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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. | |
3b2aad6e | 8 | .TH MDADM 8 "" v3.2.5 |
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, | |
128 | changing the chunk size and layout for RAID 0,4,5,6, 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 | |
7e23fc43 PS |
217 | .BR \-\-add , |
218 | .BR \-\-fail , | |
7e23fc43 | 219 | .BR \-\-remove , |
70c55e36 N |
220 | or |
221 | .BR \-\-replace , | |
e0fe762a | 222 | then the MANAGE mode is assumed. |
2ae555c3 NB |
223 | Anything other than these will cause the |
224 | .B Misc | |
225 | mode to be assumed. | |
dd0781e5 | 226 | |
2ae555c3 | 227 | .SH Options that are not mode-specific are: |
e793c2e5 | 228 | |
cd29a5c8 | 229 | .TP |
7e23fc43 | 230 | .BR \-h ", " \-\-help |
a9d69660 | 231 | Display general help message or, after one of the above options, a |
93e790af | 232 | mode-specific help message. |
56eedc1a NB |
233 | |
234 | .TP | |
7e23fc43 | 235 | .B \-\-help\-options |
56eedc1a NB |
236 | Display more detailed help about command line parsing and some commonly |
237 | used options. | |
52826846 | 238 | |
cd29a5c8 | 239 | .TP |
7e23fc43 | 240 | .BR \-V ", " \-\-version |
9a9dab36 | 241 | Print version information for mdadm. |
52826846 | 242 | |
cd29a5c8 | 243 | .TP |
7e23fc43 | 244 | .BR \-v ", " \-\-verbose |
22892d56 NB |
245 | Be more verbose about what is happening. This can be used twice to be |
246 | extra-verbose. | |
a9d69660 | 247 | The extra verbosity currently only affects |
7e23fc43 | 248 | .B \-\-detail \-\-scan |
22892d56 | 249 | and |
7e23fc43 | 250 | .BR "\-\-examine \-\-scan" . |
52826846 | 251 | |
dab6685f | 252 | .TP |
7e23fc43 | 253 | .BR \-q ", " \-\-quiet |
dab6685f | 254 | Avoid printing purely informative messages. With this, |
51ac42e3 | 255 | .I mdadm |
dab6685f NB |
256 | will be silent unless there is something really important to report. |
257 | ||
08ca2adf JS |
258 | .TP |
259 | .BR \-\-offroot | |
260 | Set first character of argv[0] to @ to indicate mdadm was launched | |
261 | from initrd/initramfs and should not be shutdown by systemd as part of | |
262 | the regular shutdown process. This option is normally only used by | |
263 | the system's initscripts. Please see here for more details on how | |
264 | systemd handled argv[0]: | |
265 | .IP | |
266 | .B http://www.freedesktop.org/wiki/Software/systemd/RootStorageDaemons | |
267 | .PP | |
268 | ||
269 | ||
e0d19036 | 270 | .TP |
7e23fc43 | 271 | .BR \-f ", " \-\-force |
93e790af | 272 | Be more forceful about certain operations. See the various modes for |
e0d19036 NB |
273 | the exact meaning of this option in different contexts. |
274 | ||
275 | .TP | |
7e23fc43 | 276 | .BR \-c ", " \-\-config= |
2ae555c3 NB |
277 | Specify the config file. Default is to use |
278 | .BR /etc/mdadm.conf , | |
93e790af | 279 | or if that is missing then |
2ae555c3 | 280 | .BR /etc/mdadm/mdadm.conf . |
5787fa49 | 281 | If the config file given is |
93e790af | 282 | .B "partitions" |
5787fa49 NB |
283 | then nothing will be read, but |
284 | .I mdadm | |
285 | will act as though the config file contained exactly | |
8fd8d9c4 | 286 | .B "DEVICE partitions containers" |
5787fa49 NB |
287 | and will read |
288 | .B /proc/partitions | |
8fd8d9c4 N |
289 | to find a list of devices to scan, and |
290 | .B /proc/mdstat | |
291 | to find a list of containers to examine. | |
d013a55e | 292 | If the word |
93e790af | 293 | .B "none" |
d013a55e NB |
294 | is given for the config file, then |
295 | .I mdadm | |
296 | will act as though the config file were empty. | |
e0d19036 NB |
297 | |
298 | .TP | |
7e23fc43 | 299 | .BR \-s ", " \-\-scan |
93e790af | 300 | Scan config file or |
e0d19036 NB |
301 | .B /proc/mdstat |
302 | for missing information. | |
303 | In general, this option gives | |
51ac42e3 | 304 | .I mdadm |
93e790af SW |
305 | permission to get any missing information (like component devices, |
306 | array devices, array identities, and alert destination) from the | |
307 | configuration file (see previous option); | |
308 | one exception is MISC mode when using | |
7e23fc43 | 309 | .B \-\-detail |
e0d19036 | 310 | or |
93e790af | 311 | .B \-\-stop, |
e0d19036 | 312 | in which case |
7e23fc43 | 313 | .B \-\-scan |
e0d19036 NB |
314 | says to get a list of array devices from |
315 | .BR /proc/mdstat . | |
316 | ||
570c0542 | 317 | .TP |
d16c7af6 | 318 | .BR \-e ", " \-\-metadata= |
e0fe762a | 319 | Declare the style of RAID metadata (superblock) to be used. The |
26f467a9 | 320 | default is {DEFAULT_METADATA} for |
7e23fc43 | 321 | .BR \-\-create , |
53e8b987 | 322 | and to guess for other operations. |
2790ffe3 GB |
323 | The default can be overridden by setting the |
324 | .B metadata | |
325 | value for the | |
326 | .B CREATE | |
327 | keyword in | |
328 | .BR mdadm.conf . | |
570c0542 NB |
329 | |
330 | Options are: | |
331 | .RS | |
26f467a9 | 332 | .ie '{DEFAULT_METADATA}'0.90' |
333 | .IP "0, 0.90, default" | |
334 | .el | |
7d5c3964 | 335 | .IP "0, 0.90" |
570c0542 | 336 | Use the original 0.90 format superblock. This format limits arrays to |
93e790af | 337 | 28 component devices and limits component devices of levels 1 and |
cd19c0cf JR |
338 | greater to 2 terabytes. It is also possible for there to be confusion |
339 | about whether the superblock applies to a whole device or just the | |
340 | last partition, if that partition starts on a 64K boundary. | |
26f467a9 | 341 | .ie '{DEFAULT_METADATA}'0.90' |
342 | .IP "1, 1.0, 1.1, 1.2" | |
343 | .el | |
7d5c3964 | 344 | .IP "1, 1.0, 1.1, 1.2 default" |
cd19c0cf JR |
345 | Use the new version-1 format superblock. This has fewer restrictions. |
346 | It can easily be moved between hosts with different endian-ness, and a | |
347 | recovery operation can be checkpointed and restarted. The different | |
348 | sub-versions store the superblock at different locations on the | |
349 | device, either at the end (for 1.0), at the start (for 1.1) or 4K from | |
7050aa3f N |
350 | the start (for 1.2). "1" is equivalent to "1.2" (the commonly |
351 | preferred 1.x format). | |
26f467a9 | 352 | 'if '{DEFAULT_METADATA}'1.2' "default" is equivalent to "1.2". |
8fd8d9c4 | 353 | .IP ddf |
e0fe762a N |
354 | Use the "Industry Standard" DDF (Disk Data Format) format defined by |
355 | SNIA. | |
356 | When creating a DDF array a | |
8fd8d9c4 N |
357 | .B CONTAINER |
358 | will be created, and normal arrays can be created in that container. | |
359 | .IP imsm | |
4cce4069 | 360 | Use the Intel(R) Matrix Storage Manager metadata format. This creates a |
8fd8d9c4 | 361 | .B CONTAINER |
4cce4069 DW |
362 | which is managed in a similar manner to DDF, and is supported by an |
363 | option-rom on some platforms: | |
364 | .IP | |
365 | .B http://www.intel.com/design/chipsets/matrixstorage_sb.htm | |
366 | .PP | |
570c0542 NB |
367 | .RE |
368 | ||
41a3b72a | 369 | .TP |
7e23fc43 | 370 | .B \-\-homehost= |
35cc5be4 | 371 | This will override any |
41a3b72a | 372 | .B HOMEHOST |
93e790af | 373 | setting in the config file and provides the identity of the host which |
41a3b72a NB |
374 | should be considered the home for any arrays. |
375 | ||
376 | When creating an array, the | |
377 | .B homehost | |
e0fe762a | 378 | will be recorded in the metadata. For version-1 superblocks, it will |
93e790af | 379 | be prefixed to the array name. For version-0.90 superblocks, part of |
41a3b72a NB |
380 | the SHA1 hash of the hostname will be stored in the later half of the |
381 | UUID. | |
382 | ||
383 | When reporting information about an array, any array which is tagged | |
384 | for the given homehost will be reported as such. | |
385 | ||
386 | When using Auto-Assemble, only arrays tagged for the given homehost | |
0ac91628 | 387 | will be allowed to use 'local' names (i.e. not ending in '_' followed |
e0fe762a N |
388 | by a digit string). See below under |
389 | .BR "Auto Assembly" . | |
41a3b72a | 390 | |
c2ecf5f6 N |
391 | .TP |
392 | .B \-\-prefer= | |
393 | When | |
394 | .I mdadm | |
395 | needs to print the name for a device it normally finds the name in | |
396 | .B /dev | |
397 | which refers to the device and is shortest. When a path component is | |
398 | given with | |
399 | .B \-\-prefer | |
400 | .I mdadm | |
401 | will prefer a longer name if it contains that component. For example | |
402 | .B \-\-prefer=by-uuid | |
403 | will prefer a name in a subdirectory of | |
404 | .B /dev | |
405 | called | |
406 | .BR by-uuid . | |
407 | ||
408 | This functionality is currently only provided by | |
409 | .B \-\-detail | |
410 | and | |
411 | .BR \-\-monitor . | |
412 | ||
2ae555c3 NB |
413 | .SH For create, build, or grow: |
414 | ||
415 | .TP | |
7e23fc43 | 416 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
417 | Specify the number of active devices in the array. This, plus the |
418 | number of spare devices (see below) must equal the number of | |
419 | .I component-devices | |
420 | (including "\fBmissing\fP" devices) | |
421 | that are listed on the command line for | |
e0fe762a | 422 | .BR \-\-create . |
2ae555c3 NB |
423 | Setting a value of 1 is probably |
424 | a mistake and so requires that | |
7e23fc43 | 425 | .B \-\-force |
2ae555c3 | 426 | be specified first. A value of 1 will then be allowed for linear, |
e0fe762a | 427 | multipath, RAID0 and RAID1. It is never allowed for RAID4, RAID5 or RAID6. |
2ae555c3 NB |
428 | .br |
429 | This number can only be changed using | |
7e23fc43 | 430 | .B \-\-grow |
e0fe762a N |
431 | for RAID1, RAID4, RAID5 and RAID6 arrays, and only on kernels which provide |
432 | the necessary support. | |
2ae555c3 NB |
433 | |
434 | .TP | |
7e23fc43 | 435 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
436 | Specify the number of spare (eXtra) devices in the initial array. |
