices are found in a system, they can be | |
2972 | passed to | |
7e23fc43 | 2973 | .B "mdadm \-\-incremental" |
8382f19b NB |
2974 | to be conditionally added to an appropriate array. |
2975 | ||
29ba4804 N |
2976 | Conversely, it can also be used with the |
2977 | .B \-\-fail | |
2978 | flag to do just the opposite and find whatever array a particular device | |
2979 | is part of and remove the device from that array. | |
2980 | ||
8fd8d9c4 N |
2981 | If the device passed is a |
2982 | .B CONTAINER | |
2983 | device created by a previous call to | |
2984 | .IR mdadm , | |
2985 | then rather than trying to add that device to an array, all the arrays | |
2986 | described by the metadata of the container will be started. | |
2987 | ||
8382f19b NB |
2988 | .I mdadm |
2989 | performs a number of tests to determine if the device is part of an | |
93e790af | 2990 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
2991 | is found, or can be created, |
2992 | .I mdadm | |
2993 | adds the device to the array and conditionally starts the array. | |
2994 | ||
2995 | Note that | |
2996 | .I mdadm | |
87eb4fab N |
2997 | will normally only add devices to an array which were previously working |
2998 | (active or spare) parts of that array. The support for automatic | |
210597d1 PC |
2999 | inclusion of a new drive as a spare in some array requires |
3000 | a configuration through POLICY in config file. | |
8382f19b | 3001 | |
8382f19b NB |
3002 | The tests that |
3003 | .I mdadm | |
3004 | makes are as follow: | |
3005 | .IP + | |
3006 | Is the device permitted by | |
3007 | .BR mdadm.conf ? | |
3008 | That is, is it listed in a | |
3009 | .B DEVICES | |
3010 | line in that file. If | |
3011 | .B DEVICES | |
b11fe74d | 3012 | is absent then the default it to allow any device. Similarly if |
8382f19b NB |
3013 | .B DEVICES |
3014 | contains the special word | |
3015 | .B partitions | |
3016 | then any device is allowed. Otherwise the device name given to | |
b11fe74d N |
3017 | .IR mdadm , |
3018 | or one of the aliases given, or an alias found in the filesystem, | |
8382f19b NB |
3019 | must match one of the names or patterns in a |
3020 | .B DEVICES | |
3021 | line. | |
3022 | ||
b11fe74d N |
3023 | This is the only context where the aliases are used. They are |
3024 | usually provided by a | |
3025 | .I udev | |
3026 | rules mentioning | |
ceb5f8ef | 3027 | .BR $env{DEVLINKS} . |
b11fe74d | 3028 | |
8382f19b | 3029 | .IP + |
cb77f620 NK |
3030 | Does the device have a valid md superblock? If a specific metadata |
3031 | version is requested with | |
7e23fc43 | 3032 | .B \-\-metadata |
8382f19b | 3033 | or |
7e23fc43 | 3034 | .B \-e |
8382f19b NB |
3035 | then only that style of metadata is accepted, otherwise |
3036 | .I mdadm | |
3037 | finds any known version of metadata. If no | |
3038 | .I md | |
210597d1 PC |
3039 | metadata is found, the device may be still added to an array |
3040 | as a spare if POLICY allows. | |
8382f19b | 3041 | |
d1302dd8 | 3042 | .ig |
8382f19b NB |
3043 | .IP + |
3044 | Does the metadata match an expected array? | |
3045 | The metadata can match in two ways. Either there is an array listed | |
3046 | in | |
3047 | .B mdadm.conf | |
3048 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 3049 | or by minor-number), or the array was created with a |
8382f19b | 3050 | .B homehost |
93e790af | 3051 | specified and that |
8382f19b | 3052 | .B homehost |
93e790af | 3053 | matches the one in |
8382f19b NB |
3054 | .B mdadm.conf |
3055 | or on the command line. | |
3056 | If | |
3057 | .I mdadm | |
3058 | is not able to positively identify the array as belonging to the | |
3059 | current host, the device will be rejected. | |
d1302dd8 | 3060 | .. |
8382f19b | 3061 | |
cb77f620 | 3062 | .PP |
8382f19b | 3063 | .I mdadm |
93e790af | 3064 | keeps a list of arrays that it has partially assembled in |
96fd06ed | 3065 | .BR {MAP_PATH} . |
e0fe762a | 3066 | If no array exists which matches |
8382f19b NB |
3067 | the metadata on the new device, |
3068 | .I mdadm | |
3069 | must choose a device name and unit number. It does this based on any | |
