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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. | |
fed12d43 | 8 | .TH MDADM 8 "" v3.3.2 |
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 |
f24e2d6c | 129 | removing a write-intent bitmap. |
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 | |
370 | .B http://www.intel.com/design/chipsets/matrixstorage_sb.htm | |
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 | |
c2ecf5f6 N |
396 | .TP |
397 | .B \-\-prefer= | |
398 | When | |
399 | .I mdadm | |
400 | needs to print the name for a device it normally finds the name in | |
401 | .B /dev | |
402 | which refers to the device and is shortest. When a path component is | |
403 | given with | |
404 | .B \-\-prefer | |
405 | .I mdadm | |
406 | will prefer a longer name if it contains that component. For example | |
407 | .B \-\-prefer=by-uuid | |
408 | will prefer a name in a subdirectory of | |
409 | .B /dev | |
410 | called | |
411 | .BR by-uuid . | |
412 | ||
413 | This functionality is currently only provided by | |
414 | .B \-\-detail | |
415 | and | |
416 | .BR \-\-monitor . | |
417 | ||
2ae555c3 NB |
418 | .SH For create, build, or grow: |
419 | ||
420 | .TP | |
7e23fc43 | 421 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
422 | Specify the number of active devices in the array. This, plus the |
423 | number of spare devices (see below) must equal the number of | |
424 | .I component-devices | |
425 | (including "\fBmissing\fP" devices) | |
426 | that are listed on the command line for | |
e0fe762a | 427 | .BR \-\-create . |
2ae555c3 NB |
428 | Setting a value of 1 is probably |
429 | a mistake and so requires that | |
7e23fc43 | 430 | .B \-\-force |
2ae555c3 | 431 | be specified first. A value of 1 will then be allowed for linear, |
e0fe762a | 432 | multipath, RAID0 and RAID1. It is never allowed for RAID4, RAID5 or RAID6. |
2ae555c3 NB |
433 | .br |
434 | This number can only be changed using | |
7e23fc43 | 435 | .B \-\-grow |
e0fe762a N |
436 | for RAID1, RAID4, RAID5 and RAID6 arrays, and only on kernels which provide |
437 | the necessary support. | |
2ae555c3 NB |
438 | |
439 | .TP | |
7e23fc43 | 440 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
441 | Specify the number of spare (eXtra) devices in the initial array. |
442 | Spares can also be added | |
443 | and removed later. The number of component devices listed | |
e0fe762a | 444 | on the command line must equal the number of RAID devices plus the |
2ae555c3 NB |
445 | number of spare devices. |
446 | ||
2ae555c3 | 447 | .TP |
7e23fc43 | 448 | .BR \-z ", " \-\-size= |
e0fe762a | 449 | Amount (in Kibibytes) of space to use from each drive in RAID levels 1/4/5/6. |
2ae555c3 NB |
450 | This must be a multiple of the chunk size, and must leave about 128Kb |
451 | of space at the end of the drive for the RAID superblock. | |
452 | If this is not specified | |
453 | (as it normally is not) the smallest drive (or partition) sets the | |
454 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
455 | issued. | |
456 | ||
36fad8ec N |
457 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
458 | Gigabytes respectively. | |
459 | ||
9ab6e80a N |
460 | Sometimes a replacement drive can be a little smaller than the |
461 | original drives though this should be minimised by IDEMA standards. | |
462 | Such a replacement drive will be rejected by | |
463 | .IR md . | |
464 | To guard against this it can be useful to set the initial size | |
465 | slightly smaller than the smaller device with the aim that it will | |
466 | still be larger than any replacement. | |
467 | ||
2ae555c3 | 468 | This value can be set with |
7e23fc43 | 469 | .B \-\-grow |
9ab6e80a N |
470 | for RAID level 1/4/5/6 though |
471 | .B CONTAINER | |
472 | based arrays such as those with IMSM metadata may not be able to | |
473 | support this. | |
474 | If the array was created with a size smaller than the currently | |
475 | active drives, the extra space can be accessed using | |
7e23fc43 | 476 | .BR \-\-grow . |
2ae555c3 NB |
477 | The size can be given as |
478 | .B max | |
479 | which means to choose the largest size that fits on all current drives. | |
52826846 | 480 | |
c26d78fe N |
481 | Before reducing the size of the array (with |
482 | .BR "\-\-grow \-\-size=" ) | |
483 | you should make sure that space isn't needed. If the device holds a | |
484 | filesystem, you would need to resize the filesystem to use less space. | |
485 | ||
486 | After reducing the array size you should check that the data stored in | |
487 | the device is still available. If the device holds a filesystem, then | |
488 | an 'fsck' of the filesystem is a minimum requirement. If there are | |
489 | problems the array can be made bigger again with no loss with another | |
490 | .B "\-\-grow \-\-size=" | |
491 | command. | |
492 | ||
9ab6e80a | 493 | This value cannot be used when creating a |
8fd8d9c4 | 494 | .B CONTAINER |
9ab6e80a N |
495 | such as with DDF and IMSM metadata, though it perfectly valid when |
496 | creating an array inside a container. | |
8fd8d9c4 | 497 | |
f24e2d6c | 498 | .TP |
c26d78fe | 499 | .BR \-Z ", " \-\-array\-size= |
f24e2d6c N |
500 | This is only meaningful with |
501 | .B \-\-grow | |
36fad8ec | 502 | and its effect is not persistent: when the array is stopped and |
f24e2d6c N |
503 | restarted the default array size will be restored. |
504 | ||
505 | Setting the array-size causes the array to appear smaller to programs | |
506 | that access the data. This is particularly needed before reshaping an | |
507 | array so that it will be smaller. As the reshape is not reversible, | |
508 | but setting the size with | |
509 | .B \-\-array-size | |
510 | is, it is required that the array size is reduced as appropriate | |
511 | before the number of devices in the array is reduced. | |
512 | ||
c26d78fe N |
513 | Before reducing the size of the array you should make sure that space |
514 | isn't needed. If the device holds a filesystem, you would need to | |
515 | resize the filesystem to use less space. | |
516 | ||
517 | After reducing the array size you should check that the data stored in | |
518 | the device is still available. If the device holds a filesystem, then | |
519 | an 'fsck' of the filesystem is a minimum requirement. If there are | |
520 | problems the array can be made bigger again with no loss with another | |
521 | .B "\-\-grow \-\-array\-size=" | |
522 | command. | |
523 | ||
36fad8ec N |
524 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
525 | Gigabytes respectively. | |
526 | A value of | |
527 | .B max | |
528 | restores the apparent size of the array to be whatever the real | |
529 | amount of available space is. | |
530 | ||
cd29a5c8 | 531 | .TP |
7e23fc43 | 532 | .BR \-c ", " \-\-chunk= |
5f175898 N |
533 | Specify chunk size of kibibytes. The default when creating an |
534 | array is 512KB. To ensure compatibility with earlier versions, the | |
422da715 | 535 | default when building an array with no persistent metadata is 64KB. |
e0fe762a | 536 | This is only meaningful for RAID0, RAID4, RAID5, RAID6, and RAID10. |
52826846 | 537 | |
a252c078 N |
538 | RAID4, RAID5, RAID6, and RAID10 require the chunk size to be a power |
539 | of 2. In any case it must be a multiple of 4KB. | |
540 | ||
36fad8ec N |
541 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
542 | Gigabytes respectively. | |
543 | ||
cd29a5c8 | 544 | .TP |
7e23fc43 | 545 | .BR \-\-rounding= |
e0fe762a N |
546 | Specify rounding factor for a Linear array. The size of each |
547 | component will be rounded down to a multiple of this size. | |
548 | This is a synonym for | |
549 | .B \-\-chunk | |
550 | but highlights the different meaning for Linear as compared to other | |
5f175898 N |
551 | RAID levels. The default is 64K if a kernel earlier than 2.6.16 is in |
552 | use, and is 0K (i.e. no rounding) in later kernels. | |
52826846 | 553 | |
cd29a5c8 | 554 | .TP |
7e23fc43 | 555 | .BR \-l ", " \-\-level= |
e0fe762a | 556 | Set RAID level. When used with |
7e23fc43 | 557 | .BR \-\-create , |
98c6faba | 558 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
8fd8d9c4 N |
559 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container. |
560 | Obviously some of these are synonymous. | |
561 | ||
562 | When a | |
563 | .B CONTAINER | |
564 | metadata type is requested, only the | |
565 | .B container | |
566 | level is permitted, and it does not need to be explicitly given. | |
aa88f531 NB |
567 | |
568 | When used with | |
7e23fc43 | 569 | .BR \-\-build , |
a9d69660 | 570 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 571 | |
fd547b50 N |
572 | Can be used with |
573 | .B \-\-grow | |
574 | to change the RAID level in some cases. See LEVEL CHANGES below. | |
2ae555c3 | 575 | |
cd29a5c8 | 576 | .TP |
7e23fc43 | 577 | .BR \-p ", " \-\-layout= |
f24e2d6c N |
578 | This option configures the fine details of data layout for RAID5, RAID6, |
579 | and RAID10 arrays, and controls the failure modes for | |
1a7dfc35 NB |
580 | .IR faulty . |
581 | ||
e0fe762a | 582 | The layout of the RAID5 parity block can be one of |
7e23fc43 PS |
583 | .BR left\-asymmetric , |
584 | .BR left\-symmetric , | |
585 | .BR right\-asymmetric , | |
586 | .BR right\-symmetric , | |
53e8b987 PS |
587 | .BR la ", " ra ", " ls ", " rs . |
588 | The default is | |
7e23fc43 | 589 | .BR left\-symmetric . |
52826846 | 590 | |
cd19c0cf | 591 | It is also possible to cause RAID5 to use a RAID4-like layout by |
e0fe762a N |
592 | choosing |
593 | .BR parity\-first , | |
594 | or | |
595 | .BR parity\-last . | |
596 | ||
597 | Finally for RAID5 there are DDF\-compatible layouts, | |
598 | .BR ddf\-zero\-restart , | |
599 | .BR ddf\-N\-restart , | |
600 | and | |
601 | .BR ddf\-N\-continue . | |
602 | ||
603 | These same layouts are available for RAID6. There are also 4 layouts | |
604 | that will provide an intermediate stage for converting between RAID5 | |
605 | and RAID6. These provide a layout which is identical to the | |
606 | corresponding RAID5 layout on the first N\-1 devices, and has the 'Q' | |
607 | syndrome (the second 'parity' block used by RAID6) on the last device. | |
608 | These layouts are: | |
609 | .BR left\-symmetric\-6 , | |
610 | .BR right\-symmetric\-6 , | |
611 | .BR left\-asymmetric\-6 , | |
612 | .BR right\-asymmetric\-6 , | |
613 | and | |
10adfe9a | 614 | .BR parity\-first\-6 . |
e0fe762a | 615 | |
93e790af SW |
616 | When setting the failure mode for level |
617 | .I faulty, | |
1a7dfc35 | 618 | the options are: |
7e23fc43 PS |
619 | .BR write\-transient ", " wt , |
620 | .BR read\-transient ", " rt , | |
621 | .BR write\-persistent ", " wp , | |
622 | .BR read\-persistent ", " rp , | |
623 | .BR write\-all , | |
624 | .BR read\-fixable ", " rf , | |
53e8b987 | 625 | .BR clear ", " flush ", " none . |
b5e64645 | 626 | |
93e790af | 627 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
628 | between fault generation. Without a number, the fault is generated |
629 | once on the first relevant request. With a number, the fault will be | |
93e790af | 630 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
631 | every time the period elapses. |
632 | ||
633 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 634 | .B \-\-grow |
53e8b987 | 635 | option to set subsequent failure modes. |
b5e64645 NB |
636 | |
637 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 638 | and "flush" will clear any persistent faults. |
b5e64645 | 639 | |
6f9a21a7 | 640 | Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 641 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 642 | |
93e790af | 643 | .I 'n' |
e0fe762a | 644 | signals 'near' copies. Multiple copies of one data block are at |
b578481c NB |
645 | similar offsets in different devices. |
646 | ||
93e790af | 647 | .I 'o' |
b578481c NB |
648 | signals 'offset' copies. Rather than the chunks being duplicated |
649 | within a stripe, whole stripes are duplicated but are rotated by one | |
650 | device so duplicate blocks are on different devices. Thus subsequent | |
651 | copies of a block are in the next drive, and are one chunk further | |
652 | down. | |
653 | ||
93e790af | 654 | .I 'f' |
1a7dfc35 | 655 | signals 'far' copies |
93e790af | 656 | (multiple copies have very different offsets). |
e0fe762a | 657 | See md(4) for more detail about 'near', 'offset', and 'far'. |
1a7dfc35 NB |
658 | |
659 | The number is the number of copies of each datablock. 2 is normal, 3 | |
660 | can be useful. This number can be at most equal to the number of | |
661 | devices in the array. It does not need to divide evenly into that | |
662 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
663 | with an odd number of devices). | |
664 | ||
f24e2d6c N |
665 | When an array is converted between RAID5 and RAID6 an intermediate |
666 | RAID6 layout is used in which the second parity block (Q) is always on | |
667 | the last device. To convert a RAID5 to RAID6 and leave it in this new | |
668 | layout (which does not require re-striping) use | |
669 | .BR \-\-layout=preserve . | |
670 | This will try to avoid any restriping. | |
671 | ||
672 | The converse of this is | |
673 | .B \-\-layout=normalise | |
674 | which will change a non-standard RAID6 layout into a more standard | |
675 | arrangement. | |
676 | ||
cd29a5c8 | 677 | .TP |
7e23fc43 | 678 | .BR \-\-parity= |
53e8b987 | 679 | same as |
7e23fc43 | 680 | .B \-\-layout |
53e8b987 | 681 | (thus explaining the p of |
7e23fc43 | 682 | .BR \-p ). |
52826846 | 683 | |
e793c2e5 | 684 | .TP |
7e23fc43 | 685 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 686 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 687 | exist unless |
7e23fc43 | 688 | .B \-\-force |
53e8b987 | 689 | is also given. The same file should be provided |
2ae555c3 | 690 | when assembling the array. If the word |
93e790af | 691 | .B "internal" |
2ae555c3 NB |
692 | is given, then the bitmap is stored with the metadata on the array, |
693 | and so is replicated on all devices. If the word | |
93e790af | 694 | .B "none" |
2ae555c3 | 695 | is given with |
7e23fc43 | 696 | .B \-\-grow |
95a05b37 GJ |
697 | mode, then any bitmap that is present is removed. If the word |
698 | .B "clustered" | |
699 | is given, the array is created for a clustered environment. One bitmap | |
700 | is created for each node as defined by the | |
701 | .B \-\-nodes | |
702 | parameter and are stored internally. | |
e793c2e5 | 703 | |
2ae555c3 NB |
704 | To help catch typing errors, the filename must contain at least one |
705 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
706 | ||
707 | Note: external bitmaps are only known to work on ext2 and ext3. | |
708 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 709 | |
748952f7 N |
710 | When creating an array on devices which are 100G or larger, |
711 | .I mdadm | |
712 | automatically adds an internal bitmap as it will usually be | |
713 | beneficial. This can be suppressed with | |
714 | .B "\-\-bitmap=none". | |
715 | ||
cd29a5c8 | 716 | .TP |
7e23fc43 | 717 | .BR \-\-bitmap\-chunk= |
e0fe762a | 718 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
719 | Kilobytes of storage. |
720 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 721 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
722 | When using an |
723 | .B internal | |
b8ab2a50 N |
724 | bitmap, the chunksize defaults to 64Meg, or larger if necessary to |
725 | fit the bitmap into the available space. | |
5787fa49 | 726 | |
36fad8ec N |
727 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