437 | Spares can also be added | |
438 | and removed later. The number of component devices listed | |
e0fe762a | 439 | on the command line must equal the number of RAID devices plus the |
2ae555c3 NB |
440 | number of spare devices. |
441 | ||
2ae555c3 | 442 | .TP |
7e23fc43 | 443 | .BR \-z ", " \-\-size= |
e0fe762a | 444 | Amount (in Kibibytes) of space to use from each drive in RAID levels 1/4/5/6. |
2ae555c3 NB |
445 | This must be a multiple of the chunk size, and must leave about 128Kb |
446 | of space at the end of the drive for the RAID superblock. | |
447 | If this is not specified | |
448 | (as it normally is not) the smallest drive (or partition) sets the | |
449 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
450 | issued. | |
451 | ||
36fad8ec N |
452 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
453 | Gigabytes respectively. | |
454 | ||
9ab6e80a N |
455 | Sometimes a replacement drive can be a little smaller than the |
456 | original drives though this should be minimised by IDEMA standards. | |
457 | Such a replacement drive will be rejected by | |
458 | .IR md . | |
459 | To guard against this it can be useful to set the initial size | |
460 | slightly smaller than the smaller device with the aim that it will | |
461 | still be larger than any replacement. | |
462 | ||
2ae555c3 | 463 | This value can be set with |
7e23fc43 | 464 | .B \-\-grow |
9ab6e80a N |
465 | for RAID level 1/4/5/6 though |
466 | .B CONTAINER | |
467 | based arrays such as those with IMSM metadata may not be able to | |
468 | support this. | |
469 | If the array was created with a size smaller than the currently | |
470 | active drives, the extra space can be accessed using | |
7e23fc43 | 471 | .BR \-\-grow . |
2ae555c3 NB |
472 | The size can be given as |
473 | .B max | |
474 | which means to choose the largest size that fits on all current drives. | |
52826846 | 475 | |
c26d78fe N |
476 | Before reducing the size of the array (with |
477 | .BR "\-\-grow \-\-size=" ) | |
478 | you should make sure that space isn't needed. If the device holds a | |
479 | filesystem, you would need to resize the filesystem to use less space. | |
480 | ||
481 | After reducing the array size you should check that the data stored in | |
482 | the device is still available. If the device holds a filesystem, then | |
483 | an 'fsck' of the filesystem is a minimum requirement. If there are | |
484 | problems the array can be made bigger again with no loss with another | |
485 | .B "\-\-grow \-\-size=" | |
486 | command. | |
487 | ||
9ab6e80a | 488 | This value cannot be used when creating a |
8fd8d9c4 | 489 | .B CONTAINER |
9ab6e80a N |
490 | such as with DDF and IMSM metadata, though it perfectly valid when |
491 | creating an array inside a container. | |
8fd8d9c4 | 492 | |
f24e2d6c | 493 | .TP |
c26d78fe | 494 | .BR \-Z ", " \-\-array\-size= |
f24e2d6c N |
495 | This is only meaningful with |
496 | .B \-\-grow | |
36fad8ec | 497 | and its effect is not persistent: when the array is stopped and |
f24e2d6c N |
498 | restarted the default array size will be restored. |
499 | ||
500 | Setting the array-size causes the array to appear smaller to programs | |
501 | that access the data. This is particularly needed before reshaping an | |
502 | array so that it will be smaller. As the reshape is not reversible, | |
503 | but setting the size with | |
504 | .B \-\-array-size | |
505 | is, it is required that the array size is reduced as appropriate | |
506 | before the number of devices in the array is reduced. | |
507 | ||
c26d78fe N |
508 | Before reducing the size of the array you should make sure that space |
509 | isn't needed. If the device holds a filesystem, you would need to | |
510 | resize the filesystem to use less space. | |
511 | ||
512 | After reducing the array size you should check that the data stored in | |
513 | the device is still available. If the device holds a filesystem, then | |
514 | an 'fsck' of the filesystem is a minimum requirement. If there are | |
515 | problems the array can be made bigger again with no loss with another | |
516 | .B "\-\-grow \-\-array\-size=" | |
517 | command. | |
518 | ||
36fad8ec N |
519 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
520 | Gigabytes respectively. | |
521 | A value of | |
522 | .B max | |
523 | restores the apparent size of the array to be whatever the real | |
524 | amount of available space is. | |
525 | ||
cd29a5c8 | 526 | .TP |
7e23fc43 | 527 | .BR \-c ", " \-\-chunk= |
5f175898 N |
528 | Specify chunk size of kibibytes. The default when creating an |
529 | array is 512KB. To ensure compatibility with earlier versions, the | |
530 | default when Building and array with no persistent metadata is 64KB. | |
e0fe762a | 531 | This is only meaningful for RAID0, RAID4, RAID5, RAID6, and RAID10. |
52826846 | 532 | |
a252c078 N |
533 | RAID4, RAID5, RAID6, and RAID10 require the chunk size to be a power |
534 | of 2. In any case it must be a multiple of 4KB. | |
535 | ||
36fad8ec N |
536 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
537 | Gigabytes respectively. | |
538 | ||
cd29a5c8 | 539 | .TP |
7e23fc43 | 540 | .BR \-\-rounding= |
e0fe762a N |
541 | Specify rounding factor for a Linear array. The size of each |
542 | component will be rounded down to a multiple of this size. | |
543 | This is a synonym for | |
544 | .B \-\-chunk | |
545 | but highlights the different meaning for Linear as compared to other | |
5f175898 N |
546 | RAID levels. The default is 64K if a kernel earlier than 2.6.16 is in |
547 | use, and is 0K (i.e. no rounding) in later kernels. | |
52826846 | 548 | |
cd29a5c8 | 549 | .TP |
7e23fc43 | 550 | .BR \-l ", " \-\-level= |
e0fe762a | 551 | Set RAID level. When used with |
7e23fc43 | 552 | .BR \-\-create , |
98c6faba | 553 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
8fd8d9c4 N |
554 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container. |
555 | Obviously some of these are synonymous. | |
556 | ||
557 | When a | |
558 | .B CONTAINER | |
559 | metadata type is requested, only the | |
560 | .B container | |
561 | level is permitted, and it does not need to be explicitly given. | |
aa88f531 NB |
562 | |
563 | When used with | |
7e23fc43 | 564 | .BR \-\-build , |
a9d69660 | 565 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 566 | |
fd547b50 N |
567 | Can be used with |
568 | .B \-\-grow | |
569 | to change the RAID level in some cases. See LEVEL CHANGES below. | |
2ae555c3 | 570 | |
cd29a5c8 | 571 | .TP |
7e23fc43 | 572 | .BR \-p ", " \-\-layout= |
f24e2d6c N |
573 | This option configures the fine details of data layout for RAID5, RAID6, |
574 | and RAID10 arrays, and controls the failure modes for | |
1a7dfc35 NB |
575 | .IR faulty . |
576 | ||
e0fe762a | 577 | The layout of the RAID5 parity block can be one of |
7e23fc43 PS |
578 | .BR left\-asymmetric , |
579 | .BR left\-symmetric , | |
580 | .BR right\-asymmetric , | |
581 | .BR right\-symmetric , | |
53e8b987 PS |
582 | .BR la ", " ra ", " ls ", " rs . |
583 | The default is | |
7e23fc43 | 584 | .BR left\-symmetric . |
52826846 | 585 | |
cd19c0cf | 586 | It is also possible to cause RAID5 to use a RAID4-like layout by |
e0fe762a N |
587 | choosing |
588 | .BR parity\-first , | |
589 | or | |
590 | .BR parity\-last . | |
591 | ||
592 | Finally for RAID5 there are DDF\-compatible layouts, | |
593 | .BR ddf\-zero\-restart , | |
594 | .BR ddf\-N\-restart , | |
595 | and | |
596 | .BR ddf\-N\-continue . | |
597 | ||
598 | These same layouts are available for RAID6. There are also 4 layouts | |
599 | that will provide an intermediate stage for converting between RAID5 | |
600 | and RAID6. These provide a layout which is identical to the | |
601 | corresponding RAID5 layout on the first N\-1 devices, and has the 'Q' | |
602 | syndrome (the second 'parity' block used by RAID6) on the last device. | |
603 | These layouts are: | |
604 | .BR left\-symmetric\-6 , | |
605 | .BR right\-symmetric\-6 , | |
606 | .BR left\-asymmetric\-6 , | |
607 | .BR right\-asymmetric\-6 , | |
608 | and | |
10adfe9a | 609 | .BR parity\-first\-6 . |
e0fe762a | 610 | |
93e790af SW |
611 | When setting the failure mode for level |
612 | .I faulty, | |
1a7dfc35 | 613 | the options are: |
7e23fc43 PS |
614 | .BR write\-transient ", " wt , |
615 | .BR read\-transient ", " rt , | |
616 | .BR write\-persistent ", " wp , | |
617 | .BR read\-persistent ", " rp , | |
618 | .BR write\-all , | |
619 | .BR read\-fixable ", " rf , | |
53e8b987 | 620 | .BR clear ", " flush ", " none . |
b5e64645 | 621 | |
93e790af | 622 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
623 | between fault generation. Without a number, the fault is generated |
624 | once on the first relevant request. With a number, the fault will be | |
93e790af | 625 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
626 | every time the period elapses. |
627 | ||
628 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 629 | .B \-\-grow |
53e8b987 | 630 | option to set subsequent failure modes. |
b5e64645 NB |
631 | |
632 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 633 | and "flush" will clear any persistent faults. |
b5e64645 | 634 | |
6f9a21a7 | 635 | Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 636 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 637 | |
93e790af | 638 | .I 'n' |
e0fe762a | 639 | signals 'near' copies. Multiple copies of one data block are at |
b578481c NB |
640 | similar offsets in different devices. |
641 | ||
93e790af | 642 | .I 'o' |
b578481c NB |
643 | signals 'offset' copies. Rather than the chunks being duplicated |
644 | within a stripe, whole stripes are duplicated but are rotated by one | |
645 | device so duplicate blocks are on different devices. Thus subsequent | |