3070 | name given in | |
3071 | .B mdadm.conf | |
3072 | or any name information stored in the metadata. If this name | |
3073 | suggests a unit number, that number will be used, otherwise a free | |
3074 | unit number will be chosen. Normally | |
3075 | .I mdadm | |
3076 | will prefer to create a partitionable array, however if the | |
3077 | .B CREATE | |
3078 | line in | |
3079 | .B mdadm.conf | |
3080 | suggests that a non-partitionable array is preferred, that will be | |
3081 | honoured. | |
3082 | ||
e0fe762a N |
3083 | If the array is not found in the config file and its metadata does not |
3084 | identify it as belonging to the "homehost", then | |
3085 | .I mdadm | |
3086 | will choose a name for the array which is certain not to conflict with | |
3087 | any array which does belong to this host. It does this be adding an | |
3088 | underscore and a small number to the name preferred by the metadata. | |
3089 | ||
8382f19b NB |
3090 | Once an appropriate array is found or created and the device is added, |
3091 | .I mdadm | |
3092 | must decide if the array is ready to be started. It will | |
3093 | normally compare the number of available (non-spare) devices to the | |
3094 | number of devices that the metadata suggests need to be active. If | |
3095 | there are at least that many, the array will be started. This means | |
3096 | that if any devices are missing the array will not be restarted. | |
3097 | ||
3098 | As an alternative, | |
7e23fc43 | 3099 | .B \-\-run |
8382f19b | 3100 | may be passed to |
51ac42e3 | 3101 | .I mdadm |
8382f19b | 3102 | in which case the array will be run as soon as there are enough |
e0fe762a N |
3103 | devices present for the data to be accessible. For a RAID1, that |
3104 | means one device will start the array. For a clean RAID5, the array | |
8382f19b NB |
3105 | will be started as soon as all but one drive is present. |
3106 | ||
93e790af | 3107 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
3108 | be known that all device discovery has completed, then |
3109 | .br | |
7e23fc43 | 3110 | .B " mdadm \-IRs" |
8382f19b NB |
3111 | .br |
3112 | can be run which will try to start all arrays that are being | |
3113 | incrementally assembled. They are started in "read-auto" mode in | |
3114 | which they are read-only until the first write request. This means | |
3115 | that no metadata updates are made and no attempt at resync or recovery | |
3116 | happens. Further devices that are found before the first write can | |
3117 | still be added safely. | |
3118 | ||
5545fa6d DW |
3119 | .SH ENVIRONMENT |
3120 | This section describes environment variables that affect how mdadm | |
3121 | operates. | |
3122 | ||
3123 | .TP | |
3124 | .B MDADM_NO_MDMON | |
3125 | Setting this value to 1 will prevent mdadm from automatically launching | |
3126 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
3127 | ||
8fd8d9c4 N |
3128 | .TP |
3129 | .B MDADM_NO_UDEV | |
3130 | Normally, | |
3131 | .I mdadm | |
3132 | does not create any device nodes in /dev, but leaves that task to | |
3133 | .IR udev . | |
3134 | If | |
3135 | .I udev | |
3136 | appears not to be configured, or if this environment variable is set | |
3137 | to '1', the | |
3138 | .I mdadm | |
3139 | will create and devices that are needed. | |
3140 | ||
f66585eb N |
3141 | .TP |
3142 | .B MDADM_NO_SYSTEMCTL | |
3143 | If | |
3144 | .I mdadm | |
3145 | detects that | |
3146 | .I systemd | |
3147 | is in use it will normally request | |
3148 | .I systemd | |
3149 | to start various background tasks (particularly | |
3150 | .IR mdmon ) | |
3151 | rather than forking and running them in the background. This can be | |
3152 | suppressed by setting | |
3153 | .BR MDADM_NO_SYSTEMCTL=1 . | |
3154 | ||
401f095c N |
3155 | .TP |
3156 | .B IMSM_NO_PLATFORM | |
3157 | A key value of IMSM metadata is that it allows interoperability with | |
3158 | boot ROMs on Intel platforms, and with other major operating systems. | |
3159 | Consequently, | |
3160 | .I mdadm | |
3161 | will only allow an IMSM array to be created or modified if detects | |