728 | Gigabytes respectively. | |
729 | ||
cd29a5c8 | 730 | .TP |
7e23fc43 | 731 | .BR \-W ", " \-\-write\-mostly |
e0fe762a | 732 | subsequent devices listed in a |
7e23fc43 PS |
733 | .BR \-\-build , |
734 | .BR \-\-create , | |
2ae555c3 | 735 | or |
7e23fc43 | 736 | .B \-\-add |
2ae555c3 NB |
737 | command will be flagged as 'write-mostly'. This is valid for RAID1 |
738 | only and means that the 'md' driver will avoid reading from these | |
739 | devices if at all possible. This can be useful if mirroring over a | |
740 | slow link. | |
52826846 | 741 | |
2ae555c3 | 742 | .TP |
7e23fc43 | 743 | .BR \-\-write\-behind= |
2ae555c3 | 744 | Specify that write-behind mode should be enabled (valid for RAID1 |
e0fe762a N |
745 | only). If an argument is specified, it will set the maximum number |
746 | of outstanding writes allowed. The default value is 256. | |
2ae555c3 NB |
747 | A write-intent bitmap is required in order to use write-behind |
748 | mode, and write-behind is only attempted on drives marked as | |
749 | .IR write-mostly . | |
dd0781e5 NB |
750 | |
751 | .TP | |
7e23fc43 | 752 | .BR \-\-assume\-clean |
dd0781e5 NB |
753 | Tell |
754 | .I mdadm | |
47d79ef8 NB |
755 | that the array pre-existed and is known to be clean. It can be useful |
756 | when trying to recover from a major failure as you can be sure that no | |
757 | data will be affected unless you actually write to the array. It can | |
758 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 759 | initial resync, however this practice \(em while normally safe \(em is not |
e0fe762a | 760 | recommended. Use this only if you really know what you are doing. |
6acad481 ME |
761 | .IP |
762 | When the devices that will be part of a new array were filled | |
763 | with zeros before creation the operator knows the array is | |
764 | actually clean. If that is the case, such as after running | |
765 | badblocks, this argument can be used to tell mdadm the | |
766 | facts the operator knows. | |
ce52f92f N |
767 | .IP |
768 | When an array is resized to a larger size with | |
769 | .B "\-\-grow \-\-size=" | |
770 | the new space is normally resynced in that same way that the whole | |
6cbf8fb8 | 771 | array is resynced at creation. From Linux version 3.0, |
ce52f92f N |
772 | .B \-\-assume\-clean |
773 | can be used with that command to avoid the automatic resync. | |
dd0781e5 | 774 | |
2ae555c3 | 775 | .TP |
7e23fc43 | 776 | .BR \-\-backup\-file= |
53e8b987 | 777 | This is needed when |
7e23fc43 | 778 | .B \-\-grow |
cd19c0cf JR |
779 | is used to increase the number of raid-devices in a RAID5 or RAID6 if |
780 | there are no spare devices available, or to shrink, change RAID level | |
781 | or layout. See the GROW MODE section below on RAID\-DEVICES CHANGES. | |
782 | The file must be stored on a separate device, not on the RAID array | |
783 | being reshaped. | |
2ae555c3 | 784 | |
40c9a66a N |
785 | .TP |
786 | .B \-\-data\-offset= | |
787 | Arrays with 1.x metadata can leave a gap between the start of the | |
788 | device and the start of array data. This gap can be used for various | |
789 | metadata. The start of data is known as the | |
790 | .IR data\-offset . | |
791 | Normally an appropriate data offset is computed automatically. | |
792 | However it can be useful to set it explicitly such as when re-creating | |
793 | an array which was originally created using a different version of | |
794 | .I mdadm | |
795 | which computed a different offset. | |
796 | ||
797 | Setting the offset explicitly over-rides the default. The value given | |
798 | is in Kilobytes unless an 'M' or 'G' suffix is given. | |
799 | ||
800 | Since Linux 3.4, | |
801 | .B \-\-data\-offset | |
802 | can also be used with | |
803 | .B --grow | |
804 | for some RAID levels (initially on RAID10). This allows the | |
72ca9bcf | 805 | data\-offset to be changed as part of the reshape process. When the |
40c9a66a N |
806 | data offset is changed, no backup file is required as the difference |
807 | in offsets is used to provide the same functionality. | |
808 | ||
809 | When the new offset is earlier than the old offset, the number of | |
810 | devices in the array cannot shrink. When it is after the old offset, | |
811 | the number of devices in the array cannot increase. | |
812 | ||
72ca9bcf N |
813 | When creating an array, |
814 | .B \-\-data\-offset | |
815 | can be specified as | |
816 | .BR variable . | |
817 | In the case each member device is expected to have a offset appended | |
818 | to the name, separated by a colon. This makes it possible to recreate | |
819 | exactly an array which has varying data offsets (as can happen when | |
820 | different versions of | |
821 | .I mdadm | |
822 | are used to add different devices). | |
823 | ||
f211a137 AK |
824 | .TP |
825 | .BR \-\-continue | |
826 | This option is complementary to the | |
827 | .B \-\-freeze-reshape | |
828 | option for assembly. It is needed when | |
829 | .B \-\-grow | |
830 | operation is interrupted and it is not restarted automatically due to | |
831 | .B \-\-freeze-reshape | |
832 | usage during array assembly. This option is used together with | |
833 | .BR \-G | |
834 | , ( | |
835 | .BR \-\-grow | |
836 | ) command and device for a pending reshape to be continued. | |
837 | All parameters required for reshape continuation will be read from array metadata. | |
838 | If initial | |
839 | .BR \-\-grow | |
840 | command had required | |
841 | .BR \-\-backup\-file= | |
842 | option to be set, continuation option will require to have exactly the same | |
843 | backup file given as well. | |
844 | .IP | |
845 | Any other parameter passed together with | |
846 | .BR \-\-continue | |
847 | option will be ignored. | |
848 | ||
947fd4dd | 849 | .TP |
7e23fc43 | 850 | .BR \-N ", " \-\-name= |
947fd4dd NB |
851 | Set a |
852 | .B name | |
853 | for the array. This is currently only effective when creating an | |
e0fe762a N |
854 | array with a version-1 superblock, or an array in a DDF container. |
855 | The name is a simple textual string that can be used to identify array | |
856 | components when assembling. If name is needed but not specified, it | |
857 | is taken from the basename of the device that is being created. | |
858 | e.g. when creating | |
859 | .I /dev/md/home | |
860 | the | |
861 | .B name | |
862 | will default to | |
863 | .IR home . | |
947fd4dd | 864 | |
dd0781e5 | 865 | .TP |
7e23fc43 | 866 | .BR \-R ", " \-\-run |
dd0781e5 NB |
867 | Insist that |
868 | .I mdadm | |
869 | run the array, even if some of the components | |
870 | appear to be active in another array or filesystem. Normally | |
871 | .I mdadm | |
872 | will ask for confirmation before including such components in an | |
873 | array. This option causes that question to be suppressed. | |
874 | ||
875 | .TP | |
7e23fc43 | 876 | .BR \-f ", " \-\-force |
dd0781e5 NB |
877 | Insist that |
878 | .I mdadm | |
879 | accept the geometry and layout specified without question. Normally | |
880 | .I mdadm | |
881 | will not allow creation of an array with only one device, and will try | |
e0fe762a | 882 | to create a RAID5 array with one missing drive (as this makes the |
dd0781e5 | 883 | initial resync work faster). With |
7e23fc43 | 884 | .BR \-\-force , |
dd0781e5 NB |
885 | .I mdadm |
886 | will not try to be so clever. | |
887 | ||
0ea8f5b1 N |
888 | .TP |
889 | .BR \-o ", " \-\-readonly | |
890 | Start the array | |
891 | .B read only | |
892 | rather than read-write as normal. No writes will be allowed to the | |
893 | array, and no resync, recovery, or reshape will be started. | |
894 | ||
dd0781e5 | 895 | .TP |
257c1dc2 N |
896 | .BR \-a ", " "\-\-auto{=yes,md,mdp,part,p}{NN}" |
897 | Instruct mdadm how to create the device file if needed, possibly allocating | |
48f7b27a | 898 | an unused minor number. "md" causes a non-partitionable array |
257c1dc2 N |
899 | to be used (though since Linux 2.6.28, these array devices are in fact |
900 | partitionable). "mdp", "part" or "p" causes a partitionable array (2.6 and | |
2ae555c3 | 901 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 902 | a 'standard' format, and the type and minor number will be determined |
257c1dc2 N |
903 | from this. With mdadm 3.0, device creation is normally left up to |
904 | .I udev | |
905 | so this option is unlikely to be needed. | |
906 | See DEVICE NAMES below. | |
48f7b27a | 907 | |
a9d69660 | 908 | The argument can also come immediately after |
7e23fc43 | 909 | "\-a". e.g. "\-ap". |
dd0781e5 | 910 | |
53e8b987 | 911 | If |
7e23fc43 | 912 | .B \-\-auto |
53e8b987 | 913 | is not given on the command line or in the config file, then |
75723446 | 914 | the default will be |
7e23fc43 | 915 | .BR \-\-auto=yes . |
75723446 | 916 | |
1337546d | 917 | If |
7e23fc43 | 918 | .B \-\-scan |
1337546d NB |
919 | is also given, then any |
920 | .I auto= | |
35cc5be4 | 921 | entries in the config file will override the |
7e23fc43 | 922 | .B \-\-auto |
1337546d NB |
923 | instruction given on the command line. |
924 | ||
dd0781e5 NB |
925 | For partitionable arrays, |
926 | .I mdadm | |
927 | will create the device file for the whole array and for the first 4 | |
928 | partitions. A different number of partitions can be specified at the | |
929 | end of this option (e.g. | |
7e23fc43 | 930 | .BR \-\-auto=p7 ). |
2ae555c3 | 931 | If the device name ends with a digit, the partition names add a 'p', |
e0fe762a N |
932 | and a number, e.g. |
933 | .IR /dev/md/home1p3 . | |
934 | If there is no trailing digit, then the partition names just have a | |
935 | number added, e.g. | |
936 | .IR /dev/md/scratch3 . | |
dd0781e5 | 937 | |
48f7b27a NB |
938 | If the md device name is in a 'standard' format as described in DEVICE |
939 | NAMES, then it will be created, if necessary, with the appropriate | |
e0fe762a N |
940 | device number based on that name. If the device name is not in one of these |
941 | formats, then a unused device number will be allocated. The device | |
48f7b27a NB |
942 | number will be considered unused if there is no active array for that |
943 | number, and there is no entry in /dev for that number and with a | |
e0fe762a | 944 | non-standard name. Names that are not in 'standard' format are only |
8fd8d9c4 N |
945 | allowed in "/dev/md/". |
946 | ||
3c7efacb NK |
947 | This is meaningful with |
948 | .B \-\-create | |
949 | or | |
950 | .BR \-\-build . | |
951 | ||
3c7efacb NK |
952 | .TP |
953 | .BR \-a ", " "\-\-add" | |
954 | This option can be used in Grow mode in two cases. | |
955 | ||
956 | If the target array is a Linear array, then | |
957 | .B \-\-add | |
958 | can be used to add one or more devices to the array. They | |
959 | are simply catenated on to the end of the array. Once added, the | |
960 | devices cannot be removed. | |
961 | ||
962 | If the | |
963 | .B \-\-raid\-disks | |
964 | option is being used to increase the number of devices in an array, | |
965 | then | |
966 | .B \-\-add | |
967 | can be used to add some extra devices to be included in the array. | |
968 | In most cases this is not needed as the extra devices can be added as | |
969 | spares first, and then the number of raid-disks can be changed. | |
970 | However for RAID0, it is not possible to add spares. So to increase | |
971 | the number of devices in a RAID0, it is necessary to set the new | |
972 | number of devices, and to add the new devices, in the same command. | |
973 | ||
52826846 NB |
974 | .SH For assemble: |
975 | ||
cd29a5c8 | 976 | .TP |
7e23fc43 | 977 | .BR \-u ", " \-\-uuid= |
e0fe762a | 978 | uuid of array to assemble. Devices which don't have this uuid are |
cd29a5c8 NB |
979 | excluded |
980 | ||
981 | .TP | |
7e23fc43 | 982 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
983 | Minor number of device that array was created for. Devices which |
984 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 985 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
986 | the array is later assembled as /dev/md2. |
987 | ||
d013a55e | 988 | Giving the literal word "dev" for |
7e23fc43 | 989 | .B \-\-super\-minor |
d013a55e NB |
990 | will cause |
991 | .I mdadm | |
992 | to use the minor number of the md device that is being assembled. | |
993 | e.g. when assembling | |
994 | .BR /dev/md0 , | |
51ac42e3 | 995 | .B \-\-super\-minor=dev |
d013a55e NB |
996 | will look for super blocks with a minor number of 0. |
997 | ||
e0fe762a N |
998 | .B \-\-super\-minor |
999 | is only relevant for v0.90 metadata, and should not normally be used. | |
1000 | Using | |
1001 | .B \-\-uuid | |
1002 | is much safer. | |
1003 | ||
947fd4dd | 1004 | .TP |
7e23fc43 | 1005 | .BR \-N ", " \-\-name= |
947fd4dd | 1006 | Specify the name of the array to assemble. This must be the name |
624920bb | 1007 | that was specified when creating the array. It must either match |
93e790af | 1008 | the name stored in the superblock exactly, or it must match |
41a3b72a | 1009 | with the current |
624920bb | 1010 | .I homehost |
93e790af | 1011 | prefixed to the start of the given name. |
947fd4dd | 1012 | |
cd29a5c8 | 1013 | .TP |
7e23fc43 | 1014 | .BR \-f ", " \-\-force |
e0fe762a N |
1015 | Assemble the array even if the metadata on some devices appears to be |
1016 | out-of-date. If | |
1017 | .I mdadm | |
1018 | cannot find enough working devices to start the array, but can find | |
1019 | some devices that are recorded as having failed, then it will mark | |
1020 | those devices as working so that the array can be started. | |
1021 | An array which requires | |
1022 | .B \-\-force | |
1023 | to be started may contain data corruption. Use it carefully. | |
52826846 | 1024 | |
cd29a5c8 | 1025 | .TP |
7e23fc43 | 1026 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
1027 | Attempt to start the array even if fewer drives were given than were |
1028 | present last time the array was active. Normally if not all the | |
1029 | expected drives are found and | |
7e23fc43 | 1030 | .B \-\-scan |
cd29a5c8 NB |
1031 | is not used, then the array will be assembled but not started. |
1032 | With | |
7e23fc43 | 1033 | .B \-\-run |
cd29a5c8 | 1034 | an attempt will be made to start it anyway. |
52826846 | 1035 | |
b8a8ccf9 | 1036 | .TP |
7e23fc43 | 1037 | .B \-\-no\-degraded |
b8a8ccf9 | 1038 | This is the reverse of |
7e23fc43 | 1039 | .B \-\-run |
93e790af | 1040 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 1041 | are present. This is only needed with |
93e790af SW |
1042 | .B \-\-scan, |
1043 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
1044 | not as reliable as you would like. |
1045 | ||
dd0781e5 | 1046 | .TP |
7e23fc43 | 1047 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
1048 | See this option under Create and Build options. |
1049 | ||
e793c2e5 | 1050 | .TP |
7e23fc43 | 1051 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
1052 | Specify the bitmap file that was given when the array was created. If |
1053 | an array has an | |
1054 | .B internal | |
1055 | bitmap, there is no need to specify this when assembling the array. | |
1056 | ||
1057 | .TP | |
7e23fc43 | 1058 | .BR \-\-backup\-file= |
2ae555c3 | 1059 | If |
7e23fc43 | 1060 | .B \-\-backup\-file |
87f26d14 N |
1061 | was used while reshaping an array (e.g. changing number of devices or |
1062 | chunk size) and the system crashed during the critical section, then the same | |
7e23fc43 | 1063 | .B \-\-backup\-file |
53e8b987 | 1064 | must be presented to |
7e23fc43 | 1065 | .B \-\-assemble |
cd19c0cf JR |
1066 | to allow possibly corrupted data to be restored, and the reshape |