646 | copies of a block are in the next drive, and are one chunk further | |
647 | down. | |
648 | ||
93e790af | 649 | .I 'f' |
1a7dfc35 | 650 | signals 'far' copies |
93e790af | 651 | (multiple copies have very different offsets). |
e0fe762a | 652 | See md(4) for more detail about 'near', 'offset', and 'far'. |
1a7dfc35 NB |
653 | |
654 | The number is the number of copies of each datablock. 2 is normal, 3 | |
655 | can be useful. This number can be at most equal to the number of | |
656 | devices in the array. It does not need to divide evenly into that | |
657 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
658 | with an odd number of devices). | |
659 | ||
f24e2d6c N |
660 | When an array is converted between RAID5 and RAID6 an intermediate |
661 | RAID6 layout is used in which the second parity block (Q) is always on | |
662 | the last device. To convert a RAID5 to RAID6 and leave it in this new | |
663 | layout (which does not require re-striping) use | |
664 | .BR \-\-layout=preserve . | |
665 | This will try to avoid any restriping. | |
666 | ||
667 | The converse of this is | |
668 | .B \-\-layout=normalise | |
669 | which will change a non-standard RAID6 layout into a more standard | |
670 | arrangement. | |
671 | ||
cd29a5c8 | 672 | .TP |
7e23fc43 | 673 | .BR \-\-parity= |
53e8b987 | 674 | same as |
7e23fc43 | 675 | .B \-\-layout |
53e8b987 | 676 | (thus explaining the p of |
7e23fc43 | 677 | .BR \-p ). |
52826846 | 678 | |
e793c2e5 | 679 | .TP |
7e23fc43 | 680 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 681 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 682 | exist unless |
7e23fc43 | 683 | .B \-\-force |
53e8b987 | 684 | is also given. The same file should be provided |
2ae555c3 | 685 | when assembling the array. If the word |
93e790af | 686 | .B "internal" |
2ae555c3 NB |
687 | is given, then the bitmap is stored with the metadata on the array, |
688 | and so is replicated on all devices. If the word | |
93e790af | 689 | .B "none" |
2ae555c3 | 690 | is given with |
7e23fc43 | 691 | .B \-\-grow |
2ae555c3 | 692 | mode, then any bitmap that is present is removed. |
e793c2e5 | 693 | |
2ae555c3 NB |
694 | To help catch typing errors, the filename must contain at least one |
695 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
696 | ||
697 | Note: external bitmaps are only known to work on ext2 and ext3. | |
698 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 699 | |
cd29a5c8 | 700 | .TP |
7e23fc43 | 701 | .BR \-\-bitmap\-chunk= |
e0fe762a | 702 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
703 | Kilobytes of storage. |
704 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 705 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
706 | When using an |
707 | .B internal | |
b8ab2a50 N |
708 | bitmap, the chunksize defaults to 64Meg, or larger if necessary to |
709 | fit the bitmap into the available space. | |
5787fa49 | 710 | |
36fad8ec N |
711 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
712 | Gigabytes respectively. | |
713 | ||
cd29a5c8 | 714 | .TP |
7e23fc43 | 715 | .BR \-W ", " \-\-write\-mostly |
e0fe762a | 716 | subsequent devices listed in a |
7e23fc43 PS |
717 | .BR \-\-build , |
718 | .BR \-\-create , | |
2ae555c3 | 719 | or |
7e23fc43 | 720 | .B \-\-add |
2ae555c3 NB |
721 | command will be flagged as 'write-mostly'. This is valid for RAID1 |
722 | only and means that the 'md' driver will avoid reading from these | |
723 | devices if at all possible. This can be useful if mirroring over a | |
724 | slow link. | |
52826846 | 725 | |
2ae555c3 | 726 | .TP |
7e23fc43 | 727 | .BR \-\-write\-behind= |
2ae555c3 | 728 | Specify that write-behind mode should be enabled (valid for RAID1 |
e0fe762a N |
729 | only). If an argument is specified, it will set the maximum number |
730 | of outstanding writes allowed. The default value is 256. | |
2ae555c3 NB |
731 | A write-intent bitmap is required in order to use write-behind |
732 | mode, and write-behind is only attempted on drives marked as | |
733 | .IR write-mostly . | |
dd0781e5 NB |
734 | |
735 | .TP | |
7e23fc43 | 736 | .BR \-\-assume\-clean |
dd0781e5 NB |
737 | Tell |
738 | .I mdadm | |
47d79ef8 NB |
739 | that the array pre-existed and is known to be clean. It can be useful |
740 | when trying to recover from a major failure as you can be sure that no | |
741 | data will be affected unless you actually write to the array. It can | |
742 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 743 | initial resync, however this practice \(em while normally safe \(em is not |
e0fe762a | 744 | recommended. Use this only if you really know what you are doing. |
6acad481 ME |
745 | .IP |
746 | When the devices that will be part of a new array were filled | |
747 | with zeros before creation the operator knows the array is | |
748 | actually clean. If that is the case, such as after running | |
749 | badblocks, this argument can be used to tell mdadm the | |
750 | facts the operator knows. | |
ce52f92f N |
751 | .IP |
752 | When an array is resized to a larger size with | |
753 | .B "\-\-grow \-\-size=" | |
754 | the new space is normally resynced in that same way that the whole | |
6cbf8fb8 | 755 | array is resynced at creation. From Linux version 3.0, |
ce52f92f N |
756 | .B \-\-assume\-clean |
757 | can be used with that command to avoid the automatic resync. | |
dd0781e5 | 758 | |
2ae555c3 | 759 | .TP |
7e23fc43 | 760 | .BR \-\-backup\-file= |
53e8b987 | 761 | This is needed when |
7e23fc43 | 762 | .B \-\-grow |
cd19c0cf JR |
763 | is used to increase the number of raid-devices in a RAID5 or RAID6 if |
764 | there are no spare devices available, or to shrink, change RAID level | |
765 | or layout. See the GROW MODE section below on RAID\-DEVICES CHANGES. | |
766 | The file must be stored on a separate device, not on the RAID array | |
767 | being reshaped. | |
2ae555c3 | 768 | |
40c9a66a N |
769 | .TP |
770 | .B \-\-data\-offset= | |
771 | Arrays with 1.x metadata can leave a gap between the start of the | |
772 | device and the start of array data. This gap can be used for various | |
773 | metadata. The start of data is known as the | |
774 | .IR data\-offset . | |
775 | Normally an appropriate data offset is computed automatically. | |
776 | However it can be useful to set it explicitly such as when re-creating | |
777 | an array which was originally created using a different version of | |
778 | .I mdadm | |
779 | which computed a different offset. | |
780 | ||
781 | Setting the offset explicitly over-rides the default. The value given | |
782 | is in Kilobytes unless an 'M' or 'G' suffix is given. | |
783 | ||
784 | Since Linux 3.4, | |
785 | .B \-\-data\-offset | |
786 | can also be used with | |
787 | .B --grow | |
788 | for some RAID levels (initially on RAID10). This allows the | |
72ca9bcf | 789 | data\-offset to be changed as part of the reshape process. When the |
40c9a66a N |
790 | data offset is changed, no backup file is required as the difference |
791 | in offsets is used to provide the same functionality. | |
792 | ||
793 | When the new offset is earlier than the old offset, the number of | |
794 | devices in the array cannot shrink. When it is after the old offset, | |
795 | the number of devices in the array cannot increase. | |
796 | ||
72ca9bcf N |
797 | When creating an array, |
798 | .B \-\-data\-offset | |
799 | can be specified as | |
800 | .BR variable . | |
801 | In the case each member device is expected to have a offset appended | |
802 | to the name, separated by a colon. This makes it possible to recreate | |
803 | exactly an array which has varying data offsets (as can happen when | |
804 | different versions of | |
805 | .I mdadm | |
806 | are used to add different devices). | |
807 | ||
f211a137 AK |
808 | .TP |
809 | .BR \-\-continue | |
810 | This option is complementary to the | |
811 | .B \-\-freeze-reshape | |
812 | option for assembly. It is needed when | |
813 | .B \-\-grow | |
814 | operation is interrupted and it is not restarted automatically due to | |
815 | .B \-\-freeze-reshape | |
816 | usage during array assembly. This option is used together with | |
817 | .BR \-G | |
818 | , ( | |
819 | .BR \-\-grow | |
820 | ) command and device for a pending reshape to be continued. | |
821 | All parameters required for reshape continuation will be read from array metadata. | |
822 | If initial | |
823 | .BR \-\-grow | |
824 | command had required | |
825 | .BR \-\-backup\-file= | |
826 | option to be set, continuation option will require to have exactly the same | |
827 | backup file given as well. | |
828 | .IP | |
829 | Any other parameter passed together with | |
830 | .BR \-\-continue | |
831 | option will be ignored. | |
832 | ||
947fd4dd | 833 | .TP |
7e23fc43 | 834 | .BR \-N ", " \-\-name= |
947fd4dd NB |
835 | Set a |
836 | .B name | |
837 | for the array. This is currently only effective when creating an | |
e0fe762a N |
838 | array with a version-1 superblock, or an array in a DDF container. |
839 | The name is a simple textual string that can be used to identify array | |
840 | components when assembling. If name is needed but not specified, it | |
841 | is taken from the basename of the device that is being created. | |
842 | e.g. when creating | |
843 | .I /dev/md/home | |
844 | the | |
845 | .B name | |
846 | will default to | |
847 | .IR home . | |
947fd4dd | 848 | |
dd0781e5 | 849 | .TP |
7e23fc43 | 850 | .BR \-R ", " \-\-run |
dd0781e5 NB |
851 | Insist that |
852 | .I mdadm | |
853 | run the array, even if some of the components | |
854 | appear to be active in another array or filesystem. Normally | |
855 | .I mdadm | |
856 | will ask for confirmation before including such components in an | |
857 | array. This option causes that question to be suppressed. | |
858 | ||
859 | .TP | |
7e23fc43 | 860 | .BR \-f ", " \-\-force |