3162 | that it is running on an Intel platform which supports IMSM, and | |
3163 | supports the particular configuration of IMSM that is being requested | |
3164 | (some functionality requires newer OROM support). | |
3165 | ||
3166 | These checks can be suppressed by setting IMSM_NO_PLATFORM=1 in the | |
3167 | environment. This can be useful for testing or for disaster | |
3168 | recovery. You should be aware that interoperability may be | |
3169 | compromised by setting this value. | |
2dfb675b | 3170 | |
f66585eb N |
3171 | .TP |
3172 | .B MDADM_GROW_ALLOW_OLD | |
3173 | If an array is stopped while it is performing a reshape and that | |
3174 | reshape was making use of a backup file, then when the array is | |
3175 | re-assembled | |
3176 | .I mdadm | |
3177 | will sometimes complain that the backup file is too old. If this | |
3178 | happens and you are certain it is the right backup file, you can | |
3179 | over-ride this check by setting | |
3180 | .B MDADM_GROW_ALLOW_OLD=1 | |
3181 | in the environment. | |
3182 | ||
2dfb675b N |
3183 | .TP |
3184 | .B MDADM_CONF_AUTO | |
3185 | Any string given in this variable is added to the start of the | |
3186 | .B AUTO | |
3187 | line in the config file, or treated as the whole | |
3188 | .B AUTO | |
3189 | line if none is given. It can be used to disable certain metadata | |
3190 | types when | |
3191 | .I mdadm | |
3192 | is called from a boot script. For example | |
3193 | .br | |
3194 | .B " export MDADM_CONF_AUTO='-ddf -imsm' | |
3195 | .br | |
3196 | will make sure that | |
3197 | .I mdadm | |
3198 | does not automatically assemble any DDF or | |
3199 | IMSM arrays that are found. This can be useful on systems configured | |
3200 | to manage such arrays with | |
3201 | .BR dmraid . | |
3202 | ||
3203 | ||
2d465520 NB |
3204 | .SH EXAMPLES |
3205 | ||
7e23fc43 | 3206 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 3207 | .br |
e0fe762a | 3208 | This will find out if a given device is a RAID array, or is part of |
5787fa49 | 3209 | one, and will provide brief information about the device. |
2d465520 | 3210 | |
7e23fc43 | 3211 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 3212 | .br |
93e790af | 3213 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 3214 | file. This command will typically go in a system startup file. |
2d465520 | 3215 | |
7e23fc43 | 3216 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 3217 | .br |
93e790af | 3218 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 3219 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 3220 | |
7e23fc43 | 3221 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 3222 | .br |
5787fa49 NB |
3223 | If (and only if) there is an Email address or program given in the |
3224 | standard config file, then | |
3225 | monitor the status of all arrays listed in that file by | |
3226 | polling them ever 2 minutes. | |
2d465520 | 3227 | |
7e23fc43 | 3228 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 3229 | .br |
5787fa49 | 3230 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 3231 | |
2d465520 | 3232 | .br |
7e23fc43 | 3233 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 3234 | .br |
7e23fc43 | 3235 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 3236 | .br |
5787fa49 NB |
3237 | This will create a prototype config file that describes currently |
3238 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
3239 | This file should be reviewed before being used as it may |
3240 | contain unwanted detail. | |
3241 | ||
7e23fc43 | 3242 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 3243 | .br |
7e23fc43 | 3244 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
3245 | .br |
3246 | This will find arrays which could be assembled from existing IDE and | |
3247 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 3248 | format of a config file. |
2d465520 NB |
3249 | This file is very likely to contain unwanted detail, particularly |
3250 | the | |
3251 | .B devices= | |
5787fa49 NB |
3252 | entries. It should be reviewed and edited before being used as an |