1067 | to be completed. | |
e793c2e5 | 1068 | |
87f26d14 N |
1069 | .TP |
1070 | .BR \-\-invalid\-backup | |
1071 | If the file needed for the above option is not available for any | |
1072 | reason an empty file can be given together with this option to | |
1073 | indicate that the backup file is invalid. In this case the data that | |
1074 | was being rearranged at the time of the crash could be irrecoverably | |
1075 | lost, but the rest of the array may still be recoverable. This option | |
1076 | should only be used as a last resort if there is no way to recover the | |
1077 | backup file. | |
1078 | ||
1079 | ||
5787fa49 | 1080 | .TP |
7e23fc43 | 1081 | .BR \-U ", " \-\-update= |
5787fa49 | 1082 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
1083 | argument given to this flag can be one of |
1084 | .BR sparc2.2 , | |
1085 | .BR summaries , | |
7d99579f | 1086 | .BR uuid , |
c4f12c13 | 1087 | .BR name , |
0237e0ca | 1088 | .BR homehost , |
e5329c37 | 1089 | .BR resync , |
586ed405 | 1090 | .BR byteorder , |
bee8ec56 | 1091 | .BR devicesize , |
5a31170d | 1092 | .BR no\-bitmap , |
688e99a7 | 1093 | .BR bbl , |
47120ad5 | 1094 | .BR no\-bbl , |
afa368f4 | 1095 | .BR metadata , |
5787fa49 | 1096 | or |
7e23fc43 | 1097 | .BR super\-minor . |
5787fa49 NB |
1098 | |
1099 | The | |
1100 | .B sparc2.2 | |
7d99579f | 1101 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
1102 | machine running a patched 2.2 Linux kernel. This kernel got the |
1103 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 1104 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
1105 | option to |
1106 | .I mdadm | |
1107 | to see what effect this would have. | |
1108 | ||
1109 | The | |
7e23fc43 | 1110 | .B super\-minor |
5787fa49 | 1111 | option will update the |
2ae555c3 | 1112 | .B "preferred minor" |
5787fa49 | 1113 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
1114 | assembled. |
1115 | This can be useful if | |
7e23fc43 | 1116 | .B \-\-examine |
45c073c9 | 1117 | reports a different "Preferred Minor" to |
7e23fc43 | 1118 | .BR \-\-detail . |
45c073c9 | 1119 | In some cases this update will be performed automatically |
e0fe762a | 1120 | by the kernel driver. In particular the update happens automatically |
45c073c9 NB |
1121 | at the first write to an array with redundancy (RAID level 1 or |
1122 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 1123 | |
7d99579f NB |
1124 | The |
1125 | .B uuid | |
1126 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 1127 | .B \-\-uuid |
53e8b987 | 1128 | option that UUID will be used as a new UUID and will |
7d99579f NB |
1129 | .B NOT |
1130 | be used to help identify the devices in the array. | |
53e8b987 | 1131 | If no |
7e23fc43 | 1132 | .B \-\-uuid |
53e8b987 | 1133 | is given, a random UUID is chosen. |
7d99579f | 1134 | |
c4f12c13 NB |
1135 | The |
1136 | .B name | |
1137 | option will change the | |
1138 | .I name | |
1139 | of the array as stored in the superblock. This is only supported for | |
1140 | version-1 superblocks. | |
1141 | ||
0237e0ca NB |
1142 | The |
1143 | .B homehost | |
1144 | option will change the | |
1145 | .I homehost | |
1146 | as recorded in the superblock. For version-0 superblocks, this is the | |
1147 | same as updating the UUID. | |
1148 | For version-1 superblocks, this involves updating the name. | |
1149 | ||
e5329c37 NB |
1150 | The |
1151 | .B resync | |
1152 | option will cause the array to be marked | |
1153 | .I dirty | |
e0fe762a N |
1154 | meaning that any redundancy in the array (e.g. parity for RAID5, |
1155 | copies for RAID1) may be incorrect. This will cause the RAID system | |
e5329c37 NB |
1156 | to perform a "resync" pass to make sure that all redundant information |
1157 | is correct. | |
1158 | ||
586ed405 NB |
1159 | The |
1160 | .B byteorder | |
1161 | option allows arrays to be moved between machines with different | |
1162 | byte-order. | |
2ae555c3 | 1163 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 1164 | .B "\-\-update=byteorder" |
586ed405 NB |
1165 | will cause |
1166 | .I mdadm | |
1167 | to expect superblocks to have their byteorder reversed, and will | |
1168 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 1169 | with original (Version 0.90) superblocks. |
586ed405 | 1170 | |
feb716e9 NB |
1171 | The |
1172 | .B summaries | |
e0fe762a | 1173 | option will correct the summaries in the superblock. That is the |
feb716e9 | 1174 | counts of total, working, active, failed, and spare devices. |
5787fa49 | 1175 | |
bee8ec56 NB |
1176 | The |
1177 | .B devicesize | |
5a31170d | 1178 | option will rarely be of use. It applies to version 1.1 and 1.2 metadata |
bee8ec56 NB |
1179 | only (where the metadata is at the start of the device) and is only |
1180 | useful when the component device has changed size (typically become | |
1181 | larger). The version 1 metadata records the amount of the device that | |
1182 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
1183 | array becomes larger, the metadata will still be visible, but the | |
1184 | extra space will not. In this case it might be useful to assemble the | |
1185 | array with | |
7e23fc43 | 1186 | .BR \-\-update=devicesize . |
bee8ec56 NB |
1187 | This will cause |
1188 | .I mdadm | |
1189 | to determine the maximum usable amount of space on each device and | |
1190 | update the relevant field in the metadata. | |
1191 | ||
afa368f4 N |
1192 | The |
1193 | .B metadata | |
1194 | option only works on v0.90 metadata arrays and will convert them to | |
1195 | v1.0 metadata. The array must not be dirty (i.e. it must not need a | |
1196 | sync) and it must not have a write-intent bitmap. | |
1197 | ||
1198 | The old metadata will remain on the devices, but will appear older | |
1199 | than the new metadata and so will usually be ignored. The old metadata | |
1200 | (or indeed the new metadata) can be removed by giving the appropriate | |
1201 | .B \-\-metadata= | |
1202 | option to | |
1203 | .BR \-\-zero\-superblock . | |
1204 | ||
5a31170d N |
1205 | The |
1206 | .B no\-bitmap | |
1207 | option can be used when an array has an internal bitmap which is | |
1208 | corrupt in some way so that assembling the array normally fails. It | |
1209 | will cause any internal bitmap to be ignored. | |
1210 | ||
688e99a7 N |
1211 | The |
1212 | .B bbl | |
1213 | option will reserve space in each device for a bad block list. This | |
1214 | will be 4K in size and positioned near the end of any free space | |
1215 | between the superblock and the data. | |
1216 | ||
1217 | The | |
1218 | .B no\-bbl | |
1219 | option will cause any reservation of space for a bad block list to be | |
1220 | removed. If the bad block list contains entries, this will fail, as | |
1221 | removing the list could cause data corruption. | |
1222 | ||
afd0a969 AK |
1223 | .TP |
1224 | .BR \-\-freeze\-reshape | |
1225 | Option is intended to be used in start-up scripts during initrd boot phase. | |
1226 | When array under reshape is assembled during initrd phase, this option | |
1227 | stops reshape after reshape critical section is being restored. This happens | |
1228 | before file system pivot operation and avoids loss of file system context. | |
1229 | Losing file system context would cause reshape to be broken. | |
1230 | ||
a6482415 N |
1231 | Reshape can be continued later using the |
1232 | .B \-\-continue | |
1233 | option for the grow command. | |
afd0a969 | 1234 | |
e0d19036 | 1235 | .SH For Manage mode: |
52826846 | 1236 | |
3d5279b0 N |
1237 | .TP |
1238 | .BR \-t ", " \-\-test | |
1239 | Unless a more serious error occurred, | |
1240 | .I mdadm | |
1241 | will exit with a status of 2 if no changes were made to the array and | |
1242 | 0 if at least one change was made. | |
1243 | This can be useful when an indirect specifier such as | |
1244 | .BR missing , | |
1245 | .B detached | |
1246 | or | |
1247 | .B faulty | |
1248 | is used in requesting an operation on the array. | |
1249 | .B \-\-test | |
1250 | will report failure if these specifiers didn't find any match. | |
1251 | ||
cd29a5c8 | 1252 | .TP |
7e23fc43 | 1253 | .BR \-a ", " \-\-add |
3d5279b0 N |
1254 | hot-add listed devices. |
1255 | If a device appears to have recently been part of the array | |
342460cb | 1256 | (possibly it failed or was removed) the device is re\-added as described |
3d5279b0 N |
1257 | in the next point. |
1258 | If that fails or the device was never part of the array, the device is | |
1259 | added as a hot-spare. | |
1260 | If the array is degraded, it will immediately start to rebuild data | |
1261 | onto that spare. | |
1262 | ||
1263 | Note that this and the following options are only meaningful on array | |
1264 | with redundancy. They don't apply to RAID0 or Linear. | |
52826846 | 1265 | |
fe80f49b | 1266 | .TP |
7e23fc43 | 1267 | .BR \-\-re\-add |
eae6b036 | 1268 | re\-add a device that was previously removed from an array. |
3d5279b0 N |
1269 | If the metadata on the device reports that it is a member of the |
1270 | array, and the slot that it used is still vacant, then the device will | |
1271 | be added back to the array in the same position. This will normally | |
1272 | cause the data for that device to be recovered. However based on the | |
1273 | event count on the device, the recovery may only require sections that | |
1274 | are flagged a write-intent bitmap to be recovered or may not require | |
1275 | any recovery at all. | |
1276 | ||
1277 | When used on an array that has no metadata (i.e. it was built with | |
1278 | .BR \-\-build) | |
1279 | it will be assumed that bitmap-based recovery is enough to make the | |
1280 | device fully consistent with the array. | |
fe80f49b | 1281 | |
688e99a7 | 1282 | When used with v1.x metadata, |
833bb0f8 N |
1283 | .B \-\-re\-add |
1284 | can be accompanied by | |
688e99a7 N |
1285 | .BR \-\-update=devicesize , |
1286 | .BR \-\-update=bbl ", or" | |
1287 | .BR \-\-update=no\-bbl . | |
1288 | See the description of these option when used in Assemble mode for an | |
1289 | explanation of their use. | |
833bb0f8 | 1290 | |
a4e13010 N |
1291 | If the device name given is |
1292 | .B missing | |
262e3b7f N |
1293 | then |
1294 | .I mdadm | |
1295 | will try to find any device that looks like it should be | |
a4e13010 N |
1296 | part of the array but isn't and will try to re\-add all such devices. |
1297 | ||
262e3b7f N |
1298 | If the device name given is |
1299 | .B faulty | |
1300 | then | |
1301 | .I mdadm | |
1302 | will find all devices in the array that are marked | |
1303 | .BR faulty , | |
1304 | remove them and attempt to immediately re\-add them. This can be | |
1305 | useful if you are certain that the reason for failure has been | |
1306 | resolved. | |
1307 | ||
f33a71f1 N |
1308 | .TP |
1309 | .B \-\-add\-spare | |
1310 | Add a device as a spare. This is similar to | |
1311 | .B \-\-add | |
1312 | except that it does not attempt | |
1313 | .B \-\-re\-add | |
1314 | first. The device will be added as a spare even if it looks like it | |
1315 | could be an recent member of the array. | |
1316 | ||
cd29a5c8 | 1317 | .TP |
7e23fc43 | 1318 | .BR \-r ", " \-\-remove |
2d465520 | 1319 | remove listed devices. They must not be active. i.e. they should |
64a78416 N |
1320 | be failed or spare devices. |
1321 | ||
1322 | As well as the name of a device file | |
b80da661 NB |
1323 | (e.g. |
1324 | .BR /dev/sda1 ) | |
1325 | the words | |
64a78416 | 1326 | .BR failed , |
b80da661 | 1327 | .B detached |
64a78416 N |
1328 | and names like |
1329 | .B set-A | |
b80da661 NB |
1330 | can be given to |
1331 | .BR \-\-remove . | |
1332 | The first causes all failed device to be removed. The second causes | |
93e790af | 1333 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
1334 | returns |
1335 | .BR ENXIO ) | |
64a78416 N |
1336 | to be removed. |
1337 | The third will remove a set as describe below under | |
1338 | .BR \-\-fail . | |
52826846 | 1339 | |
cd29a5c8 | 1340 | .TP |
7e23fc43 | 1341 | .BR \-f ", " \-\-fail |
70c55e36 | 1342 | Mark listed devices as faulty. |
b80da661 NB |
1343 | As well as the name of a device file, the word |
1344 | .B detached | |
64a78416 N |
1345 | or a set name like |
1346 | .B set\-A | |
1347 | can be given. The former will cause any device that has been detached from | |
b80da661 | 1348 | the system to be marked as failed. It can then be removed. |
52826846 | 1349 | |
64a78416 N |
1350 | For RAID10 arrays where the number of copies evenly divides the number |
1351 | of devices, the devices can be conceptually divided into sets where | |
1352 | each set contains a single complete copy of the data on the array. | |
1353 | Sometimes a RAID10 array will be configured so that these sets are on | |
1354 | separate controllers. In this case all the devices in one set can be | |
1355 | failed by giving a name like | |
1356 | .B set\-A | |
1357 | or | |
1358 | .B set\-B | |
1359 | to | |
1360 | .BR \-\-fail . | |
1361 | The appropriate set names are reported by | |
1362 | .BR \-\-detail . | |
1363 | ||
cd29a5c8 | 1364 | .TP |
7e23fc43 | 1365 | .BR \-\-set\-faulty |
53e8b987 | 1366 | same as |
7e23fc43 | 1367 | .BR \-\-fail . |
52826846 | 1368 | |
70c55e36 N |
1369 | .TP |
1370 | .B \-\-replace | |
1371 | Mark listed devices as requiring replacement. As soon as a spare is | |
1372 | available, it will be rebuilt and will replace the marked device. | |
1373 | This is similar to marking a device as faulty, but the device remains | |
1374 | in service during the recovery process to increase resilience against | |
1375 | multiple failures. When the replacement process finishes, the | |
1376 | replaced device will be marked as faulty. | |
1377 | ||
1378 | .TP | |
1379 | .B \-\-with | |
1380 | This can follow a list of | |
1381 | .B \-\-replace | |
1382 | devices. The devices listed after | |
1383 | .B \-\-with | |
1384 | will be preferentially used to replace the devices listed after | |
1385 | .BR \-\-replace . | |
1386 | These device must already be spare devices in the array. | |
1387 | ||
b3d31955 N |
1388 | .TP |
1389 | .BR \-\-write\-mostly | |
a4e13010 | 1390 | Subsequent devices that are added or re\-added will have the 'write-mostly' |
e0fe762a | 1391 | flag set. This is only valid for RAID1 and means that the 'md' driver |
b3d31955 N |
1392 | will avoid reading from these devices if possible. |
1393 | .TP | |
1394 | .BR \-\-readwrite | |
a4e13010 | 1395 | Subsequent devices that are added or re\-added will have the 'write-mostly' |
b3d31955 N |
1396 | flag cleared. |
1397 | ||
2ae555c3 | 1398 | .P |
e0fe762a | 1399 | Each of these options requires that the first device listed is the array |
93e790af | 1400 | to be acted upon, and the remainder are component devices to be added, |
e0fe762a | 1401 | removed, marked as faulty, etc. Several different operations can be |
2ae555c3 NB |
1402 | specified for different devices, e.g. |
1403 | .in +5 | |
7e23fc43 | 1404 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
1405 | .in -5 |
1406 | Each operation applies to all devices listed until the next | |
93e790af | 1407 | operation. |
2ae555c3 NB |
1408 | |
1409 | If an array is using a write-intent bitmap, then devices which have | |
a4e13010 | 1410 | been removed can be re\-added in a way that avoids a full |
93e790af | 1411 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
1412 | since the device was removed. For arrays with persistent metadata |
1413 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 1414 | .B \-\-build |