dd0781e5 NB |
861 | Insist that |
862 | .I mdadm | |
863 | accept the geometry and layout specified without question. Normally | |
864 | .I mdadm | |
865 | will not allow creation of an array with only one device, and will try | |
e0fe762a | 866 | to create a RAID5 array with one missing drive (as this makes the |
dd0781e5 | 867 | initial resync work faster). With |
7e23fc43 | 868 | .BR \-\-force , |
dd0781e5 NB |
869 | .I mdadm |
870 | will not try to be so clever. | |
871 | ||
0ea8f5b1 N |
872 | .TP |
873 | .BR \-o ", " \-\-readonly | |
874 | Start the array | |
875 | .B read only | |
876 | rather than read-write as normal. No writes will be allowed to the | |
877 | array, and no resync, recovery, or reshape will be started. | |
878 | ||
dd0781e5 | 879 | .TP |
257c1dc2 N |
880 | .BR \-a ", " "\-\-auto{=yes,md,mdp,part,p}{NN}" |
881 | Instruct mdadm how to create the device file if needed, possibly allocating | |
48f7b27a | 882 | an unused minor number. "md" causes a non-partitionable array |
257c1dc2 N |
883 | to be used (though since Linux 2.6.28, these array devices are in fact |
884 | partitionable). "mdp", "part" or "p" causes a partitionable array (2.6 and | |
2ae555c3 | 885 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 886 | a 'standard' format, and the type and minor number will be determined |
257c1dc2 N |
887 | from this. With mdadm 3.0, device creation is normally left up to |
888 | .I udev | |
889 | so this option is unlikely to be needed. | |
890 | See DEVICE NAMES below. | |
48f7b27a | 891 | |
a9d69660 | 892 | The argument can also come immediately after |
7e23fc43 | 893 | "\-a". e.g. "\-ap". |
dd0781e5 | 894 | |
53e8b987 | 895 | If |
7e23fc43 | 896 | .B \-\-auto |
53e8b987 | 897 | is not given on the command line or in the config file, then |
75723446 | 898 | the default will be |
7e23fc43 | 899 | .BR \-\-auto=yes . |
75723446 | 900 | |
1337546d | 901 | If |
7e23fc43 | 902 | .B \-\-scan |
1337546d NB |
903 | is also given, then any |
904 | .I auto= | |
35cc5be4 | 905 | entries in the config file will override the |
7e23fc43 | 906 | .B \-\-auto |
1337546d NB |
907 | instruction given on the command line. |
908 | ||
dd0781e5 NB |
909 | For partitionable arrays, |
910 | .I mdadm | |
911 | will create the device file for the whole array and for the first 4 | |
912 | partitions. A different number of partitions can be specified at the | |
913 | end of this option (e.g. | |
7e23fc43 | 914 | .BR \-\-auto=p7 ). |
2ae555c3 | 915 | If the device name ends with a digit, the partition names add a 'p', |
e0fe762a N |
916 | and a number, e.g. |
917 | .IR /dev/md/home1p3 . | |
918 | If there is no trailing digit, then the partition names just have a | |
919 | number added, e.g. | |
920 | .IR /dev/md/scratch3 . | |
dd0781e5 | 921 | |
48f7b27a NB |
922 | If the md device name is in a 'standard' format as described in DEVICE |
923 | NAMES, then it will be created, if necessary, with the appropriate | |
e0fe762a N |
924 | device number based on that name. If the device name is not in one of these |
925 | formats, then a unused device number will be allocated. The device | |
48f7b27a NB |
926 | number will be considered unused if there is no active array for that |
927 | number, and there is no entry in /dev for that number and with a | |
e0fe762a | 928 | non-standard name. Names that are not in 'standard' format are only |
8fd8d9c4 N |
929 | allowed in "/dev/md/". |
930 | ||
3c7efacb NK |
931 | This is meaningful with |
932 | .B \-\-create | |
933 | or | |
934 | .BR \-\-build . | |
935 | ||
3c7efacb NK |
936 | .TP |
937 | .BR \-a ", " "\-\-add" | |
938 | This option can be used in Grow mode in two cases. | |
939 | ||
940 | If the target array is a Linear array, then | |
941 | .B \-\-add | |
942 | can be used to add one or more devices to the array. They | |
943 | are simply catenated on to the end of the array. Once added, the | |
944 | devices cannot be removed. | |
945 | ||
946 | If the | |
947 | .B \-\-raid\-disks | |
948 | option is being used to increase the number of devices in an array, | |
949 | then | |
950 | .B \-\-add | |
951 | can be used to add some extra devices to be included in the array. | |
952 | In most cases this is not needed as the extra devices can be added as | |
953 | spares first, and then the number of raid-disks can be changed. | |
954 | However for RAID0, it is not possible to add spares. So to increase | |
955 | the number of devices in a RAID0, it is necessary to set the new | |
956 | number of devices, and to add the new devices, in the same command. | |
957 | ||
52826846 NB |
958 | .SH For assemble: |
959 | ||
cd29a5c8 | 960 | .TP |
7e23fc43 | 961 | .BR \-u ", " \-\-uuid= |
e0fe762a | 962 | uuid of array to assemble. Devices which don't have this uuid are |
cd29a5c8 NB |
963 | excluded |
964 | ||
965 | .TP | |
7e23fc43 | 966 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
967 | Minor number of device that array was created for. Devices which |
968 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 969 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
970 | the array is later assembled as /dev/md2. |
971 | ||
d013a55e | 972 | Giving the literal word "dev" for |
7e23fc43 | 973 | .B \-\-super\-minor |
d013a55e NB |
974 | will cause |
975 | .I mdadm | |
976 | to use the minor number of the md device that is being assembled. | |
977 | e.g. when assembling | |
978 | .BR /dev/md0 , | |
51ac42e3 | 979 | .B \-\-super\-minor=dev |
d013a55e NB |
980 | will look for super blocks with a minor number of 0. |
981 | ||
e0fe762a N |
982 | .B \-\-super\-minor |
983 | is only relevant for v0.90 metadata, and should not normally be used. | |
984 | Using | |
985 | .B \-\-uuid | |
986 | is much safer. | |
987 | ||
947fd4dd | 988 | .TP |
7e23fc43 | 989 | .BR \-N ", " \-\-name= |
947fd4dd | 990 | Specify the name of the array to assemble. This must be the name |
624920bb | 991 | that was specified when creating the array. It must either match |
93e790af | 992 | the name stored in the superblock exactly, or it must match |
41a3b72a | 993 | with the current |
624920bb | 994 | .I homehost |
93e790af | 995 | prefixed to the start of the given name. |
947fd4dd | 996 | |
cd29a5c8 | 997 | .TP |
7e23fc43 | 998 | .BR \-f ", " \-\-force |
e0fe762a N |
999 | Assemble the array even if the metadata on some devices appears to be |
1000 | out-of-date. If | |
1001 | .I mdadm | |
1002 | cannot find enough working devices to start the array, but can find | |
1003 | some devices that are recorded as having failed, then it will mark | |
1004 | those devices as working so that the array can be started. | |
1005 | An array which requires | |
1006 | .B \-\-force | |
1007 | to be started may contain data corruption. Use it carefully. | |
52826846 | 1008 | |
cd29a5c8 | 1009 | .TP |
7e23fc43 | 1010 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
1011 | Attempt to start the array even if fewer drives were given than were |
1012 | present last time the array was active. Normally if not all the | |
1013 | expected drives are found and | |
7e23fc43 | 1014 | .B \-\-scan |
cd29a5c8 NB |
1015 | is not used, then the array will be assembled but not started. |
1016 | With | |
7e23fc43 | 1017 | .B \-\-run |
cd29a5c8 | 1018 | an attempt will be made to start it anyway. |
52826846 | 1019 | |
b8a8ccf9 | 1020 | .TP |
7e23fc43 | 1021 | .B \-\-no\-degraded |
b8a8ccf9 | 1022 | This is the reverse of |
7e23fc43 | 1023 | .B \-\-run |
93e790af | 1024 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 1025 | are present. This is only needed with |
93e790af SW |
1026 | .B \-\-scan, |
1027 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
1028 | not as reliable as you would like. |
1029 | ||
dd0781e5 | 1030 | .TP |
7e23fc43 | 1031 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
1032 | See this option under Create and Build options. |
1033 | ||
e793c2e5 | 1034 | .TP |
7e23fc43 | 1035 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
1036 | Specify the bitmap file that was given when the array was created. If |
1037 | an array has an | |
1038 | .B internal | |
1039 | bitmap, there is no need to specify this when assembling the array. | |
1040 | ||
1041 | .TP | |
7e23fc43 | 1042 | .BR \-\-backup\-file= |
2ae555c3 | 1043 | If |
7e23fc43 | 1044 | .B \-\-backup\-file |
87f26d14 N |
1045 | was used while reshaping an array (e.g. changing number of devices or |
1046 | chunk size) and the system crashed during the critical section, then the same | |
7e23fc43 | 1047 | .B \-\-backup\-file |
53e8b987 | 1048 | must be presented to |
7e23fc43 | 1049 | .B \-\-assemble |
cd19c0cf JR |
1050 | to allow possibly corrupted data to be restored, and the reshape |
1051 | to be completed. | |
e793c2e5 | 1052 | |
87f26d14 N |
1053 | .TP |
1054 | .BR \-\-invalid\-backup | |
1055 | If the file needed for the above option is not available for any | |
1056 | reason an empty file can be given together with this option to | |
1057 | indicate that the backup file is invalid. In this case the data that | |
1058 | was being rearranged at the time of the crash could be irrecoverably | |
1059 | lost, but the rest of the array may still be recoverable. This option | |
1060 | should only be used as a last resort if there is no way to recover the | |
1061 | backup file. | |
1062 | ||
1063 | ||
5787fa49 | 1064 | .TP |
7e23fc43 | 1065 | .BR \-U ", " \-\-update= |
5787fa49 | 1066 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
1067 | argument given to this flag can be one of |
1068 | .BR sparc2.2 , | |
1069 | .BR summaries , | |
7d99579f | 1070 | .BR uuid , |
c4f12c13 | 1071 | .BR name , |
0237e0ca | 1072 | .BR homehost , |
e5329c37 | 1073 | .BR resync , |
586ed405 | 1074 | .BR byteorder , |
bee8ec56 | 1075 | .BR devicesize , |
5a31170d | 1076 | .BR no\-bitmap , |