3253 | actual config file. | |
2d465520 | 3254 | |
7e23fc43 | 3255 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 3256 | .br |
7e23fc43 | 3257 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
3258 | .br |
3259 | Create a list of devices by reading | |
3260 | .BR /proc/partitions , | |
3261 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 3262 | that were found. |
2d465520 | 3263 | |
7e23fc43 | 3264 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 3265 | .br |
5787fa49 NB |
3266 | Scan all partitions and devices listed in |
3267 | .BR /proc/partitions | |
3268 | and assemble | |
3269 | .B /dev/md0 | |
3270 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 3271 | |
96fd06ed | 3272 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /run/mdadm/mon.pid" |
d013a55e NB |
3273 | .br |
3274 | If config file contains a mail address or alert program, run mdadm in | |
3275 | the background in monitor mode monitoring all md devices. Also write | |
3276 | pid of mdadm daemon to | |
96fd06ed | 3277 | .BR /run/mdadm/mon.pid . |
d013a55e | 3278 | |
7e23fc43 | 3279 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
3280 | .br |
3281 | Try to incorporate newly discovered device into some array as | |
3282 | appropriate. | |
3283 | ||
7e6140e6 | 3284 | .B " mdadm \-\-incremental \-\-rebuild\-map \-\-run \-\-scan" |
8382f19b NB |
3285 | .br |
3286 | Rebuild the array map from any current arrays, and then start any that | |
3287 | can be started. | |
3288 | ||
b80da661 NB |
3289 | .B " mdadm /dev/md4 --fail detached --remove detached" |
3290 | .br | |
3291 | Any devices which are components of /dev/md4 will be marked as faulty | |
3292 | and then remove from the array. | |
3293 | ||
cb77f620 | 3294 | .B " mdadm --grow /dev/md4 --level=6 --backup-file=/root/backup-md4" |
f24e2d6c N |
3295 | .br |
3296 | The array | |
3297 | .B /dev/md4 | |
3298 | which is currently a RAID5 array will be converted to RAID6. There | |
3299 | should normally already be a spare drive attached to the array as a | |
3300 | RAID6 needs one more drive than a matching RAID5. | |
3301 | ||
8fd8d9c4 N |
3302 | .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]" |
3303 | .br | |
3304 | Create a DDF array over 6 devices. | |
3305 | ||
3306 | .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf" | |
3307 | .br | |
e0fe762a | 3308 | Create a RAID5 array over any 3 devices in the given DDF set. Use |
8fd8d9c4 N |
3309 | only 30 gigabytes of each device. |
3310 | ||
3311 | .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]" | |
3312 | .br | |
3313 | Assemble a pre-exist ddf array. | |
3314 | ||
3315 | .B " mdadm -I /dev/md/ddf1" | |
3316 | .br | |
3317 | Assemble all arrays contained in the ddf array, assigning names as | |
3318 | appropriate. | |
3319 | ||
7e23fc43 | 3320 | .B " mdadm \-\-create \-\-help" |
2d465520 | 3321 | .br |
2ae555c3 | 3322 | Provide help about the Create mode. |
2d465520 | 3323 | |
7e23fc43 | 3324 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
3325 | .br |
3326 | Provide help about the format of the config file. | |
2d465520 | 3327 | |
7e23fc43 | 3328 | .B " mdadm \-\-help" |
5787fa49 NB |
3329 | .br |
3330 | Provide general help. | |
cd29a5c8 | 3331 | |
cd29a5c8 NB |
3332 | .SH FILES |
3333 | ||
3334 | .SS /proc/mdstat | |
3335 | ||
2ae555c3 NB |
3336 | If you're using the |
3337 | .B /proc | |
cd29a5c8 NB |
3338 | filesystem, |
3339 | .B /proc/mdstat | |
2d465520 | 3340 | lists all active md devices with information about them. |
51ac42e3 | 3341 | .I mdadm |
2d465520 | 3342 | uses this to find arrays when |
7e23fc43 | 3343 | .B \-\-scan |
2d465520 NB |
3344 | is given in Misc mode, and to monitor array reconstruction |
3345 | on Monitor mode. | |
3346 | ||
9a9dab36 | 3347 | .SS /etc/mdadm.conf |
cd29a5c8 | 3348 | |
11a3e71d NB |
3349 | The config file lists which devices may be scanned to see if |
3350 | they contain MD super block, and gives identifying information | |
3351 | (e.g. UUID) about known MD arrays. See | |
3352 | .BR mdadm.conf (5) | |
3353 | for more details. | |
cd29a5c8 | 3354 | |
9dc70cbc N |