2ae555c3 | 1415 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 1416 | .BR \-\-re\-add . |
2ae555c3 NB |
1417 | |
1418 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
1419 | use, i.e. that must be spares or failed devices. To remove an active |
1420 | device, it must first be marked as | |
1421 | .B faulty. | |
2ae555c3 NB |
1422 | |
1423 | .SH For Misc mode: | |
1424 | ||
1425 | .TP | |
7e23fc43 | 1426 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
1427 | Examine a device to see |
1428 | (1) if it is an md device and (2) if it is a component of an md | |
1429 | array. | |
1430 | Information about what is discovered is presented. | |
1431 | ||
1432 | .TP | |
7e23fc43 | 1433 | .BR \-D ", " \-\-detail |
e0fe762a | 1434 | Print details of one or more md devices. |
5787fa49 | 1435 | |
4cce4069 DW |
1436 | .TP |
1437 | .BR \-\-detail\-platform | |
e0fe762a | 1438 | Print details of the platform's RAID capabilities (firmware / hardware |
9eafa1de MN |
1439 | topology) for a given metadata format. If used without argument, mdadm |
1440 | will scan all controllers looking for their capabilities. Otherwise, mdadm | |
1441 | will only look at the controller specified by the argument in form of an | |
1442 | absolute filepath or a link, e.g. | |
1443 | .IR /sys/devices/pci0000:00/0000:00:1f.2 . | |
4cce4069 | 1444 | |
54bad364 KS |
1445 | .TP |
1446 | .BR \-Y ", " \-\-export | |
1447 | When used with | |
9ca39acb N |
1448 | .BR \-\-detail , |
1449 | .BR \-\-detail-platform , | |
0d726f17 | 1450 | .BR \-\-examine , |
9ca39acb N |
1451 | or |
1452 | .B \-\-incremental | |
54bad364 KS |
1453 | output will be formatted as |
1454 | .B key=value | |
1455 | pairs for easy import into the environment. | |
1456 | ||
9ca39acb N |
1457 | With |
1458 | .B \-\-incremental | |
1459 | The value | |
1460 | .B MD_STARTED | |
1461 | indicates whether an array was started | |
1462 | .RB ( yes ) | |
1463 | or not, which may include a reason | |
1464 | .RB ( unsafe ", " nothing ", " no ). | |
1465 | Also the value | |
1466 | .B MD_FOREIGN | |
1467 | indicates if the array is expected on this host | |
1468 | .RB ( no ), | |
1469 | or seems to be from elsewhere | |
1470 | .RB ( yes ). | |
1471 | ||
2ae555c3 | 1472 | .TP |
7e23fc43 | 1473 | .BR \-E ", " \-\-examine |
e0fe762a N |
1474 | Print contents of the metadata stored on the named device(s). |
1475 | Note the contrast between | |
1476 | .B \-\-examine | |
1477 | and | |
1478 | .BR \-\-detail . | |
1479 | .B \-\-examine | |
1480 | applies to devices which are components of an array, while | |
1481 | .B \-\-detail | |
1482 | applies to a whole array which is currently active. | |
5787fa49 | 1483 | .TP |
7e23fc43 | 1484 | .B \-\-sparc2.2 |
e0fe762a N |
1485 | If an array was created on a SPARC machine with a 2.2 Linux kernel |
1486 | patched with RAID support, the superblock will have been created | |
1487 | incorrectly, or at least incompatibly with 2.4 and later kernels. | |
1488 | Using the | |
7e23fc43 | 1489 | .B \-\-sparc2.2 |
5787fa49 | 1490 | flag with |
7e23fc43 | 1491 | .B \-\-examine |
5787fa49 NB |
1492 | will fix the superblock before displaying it. If this appears to do |
1493 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 1494 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 1495 | |
2ae555c3 | 1496 | .TP |
7e23fc43 | 1497 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 1498 | Report information about a bitmap file. |
01d9299c | 1499 | The argument is either an external bitmap file or an array component |
e0fe762a N |
1500 | in case of an internal bitmap. Note that running this on an array |
1501 | device (e.g. | |
1502 | .BR /dev/md0 ) | |
1503 | does not report the bitmap for that array. | |
e0d19036 | 1504 | |
6d388a88 N |
1505 | .TP |
1506 | .B \-\-examine\-badblocks | |
1507 | List the bad-blocks recorded for the device, if a bad-blocks list has | |
1508 | been configured. Currently only | |
1509 | .B 1.x | |
1510 | metadata supports bad-blocks lists. | |
1511 | ||
74db60b0 N |
1512 | .TP |
1513 | .BI \-\-dump= directory | |
1514 | .TP | |
1515 | .BI \-\-restore= directory | |
1516 | Save metadata from lists devices, or restore metadata to listed devices. | |
1517 | ||
cd29a5c8 | 1518 | .TP |
7e23fc43 | 1519 | .BR \-R ", " \-\-run |
e0fe762a N |
1520 | start a partially assembled array. If |
1521 | .B \-\-assemble | |
1522 | did not find enough devices to fully start the array, it might leaving | |
1523 | it partially assembled. If you wish, you can then use | |
1524 | .B \-\-run | |
1525 | to start the array in degraded mode. | |
52826846 | 1526 | |
cd29a5c8 | 1527 | .TP |
7e23fc43 | 1528 | .BR \-S ", " \-\-stop |
cd29a5c8 | 1529 | deactivate array, releasing all resources. |
52826846 | 1530 | |
cd29a5c8 | 1531 | .TP |
7e23fc43 | 1532 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 1533 | mark array as readonly. |
52826846 | 1534 | |
cd29a5c8 | 1535 | .TP |
7e23fc43 | 1536 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 1537 | mark array as readwrite. |
52826846 | 1538 | |
e0d19036 | 1539 | .TP |
7e23fc43 | 1540 | .B \-\-zero\-superblock |
e0d19036 | 1541 | If the device contains a valid md superblock, the block is |
35cc5be4 | 1542 | overwritten with zeros. With |
7e23fc43 | 1543 | .B \-\-force |
35cc5be4 | 1544 | the block where the superblock would be is overwritten even if it |
e0d19036 | 1545 | doesn't appear to be valid. |
52826846 | 1546 | |
33414a01 DW |
1547 | .TP |
1548 | .B \-\-kill\-subarray= | |
1549 | If the device is a container and the argument to \-\-kill\-subarray | |
1550 | specifies an inactive subarray in the container, then the subarray is | |
1551 | deleted. Deleting all subarrays will leave an 'empty-container' or | |
afa368f4 N |
1552 | spare superblock on the drives. See |
1553 | .B \-\-zero\-superblock | |
1554 | for completely | |
33414a01 DW |
1555 | removing a superblock. Note that some formats depend on the subarray |
1556 | index for generating a UUID, this command will fail if it would change | |
1557 | the UUID of an active subarray. | |
1558 | ||
aa534678 DW |
1559 | .TP |
1560 | .B \-\-update\-subarray= | |
1561 | If the device is a container and the argument to \-\-update\-subarray | |
1562 | specifies a subarray in the container, then attempt to update the given | |
1563 | superblock field in the subarray. See below in | |
1564 | .B MISC MODE | |
1565 | for details. | |
1566 | ||
feb716e9 | 1567 | .TP |
7e23fc43 | 1568 | .BR \-t ", " \-\-test |
feb716e9 | 1569 | When used with |
7e23fc43 | 1570 | .BR \-\-detail , |
feb716e9 NB |
1571 | the exit status of |
1572 | .I mdadm | |
e0fe762a N |
1573 | is set to reflect the status of the device. See below in |
1574 | .B MISC MODE | |
1575 | for details. | |
feb716e9 | 1576 | |
b90c0e9a | 1577 | .TP |
7e23fc43 | 1578 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1579 | For each md device given, wait for any resync, recovery, or reshape |
1580 | activity to finish before returning. | |
1581 | .I mdadm | |
1582 | will return with success if it actually waited for every device | |
1583 | listed, otherwise it will return failure. | |
1584 | ||
1770662b DW |
1585 | .TP |
1586 | .BR \-\-wait\-clean | |
fabbfd48 DW |
1587 | For each md device given, or each device in /proc/mdstat if |
1588 | .B \-\-scan | |
1589 | is given, arrange for the array to be marked clean as soon as possible. | |
7146ec6a DW |
1590 | .I mdadm |
1591 | will return with success if the array uses external metadata and we | |
1592 | successfully waited. For native arrays this returns immediately as the | |
6a0ee6a0 DW |
1593 | kernel handles dirty-clean transitions at shutdown. No action is taken |
1594 | if safe-mode handling is disabled. | |
1770662b | 1595 | |
a740cf64 N |
1596 | .TP |
1597 | .B \-\-action= | |
1598 | Set the "sync_action" for all md devices given to one of | |
1599 | .BR idle , | |
1600 | .BR frozen , | |
1601 | .BR check , | |
1602 | .BR repair . | |
1603 | Setting to | |
1604 | .B idle | |
1605 | will abort any currently running action though some actions will | |
1606 | automatically restart. | |
1607 | Setting to | |
1608 | .B frozen | |
1609 | will abort any current action and ensure no other action starts | |
1610 | automatically. | |
1611 | ||
1612 | Details of | |
1613 | .B check | |
1614 | and | |
1615 | .B repair | |
1616 | can be found it | |
1617 | .IR md (4) | |
1618 | under | |
1619 | .BR "SCRUBBING AND MISMATCHES" . | |
1620 | ||
8382f19b NB |
1621 | .SH For Incremental Assembly mode: |
1622 | .TP | |
7e23fc43 | 1623 | .BR \-\-rebuild\-map ", " \-r |
8382f19b | 1624 | Rebuild the map file |
96fd06ed | 1625 | .RB ( {MAP_PATH} ) |
8382f19b NB |
1626 | that |
1627 | .I mdadm | |
1628 | uses to help track which arrays are currently being assembled. | |
1629 | ||
1630 | .TP | |
7e23fc43 | 1631 | .BR \-\-run ", " \-R |
8382f19b NB |
1632 | Run any array assembled as soon as a minimal number of devices are |
1633 | available, rather than waiting until all expected devices are present. | |
1634 | ||
1635 | .TP | |
7e23fc43 | 1636 | .BR \-\-scan ", " \-s |
8382f19b | 1637 | Only meaningful with |
7e23fc43 | 1638 | .B \-R |
8382f19b NB |
1639 | this will scan the |
1640 | .B map | |
1641 | file for arrays that are being incrementally assembled and will try to | |
1642 | start any that are not already started. If any such array is listed | |
1643 | in | |
1644 | .B mdadm.conf | |
1645 | as requiring an external bitmap, that bitmap will be attached first. | |
1646 | ||
29ba4804 N |
1647 | .TP |
1648 | .BR \-\-fail ", " \-f | |
1649 | This allows the hot-plug system to remove devices that have fully disappeared | |
1650 | from the kernel. It will first fail and then remove the device from any | |
1651 | array it belongs to. | |
1652 | The device name given should be a kernel device name such as "sda", | |
1653 | not a name in | |
1654 | .IR /dev . | |
1655 | ||
210597d1 PC |
1656 | .TP |
1657 | .BR \-\-path= | |
87eb4fab N |
1658 | Only used with \-\-fail. The 'path' given will be recorded so that if |
1659 | a new device appears at the same location it can be automatically | |
1660 | added to the same array. This allows the failed device to be | |
1661 | automatically replaced by a new device without metadata if it appears | |
1662 | at specified path. This option is normally only set by a | |
1663 | .I udev | |
1664 | script. | |
210597d1 | 1665 | |
e0d19036 NB |
1666 | .SH For Monitor mode: |
1667 | .TP | |
7e23fc43 | 1668 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1669 | Give a mail address to send alerts to. |
1670 | ||
1671 | .TP | |
7e23fc43 | 1672 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1673 | Give a program to be run whenever an event is detected. |
1674 | ||
773135f5 | 1675 | .TP |
7e23fc43 | 1676 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1677 | Cause all events to be reported through 'syslog'. The messages have |
1678 | facility of 'daemon' and varying priorities. | |
1679 | ||
e0d19036 | 1680 | .TP |
7e23fc43 | 1681 | .BR \-d ", " \-\-delay |
e0d19036 | 1682 | Give a delay in seconds. |
51ac42e3 | 1683 | .I mdadm |
e0d19036 | 1684 | polls the md arrays and then waits this many seconds before polling |
e0fe762a N |
1685 | again. The default is 60 seconds. Since 2.6.16, there is no need to |
1686 | reduce this as the kernel alerts | |
1687 | .I mdadm | |
1688 | immediately when there is any change. | |
e0d19036 | 1689 | |
9a36a9b7 ZB |
1690 | .TP |
1691 | .BR \-r ", " \-\-increment | |
1692 | Give a percentage increment. | |
1693 | .I mdadm | |
1694 | will generate RebuildNN events with the given percentage increment. | |
1695 | ||
d013a55e | 1696 | .TP |
7e23fc43 | 1697 | .BR \-f ", " \-\-daemonise |
d013a55e | 1698 | Tell |
51ac42e3 | 1699 | .I mdadm |
d013a55e | 1700 | to run as a background daemon if it decides to monitor anything. This |
e0fe762a | 1701 | causes it to fork and run in the child, and to disconnect from the |
d013a55e NB |
1702 | terminal. The process id of the child is written to stdout. |
1703 | This is useful with | |
7e23fc43 | 1704 | .B \-\-scan |
d013a55e NB |
1705 | which will only continue monitoring if a mail address or alert program |
1706 | is found in the config file. | |
1707 | ||
b5e64645 | 1708 | .TP |
7e23fc43 | 1709 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1710 | When |
51ac42e3 | 1711 | .I mdadm |
b5e64645 NB |
1712 | is running in daemon mode, write the pid of the daemon process to |
1713 | the specified file, instead of printing it on standard output. | |
1714 | ||
aa88f531 | 1715 | .TP |
7e23fc43 | 1716 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1717 | Check arrays only once. This will generate |
1718 | .B NewArray | |
1719 | events and more significantly | |
1720 | .B DegradedArray | |
a9d69660 NB |
1721 | and |
1722 | .B SparesMissing | |
aa88f531 NB |
1723 | events. Running |
1724 | .in +5 | |
7e23fc43 | 1725 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1726 | .in -5 |
1727 | from a cron script will ensure regular notification of any degraded arrays. | |
1728 | ||
98c6faba | 1729 | .TP |
7e23fc43 | 1730 | .BR \-t ", " \-\-test |
98c6faba NB |
1731 | Generate a |
1732 | .B TestMessage | |
1733 | alert for every array found at startup. This alert gets mailed and | |
1734 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1735 | message do get through successfully. |
98c6faba | 1736 | |
210597d1 PC |
1737 | .TP |
1738 | .BR \-\-no\-sharing | |
87eb4fab | 1739 | This inhibits the functionality for moving spares between arrays. |
210597d1 PC |
1740 | Only one monitoring process started with |
1741 | .B \-\-scan | |
87eb4fab N |
1742 | but without this flag is allowed, otherwise the two could interfere |
1743 | with each other. | |
210597d1 | 1744 | |
e0d19036 | 1745 | .SH ASSEMBLE MODE |
52826846 | 1746 | |
cd29a5c8 NB |
1747 | .HP 12 |
1748 | Usage: | |
7e23fc43 | 1749 | .B mdadm \-\-assemble |
5787fa49 NB |
1750 | .I md-device options-and-component-devices... |
1751 | .HP 12 | |
1752 | Usage: | |
7e23fc43 | 1753 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1754 | .I md-devices-and-options... |
cd29a5c8 NB |
1755 | .HP 12 |
1756 | Usage: | |
7e23fc43 | 1757 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1758 | .I options... |
52826846 | 1759 | |
cd29a5c8 | 1760 | .PP |
e0fe762a | 1761 | This usage assembles one or more RAID arrays from pre-existing components. |
9a9dab36 | 1762 | For each array, mdadm needs to know the md device, the identity of the |
e0fe762a | 1763 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1764 | |
5787fa49 | 1765 | In the first usage example (without the |
7e23fc43 | 1766 | .BR \-\-scan ) |
5787fa49 NB |
1767 | the first device given is the md device. |
1768 | In the second usage example, all devices listed are treated as md | |
1769 | devices and assembly is attempted. | |
1770 | In the third (where no devices are listed) all md devices that are | |
cb77f620 | 1771 | listed in the configuration file are assembled. If no arrays are |
e0fe762a N |
1772 | described by the configuration file, then any arrays that |
1773 | can be found on unused devices will be assembled. | |
52826846 | 1774 | |
d013a55e | 1775 | If precisely one device is listed, but |
7e23fc43 | 1776 | .B \-\-scan |
dd0781e5 | 1777 | is not given, then |
d013a55e NB |
1778 | .I mdadm |
1779 | acts as though | |
7e23fc43 | 1780 | .B \-\-scan |
93e790af | 1781 | was given and identity information is extracted from the configuration file. |
d013a55e | 1782 | |
2ae555c3 | 1783 | The identity can be given with the |
7e23fc43 | 1784 | .B \-\-uuid |