688e99a7 N |
1077 | .BR bbl , |
1078 | .BR no-\bbl , | |
5787fa49 | 1079 | or |
7e23fc43 | 1080 | .BR super\-minor . |
5787fa49 NB |
1081 | |
1082 | The | |
1083 | .B sparc2.2 | |
7d99579f | 1084 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
1085 | machine running a patched 2.2 Linux kernel. This kernel got the |
1086 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 1087 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
1088 | option to |
1089 | .I mdadm | |
1090 | to see what effect this would have. | |
1091 | ||
1092 | The | |
7e23fc43 | 1093 | .B super\-minor |
5787fa49 | 1094 | option will update the |
2ae555c3 | 1095 | .B "preferred minor" |
5787fa49 | 1096 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
1097 | assembled. |
1098 | This can be useful if | |
7e23fc43 | 1099 | .B \-\-examine |
45c073c9 | 1100 | reports a different "Preferred Minor" to |
7e23fc43 | 1101 | .BR \-\-detail . |
45c073c9 | 1102 | In some cases this update will be performed automatically |
e0fe762a | 1103 | by the kernel driver. In particular the update happens automatically |
45c073c9 NB |
1104 | at the first write to an array with redundancy (RAID level 1 or |
1105 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 1106 | |
7d99579f NB |
1107 | The |
1108 | .B uuid | |
1109 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 1110 | .B \-\-uuid |
53e8b987 | 1111 | option that UUID will be used as a new UUID and will |
7d99579f NB |
1112 | .B NOT |
1113 | be used to help identify the devices in the array. | |
53e8b987 | 1114 | If no |
7e23fc43 | 1115 | .B \-\-uuid |
53e8b987 | 1116 | is given, a random UUID is chosen. |
7d99579f | 1117 | |
c4f12c13 NB |
1118 | The |
1119 | .B name | |
1120 | option will change the | |
1121 | .I name | |
1122 | of the array as stored in the superblock. This is only supported for | |
1123 | version-1 superblocks. | |
1124 | ||
0237e0ca NB |
1125 | The |
1126 | .B homehost | |
1127 | option will change the | |
1128 | .I homehost | |
1129 | as recorded in the superblock. For version-0 superblocks, this is the | |
1130 | same as updating the UUID. | |
1131 | For version-1 superblocks, this involves updating the name. | |
1132 | ||
e5329c37 NB |
1133 | The |
1134 | .B resync | |
1135 | option will cause the array to be marked | |
1136 | .I dirty | |
e0fe762a N |
1137 | meaning that any redundancy in the array (e.g. parity for RAID5, |
1138 | copies for RAID1) may be incorrect. This will cause the RAID system | |
e5329c37 NB |
1139 | to perform a "resync" pass to make sure that all redundant information |
1140 | is correct. | |
1141 | ||
586ed405 NB |
1142 | The |
1143 | .B byteorder | |
1144 | option allows arrays to be moved between machines with different | |
1145 | byte-order. | |
2ae555c3 | 1146 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 1147 | .B "\-\-update=byteorder" |
586ed405 NB |
1148 | will cause |
1149 | .I mdadm | |
1150 | to expect superblocks to have their byteorder reversed, and will | |
1151 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 1152 | with original (Version 0.90) superblocks. |
586ed405 | 1153 | |
feb716e9 NB |
1154 | The |
1155 | .B summaries | |
e0fe762a | 1156 | option will correct the summaries in the superblock. That is the |
feb716e9 | 1157 | counts of total, working, active, failed, and spare devices. |
5787fa49 | 1158 | |
bee8ec56 NB |
1159 | The |
1160 | .B devicesize | |
5a31170d | 1161 | option will rarely be of use. It applies to version 1.1 and 1.2 metadata |
bee8ec56 NB |
1162 | only (where the metadata is at the start of the device) and is only |
1163 | useful when the component device has changed size (typically become | |
1164 | larger). The version 1 metadata records the amount of the device that | |
1165 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
1166 | array becomes larger, the metadata will still be visible, but the | |
1167 | extra space will not. In this case it might be useful to assemble the | |
1168 | array with | |
7e23fc43 | 1169 | .BR \-\-update=devicesize . |
bee8ec56 NB |
1170 | This will cause |
1171 | .I mdadm | |
1172 | to determine the maximum usable amount of space on each device and | |
1173 | update the relevant field in the metadata. | |
1174 | ||
5a31170d N |
1175 | The |
1176 | .B no\-bitmap | |
1177 | option can be used when an array has an internal bitmap which is | |
1178 | corrupt in some way so that assembling the array normally fails. It | |
1179 | will cause any internal bitmap to be ignored. | |
1180 | ||
688e99a7 N |
1181 | The |
1182 | .B bbl | |
1183 | option will reserve space in each device for a bad block list. This | |
1184 | will be 4K in size and positioned near the end of any free space | |
1185 | between the superblock and the data. | |
1186 | ||
1187 | The | |
1188 | .B no\-bbl | |
1189 | option will cause any reservation of space for a bad block list to be | |
1190 | removed. If the bad block list contains entries, this will fail, as | |
1191 | removing the list could cause data corruption. | |
1192 | ||
afd0a969 AK |
1193 | .TP |
1194 | .BR \-\-freeze\-reshape | |
1195 | Option is intended to be used in start-up scripts during initrd boot phase. | |
1196 | When array under reshape is assembled during initrd phase, this option | |
1197 | stops reshape after reshape critical section is being restored. This happens | |
1198 | before file system pivot operation and avoids loss of file system context. | |
1199 | Losing file system context would cause reshape to be broken. | |
1200 | ||
a6482415 N |
1201 | Reshape can be continued later using the |
1202 | .B \-\-continue | |
1203 | option for the grow command. | |
afd0a969 | 1204 | |
e0d19036 | 1205 | .SH For Manage mode: |
52826846 | 1206 | |
3d5279b0 N |
1207 | .TP |
1208 | .BR \-t ", " \-\-test | |
1209 | Unless a more serious error occurred, | |
1210 | .I mdadm | |
1211 | will exit with a status of 2 if no changes were made to the array and | |
1212 | 0 if at least one change was made. | |
1213 | This can be useful when an indirect specifier such as | |
1214 | .BR missing , | |
1215 | .B detached | |
1216 | or | |
1217 | .B faulty | |
1218 | is used in requesting an operation on the array. | |
1219 | .B \-\-test | |
1220 | will report failure if these specifiers didn't find any match. | |
1221 | ||
cd29a5c8 | 1222 | .TP |
7e23fc43 | 1223 | .BR \-a ", " \-\-add |
3d5279b0 N |
1224 | hot-add listed devices. |
1225 | If a device appears to have recently been part of the array | |
342460cb | 1226 | (possibly it failed or was removed) the device is re\-added as described |
3d5279b0 N |
1227 | in the next point. |
1228 | If that fails or the device was never part of the array, the device is | |
1229 | added as a hot-spare. | |
1230 | If the array is degraded, it will immediately start to rebuild data | |
1231 | onto that spare. | |
1232 | ||
1233 | Note that this and the following options are only meaningful on array | |
1234 | with redundancy. They don't apply to RAID0 or Linear. | |
52826846 | 1235 | |
fe80f49b | 1236 | .TP |
7e23fc43 | 1237 | .BR \-\-re\-add |
3d5279b0 N |
1238 | re\-add a device that was previous removed from an array. |
1239 | If the metadata on the device reports that it is a member of the | |
1240 | array, and the slot that it used is still vacant, then the device will | |
1241 | be added back to the array in the same position. This will normally | |
1242 | cause the data for that device to be recovered. However based on the | |
1243 | event count on the device, the recovery may only require sections that | |
1244 | are flagged a write-intent bitmap to be recovered or may not require | |
1245 | any recovery at all. | |
1246 | ||
1247 | When used on an array that has no metadata (i.e. it was built with | |
1248 | .BR \-\-build) | |
1249 | it will be assumed that bitmap-based recovery is enough to make the | |
1250 | device fully consistent with the array. | |
fe80f49b | 1251 | |
688e99a7 | 1252 | When used with v1.x metadata, |
833bb0f8 N |
1253 | .B \-\-re\-add |
1254 | can be accompanied by | |
688e99a7 N |
1255 | .BR \-\-update=devicesize , |
1256 | .BR \-\-update=bbl ", or" | |
1257 | .BR \-\-update=no\-bbl . | |
1258 | See the description of these option when used in Assemble mode for an | |
1259 | explanation of their use. | |
833bb0f8 | 1260 | |
a4e13010 N |
1261 | If the device name given is |
1262 | .B missing | |
1263 | then mdadm will try to find any device that looks like it should be | |
1264 | part of the array but isn't and will try to re\-add all such devices. | |
1265 | ||
cd29a5c8 | 1266 | .TP |
7e23fc43 | 1267 | .BR \-r ", " \-\-remove |
2d465520 | 1268 | remove listed devices. They must not be active. i.e. they should |
b80da661 NB |
1269 | be failed or spare devices. As well as the name of a device file |
1270 | (e.g. | |
1271 | .BR /dev/sda1 ) | |
1272 | the words | |
1273 | .B failed | |
1274 | and | |
1275 | .B detached | |
1276 | can be given to | |
1277 | .BR \-\-remove . | |
1278 | The first causes all failed device to be removed. The second causes | |
93e790af | 1279 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
1280 | returns |
1281 | .BR ENXIO ) | |
1282 | to be removed. This will only succeed for devices that are spares or | |
1283 | have already been marked as failed. | |
52826846 | 1284 | |
cd29a5c8 | 1285 | .TP |
7e23fc43 | 1286 | .BR \-f ", " \-\-fail |
70c55e36 | 1287 | Mark listed devices as faulty. |
b80da661 NB |
1288 | As well as the name of a device file, the word |
1289 | .B detached | |
1290 | can be given. This will cause any device that has been detached from | |
1291 | the system to be marked as failed. It can then be removed. | |
52826846 | 1292 | |
cd29a5c8 | 1293 | .TP |
7e23fc43 | 1294 | .BR \-\-set\-faulty |
53e8b987 | 1295 | same as |
7e23fc43 | 1296 | .BR \-\-fail . |