3355 | .SS /etc/mdadm.conf.d |
3356 | ||
3357 | A directory containing configuration files which are read in lexical | |
3358 | order. | |
3359 | ||
96fd06ed | 3360 | .SS {MAP_PATH} |
8382f19b | 3361 | When |
7e23fc43 | 3362 | .B \-\-incremental |
93e790af | 3363 | mode is used, this file gets a list of arrays currently being created. |
8382f19b | 3364 | |
48f7b27a NB |
3365 | .SH DEVICE NAMES |
3366 | ||
48f7b27a | 3367 | .I mdadm |
8fd8d9c4 N |
3368 | understand two sorts of names for array devices. |
3369 | ||
3370 | The first is the so-called 'standard' format name, which matches the | |
3371 | names used by the kernel and which appear in | |
3372 | .IR /proc/mdstat . | |
3373 | ||
3374 | The second sort can be freely chosen, but must reside in | |
3375 | .IR /dev/md/ . | |
3376 | When giving a device name to | |
3377 | .I mdadm | |
3378 | to create or assemble an array, either full path name such as | |
3379 | .I /dev/md0 | |
3380 | or | |
3381 | .I /dev/md/home | |
3382 | can be given, or just the suffix of the second sort of name, such as | |
3383 | .I home | |
3384 | can be given. | |
3385 | ||
3386 | When | |
3387 | .I mdadm | |
e0fe762a N |
3388 | chooses device names during auto-assembly or incremental assembly, it |
3389 | will sometimes add a small sequence number to the end of the name to | |
3390 | avoid conflicted between multiple arrays that have the same name. If | |
8fd8d9c4 N |
3391 | .I mdadm |
3392 | can reasonably determine that the array really is meant for this host, | |
3393 | either by a hostname in the metadata, or by the presence of the array | |
87eb4fab N |
3394 | in |
3395 | .BR mdadm.conf , | |
3396 | then it will leave off the suffix if possible. | |
e0fe762a N |
3397 | Also if the homehost is specified as |
3398 | .B <ignore> | |
3399 | .I mdadm | |
3400 | will only use a suffix if a different array of the same name already | |
3401 | exists or is listed in the config file. | |
48f7b27a NB |
3402 | |
3403 | The standard names for non-partitioned arrays (the only sort of md | |
8fd8d9c4 | 3404 | array available in 2.4 and earlier) are of the form |
48f7b27a | 3405 | .IP |
eca944fa | 3406 | .RB /dev/md NN |
48f7b27a NB |
3407 | .PP |
3408 | where NN is a number. | |
3409 | The standard names for partitionable arrays (as available from 2.6 | |
eca944fa | 3410 | onwards) are of the form: |
48f7b27a | 3411 | .IP |
eca944fa | 3412 | .RB /dev/md_d NN |
48f7b27a | 3413 | .PP |
eca944fa | 3414 | Partition numbers should be indicated by adding "pMM" to these, thus "/dev/md/d1p2". |
8fd8d9c4 | 3415 | .PP |
eca944fa N |
3416 | From kernel version 2.6.28 the "non-partitioned array" can actually |
3417 | be partitioned. So the "md_d\fBNN\fP" | |
3418 | names are no longer needed, and | |
0de5349e | 3419 | partitions such as "/dev/md\fBNN\fPp\fBXX\fP" |
eca944fa N |
3420 | are possible. |
3421 | .PP | |
3422 | From kernel version 2.6.29 standard names can be non-numeric following | |
3423 | the form: | |
3424 | .IP | |
3425 | .RB /dev/md_ XXX | |
3426 | .PP | |
3427 | where | |
3428 | .B XXX | |
3429 | is any string. These names are supported by | |
3430 | .I mdadm | |
3431 | since version 3.3 provided they are enabled in | |
3432 | .IR mdadm.conf . | |
52826846 | 3433 | |
2d465520 | 3434 | .SH NOTE |
51ac42e3 | 3435 | .I mdadm |
2d465520 | 3436 | was previously known as |
51ac42e3 | 3437 | .IR mdctl . |
a9d69660 | 3438 | |
52826846 | 3439 | .SH SEE ALSO |
75f74377 | 3440 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 3441 | RAID, see: |
3cdfb6a7 | 3442 | .IP |
8e41153c | 3443 | .B https://raid.wiki.kernel.org/ |
75f74377 DG |
3444 | .PP |
3445 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
cd29a5c8 | 3446 | .PP |
2ae555c3 | 3447 | The latest version of |
a9d69660 NB |
3448 | .I mdadm |
3449 | should always be available from | |
cd29a5c8 | 3450 | .IP |
8e41153c | 3451 | .B https://www.kernel.org/pub/linux/utils/raid/mdadm/ |
11cd8b79 N |
3452 | .PP |
3453 | Related man pages: | |
cd29a5c8 | 3454 | .PP |
e0fe762a | 3455 | .IR mdmon (8), |
a9d69660 NB |
3456 | .IR mdadm.conf (5), |
3457 | .IR md (4). |