e0fe762a N |
1785 | option, the |
1786 | .B \-\-name | |
1787 | option, or the | |
7e23fc43 | 1788 | .B \-\-super\-minor |
93e790af SW |
1789 | option, will be taken from the md-device record in the config file, or |
1790 | will be taken from the super block of the first component-device | |
1791 | listed on the command line. | |
52826846 | 1792 | |
2ae555c3 | 1793 | Devices can be given on the |
7e23fc43 | 1794 | .B \-\-assemble |
e0fe762a | 1795 | command line or in the config file. Only devices which have an md |
5787fa49 NB |
1796 | superblock which contains the right identity will be considered for |
1797 | any array. | |
52826846 | 1798 | |
2ae555c3 | 1799 | The config file is only used if explicitly named with |
7e23fc43 | 1800 | .B \-\-config |
d013a55e | 1801 | or requested with (a possibly implicit) |
7e23fc43 | 1802 | .BR \-\-scan . |
52826846 | 1803 | In the later case, |
9a9dab36 | 1804 | .B /etc/mdadm.conf |
8fd8d9c4 N |
1805 | or |
1806 | .B /etc/mdadm/mdadm.conf | |
52826846 NB |
1807 | is used. |
1808 | ||
2ae555c3 | 1809 | If |
7e23fc43 | 1810 | .B \-\-scan |
cd29a5c8 NB |
1811 | is not given, then the config file will only be used to find the |
1812 | identity of md arrays. | |
52826846 | 1813 | |
2d465520 | 1814 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 1815 | .B \-\-scan |
e0fe762a N |
1816 | is not given and not all expected drives were listed, then the array |
1817 | is not started (to guard against usage errors). To insist that the | |
1818 | array be started in this case (as may work for RAID1, 4, 5, 6, or 10), | |
1819 | give the | |
7e23fc43 | 1820 | .B \-\-run |
cd29a5c8 | 1821 | flag. |
52826846 | 1822 | |
e0fe762a N |
1823 | If |
1824 | .I udev | |
1825 | is active, | |
1826 | .I mdadm | |
1827 | does not create any entries in | |
dd0781e5 | 1828 | .B /dev |
e0fe762a N |
1829 | but leaves that to |
1830 | .IR udev . | |
1831 | It does record information in | |
96fd06ed | 1832 | .B {MAP_PATH} |
e0fe762a N |
1833 | which will allow |
1834 | .I udev | |
1835 | to choose the correct name. | |
dd0781e5 | 1836 | |
e0fe762a N |
1837 | If |
1838 | .I mdadm | |
1839 | detects that udev is not configured, it will create the devices in | |
1840 | .B /dev | |
1841 | itself. | |
dd0781e5 | 1842 | |
e0fe762a N |
1843 | In Linux kernels prior to version 2.6.28 there were two distinctly |
1844 | different types of md devices that could be created: one that could be | |
1845 | partitioned using standard partitioning tools and one that could not. | |
1846 | Since 2.6.28 that distinction is no longer relevant as both type of | |
1847 | devices can be partitioned. | |
1848 | .I mdadm | |
1849 | will normally create the type that originally could not be partitioned | |
1850 | as it has a well defined major number (9). | |
dd0781e5 | 1851 | |
e0fe762a N |
1852 | Prior to 2.6.28, it is important that mdadm chooses the correct type |
1853 | of array device to use. This can be controlled with the | |
1854 | .B \-\-auto | |
1855 | option. In particular, a value of "mdp" or "part" or "p" tells mdadm | |
1856 | to use a partitionable device rather than the default. | |
dd0781e5 | 1857 | |
e0fe762a N |
1858 | In the no-udev case, the value given to |
1859 | .B \-\-auto | |
1860 | can be suffixed by a number. This tells | |
1861 | .I mdadm | |
1862 | to create that number of partition devices rather than the default of 4. | |
dd0781e5 | 1863 | |
e0fe762a | 1864 | The value given to |
7e23fc43 | 1865 | .B \-\-auto |
e0fe762a N |
1866 | can also be given in the configuration file as a word starting |
1867 | .B auto= | |
1868 | on the ARRAY line for the relevant array. | |
52826846 | 1869 | |
41a3b72a NB |
1870 | .SS Auto Assembly |
1871 | When | |
7e23fc43 | 1872 | .B \-\-assemble |
41a3b72a | 1873 | is used with |
7e23fc43 | 1874 | .B \-\-scan |
41a3b72a NB |
1875 | and no devices are listed, |
1876 | .I mdadm | |
1877 | will first attempt to assemble all the arrays listed in the config | |
1878 | file. | |
1879 | ||
cb77f620 | 1880 | If no arrays are listed in the config (other than those marked |
e0fe762a N |
1881 | .BR <ignore> ) |
1882 | it will look through the available devices for possible arrays and | |
1883 | will try to assemble anything that it finds. Arrays which are tagged | |
1884 | as belonging to the given homehost will be assembled and started | |
1885 | normally. Arrays which do not obviously belong to this host are given | |
1886 | names that are expected not to conflict with anything local, and are | |
1887 | started "read-auto" so that nothing is written to any device until the | |
1888 | array is written to. i.e. automatic resync etc is delayed. | |
41a3b72a NB |
1889 | |
1890 | If | |
1891 | .I mdadm | |
1892 | finds a consistent set of devices that look like they should comprise | |
1893 | an array, and if the superblock is tagged as belonging to the given | |
1894 | home host, it will automatically choose a device name and try to | |
1895 | assemble the array. If the array uses version-0.90 metadata, then the | |
1896 | .B minor | |
1897 | number as recorded in the superblock is used to create a name in | |
1898 | .B /dev/md/ | |
1899 | so for example | |
1900 | .BR /dev/md/3 . | |
1901 | If the array uses version-1 metadata, then the | |
1902 | .B name | |
1903 | from the superblock is used to similarly create a name in | |
e0fe762a | 1904 | .B /dev/md/ |
93e790af | 1905 | (the name will have any 'host' prefix stripped first). |
41a3b72a | 1906 | |
c64ba03a N |
1907 | This behaviour can be modified by the |
1908 | .I AUTO | |
1909 | line in the | |
1910 | .I mdadm.conf | |
1911 | configuration file. This line can indicate that specific metadata | |
1912 | type should, or should not, be automatically assembled. If an array | |
1913 | is found which is not listed in | |
1914 | .I mdadm.conf | |
1915 | and has a metadata format that is denied by the | |
1916 | .I AUTO | |
1917 | line, then it will not be assembled. | |
1918 | The | |
1919 | .I AUTO | |
1920 | line can also request that all arrays identified as being for this | |
1921 | homehost should be assembled regardless of their metadata type. | |
1922 | See | |
1923 | .IR mdadm.conf (5) | |
1924 | for further details. | |
1925 | ||
246cebdb AK |
1926 | Note: Auto assembly cannot be used for assembling and activating some |
1927 | arrays which are undergoing reshape. In particular as the | |
1928 | .B backup\-file | |
1929 | cannot be given, any reshape which requires a backup-file to continue | |
1930 | cannot be started by auto assembly. An array which is growing to more | |
1931 | devices and has passed the critical section can be assembled using | |
1932 | auto-assembly. | |
41a3b72a | 1933 | |
cd29a5c8 | 1934 | .SH BUILD MODE |
52826846 | 1935 | |
cd29a5c8 NB |
1936 | .HP 12 |
1937 | Usage: | |
7e23fc43 | 1938 | .B mdadm \-\-build |
93e790af | 1939 | .I md-device |
7e23fc43 PS |
1940 | .BI \-\-chunk= X |
1941 | .BI \-\-level= Y | |
1942 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
1943 | .I devices |
1944 | ||
1945 | .PP | |
2ae555c3 | 1946 | This usage is similar to |
7e23fc43 | 1947 | .BR \-\-create . |
e0fe762a | 1948 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 1949 | these arrays there is no difference between initially creating the array and |
52826846 NB |
1950 | subsequently assembling the array, except that hopefully there is useful |
1951 | data there in the second case. | |
1952 | ||
e0fe762a N |
1953 | The level may raid0, linear, raid1, raid10, multipath, or faulty, or |
1954 | one of their synonyms. All devices must be listed and the array will | |
1955 | be started once complete. It will often be appropriate to use | |
1956 | .B \-\-assume\-clean | |
1957 | with levels raid1 or raid10. | |
cd29a5c8 NB |
1958 | |
1959 | .SH CREATE MODE | |
1960 | ||
1961 | .HP 12 | |
1962 | Usage: | |
7e23fc43 | 1963 | .B mdadm \-\-create |
93e790af | 1964 | .I md-device |
7e23fc43 PS |
1965 | .BI \-\-chunk= X |
1966 | .BI \-\-level= Y | |
cd29a5c8 | 1967 | .br |
7e23fc43 | 1968 | .BI \-\-raid\-devices= Z |
e0fe762a | 1969 | .I devices |
cd29a5c8 NB |
1970 | |
1971 | .PP | |
1972 | This usage will initialise a new md array, associate some devices with | |
1973 | it, and activate the array. | |
1974 | ||
e0fe762a N |
1975 | The named device will normally not exist when |
1976 | .I "mdadm \-\-create" | |
1977 | is run, but will be created by | |
1978 | .I udev | |
1979 | once the array becomes active. | |
dd0781e5 | 1980 | |
e0fe762a N |
1981 | As devices are added, they are checked to see if they contain RAID |
1982 | superblocks or filesystems. They are also checked to see if the variance in | |
cd29a5c8 NB |
1983 | device size exceeds 1%. |
1984 | ||
1985 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 1986 | the presence of a |
7e23fc43 | 1987 | .B \-\-run |
cd29a5c8 NB |
1988 | can override this caution. |
1989 | ||
2d465520 | 1990 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 1991 | give the word "\fBmissing\fP" |
2d465520 | 1992 | in place of a device name. This will cause |
51ac42e3 | 1993 | .I mdadm |
2d465520 NB |
1994 | to leave the corresponding slot in the array empty. |
1995 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 1996 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
1997 | For a RAID1 array, only one real device needs to be given. All of the |
1998 | others can be | |
d013a55e | 1999 | "\fBmissing\fP". |
2d465520 | 2000 | |
feb716e9 | 2001 | When creating a RAID5 array, |
51ac42e3 | 2002 | .I mdadm |
feb716e9 | 2003 | will automatically create a degraded array with an extra spare drive. |
e0fe762a N |
2004 | This is because building the spare into a degraded array is in general |
2005 | faster than resyncing the parity on a non-degraded, but not clean, | |
2006 | array. This feature can be overridden with the | |
7e23fc43 | 2007 | .B \-\-force |
feb716e9 NB |
2008 | option. |
2009 | ||
0ee4da98 | 2010 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
2011 | required. |
2012 | If this is not given with the | |
7e23fc43 | 2013 | .B \-\-name |
41a3b72a NB |
2014 | option, |
2015 | .I mdadm | |
0ee4da98 | 2016 | will choose a name based on the last component of the name of the |
41a3b72a NB |
2017 | device being created. So if |
2018 | .B /dev/md3 | |
2019 | is being created, then the name | |
2020 | .B 3 | |
2021 | will be chosen. | |
2022 | If | |
2023 | .B /dev/md/home | |
2024 | is being created, then the name | |
2025 | .B home | |
2026 | will be used. | |
2027 | ||
e0fe762a N |
2028 | When creating a partition based array, using |
2029 | .I mdadm | |
2030 | with version-1.x metadata, the partition type should be set to | |
e0f31f50 | 2031 | .B 0xDA |
e0fe762a | 2032 | (non fs-data). This type selection allows for greater precision since |
e0f31f50 PC |
2033 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], |
2034 | might create problems in the event of array recovery through a live cdrom. | |
2035 | ||
3d3dd91e NB |
2036 | A new array will normally get a randomly assigned 128bit UUID which is |
2037 | very likely to be unique. If you have a specific need, you can choose | |
2038 | a UUID for the array by giving the | |
7e23fc43 | 2039 | .B \-\-uuid= |
3d3dd91e NB |
2040 | option. Be warned that creating two arrays with the same UUID is a |
2041 | recipe for disaster. Also, using | |
7e23fc43 | 2042 | .B \-\-uuid= |
3d3dd91e | 2043 | when creating a v0.90 array will silently override any |
7e23fc43 | 2044 | .B \-\-homehost= |
3d3dd91e | 2045 | setting. |
e43d0cda NB |
2046 | .\"If the |
2047 | .\".B \-\-size | |
2048 | .\"option is given, it is not necessary to list any component-devices in this command. | |
2049 | .\"They can be added later, before a | |
2050 | .\".B \-\-run. | |
2051 | .\"If no | |
2052 | .\".B \-\-size | |
2053 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 2054 | |
748952f7 N |
2055 | If the array type supports a write-intent bitmap, and if the devices |
2056 | in the array exceed 100G is size, an internal write-intent bitmap | |
2057 | will automatically be added unless some other option is explicitly | |
2058 | requested with the | |
2059 | .B \-\-bitmap | |
2060 | option. In any case space for a bitmap will be reserved so that one | |
2061 | can be added layer with | |
2062 | .BR "\-\-grow \-\-bitmap=internal" . | |
2063 | ||
bf95d0f3 N |
2064 | If the metadata type supports it (currently only 1.x metadata), space |
2065 | will be allocated to store a bad block list. This allows a modest | |
2066 | number of bad blocks to be recorded, allowing the drive to remain in | |
2067 | service while only partially functional. | |
2068 | ||
8fd8d9c4 N |
2069 | When creating an array within a |
2070 | .B CONTAINER | |
2071 | .I mdadm | |
2072 | can be given either the list of devices to use, or simply the name of | |
2073 | the container. The former case gives control over which devices in | |
2074 | the container will be used for the array. The latter case allows | |
2075 | .I mdadm | |
2076 | to automatically choose which devices to use based on how much spare | |
2077 | space is available. | |
2078 | ||
53e8b987 | 2079 | The General Management options that are valid with |
7e23fc43 | 2080 | .B \-\-create |
53e8b987 | 2081 | are: |
cd29a5c8 | 2082 | .TP |
7e23fc43 | 2083 | .B \-\-run |
dd0781e5 | 2084 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
2085 | be in use. |
2086 | ||
2087 | .TP | |
7e23fc43 | 2088 | .B \-\-readonly |
b3f1c093 | 2089 | start the array readonly \(em not supported yet. |
52826846 | 2090 | |
e0d19036 | 2091 | .SH MANAGE MODE |
cd29a5c8 NB |
2092 | .HP 12 |
2093 | Usage: | |
e0d19036 NB |
2094 | .B mdadm |
2095 | .I device | |
2096 | .I options... devices... | |
cd29a5c8 NB |
2097 | .PP |
2098 | ||
e0d19036 NB |
2099 | This usage will allow individual devices in an array to be failed, |
2100 | removed or added. It is possible to perform multiple operations with | |
e0fe762a | 2101 | on command. For example: |
e0d19036 | 2102 | .br |
7e23fc43 | 2103 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
2104 | .br |
2105 | will firstly mark | |
2106 | .B /dev/hda1 | |
2107 | as faulty in | |
2108 | .B /dev/md0 | |
2109 | and will then remove it from the array and finally add it back | |
2d465520 | 2110 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 2111 | command. |
e0d19036 | 2112 | |
e0fe762a N |
2113 | When a device is added to an active array, mdadm checks to see if it |
2114 | has metadata on it which suggests that it was recently a member of the | |
a4e13010 | 2115 | array. If it does, it tries to "re\-add" the device. If there have |
e0fe762a N |
2116 | been no changes since the device was removed, or if the array has a |
2117 | write-intent bitmap which has recorded whatever changes there were, | |
2118 | then the device will immediately become a full member of the array and | |
2119 | those differences recorded in the bitmap will be resolved. | |
2120 | ||
e0d19036 NB |
2121 | .SH MISC MODE |
2122 | .HP 12 | |
2123 | Usage: | |
9a9dab36 | 2124 | .B mdadm |
e0d19036 | 2125 | .I options ... |
e0fe762a | 2126 | .I devices ... |
e0d19036 | 2127 | .PP |
cd29a5c8 | 2128 | |
b5e64645 | 2129 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
2130 | operate on distinct devices. The operations are: |
2131 | .TP | |
962a108f | 2132 | .B \-\-query |
e0d19036 NB |
2133 | The device is examined to see if it is |
2134 | (1) an active md array, or | |
2135 | (2) a component of an md array. | |
2136 | The information discovered is reported. | |
2137 | ||
2138 | .TP | |