52826846 | 1297 | |
70c55e36 N |
1298 | .TP |
1299 | .B \-\-replace | |
1300 | Mark listed devices as requiring replacement. As soon as a spare is | |
1301 | available, it will be rebuilt and will replace the marked device. | |
1302 | This is similar to marking a device as faulty, but the device remains | |
1303 | in service during the recovery process to increase resilience against | |
1304 | multiple failures. When the replacement process finishes, the | |
1305 | replaced device will be marked as faulty. | |
1306 | ||
1307 | .TP | |
1308 | .B \-\-with | |
1309 | This can follow a list of | |
1310 | .B \-\-replace | |
1311 | devices. The devices listed after | |
1312 | .B \-\-with | |
1313 | will be preferentially used to replace the devices listed after | |
1314 | .BR \-\-replace . | |
1315 | These device must already be spare devices in the array. | |
1316 | ||
b3d31955 N |
1317 | .TP |
1318 | .BR \-\-write\-mostly | |
a4e13010 | 1319 | Subsequent devices that are added or re\-added will have the 'write-mostly' |
e0fe762a | 1320 | flag set. This is only valid for RAID1 and means that the 'md' driver |
b3d31955 N |
1321 | will avoid reading from these devices if possible. |
1322 | .TP | |
1323 | .BR \-\-readwrite | |
a4e13010 | 1324 | Subsequent devices that are added or re\-added will have the 'write-mostly' |
b3d31955 N |
1325 | flag cleared. |
1326 | ||
2ae555c3 | 1327 | .P |
e0fe762a | 1328 | Each of these options requires that the first device listed is the array |
93e790af | 1329 | to be acted upon, and the remainder are component devices to be added, |
e0fe762a | 1330 | removed, marked as faulty, etc. Several different operations can be |
2ae555c3 NB |
1331 | specified for different devices, e.g. |
1332 | .in +5 | |
7e23fc43 | 1333 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
1334 | .in -5 |
1335 | Each operation applies to all devices listed until the next | |
93e790af | 1336 | operation. |
2ae555c3 NB |
1337 | |
1338 | If an array is using a write-intent bitmap, then devices which have | |
a4e13010 | 1339 | been removed can be re\-added in a way that avoids a full |
93e790af | 1340 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
1341 | since the device was removed. For arrays with persistent metadata |
1342 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 1343 | .B \-\-build |
2ae555c3 | 1344 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 1345 | .BR \-\-re\-add . |
2ae555c3 NB |
1346 | |
1347 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
1348 | use, i.e. that must be spares or failed devices. To remove an active |
1349 | device, it must first be marked as | |
1350 | .B faulty. | |
2ae555c3 NB |
1351 | |
1352 | .SH For Misc mode: | |
1353 | ||
1354 | .TP | |
7e23fc43 | 1355 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
1356 | Examine a device to see |
1357 | (1) if it is an md device and (2) if it is a component of an md | |
1358 | array. | |
1359 | Information about what is discovered is presented. | |
1360 | ||
1361 | .TP | |
7e23fc43 | 1362 | .BR \-D ", " \-\-detail |
e0fe762a | 1363 | Print details of one or more md devices. |
5787fa49 | 1364 | |
4cce4069 DW |
1365 | .TP |
1366 | .BR \-\-detail\-platform | |
e0fe762a | 1367 | Print details of the platform's RAID capabilities (firmware / hardware |
9eafa1de MN |
1368 | topology) for a given metadata format. If used without argument, mdadm |
1369 | will scan all controllers looking for their capabilities. Otherwise, mdadm | |
1370 | will only look at the controller specified by the argument in form of an | |
1371 | absolute filepath or a link, e.g. | |
1372 | .IR /sys/devices/pci0000:00/0000:00:1f.2 . | |
4cce4069 | 1373 | |
54bad364 KS |
1374 | .TP |
1375 | .BR \-Y ", " \-\-export | |
1376 | When used with | |
e50cf220 | 1377 | .B \-\-detail , \-\-detail-platform |
0d726f17 KS |
1378 | or |
1379 | .BR \-\-examine , | |
54bad364 KS |
1380 | output will be formatted as |
1381 | .B key=value | |
1382 | pairs for easy import into the environment. | |
1383 | ||
2ae555c3 | 1384 | .TP |
7e23fc43 | 1385 | .BR \-E ", " \-\-examine |
e0fe762a N |
1386 | Print contents of the metadata stored on the named device(s). |
1387 | Note the contrast between | |
1388 | .B \-\-examine | |
1389 | and | |
1390 | .BR \-\-detail . | |
1391 | .B \-\-examine | |
1392 | applies to devices which are components of an array, while | |
1393 | .B \-\-detail | |
1394 | applies to a whole array which is currently active. | |
5787fa49 | 1395 | .TP |
7e23fc43 | 1396 | .B \-\-sparc2.2 |
e0fe762a N |
1397 | If an array was created on a SPARC machine with a 2.2 Linux kernel |
1398 | patched with RAID support, the superblock will have been created | |
1399 | incorrectly, or at least incompatibly with 2.4 and later kernels. | |
1400 | Using the | |
7e23fc43 | 1401 | .B \-\-sparc2.2 |
5787fa49 | 1402 | flag with |
7e23fc43 | 1403 | .B \-\-examine |
5787fa49 NB |
1404 | will fix the superblock before displaying it. If this appears to do |
1405 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 1406 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 1407 | |
2ae555c3 | 1408 | .TP |
7e23fc43 | 1409 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 1410 | Report information about a bitmap file. |
01d9299c | 1411 | The argument is either an external bitmap file or an array component |
e0fe762a N |
1412 | in case of an internal bitmap. Note that running this on an array |
1413 | device (e.g. | |
1414 | .BR /dev/md0 ) | |
1415 | does not report the bitmap for that array. | |
e0d19036 | 1416 | |
cd29a5c8 | 1417 | .TP |
7e23fc43 | 1418 | .BR \-R ", " \-\-run |
e0fe762a N |
1419 | start a partially assembled array. If |
1420 | .B \-\-assemble | |
1421 | did not find enough devices to fully start the array, it might leaving | |
1422 | it partially assembled. If you wish, you can then use | |
1423 | .B \-\-run | |
1424 | to start the array in degraded mode. | |
52826846 | 1425 | |
cd29a5c8 | 1426 | .TP |
7e23fc43 | 1427 | .BR \-S ", " \-\-stop |
cd29a5c8 | 1428 | deactivate array, releasing all resources. |
52826846 | 1429 | |
cd29a5c8 | 1430 | .TP |
7e23fc43 | 1431 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 1432 | mark array as readonly. |
52826846 | 1433 | |
cd29a5c8 | 1434 | .TP |
7e23fc43 | 1435 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 1436 | mark array as readwrite. |
52826846 | 1437 | |
e0d19036 | 1438 | .TP |
7e23fc43 | 1439 | .B \-\-zero\-superblock |
e0d19036 | 1440 | If the device contains a valid md superblock, the block is |
35cc5be4 | 1441 | overwritten with zeros. With |
7e23fc43 | 1442 | .B \-\-force |
35cc5be4 | 1443 | the block where the superblock would be is overwritten even if it |
e0d19036 | 1444 | doesn't appear to be valid. |
52826846 | 1445 | |
33414a01 DW |
1446 | .TP |
1447 | .B \-\-kill\-subarray= | |
1448 | If the device is a container and the argument to \-\-kill\-subarray | |
1449 | specifies an inactive subarray in the container, then the subarray is | |
1450 | deleted. Deleting all subarrays will leave an 'empty-container' or | |
1451 | spare superblock on the drives. See \-\-zero\-superblock for completely | |
1452 | removing a superblock. Note that some formats depend on the subarray | |
1453 | index for generating a UUID, this command will fail if it would change | |
1454 | the UUID of an active subarray. | |
1455 | ||
aa534678 DW |
1456 | .TP |
1457 | .B \-\-update\-subarray= | |
1458 | If the device is a container and the argument to \-\-update\-subarray | |
1459 | specifies a subarray in the container, then attempt to update the given | |
1460 | superblock field in the subarray. See below in | |
1461 | .B MISC MODE | |
1462 | for details. | |
1463 | ||
feb716e9 | 1464 | .TP |
7e23fc43 | 1465 | .BR \-t ", " \-\-test |
feb716e9 | 1466 | When used with |
7e23fc43 | 1467 | .BR \-\-detail , |
feb716e9 NB |
1468 | the exit status of |
1469 | .I mdadm | |
e0fe762a N |
1470 | is set to reflect the status of the device. See below in |
1471 | .B MISC MODE | |
1472 | for details. | |
feb716e9 | 1473 | |
b90c0e9a | 1474 | .TP |
7e23fc43 | 1475 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1476 | For each md device given, wait for any resync, recovery, or reshape |
1477 | activity to finish before returning. | |
1478 | .I mdadm | |
1479 | will return with success if it actually waited for every device | |
1480 | listed, otherwise it will return failure. | |
1481 | ||
1770662b DW |
1482 | .TP |
1483 | .BR \-\-wait\-clean | |
fabbfd48 DW |
1484 | For each md device given, or each device in /proc/mdstat if |
1485 | .B \-\-scan | |
1486 | is given, arrange for the array to be marked clean as soon as possible. | |
7146ec6a DW |
1487 | .I mdadm |
1488 | will return with success if the array uses external metadata and we | |
1489 | successfully waited. For native arrays this returns immediately as the | |
6a0ee6a0 DW |
1490 | kernel handles dirty-clean transitions at shutdown. No action is taken |
1491 | if safe-mode handling is disabled. | |
1770662b | 1492 | |
8382f19b NB |
1493 | .SH For Incremental Assembly mode: |
1494 | .TP | |
7e23fc43 | 1495 | .BR \-\-rebuild\-map ", " \-r |
8382f19b | 1496 | Rebuild the map file |
96fd06ed | 1497 | .RB ( {MAP_PATH} ) |
8382f19b NB |
1498 | that |
1499 | .I mdadm | |
1500 | uses to help track which arrays are currently being assembled. | |
1501 | ||
1502 | .TP | |
7e23fc43 | 1503 | .BR \-\-run ", " \-R |
8382f19b NB |
1504 | Run any array assembled as soon as a minimal number of devices are |
1505 | available, rather than waiting until all expected devices are present. | |
1506 | ||
1507 | .TP | |
7e23fc43 | 1508 | .BR \-\-scan ", " \-s |
8382f19b | 1509 | Only meaningful with |
7e23fc43 | 1510 | .B \-R |
8382f19b NB |
1511 | this will scan the |
1512 | .B map | |
1513 | file for arrays that are being incrementally assembled and will try to | |
1514 | start any that are not already started. If any such array is listed | |
1515 | in | |
1516 | .B mdadm.conf | |
1517 | as requiring an external bitmap, that bitmap will be attached first. | |
1518 | ||
29ba4804 N |
1519 | .TP |
1520 | .BR \-\-fail ", " \-f | |
1521 | This allows the hot-plug system to remove devices that have fully disappeared | |
1522 | from the kernel. It will first fail and then remove the device from any | |
1523 | array it belongs to. | |
1524 | The device name given should be a kernel device name such as "sda", | |
1525 | not a name in | |
1526 | .IR /dev . | |
1527 | ||
210597d1 PC |
1528 | .TP |
1529 | .BR \-\-path= | |
87eb4fab N |
1530 | Only used with \-\-fail. The 'path' given will be recorded so that if |
1531 | a new device appears at the same location it can be automatically | |
1532 | added to the same array. This allows the failed device to be | |
1533 | automatically replaced by a new device without metadata if it appears | |
1534 | at specified path. This option is normally only set by a | |
1535 | .I udev | |
1536 | script. | |
210597d1 | 1537 | |
e0d19036 NB |
1538 | .SH For Monitor mode: |
1539 | .TP | |
7e23fc43 | 1540 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1541 | Give a mail address to send alerts to. |
1542 | ||
1543 | .TP | |
7e23fc43 | 1544 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1545 | Give a program to be run whenever an event is detected. |
1546 | ||
773135f5 | 1547 | .TP |
7e23fc43 | 1548 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1549 | Cause all events to be reported through 'syslog'. The messages have |
1550 | facility of 'daemon' and varying priorities. | |
1551 | ||
e0d19036 | 1552 | .TP |
7e23fc43 | 1553 | .BR \-d ", " \-\-delay |
e0d19036 | 1554 | Give a delay in seconds. |
51ac42e3 | 1555 | .I mdadm |
e0d19036 | 1556 | polls the md arrays and then waits this many seconds before polling |
e0fe762a N |
1557 | again. The default is 60 seconds. Since 2.6.16, there is no need to |
1558 | reduce this as the kernel alerts | |
1559 | .I mdadm | |
1560 | immediately when there is any change. | |
e0d19036 | 1561 | |
9a36a9b7 ZB |
1562 | .TP |
1563 | .BR \-r ", " \-\-increment | |
1564 | Give a percentage increment. | |
1565 | .I mdadm | |
1566 | will generate RebuildNN events with the given percentage increment. | |
1567 | ||
d013a55e | 1568 | .TP |
7e23fc43 | 1569 | .BR \-f ", " \-\-daemonise |
d013a55e | 1570 | Tell |
51ac42e3 | 1571 | .I mdadm |
d013a55e | 1572 | to run as a background daemon if it decides to monitor anything. This |
e0fe762a | 1573 | causes it to fork and run in the child, and to disconnect from the |
d013a55e NB |
1574 | terminal. The process id of the child is written to stdout. |
1575 | This is useful with | |
7e23fc43 | 1576 | .B \-\-scan |
d013a55e NB |
1577 | which will only continue monitoring if a mail address or alert program |
1578 | is found in the config file. | |
1579 | ||
b5e64645 | 1580 | .TP |
7e23fc43 | 1581 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1582 | When |
51ac42e3 | 1583 | .I mdadm |
b5e64645 NB |
1584 | is running in daemon mode, write the pid of the daemon process to |
1585 | the specified file, instead of printing it on standard output. | |
1586 | ||
aa88f531 | 1587 | .TP |
7e23fc43 | 1588 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1589 | Check arrays only once. This will generate |
1590 | .B NewArray | |
1591 | events and more significantly | |
1592 | .B DegradedArray | |
a9d69660 NB |
1593 | and |
1594 | .B SparesMissing | |
aa88f531 NB |
1595 | events. Running |
1596 | .in +5 | |
7e23fc43 | 1597 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1598 | .in -5 |
1599 | from a cron script will ensure regular notification of any degraded arrays. | |
1600 | ||
98c6faba | 1601 | .TP |
7e23fc43 | 1602 | .BR \-t ", " \-\-test |
98c6faba NB |
1603 | Generate a |
1604 | .B TestMessage | |
1605 | alert for every array found at startup. This alert gets mailed and | |
1606 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1607 | message do get through successfully. |
98c6faba | 1608 | |
210597d1 PC |
1609 | .TP |
1610 | .BR \-\-no\-sharing | |
87eb4fab | 1611 | This inhibits the functionality for moving spares between arrays. |
210597d1 PC |
1612 | Only one monitoring process started with |
1613 | .B \-\-scan | |
87eb4fab N |
1614 | but without this flag is allowed, otherwise the two could interfere |
1615 | with each other. | |
210597d1 | 1616 | |
e0d19036 | 1617 | .SH ASSEMBLE MODE |
52826846 | 1618 | |
cd29a5c8 NB |
1619 | .HP 12 |
1620 | Usage: | |
7e23fc43 | 1621 | .B mdadm \-\-assemble |
5787fa49 NB |
1622 | .I md-device options-and-component-devices... |
1623 | .HP 12 | |
1624 | Usage: | |
7e23fc43 | 1625 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1626 | .I md-devices-and-options... |
cd29a5c8 NB |
1627 | .HP 12 |
1628 | Usage: | |
7e23fc43 | 1629 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1630 | .I options... |
52826846 | 1631 | |
cd29a5c8 | 1632 | .PP |
e0fe762a | 1633 | This usage assembles one or more RAID arrays from pre-existing components. |
9a9dab36 | 1634 | For each array, mdadm needs to know the md device, the identity of the |
e0fe762a | 1635 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1636 | |
5787fa49 | 1637 | In the first usage example (without the |
7e23fc43 | 1638 | .BR \-\-scan ) |
5787fa49 NB |
1639 | the first device given is the md device. |
1640 | In the second usage example, all devices listed are treated as md | |
1641 | devices and assembly is attempted. | |
1642 | In the third (where no devices are listed) all md devices that are | |
cb77f620 | 1643 | listed in the configuration file are assembled. If no arrays are |
e0fe762a N |
1644 | described by the configuration file, then any arrays that |
1645 | can be found on unused devices will be assembled. | |
52826846 | 1646 | |
d013a55e | 1647 | If precisely one device is listed, but |
7e23fc43 | 1648 | .B \-\-scan |
dd0781e5 | 1649 | is not given, then |
d013a55e NB |
1650 | .I mdadm |
1651 | acts as though | |
7e23fc43 | 1652 | .B \-\-scan |
93e790af | 1653 | was given and identity information is extracted from the configuration file. |
d013a55e | 1654 | |
2ae555c3 | 1655 | The identity can be given with the |
7e23fc43 | 1656 | .B \-\-uuid |
e0fe762a N |
1657 | option, the |
1658 | .B \-\-name | |
1659 | option, or the | |
7e23fc43 | 1660 | .B \-\-super\-minor |
93e790af SW |
1661 | option, will be taken from the md-device record in the config file, or |
1662 | will be taken from the super block of the first component-device | |
1663 | listed on the command line. | |
52826846 | 1664 | |
2ae555c3 | 1665 | Devices can be given on the |
7e23fc43 | 1666 | .B \-\-assemble |
e0fe762a | 1667 | command line or in the config file. Only devices which have an md |
5787fa49 NB |
1668 | superblock which contains the right identity will be considered for |
1669 | any array. | |
52826846 | 1670 | |
2ae555c3 | 1671 | The config file is only used if explicitly named with |
7e23fc43 | 1672 | .B \-\-config |
d013a55e | 1673 | or requested with (a possibly implicit) |
7e23fc43 | 1674 | .BR \-\-scan . |
52826846 | 1675 | In the later case, |
9a9dab36 | 1676 | .B /etc/mdadm.conf |
8fd8d9c4 N |
1677 | or |
1678 | .B /etc/mdadm/mdadm.conf | |
52826846 NB |
1679 | is used. |
1680 | ||
2ae555c3 | 1681 | If |
7e23fc43 | 1682 | .B \-\-scan |
cd29a5c8 NB |
1683 | is not given, then the config file will only be used to find the |
1684 | identity of md arrays. | |
52826846 | 1685 | |
2d465520 | 1686 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 1687 | .B \-\-scan |
e0fe762a N |
1688 | is not given and not all expected drives were listed, then the array |
1689 | is not started (to guard against usage errors). To insist that the | |
1690 | array be started in this case (as may work for RAID1, 4, 5, 6, or 10), | |
1691 | give the | |
7e23fc43 | 1692 | .B \-\-run |
cd29a5c8 | 1693 | flag. |
52826846 | 1694 | |
e0fe762a N |
1695 | If |
1696 | .I udev | |
1697 | is active, | |
1698 | .I mdadm | |
1699 | does not create any entries in | |
dd0781e5 | 1700 | .B /dev |
e0fe762a N |
1701 | but leaves that to |
1702 | .IR udev . | |
1703 | It does record information in | |
96fd06ed | 1704 | .B {MAP_PATH} |
e0fe762a N |
1705 | which will allow |
1706 | .I udev | |
1707 | to choose the correct name. | |
dd0781e5 | 1708 | |
e0fe762a N |
1709 | If |
1710 | .I mdadm | |
1711 | detects that udev is not configured, it will create the devices in | |
1712 | .B /dev | |
1713 | itself. | |
dd0781e5 | 1714 | |
e0fe762a N |
1715 | In Linux kernels prior to version 2.6.28 there were two distinctly |
1716 | different types of md devices that could be created: one that could be | |
1717 | partitioned using standard partitioning tools and one that could not. | |
1718 | Since 2.6.28 that distinction is no longer relevant as both type of | |
1719 | devices can be partitioned. | |
1720 | .I mdadm | |
1721 | will normally create the type that originally could not be partitioned | |
1722 | as it has a well defined major number (9). | |
dd0781e5 | 1723 | |
e0fe762a N |
1724 | Prior to 2.6.28, it is important that mdadm chooses the correct type |
1725 | of array device to use. This can be controlled with the | |
1726 | .B \-\-auto | |
1727 | option. In particular, a value of "mdp" or "part" or "p" tells mdadm | |
1728 | to use a partitionable device rather than the default. | |
dd0781e5 | 1729 | |
e0fe762a N |
1730 | In the no-udev case, the value given to |
1731 | .B \-\-auto | |
1732 | can be suffixed by a number. This tells | |
1733 | .I mdadm | |
1734 | to create that number of partition devices rather than the default of 4. | |
dd0781e5 | 1735 | |
e0fe762a | 1736 | The value given to |