962a108f | 2139 | .B \-\-detail |
2d465520 | 2140 | The device should be an active md device. |
e0fe762a | 2141 | .B mdadm |
2d465520 | 2142 | will display a detailed description of the array. |
7e23fc43 | 2143 | .B \-\-brief |
2d465520 | 2144 | or |
7e23fc43 | 2145 | .B \-\-scan |
2d465520 | 2146 | will cause the output to be less detailed and the format to be |
e0d19036 | 2147 | suitable for inclusion in |
87eb4fab | 2148 | .BR mdadm.conf . |
feb716e9 NB |
2149 | The exit status of |
2150 | .I mdadm | |
2151 | will normally be 0 unless | |
2152 | .I mdadm | |
93e790af | 2153 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 2154 | .B \-\-test |
feb716e9 NB |
2155 | option is given, then the exit status will be: |
2156 | .RS | |
2157 | .TP | |
2158 | 0 | |
2159 | The array is functioning normally. | |
2160 | .TP | |
2161 | 1 | |
2162 | The array has at least one failed device. | |
2163 | .TP | |
2164 | 2 | |
a77be586 | 2165 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
2166 | .TP |
2167 | 4 | |
2168 | There was an error while trying to get information about the device. | |
2169 | .RE | |
cd29a5c8 | 2170 | |
4cce4069 DW |
2171 | .TP |
2172 | .B \-\-detail\-platform | |
e0fe762a | 2173 | Print detail of the platform's RAID capabilities (firmware / hardware |
4cce4069 DW |
2174 | topology). If the metadata is specified with |
2175 | .B \-e | |
2176 | or | |
2177 | .B \-\-metadata= | |
2178 | then the return status will be: | |
2179 | .RS | |
2180 | .TP | |
2181 | 0 | |
2182 | metadata successfully enumerated its platform components on this system | |
2183 | .TP | |
2184 | 1 | |
2185 | metadata is platform independent | |
2186 | .TP | |
2187 | 2 | |
2188 | metadata failed to find its platform components on this system | |
2189 | .RE | |
2190 | ||
aa534678 DW |
2191 | .TP |
2192 | .B \-\-update\-subarray= | |
2193 | If the device is a container and the argument to \-\-update\-subarray | |
2194 | specifies a subarray in the container, then attempt to update the given | |
2195 | superblock field in the subarray. Similar to updating an array in | |
2196 | "assemble" mode, the field to update is selected by | |
2197 | .B \-U | |
2198 | or | |
2199 | .B \-\-update= | |
2200 | option. Currently only | |
2201 | .B name | |
2202 | is supported. | |
2203 | ||
2204 | The | |
2205 | .B name | |
2206 | option updates the subarray name in the metadata, it may not affect the | |
2207 | device node name or the device node symlink until the subarray is | |
2208 | re\-assembled. If updating | |
2209 | .B name | |
2210 | would change the UUID of an active subarray this operation is blocked, | |
2211 | and the command will end in an error. | |
2212 | ||
e0d19036 | 2213 | .TP |
962a108f | 2214 | .B \-\-examine |
2d465520 | 2215 | The device should be a component of an md array. |
51ac42e3 | 2216 | .I mdadm |
2d465520 | 2217 | will read the md superblock of the device and display the contents. |
e0d19036 | 2218 | If |
7e23fc43 | 2219 | .B \-\-brief |
93e790af | 2220 | or |
7e23fc43 | 2221 | .B \-\-scan |
93e790af | 2222 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
2223 | are grouped together and reported in a single entry suitable |
2224 | for inclusion in | |
87eb4fab | 2225 | .BR mdadm.conf . |
e0d19036 | 2226 | |
2d465520 | 2227 | Having |
7e23fc43 | 2228 | .B \-\-scan |
e0d19036 NB |
2229 | without listing any devices will cause all devices listed in the |
2230 | config file to be examined. | |
2231 | ||
74db60b0 N |
2232 | .TP |
2233 | .BI \-\-dump= directory | |
2234 | If the device contains RAID metadata, a file will be created in the | |
2235 | .I directory | |
2236 | and the metadata will be written to it. The file will be the same | |
2237 | size as the device and have the metadata written in the file at the | |
2238 | same locate that it exists in the device. However the file will be "sparse" so | |
2239 | that only those blocks containing metadata will be allocated. The | |
2240 | total space used will be small. | |
2241 | ||
2242 | The file name used in the | |
2243 | .I directory | |
2244 | will be the base name of the device. Further if any links appear in | |
2245 | .I /dev/disk/by-id | |
2246 | which point to the device, then hard links to the file will be created | |
2247 | in | |
2248 | .I directory | |
2249 | based on these | |
2250 | .I by-id | |
2251 | names. | |
2252 | ||
2253 | Multiple devices can be listed and their metadata will all be stored | |
2254 | in the one directory. | |
2255 | ||
2256 | .TP | |
2257 | .BI \-\-restore= directory | |
2258 | This is the reverse of | |
2259 | .BR \-\-dump . | |
2260 | .I mdadm | |
2261 | will locate a file in the directory that has a name appropriate for | |
2262 | the given device and will restore metadata from it. Names that match | |
2263 | .I /dev/disk/by-id | |
2264 | names are preferred, however if two of those refer to different files, | |
2265 | .I mdadm | |
2266 | will not choose between them but will abort the operation. | |
2267 | ||
2268 | If a file name is given instead of a | |
2269 | .I directory | |
2270 | then | |
2271 | .I mdadm | |
2272 | will restore from that file to a single device, always provided the | |
2273 | size of the file matches that of the device, and the file contains | |
2274 | valid metadata. | |
e0d19036 | 2275 | .TP |
962a108f | 2276 | .B \-\-stop |
98c6faba NB |
2277 | The devices should be active md arrays which will be deactivated, as |
2278 | long as they are not currently in use. | |
e0d19036 NB |
2279 | |
2280 | .TP | |
962a108f | 2281 | .B \-\-run |
e0d19036 NB |
2282 | This will fully activate a partially assembled md array. |
2283 | ||
2284 | .TP | |
962a108f | 2285 | .B \-\-readonly |
e0d19036 NB |
2286 | This will mark an active array as read-only, providing that it is |
2287 | not currently being used. | |
2288 | ||
2289 | .TP | |
962a108f | 2290 | .B \-\-readwrite |
e0d19036 NB |
2291 | This will change a |
2292 | .B readonly | |
2293 | array back to being read/write. | |
2294 | ||
2d465520 | 2295 | .TP |
962a108f | 2296 | .B \-\-scan |
2d465520 | 2297 | For all operations except |
7e23fc43 PS |
2298 | .BR \-\-examine , |
2299 | .B \-\-scan | |
2d465520 NB |
2300 | will cause the operation to be applied to all arrays listed in |
2301 | .BR /proc/mdstat . | |
2302 | For | |
7e23fc43 PS |
2303 | .BR \-\-examine, |
2304 | .B \-\-scan | |
2d465520 NB |
2305 | causes all devices listed in the config file to be examined. |
2306 | ||
a1331cc4 N |
2307 | .TP |
2308 | .BR \-b ", " \-\-brief | |
2309 | Be less verbose. This is used with | |
2310 | .B \-\-detail | |
2311 | and | |
2312 | .BR \-\-examine . | |
2313 | Using | |
2314 | .B \-\-brief | |
2315 | with | |
2316 | .B \-\-verbose | |
2317 | gives an intermediate level of verbosity. | |
2318 | ||
e0d19036 NB |
2319 | .SH MONITOR MODE |
2320 | ||
cd29a5c8 NB |
2321 | .HP 12 |
2322 | Usage: | |
7e23fc43 | 2323 | .B mdadm \-\-monitor |
e0d19036 NB |
2324 | .I options... devices... |
2325 | ||
cd29a5c8 | 2326 | .PP |
e0d19036 | 2327 | This usage causes |
51ac42e3 | 2328 | .I mdadm |
e0d19036 NB |
2329 | to periodically poll a number of md arrays and to report on any events |
2330 | noticed. | |
51ac42e3 | 2331 | .I mdadm |
e0d19036 NB |
2332 | will never exit once it decides that there are arrays to be checked, |
2333 | so it should normally be run in the background. | |
2334 | ||
2d465520 | 2335 | As well as reporting events, |
51ac42e3 | 2336 | .I mdadm |
2d465520 NB |
2337 | may move a spare drive from one array to another if they are in the |
2338 | same | |
2339 | .B spare-group | |
210597d1 PC |
2340 | or |
2341 | .B domain | |
a9d69660 | 2342 | and if the destination array has a failed drive but no spares. |
2d465520 | 2343 | |
e0d19036 | 2344 | If any devices are listed on the command line, |
51ac42e3 | 2345 | .I mdadm |
e0fe762a | 2346 | will only monitor those devices. Otherwise all arrays listed in the |
e0d19036 | 2347 | configuration file will be monitored. Further, if |
7e23fc43 | 2348 | .B \-\-scan |
e0d19036 NB |
2349 | is given, then any other md devices that appear in |
2350 | .B /proc/mdstat | |
2351 | will also be monitored. | |
2352 | ||
2353 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 2354 | These events are passed to a separate program (if specified) and may |
2d465520 | 2355 | be mailed to a given E-mail address. |
e0d19036 | 2356 | |
93e790af SW |
2357 | When passing events to a program, the program is run once for each event, |
2358 | and is given 2 or 3 command-line arguments: the first is the | |
2359 | name of the event (see below), the second is the name of the | |
bd526cee | 2360 | md device which is affected, and the third is the name of a related |
93e790af | 2361 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
2362 | |
2363 | If | |
7e23fc43 | 2364 | .B \-\-scan |
e0d19036 NB |
2365 | is given, then a program or an E-mail address must be specified on the |
2366 | command line or in the config file. If neither are available, then | |
51ac42e3 | 2367 | .I mdadm |
e0d19036 NB |
2368 | will not monitor anything. |
2369 | Without | |
93e790af | 2370 | .B \-\-scan, |
51ac42e3 | 2371 | .I mdadm |
2d465520 | 2372 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
2373 | no program or email is given, then each event is reported to |
2374 | .BR stdout . | |
cd29a5c8 | 2375 | |
e0d19036 NB |
2376 | The different events are: |
2377 | ||
2378 | .RS 4 | |
2379 | .TP | |
2380 | .B DeviceDisappeared | |
2d465520 | 2381 | An md array which previously was configured appears to no longer be |
773135f5 | 2382 | configured. (syslog priority: Critical) |
e0d19036 | 2383 | |
b8f72a62 NB |
2384 | If |
2385 | .I mdadm | |
2386 | was told to monitor an array which is RAID0 or Linear, then it will | |
2387 | report | |
2388 | .B DeviceDisappeared | |
2389 | with the extra information | |
2390 | .BR Wrong-Level . | |
2391 | This is because RAID0 and Linear do not support the device-failed, | |
2392 | hot-spare and resync operations which are monitored. | |
2393 | ||
e0d19036 NB |
2394 | .TP |
2395 | .B RebuildStarted | |
2ca20929 JC |
2396 | An md array started reconstruction (e.g. recovery, resync, reshape, |
2397 | check, repair). (syslog priority: Warning) | |
e0d19036 NB |
2398 | |
2399 | .TP | |
2400 | .BI Rebuild NN | |
2401 | Where | |
2402 | .I NN | |
9a36a9b7 ZB |
2403 | is a two-digit number (ie. 05, 48). This indicates that rebuild |
2404 | has passed that many percent of the total. The events are generated | |
2405 | with fixed increment since 0. Increment size may be specified with | |
2406 | a commandline option (default is 20). (syslog priority: Warning) | |
e0d19036 | 2407 | |
98c6faba NB |
2408 | .TP |
2409 | .B RebuildFinished | |
2410 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 2411 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 2412 | |
e0d19036 NB |
2413 | .TP |
2414 | .B Fail | |
773135f5 NB |
2415 | An active component device of an array has been marked as |
2416 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
2417 | |
2418 | .TP | |
2419 | .B FailSpare | |
2420 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 2421 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
2422 | |
2423 | .TP | |
2424 | .B SpareActive | |
2425 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 2426 | device has been successfully rebuilt and has been made active. |
773135f5 | 2427 | (syslog priority: Info) |
e0d19036 NB |
2428 | |
2429 | .TP | |
2430 | .B NewArray | |
2431 | A new md array has been detected in the | |
2432 | .B /proc/mdstat | |
e0fe762a | 2433 | file. (syslog priority: Info) |
e0d19036 | 2434 | |
aa88f531 NB |
2435 | .TP |
2436 | .B DegradedArray | |
2437 | A newly noticed array appears to be degraded. This message is not | |
2438 | generated when | |
2439 | .I mdadm | |
2440 | notices a drive failure which causes degradation, but only when | |
2441 | .I mdadm | |
2442 | notices that an array is degraded when it first sees the array. | |
93e790af | 2443 | (syslog priority: Critical) |
aa88f531 | 2444 | |
e0d19036 NB |
2445 | .TP |
2446 | .B MoveSpare | |
2447 | A spare drive has been moved from one array in a | |
2448 | .B spare-group | |
210597d1 PC |
2449 | or |
2450 | .B domain | |
e0d19036 | 2451 | to another to allow a failed drive to be replaced. |
773135f5 | 2452 | (syslog priority: Info) |
e0d19036 | 2453 | |
b8f72a62 NB |
2454 | .TP |
2455 | .B SparesMissing | |
2456 | If | |
2457 | .I mdadm | |
2458 | has been told, via the config file, that an array should have a certain | |
2459 | number of spare devices, and | |
2460 | .I mdadm | |
93e790af | 2461 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
2462 | array, it will report a |
2463 | .B SparesMissing | |
2464 | message. | |
d1732eeb | 2465 | (syslog priority: Warning) |
b8f72a62 | 2466 | |
98c6faba NB |
2467 | .TP |
2468 | .B TestMessage | |
2469 | An array was found at startup, and the | |
7e23fc43 | 2470 | .B \-\-test |
98c6faba | 2471 | flag was given. |
773135f5 | 2472 | (syslog priority: Info) |
e0d19036 NB |
2473 | .RE |
2474 | ||
2475 | Only | |
93e790af SW |
2476 | .B Fail, |
2477 | .B FailSpare, | |
2478 | .B DegradedArray, | |
2479 | .B SparesMissing | |
e0d19036 | 2480 | and |
98c6faba | 2481 | .B TestMessage |
e0d19036 | 2482 | cause Email to be sent. All events cause the program to be run. |
93e790af | 2483 | The program is run with two or three arguments: the event |
e0d19036 NB |
2484 | name, the array device and possibly a second device. |
2485 | ||
2486 | Each event has an associated array device (e.g. | |
2487 | .BR /dev/md1 ) | |
2488 | and possibly a second device. For | |
2489 | .BR Fail , | |
2490 | .BR FailSpare , | |
2491 | and | |
2492 | .B SpareActive | |
2493 | the second device is the relevant component device. | |
2494 | For | |
2495 | .B MoveSpare | |
2496 | the second device is the array that the spare was moved from. | |
2497 | ||
2498 | For | |
51ac42e3 | 2499 | .I mdadm |
e0d19036 | 2500 | to move spares from one array to another, the different arrays need to |
93e790af | 2501 | be labeled with the same |
e0d19036 | 2502 | .B spare-group |
210597d1 | 2503 | or the spares must be allowed to migrate through matching POLICY domains |
e0d19036 NB |
2504 | in the configuration file. The |
2505 | .B spare-group | |
93e790af | 2506 | name can be any string; it is only necessary that different spare |
2d465520 | 2507 | groups use different names. |
e0d19036 NB |
2508 | |
2509 | When | |
51ac42e3 | 2510 | .I mdadm |
93e790af | 2511 | detects that an array in a spare group has fewer active |
e0d19036 NB |
2512 | devices than necessary for the complete array, and has no spare |
2513 | devices, it will look for another array in the same spare group that | |
2514 | has a full complement of working drive and a spare. It will then | |
2515 | attempt to remove the spare from the second drive and add it to the | |
2516 | first. | |
2517 | If the removal succeeds but the adding fails, then it is added back to | |
2518 | the original array. | |
2519 | ||
210597d1 PC |
2520 | If the spare group for a degraded array is not defined, |
2521 | .I mdadm | |
2522 | will look at the rules of spare migration specified by POLICY lines in | |
87eb4fab | 2523 | .B mdadm.conf |
210597d1 PC |
2524 | and then follow similar steps as above if a matching spare is found. |
2525 | ||
dd0781e5 NB |
2526 | .SH GROW MODE |
2527 | The GROW mode is used for changing the size or shape of an active | |
2528 | array. | |
2529 | For this to work, the kernel must support the necessary change. | |
c64881d7 | 2530 | Various types of growth are being added during 2.6 development. |
dd0781e5 | 2531 | |
c64881d7 | 2532 | Currently the supported changes include |
dfd4d8ee | 2533 | .IP \(bu 4 |
c64881d7 | 2534 | change the "size" attribute for RAID1, RAID4, RAID5 and RAID6. |
dfd4d8ee | 2535 | .IP \(bu 4 |
c64881d7 N |
2536 | increase or decrease the "raid\-devices" attribute of RAID0, RAID1, RAID4, |
2537 | RAID5, and RAID6. | |
cb77f620 | 2538 | .IP \(bu 4 |
17790db6 | 2539 | change the chunk-size and layout of RAID0, RAID4, RAID5, RAID6 and RAID10. |
cb77f620 | 2540 | .IP \(bu 4 |
c64881d7 | 2541 | convert between RAID1 and RAID5, between RAID5 and RAID6, between |
cb77f620 | 2542 | RAID0, RAID4, and RAID5, and between RAID0 and RAID10 (in the near-2 mode). |
dfd4d8ee | 2543 | .IP \(bu 4 |
93e790af | 2544 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 2545 | remove a write-intent bitmap from such an array. |
dfd4d8ee | 2546 | .PP |
dd0781e5 | 2547 | |
9ab6e80a | 2548 | Using GROW on containers is currently supported only for Intel's IMSM |
c64881d7 N |
2549 | container format. The number of devices in a container can be |
2550 | increased - which affects all arrays in the container - or an array | |
2551 | in a container can be converted between levels where those levels are | |
2552 | supported by the container, and the conversion is on of those listed | |
9ab6e80a N |
2553 | above. Resizing arrays in an IMSM container with |
2554 | .B "--grow --size" | |
2555 | is not yet supported. | |
8fd8d9c4 | 2556 | |
ca24ddb0 AK |
2557 | Grow functionality (e.g. expand a number of raid devices) for Intel's |
2558 | IMSM container format has an experimental status. It is guarded by the | |
2559 | .B MDADM_EXPERIMENTAL | |
2560 | environment variable which must be set to '1' for a GROW command to | |
2561 | succeed. | |
2562 | This is for the following reasons: | |
2563 | ||
2564 | .IP 1. | |
0de8d44d AK |
2565 | Intel's native IMSM check-pointing is not fully tested yet. |
2566 | This can causes IMSM incompatibility during the grow process: an array | |
ca24ddb0 AK |
2567 | which is growing cannot roam between Microsoft Windows(R) and Linux |
2568 | systems. | |
2569 | ||
2570 | .IP 2. | |
2571 | Interrupting a grow operation is not recommended, because it | |
2572 | has not been fully tested for Intel's IMSM container format yet. | |
2573 | ||
0de8d44d AK |
2574 | .PP |
2575 | Note: Intel's native checkpointing doesn't use | |
2576 | .B --backup-file | |
2577 | option and it is transparent for assembly feature. | |
2578 | ||
2ae555c3 | 2579 | .SS SIZE CHANGES |
c64881d7 | 2580 | Normally when an array is built the "size" is taken from the smallest |
dd0781e5 NB |
2581 | of the drives. If all the small drives in an arrays are, one at a |
2582 | time, removed and replaced with larger drives, then you could have an | |
2583 | array of large drives with only a small amount used. In this | |
2584 | situation, changing the "size" with "GROW" mode will allow the extra | |
2585 | space to start being used. If the size is increased in this way, a | |
2586 | "resync" process will start to make sure the new parts of the array | |
2587 | are synchronised. | |
2588 | ||
2589 | Note that when an array changes size, any filesystem that may be | |
cb77f620 | 2590 | stored in the array will not automatically grow or shrink to use or |
88b496c2 | 2591 | vacate the space. The |
666bba9b N |
2592 | filesystem will need to be explicitly told to use the extra space |
2593 | after growing, or to reduce its size | |
2594 | .B prior | |
2595 | to shrinking the array. | |
dd0781e5 | 2596 | |
e0fe762a N |
2597 | Also the size of an array cannot be changed while it has an active |
2598 | bitmap. If an array has a bitmap, it must be removed before the size | |
cb77f620 | 2599 | can be changed. Once the change is complete a new bitmap can be created. |
e0fe762a N |
2600 | |
2601 | .SS RAID\-DEVICES CHANGES | |
2ae555c3 | 2602 | |
dd0781e5 NB |
2603 | A RAID1 array can work with any number of devices from 1 upwards |
2604 | (though 1 is not very useful). There may be times which you want to | |
2605 | increase or decrease the number of active devices. Note that this is | |
2606 | different to hot-add or hot-remove which changes the number of | |
2607 | inactive devices. | |
2608 | ||
2609 | When reducing the number of devices in a RAID1 array, the slots which | |
2610 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 2611 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
2612 | |
2613 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 2614 | present will be activated immediately. |
dd0781e5 | 2615 | |
f24e2d6c | 2616 | Changing the number of active devices in a RAID5 or RAID6 is much more |
2ae555c3 | 2617 | effort. Every block in the array will need to be read and written |
f24e2d6c | 2618 | back to a new location. From 2.6.17, the Linux Kernel is able to |
ca4f89a3 N |
2619 | increase the number of devices in a RAID5 safely, including restarting |
2620 | an interrupted "reshape". From 2.6.31, the Linux Kernel is able to | |
f24e2d6c N |
2621 | increase or decrease the number of devices in a RAID5 or RAID6. |
2622 | ||
c64881d7 N |
2623 | From 2.6.35, the Linux Kernel is able to convert a RAID0 in to a RAID4 |
2624 | or RAID5. | |
2625 | .I mdadm | |
2626 | uses this functionality and the ability to add | |
2627 | devices to a RAID4 to allow devices to be added to a RAID0. When | |
2628 | requested to do this, | |
2629 | .I mdadm | |
2630 | will convert the RAID0 to a RAID4, add the necessary disks and make | |
2631 | the reshape happen, and then convert the RAID4 back to RAID0. | |
2632 | ||
f24e2d6c N |
2633 | When decreasing the number of devices, the size of the array will also |
2634 | decrease. If there was data in the array, it could get destroyed and | |
666bba9b N |
2635 | this is not reversible, so you should firstly shrink the filesystem on |
2636 | the array to fit within the new size. To help prevent accidents, | |
f24e2d6c N |
2637 | .I mdadm |
2638 | requires that the size of the array be decreased first with | |
2639 | .BR "mdadm --grow --array-size" . | |
2640 | This is a reversible change which simply makes the end of the array | |
2641 | inaccessible. The integrity of any data can then be checked before | |
2642 | the non-reversible reduction in the number of devices is request. | |
2ae555c3 | 2643 | |
cd19c0cf JR |
2644 | When relocating the first few stripes on a RAID5 or RAID6, it is not |
2645 | possible to keep the data on disk completely consistent and | |
2646 | crash-proof. To provide the required safety, mdadm disables writes to | |
2647 | the array while this "critical section" is reshaped, and takes a | |
2648 | backup of the data that is in that section. For grows, this backup may be | |
2649 | stored in any spare devices that the array has, however it can also be | |
2650 | stored in a separate file specified with the | |
7e23fc43 | 2651 | .B \-\-backup\-file |
cd19c0cf JR |
2652 | option, and is required to be specified for shrinks, RAID level |
2653 | changes and layout changes. If this option is used, and the system | |
2654 | does crash during the critical period, the same file must be passed to | |
7e23fc43 | 2655 | .B \-\-assemble |
cd19c0cf JR |
2656 | to restore the backup and reassemble the array. When shrinking rather |
2657 | than growing the array, the reshape is done from the end towards the | |
2658 | beginning, so the "critical section" is at the end of the reshape. | |
2ae555c3 | 2659 | |
f24e2d6c N |
2660 | .SS LEVEL CHANGES |
2661 | ||
2662 | Changing the RAID level of any array happens instantaneously. However | |
cd19c0cf | 2663 | in the RAID5 to RAID6 case this requires a non-standard layout of the |
f24e2d6c | 2664 | RAID6 data, and in the RAID6 to RAID5 case that non-standard layout is |
cd19c0cf | 2665 | required before the change can be accomplished. So while the level |
f24e2d6c | 2666 | change is instant, the accompanying layout change can take quite a |
cd19c0cf JR |
2667 | long time. A |
2668 | .B \-\-backup\-file | |
2669 | is required. If the array is not simultaneously being grown or | |
2670 | shrunk, so that the array size will remain the same - for example, | |
2671 | reshaping a 3-drive RAID5 into a 4-drive RAID6 - the backup file will | |
2672 | be used not just for a "cricital section" but throughout the reshape | |
2673 | operation, as described below under LAYOUT CHANGES. | |
f24e2d6c N |
2674 | |
2675 | .SS CHUNK-SIZE AND LAYOUT CHANGES | |
2676 | ||
2677 | Changing the chunk-size of layout without also changing the number of | |
2678 | devices as the same time will involve re-writing all blocks in-place. | |
2679 | To ensure against data loss in the case of a crash, a | |
2680 | .B --backup-file | |
2681 | must be provided for these changes. Small sections of the array will | |
cd19c0cf JR |
2682 | be copied to the backup file while they are being rearranged. This |
2683 | means that all the data is copied twice, once to the backup and once | |
2684 | to the new layout on the array, so this type of reshape will go very | |
2685 | slowly. | |
f24e2d6c N |
2686 | |
2687 | If the reshape is interrupted for any reason, this backup file must be | |
cd19c0cf | 2688 | made available to |
f24e2d6c N |
2689 | .B "mdadm --assemble" |
2690 | so the array can be reassembled. Consequently the file cannot be | |
2691 | stored on the device being reshaped. | |
2692 | ||
2693 | ||
2ae555c3 NB |
2694 | .SS BITMAP CHANGES |
2695 | ||
2696 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 2697 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b | 2698 | can be added. Note that if you add a bitmap stored in a file which is |
e0fe762a | 2699 | in a filesystem that is on the RAID array being affected, the system |
fe80f49b NB |
2700 | will deadlock. The bitmap must be on a separate filesystem. |
2701 | ||
8382f19b NB |
2702 | .SH INCREMENTAL MODE |
2703 | ||
2704 | .HP 12 | |
2705 | Usage: | |
7e23fc43 PS |
2706 | .B mdadm \-\-incremental |
2707 | .RB [ \-\-run ] | |
2708 | .RB [ \-\-quiet ] | |
8382f19b | 2709 | .I component-device |
b11fe74d | 2710 | .RI [ optional-aliases-for-device ] |
8382f19b NB |
2711 | .HP 12 |
2712 | Usage: | |
29ba4804 N |
2713 | .B mdadm \-\-incremental \-\-fail |
2714 | .I component-device | |
2715 | .HP 12 | |
2716 | Usage: | |
7e6140e6 | 2717 | .B mdadm \-\-incremental \-\-rebuild\-map |
8382f19b NB |
2718 | .HP 12 |
2719 | Usage: | |
7e23fc43 | 2720 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b | 2721 | |
8382f19b NB |
2722 | .PP |
2723 | This mode is designed to be used in conjunction with a device | |
2724 | discovery system. As devices are found in a system, they can be | |
2725 | passed to | |
7e23fc43 | 2726 | .B "mdadm \-\-incremental" |
8382f19b NB |
2727 | to be conditionally added to an appropriate array. |
2728 | ||
29ba4804 N |
2729 | Conversely, it can also be used with the |
2730 | .B \-\-fail | |
2731 | flag to do just the opposite and find whatever array a particular device | |
2732 | is part of and remove the device from that array. | |
2733 | ||
8fd8d9c4 N |
2734 | If the device passed is a |
2735 | .B CONTAINER | |
2736 | device created by a previous call to | |
2737 | .IR mdadm , | |
2738 | then rather than trying to add that device to an array, all the arrays | |
2739 | described by the metadata of the container will be started. | |
2740 | ||
8382f19b NB |
2741 | .I mdadm |
2742 | performs a number of tests to determine if the device is part of an | |
93e790af | 2743 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
2744 | is found, or can be created, |
2745 | .I mdadm | |
2746 | adds the device to the array and conditionally starts the array. | |
2747 | ||
2748 | Note that | |
2749 | .I mdadm | |
87eb4fab N |
2750 | will normally only add devices to an array which were previously working |
2751 | (active or spare) parts of that array. The support for automatic | |
210597d1 PC |
2752 | inclusion of a new drive as a spare in some array requires |
2753 | a configuration through POLICY in config file. | |
8382f19b | 2754 | |
8382f19b NB |
2755 | The tests that |
2756 | .I mdadm | |
2757 | makes are as follow: | |
2758 | .IP + | |
2759 | Is the device permitted by | |
2760 | .BR mdadm.conf ? | |
2761 | That is, is it listed in a | |
2762 | .B DEVICES | |
2763 | line in that file. If | |
2764 | .B DEVICES | |
b11fe74d | 2765 | is absent then the default it to allow any device. Similarly if |
8382f19b NB |
2766 | .B DEVICES |
2767 | contains the special word | |
2768 | .B partitions | |
2769 | then any device is allowed. Otherwise the device name given to | |
b11fe74d N |
2770 | .IR mdadm , |
2771 | or one of the aliases given, or an alias found in the filesystem, | |
8382f19b NB |
2772 | must match one of the names or patterns in a |
2773 | .B DEVICES | |
2774 | line. | |
2775 | ||
b11fe74d N |
2776 | This is the only context where the aliases are used. They are |
2777 | usually provided by a | |
2778 | .I udev | |
2779 | rules mentioning | |
2780 | .BR ${DEVLINKS} . | |
2781 | ||
8382f19b | 2782 | .IP + |
cb77f620 NK |
2783 | Does the device have a valid md superblock? If a specific metadata |
2784 | version is requested with | |
7e23fc43 | 2785 | .B \-\-metadata |
8382f19b | 2786 | or |
7e23fc43 | 2787 | .B \-e |
8382f19b NB |
2788 | then only that style of metadata is accepted, otherwise |
2789 | .I mdadm | |
2790 | finds any known version of metadata. If no | |
2791 | .I md | |
210597d1 PC |
2792 | metadata is found, the device may be still added to an array |
2793 | as a spare if POLICY allows. | |
8382f19b | 2794 | |
d1302dd8 | 2795 | .ig |
8382f19b NB |
2796 | .IP + |
2797 | Does the metadata match an expected array? | |
2798 | The metadata can match in two ways. Either there is an array listed | |
2799 | in | |
2800 | .B mdadm.conf | |
2801 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 2802 | or by minor-number), or the array was created with a |
8382f19b | 2803 | .B homehost |
93e790af | 2804 | specified and that |
8382f19b | 2805 | .B homehost |
93e790af | 2806 | matches the one in |
8382f19b NB |
2807 | .B mdadm.conf |
2808 | or on the command line. | |
2809 | If | |
2810 | .I mdadm | |
2811 | is not able to positively identify the array as belonging to the | |
2812 | current host, the device will be rejected. | |
d1302dd8 | 2813 | .. |
8382f19b | 2814 | |
cb77f620 | 2815 | .PP |
8382f19b | 2816 | .I mdadm |
93e790af | 2817 | keeps a list of arrays that it has partially assembled in |
96fd06ed | 2818 | .BR {MAP_PATH} . |
e0fe762a | 2819 | If no array exists which matches |
8382f19b NB |
2820 | the metadata on the new device, |
2821 | .I mdadm | |
2822 | must choose a device name and unit number. It does this based on any | |
2823 | name given in | |
2824 | .B mdadm.conf | |
2825 | or any name information stored in the metadata. If this name | |
2826 | suggests a unit number, that number will be used, otherwise a free | |
2827 | unit number will be chosen. Normally | |
2828 | .I mdadm | |
2829 | will prefer to create a partitionable array, however if the | |
2830 | .B CREATE | |
2831 | line in | |
2832 | .B mdadm.conf | |
2833 | suggests that a non-partitionable array is preferred, that will be | |
2834 | honoured. | |
2835 | ||
e0fe762a N |
2836 | If the array is not found in the config file and its metadata does not |
2837 | identify it as belonging to the "homehost", then | |
2838 | .I mdadm | |
2839 | will choose a name for the array which is certain not to conflict with | |
2840 | any array which does belong to this host. It does this be adding an | |
2841 | underscore and a small number to the name preferred by the metadata. | |
2842 | ||
8382f19b NB |
2843 | Once an appropriate array is found or created and the device is added, |
2844 | .I mdadm | |
2845 | must decide if the array is ready to be started. It will | |
2846 | normally compare the number of available (non-spare) devices to the | |
2847 | number of devices that the metadata suggests need to be active. If | |
2848 | there are at least that many, the array will be started. This means | |
2849 | that if any devices are missing the array will not be restarted. | |
2850 | ||
2851 | As an alternative, | |
7e23fc43 | 2852 | .B \-\-run |
8382f19b | 2853 | may be passed to |
51ac42e3 | 2854 | .I mdadm |
8382f19b | 2855 | in which case the array will be run as soon as there are enough |
e0fe762a N |
2856 | devices present for the data to be accessible. For a RAID1, that |
2857 | means one device will start the array. For a clean RAID5, the array | |
8382f19b NB |
2858 | will be started as soon as all but one drive is present. |
2859 | ||
93e790af | 2860 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
2861 | be known that all device discovery has completed, then |
2862 | .br | |
7e23fc43 | 2863 | .B " mdadm \-IRs" |
8382f19b NB |
2864 | .br |
2865 | can be run which will try to start all arrays that are being | |
2866 | incrementally assembled. They are started in "read-auto" mode in | |
2867 | which they are read-only until the first write request. This means | |
2868 | that no metadata updates are made and no attempt at resync or recovery | |
2869 | happens. Further devices that are found before the first write can | |
2870 | still be added safely. | |
2871 | ||
5545fa6d DW |
2872 | .SH ENVIRONMENT |
2873 | This section describes environment variables that affect how mdadm | |
2874 | operates. | |
2875 | ||
2876 | .TP | |
2877 | .B MDADM_NO_MDMON | |
2878 | Setting this value to 1 will prevent mdadm from automatically launching | |
2879 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
2880 | ||
8fd8d9c4 N |
2881 | .TP |
2882 | .B MDADM_NO_UDEV | |
2883 | Normally, | |
2884 | .I mdadm | |
2885 | does not create any device nodes in /dev, but leaves that task to | |
2886 | .IR udev . | |
2887 | If | |
2888 | .I udev | |
2889 | appears not to be configured, or if this environment variable is set | |
2890 | to '1', the | |
2891 | .I mdadm | |
2892 | will create and devices that are needed. | |
2893 | ||
f66585eb N |
2894 | .TP |
2895 | .B MDADM_NO_SYSTEMCTL | |
2896 | If | |
2897 | .I mdadm | |
2898 | detects that | |
2899 | .I systemd | |
2900 | is in use it will normally request | |
2901 | .I systemd | |
2902 | to start various background tasks (particularly | |
2903 | .IR mdmon ) | |
2904 | rather than forking and running them in the background. This can be | |
2905 | suppressed by setting | |
2906 | .BR MDADM_NO_SYSTEMCTL=1 . | |
2907 | ||
401f095c N |
2908 | .TP |
2909 | .B IMSM_NO_PLATFORM | |
2910 | A key value of IMSM metadata is that it allows interoperability with | |
2911 | boot ROMs on Intel platforms, and with other major operating systems. | |
2912 | Consequently, | |
2913 | .I mdadm | |
2914 | will only allow an IMSM array to be created or modified if detects | |
2915 | that it is running on an Intel platform which supports IMSM, and | |
2916 | supports the particular configuration of IMSM that is being requested | |
2917 | (some functionality requires newer OROM support). | |
2918 | ||
2919 | These checks can be suppressed by setting IMSM_NO_PLATFORM=1 in the | |
2920 | environment. This can be useful for testing or for disaster | |
2921 | recovery. You should be aware that interoperability may be | |
2922 | compromised by setting this value. | |
2dfb675b | 2923 | |
f66585eb N |
2924 | .TP |
2925 | .B MDADM_GROW_ALLOW_OLD | |
2926 | If an array is stopped while it is performing a reshape and that | |
2927 | reshape was making use of a backup file, then when the array is | |
2928 | re-assembled | |
2929 | .I mdadm | |
2930 | will sometimes complain that the backup file is too old. If this | |
2931 | happens and you are certain it is the right backup file, you can | |
2932 | over-ride this check by setting | |
2933 | .B MDADM_GROW_ALLOW_OLD=1 | |
2934 | in the environment. | |
2935 | ||
2dfb675b N |
2936 | .TP |
2937 | .B MDADM_CONF_AUTO | |
2938 | Any string given in this variable is added to the start of the | |
2939 | .B AUTO | |
2940 | line in the config file, or treated as the whole | |
2941 | .B AUTO | |
2942 | line if none is given. It can be used to disable certain metadata | |
2943 | types when | |
2944 | .I mdadm | |
2945 | is called from a boot script. For example | |
2946 | .br | |
2947 | .B " export MDADM_CONF_AUTO='-ddf -imsm' | |
2948 | .br | |
2949 | will make sure that | |
2950 | .I mdadm | |
2951 | does not automatically assemble any DDF or | |
2952 | IMSM arrays that are found. This can be useful on systems configured | |
2953 | to manage such arrays with | |
2954 | .BR dmraid . | |
2955 | ||
2956 | ||
2d465520 NB |
2957 | .SH EXAMPLES |
2958 | ||
7e23fc43 | 2959 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 2960 | .br |
e0fe762a | 2961 | This will find out if a given device is a RAID array, or is part of |
5787fa49 | 2962 | one, and will provide brief information about the device. |
2d465520 | 2963 | |
7e23fc43 | 2964 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 2965 | .br |
93e790af | 2966 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 2967 | file. This command will typically go in a system startup file. |
2d465520 | 2968 | |
7e23fc43 | 2969 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 2970 | .br |
93e790af | 2971 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 2972 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 2973 | |
7e23fc43 | 2974 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 2975 | .br |
5787fa49 NB |
2976 | If (and only if) there is an Email address or program given in the |
2977 | standard config file, then | |
2978 | monitor the status of all arrays listed in that file by | |
2979 | polling them ever 2 minutes. | |
2d465520 | 2980 | |
7e23fc43 | 2981 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 2982 | .br |
5787fa49 | 2983 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 2984 | |
2d465520 | 2985 | .br |
7e23fc43 | 2986 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 2987 | .br |
7e23fc43 | 2988 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 2989 | .br |
5787fa49 NB |
2990 | This will create a prototype config file that describes currently |
2991 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
2992 | This file should be reviewed before being used as it may |
2993 | contain unwanted detail. | |
2994 | ||
7e23fc43 | 2995 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 2996 | .br |
7e23fc43 | 2997 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
2998 | .br |
2999 | This will find arrays which could be assembled from existing IDE and | |
3000 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 3001 | format of a config file. |
2d465520 NB |
3002 | This file is very likely to contain unwanted detail, particularly |
3003 | the | |
3004 | .B devices= | |
5787fa49 NB |
3005 | entries. It should be reviewed and edited before being used as an |
3006 | actual config file. | |
2d465520 | 3007 | |
7e23fc43 | 3008 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 3009 | .br |
7e23fc43 | 3010 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
3011 | .br |
3012 | Create a list of devices by reading | |
3013 | .BR /proc/partitions , | |
3014 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 3015 | that were found. |
2d465520 | 3016 | |
7e23fc43 | 3017 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 3018 | .br |
5787fa49 NB |
3019 | Scan all partitions and devices listed in |
3020 | .BR /proc/partitions | |
3021 | and assemble | |
3022 | .B /dev/md0 | |
3023 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 3024 | |
96fd06ed | 3025 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /run/mdadm/mon.pid" |
d013a55e NB |
3026 | .br |
3027 | If config file contains a mail address or alert program, run mdadm in | |
3028 | the background in monitor mode monitoring all md devices. Also write | |
3029 | pid of mdadm daemon to | |
96fd06ed | 3030 | .BR /run/mdadm/mon.pid . |
d013a55e | 3031 | |
7e23fc43 | 3032 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
3033 | .br |
3034 | Try to incorporate newly discovered device into some array as | |
3035 | appropriate. | |
3036 | ||
7e6140e6 | 3037 | .B " mdadm \-\-incremental \-\-rebuild\-map \-\-run \-\-scan" |
8382f19b NB |
3038 | .br |
3039 | Rebuild the array map from any current arrays, and then start any that | |
3040 | can be started. | |
3041 | ||
b80da661 NB |
3042 | .B " mdadm /dev/md4 --fail detached --remove detached" |
3043 | .br | |
3044 | Any devices which are components of /dev/md4 will be marked as faulty | |
3045 | and then remove from the array. | |
3046 | ||
cb77f620 | 3047 | .B " mdadm --grow /dev/md4 --level=6 --backup-file=/root/backup-md4" |
f24e2d6c N |
3048 | .br |
3049 | The array | |
3050 | .B /dev/md4 | |
3051 | which is currently a RAID5 array will be converted to RAID6. There | |
3052 | should normally already be a spare drive attached to the array as a | |
3053 | RAID6 needs one more drive than a matching RAID5. | |
3054 | ||
8fd8d9c4 N |
3055 | .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]" |
3056 | .br | |
3057 | Create a DDF array over 6 devices. | |
3058 | ||
3059 | .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf" | |
3060 | .br | |
e0fe762a | 3061 | Create a RAID5 array over any 3 devices in the given DDF set. Use |
8fd8d9c4 N |
3062 | only 30 gigabytes of each device. |
3063 | ||
3064 | .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]" | |
3065 | .br | |
3066 | Assemble a pre-exist ddf array. | |
3067 | ||
3068 | .B " mdadm -I /dev/md/ddf1" | |
3069 | .br | |
3070 | Assemble all arrays contained in the ddf array, assigning names as | |
3071 | appropriate. | |
3072 | ||
7e23fc43 | 3073 | .B " mdadm \-\-create \-\-help" |
2d465520 | 3074 | .br |
2ae555c3 | 3075 | Provide help about the Create mode. |
2d465520 | 3076 | |
7e23fc43 | 3077 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
3078 | .br |
3079 | Provide help about the format of the config file. | |
2d465520 | 3080 | |
7e23fc43 | 3081 | .B " mdadm \-\-help" |
5787fa49 NB |
3082 | .br |
3083 | Provide general help. | |
cd29a5c8 | 3084 | |
cd29a5c8 NB |
3085 | .SH FILES |
3086 | ||
3087 | .SS /proc/mdstat | |
3088 | ||
2ae555c3 NB |
3089 | If you're using the |
3090 | .B /proc | |
cd29a5c8 NB |
3091 | filesystem, |
3092 | .B /proc/mdstat | |
2d465520 | 3093 | lists all active md devices with information about them. |
51ac42e3 | 3094 | .I mdadm |
2d465520 | 3095 | uses this to find arrays when |
7e23fc43 | 3096 | .B \-\-scan |
2d465520 NB |
3097 | is given in Misc mode, and to monitor array reconstruction |
3098 | on Monitor mode. | |
3099 | ||
9a9dab36 | 3100 | .SS /etc/mdadm.conf |
cd29a5c8 | 3101 | |
11a3e71d NB |
3102 | The config file lists which devices may be scanned to see if |
3103 | they contain MD super block, and gives identifying information | |
3104 | (e.g. UUID) about known MD arrays. See | |
3105 | .BR mdadm.conf (5) | |
3106 | for more details. | |
cd29a5c8 | 3107 | |
9dc70cbc N |
3108 | .SS /etc/mdadm.conf.d |
3109 | ||
3110 | A directory containing configuration files which are read in lexical | |
3111 | order. | |
3112 | ||
96fd06ed | 3113 | .SS {MAP_PATH} |
8382f19b | 3114 | When |
7e23fc43 | 3115 | .B \-\-incremental |
93e790af | 3116 | mode is used, this file gets a list of arrays currently being created. |
8382f19b | 3117 | |
48f7b27a NB |
3118 | .SH DEVICE NAMES |
3119 | ||
48f7b27a | 3120 | .I mdadm |
8fd8d9c4 N |
3121 | understand two sorts of names for array devices. |
3122 | ||
3123 | The first is the so-called 'standard' format name, which matches the | |
3124 | names used by the kernel and which appear in | |
3125 | .IR /proc/mdstat . | |
3126 | ||
3127 | The second sort can be freely chosen, but must reside in | |
3128 | .IR /dev/md/ . | |
3129 | When giving a device name to | |
3130 | .I mdadm | |
3131 | to create or assemble an array, either full path name such as | |
3132 | .I /dev/md0 | |
3133 | or | |
3134 | .I /dev/md/home | |
3135 | can be given, or just the suffix of the second sort of name, such as | |
3136 | .I home | |
3137 | can be given. | |
3138 | ||
3139 | When | |
3140 | .I mdadm | |
e0fe762a N |
3141 | chooses device names during auto-assembly or incremental assembly, it |
3142 | will sometimes add a small sequence number to the end of the name to | |
3143 | avoid conflicted between multiple arrays that have the same name. If | |
8fd8d9c4 N |
3144 | .I mdadm |
3145 | can reasonably determine that the array really is meant for this host, | |
3146 | either by a hostname in the metadata, or by the presence of the array | |
87eb4fab N |
3147 | in |
3148 | .BR mdadm.conf , | |
3149 | then it will leave off the suffix if possible. | |
e0fe762a N |
3150 | Also if the homehost is specified as |
3151 | .B <ignore> | |
3152 | .I mdadm | |
3153 | will only use a suffix if a different array of the same name already | |
3154 | exists or is listed in the config file. | |
48f7b27a NB |
3155 | |
3156 | The standard names for non-partitioned arrays (the only sort of md | |
8fd8d9c4 | 3157 | array available in 2.4 and earlier) are of the form |
48f7b27a | 3158 | .IP |
eca944fa | 3159 | .RB /dev/md NN |
48f7b27a NB |
3160 | .PP |
3161 | where NN is a number. | |
3162 | The standard names for partitionable arrays (as available from 2.6 | |
eca944fa | 3163 | onwards) are of the form: |
48f7b27a | 3164 | .IP |
eca944fa | 3165 | .RB /dev/md_d NN |
48f7b27a | 3166 | .PP |
eca944fa | 3167 | Partition numbers should be indicated by adding "pMM" to these, thus "/dev/md/d1p2". |
8fd8d9c4 | 3168 | .PP |
eca944fa N |
3169 | From kernel version 2.6.28 the "non-partitioned array" can actually |
3170 | be partitioned. So the "md_d\fBNN\fP" | |
3171 | names are no longer needed, and | |
0de5349e | 3172 | partitions such as "/dev/md\fBNN\fPp\fBXX\fP" |
eca944fa N |
3173 | are possible. |
3174 | .PP | |
3175 | From kernel version 2.6.29 standard names can be non-numeric following | |
3176 | the form: | |
3177 | .IP | |
3178 | .RB /dev/md_ XXX | |
3179 | .PP | |
3180 | where | |
3181 | .B XXX | |
3182 | is any string. These names are supported by | |
3183 | .I mdadm | |
3184 | since version 3.3 provided they are enabled in | |
3185 | .IR mdadm.conf . | |
52826846 | 3186 | |
2d465520 | 3187 | .SH NOTE |
51ac42e3 | 3188 | .I mdadm |
2d465520 | 3189 | was previously known as |
51ac42e3 | 3190 | .IR mdctl . |
a9d69660 | 3191 | |
52826846 | 3192 | .SH SEE ALSO |
75f74377 | 3193 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 3194 | RAID, see: |
3cdfb6a7 | 3195 | .IP |
cb77f620 | 3196 | .B http://raid.wiki.kernel.org/ |
75f74377 DG |
3197 | .PP |
3198 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
cd29a5c8 | 3199 | .PP |
2ae555c3 | 3200 | The latest version of |
a9d69660 NB |
3201 | .I mdadm |
3202 | should always be available from | |
cd29a5c8 | 3203 | .IP |
11cd8b79 N |
3204 | .B http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
3205 | .PP | |
3206 | Related man pages: | |
cd29a5c8 | 3207 | .PP |
e0fe762a | 3208 | .IR mdmon (8), |
a9d69660 NB |
3209 | .IR mdadm.conf (5), |
3210 | .IR md (4). |