7e23fc43 | 1737 | .B \-\-auto |
e0fe762a N |
1738 | can also be given in the configuration file as a word starting |
1739 | .B auto= | |
1740 | on the ARRAY line for the relevant array. | |
52826846 | 1741 | |
41a3b72a NB |
1742 | .SS Auto Assembly |
1743 | When | |
7e23fc43 | 1744 | .B \-\-assemble |
41a3b72a | 1745 | is used with |
7e23fc43 | 1746 | .B \-\-scan |
41a3b72a NB |
1747 | and no devices are listed, |
1748 | .I mdadm | |
1749 | will first attempt to assemble all the arrays listed in the config | |
1750 | file. | |
1751 | ||
cb77f620 | 1752 | If no arrays are listed in the config (other than those marked |
e0fe762a N |
1753 | .BR <ignore> ) |
1754 | it will look through the available devices for possible arrays and | |
1755 | will try to assemble anything that it finds. Arrays which are tagged | |
1756 | as belonging to the given homehost will be assembled and started | |
1757 | normally. Arrays which do not obviously belong to this host are given | |
1758 | names that are expected not to conflict with anything local, and are | |
1759 | started "read-auto" so that nothing is written to any device until the | |
1760 | array is written to. i.e. automatic resync etc is delayed. | |
41a3b72a NB |
1761 | |
1762 | If | |
1763 | .I mdadm | |
1764 | finds a consistent set of devices that look like they should comprise | |
1765 | an array, and if the superblock is tagged as belonging to the given | |
1766 | home host, it will automatically choose a device name and try to | |
1767 | assemble the array. If the array uses version-0.90 metadata, then the | |
1768 | .B minor | |
1769 | number as recorded in the superblock is used to create a name in | |
1770 | .B /dev/md/ | |
1771 | so for example | |
1772 | .BR /dev/md/3 . | |
1773 | If the array uses version-1 metadata, then the | |
1774 | .B name | |
1775 | from the superblock is used to similarly create a name in | |
e0fe762a | 1776 | .B /dev/md/ |
93e790af | 1777 | (the name will have any 'host' prefix stripped first). |
41a3b72a | 1778 | |
c64ba03a N |
1779 | This behaviour can be modified by the |
1780 | .I AUTO | |
1781 | line in the | |
1782 | .I mdadm.conf | |
1783 | configuration file. This line can indicate that specific metadata | |
1784 | type should, or should not, be automatically assembled. If an array | |
1785 | is found which is not listed in | |
1786 | .I mdadm.conf | |
1787 | and has a metadata format that is denied by the | |
1788 | .I AUTO | |
1789 | line, then it will not be assembled. | |
1790 | The | |
1791 | .I AUTO | |
1792 | line can also request that all arrays identified as being for this | |
1793 | homehost should be assembled regardless of their metadata type. | |
1794 | See | |
1795 | .IR mdadm.conf (5) | |
1796 | for further details. | |
1797 | ||
246cebdb AK |
1798 | Note: Auto assembly cannot be used for assembling and activating some |
1799 | arrays which are undergoing reshape. In particular as the | |
1800 | .B backup\-file | |
1801 | cannot be given, any reshape which requires a backup-file to continue | |
1802 | cannot be started by auto assembly. An array which is growing to more | |
1803 | devices and has passed the critical section can be assembled using | |
1804 | auto-assembly. | |
41a3b72a | 1805 | |
cd29a5c8 | 1806 | .SH BUILD MODE |
52826846 | 1807 | |
cd29a5c8 NB |
1808 | .HP 12 |
1809 | Usage: | |
7e23fc43 | 1810 | .B mdadm \-\-build |
93e790af | 1811 | .I md-device |
7e23fc43 PS |
1812 | .BI \-\-chunk= X |
1813 | .BI \-\-level= Y | |
1814 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
1815 | .I devices |
1816 | ||
1817 | .PP | |
2ae555c3 | 1818 | This usage is similar to |
7e23fc43 | 1819 | .BR \-\-create . |
e0fe762a | 1820 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 1821 | these arrays there is no difference between initially creating the array and |
52826846 NB |
1822 | subsequently assembling the array, except that hopefully there is useful |
1823 | data there in the second case. | |
1824 | ||
e0fe762a N |
1825 | The level may raid0, linear, raid1, raid10, multipath, or faulty, or |
1826 | one of their synonyms. All devices must be listed and the array will | |
1827 | be started once complete. It will often be appropriate to use | |
1828 | .B \-\-assume\-clean | |
1829 | with levels raid1 or raid10. | |
cd29a5c8 NB |
1830 | |
1831 | .SH CREATE MODE | |
1832 | ||
1833 | .HP 12 | |
1834 | Usage: | |
7e23fc43 | 1835 | .B mdadm \-\-create |
93e790af | 1836 | .I md-device |
7e23fc43 PS |
1837 | .BI \-\-chunk= X |
1838 | .BI \-\-level= Y | |
cd29a5c8 | 1839 | .br |
7e23fc43 | 1840 | .BI \-\-raid\-devices= Z |
e0fe762a | 1841 | .I devices |
cd29a5c8 NB |
1842 | |
1843 | .PP | |
1844 | This usage will initialise a new md array, associate some devices with | |
1845 | it, and activate the array. | |
1846 | ||
e0fe762a N |
1847 | The named device will normally not exist when |
1848 | .I "mdadm \-\-create" | |
1849 | is run, but will be created by | |
1850 | .I udev | |
1851 | once the array becomes active. | |
dd0781e5 | 1852 | |
e0fe762a N |
1853 | As devices are added, they are checked to see if they contain RAID |
1854 | superblocks or filesystems. They are also checked to see if the variance in | |
cd29a5c8 NB |
1855 | device size exceeds 1%. |
1856 | ||
1857 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 1858 | the presence of a |
7e23fc43 | 1859 | .B \-\-run |
cd29a5c8 NB |
1860 | can override this caution. |
1861 | ||
2d465520 | 1862 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 1863 | give the word "\fBmissing\fP" |
2d465520 | 1864 | in place of a device name. This will cause |
51ac42e3 | 1865 | .I mdadm |
2d465520 NB |
1866 | to leave the corresponding slot in the array empty. |
1867 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 1868 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
1869 | For a RAID1 array, only one real device needs to be given. All of the |
1870 | others can be | |
d013a55e | 1871 | "\fBmissing\fP". |
2d465520 | 1872 | |
feb716e9 | 1873 | When creating a RAID5 array, |
51ac42e3 | 1874 | .I mdadm |
feb716e9 | 1875 | will automatically create a degraded array with an extra spare drive. |
e0fe762a N |
1876 | This is because building the spare into a degraded array is in general |
1877 | faster than resyncing the parity on a non-degraded, but not clean, | |
1878 | array. This feature can be overridden with the | |
7e23fc43 | 1879 | .B \-\-force |
feb716e9 NB |
1880 | option. |
1881 | ||
0ee4da98 | 1882 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
1883 | required. |
1884 | If this is not given with the | |
7e23fc43 | 1885 | .B \-\-name |
41a3b72a NB |
1886 | option, |
1887 | .I mdadm | |
0ee4da98 | 1888 | will choose a name based on the last component of the name of the |
41a3b72a NB |
1889 | device being created. So if |
1890 | .B /dev/md3 | |
1891 | is being created, then the name | |
1892 | .B 3 | |
1893 | will be chosen. | |
1894 | If | |
1895 | .B /dev/md/home | |
1896 | is being created, then the name | |
1897 | .B home | |
1898 | will be used. | |
1899 | ||
e0fe762a N |
1900 | When creating a partition based array, using |
1901 | .I mdadm | |
1902 | with version-1.x metadata, the partition type should be set to | |
e0f31f50 | 1903 | .B 0xDA |
e0fe762a | 1904 | (non fs-data). This type selection allows for greater precision since |
e0f31f50 PC |
1905 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], |
1906 | might create problems in the event of array recovery through a live cdrom. | |
1907 | ||
3d3dd91e NB |
1908 | A new array will normally get a randomly assigned 128bit UUID which is |
1909 | very likely to be unique. If you have a specific need, you can choose | |
1910 | a UUID for the array by giving the | |
7e23fc43 | 1911 | .B \-\-uuid= |
3d3dd91e NB |
1912 | option. Be warned that creating two arrays with the same UUID is a |
1913 | recipe for disaster. Also, using | |
7e23fc43 | 1914 | .B \-\-uuid= |
3d3dd91e | 1915 | when creating a v0.90 array will silently override any |
7e23fc43 | 1916 | .B \-\-homehost= |
3d3dd91e | 1917 | setting. |
e43d0cda NB |
1918 | .\"If the |
1919 | .\".B \-\-size | |
1920 | .\"option is given, it is not necessary to list any component-devices in this command. | |
1921 | .\"They can be added later, before a | |
1922 | .\".B \-\-run. | |
1923 | .\"If no | |
1924 | .\".B \-\-size | |
1925 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 1926 | |
bf95d0f3 N |
1927 | If the metadata type supports it (currently only 1.x metadata), space |
1928 | will be allocated to store a bad block list. This allows a modest | |
1929 | number of bad blocks to be recorded, allowing the drive to remain in | |
1930 | service while only partially functional. | |
1931 | ||
8fd8d9c4 N |
1932 | When creating an array within a |
1933 | .B CONTAINER | |
1934 | .I mdadm | |
1935 | can be given either the list of devices to use, or simply the name of | |
1936 | the container. The former case gives control over which devices in | |
1937 | the container will be used for the array. The latter case allows | |
1938 | .I mdadm | |
1939 | to automatically choose which devices to use based on how much spare | |
1940 | space is available. | |
1941 | ||
53e8b987 | 1942 | The General Management options that are valid with |
7e23fc43 | 1943 | .B \-\-create |
53e8b987 | 1944 | are: |
cd29a5c8 | 1945 | .TP |
7e23fc43 | 1946 | .B \-\-run |
dd0781e5 | 1947 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
1948 | be in use. |
1949 | ||
1950 | .TP | |
7e23fc43 | 1951 | .B \-\-readonly |
b3f1c093 | 1952 | start the array readonly \(em not supported yet. |
52826846 | 1953 | |
e0d19036 | 1954 | .SH MANAGE MODE |
cd29a5c8 NB |
1955 | .HP 12 |
1956 | Usage: | |
e0d19036 NB |
1957 | .B mdadm |
1958 | .I device | |
1959 | .I options... devices... | |
cd29a5c8 NB |
1960 | .PP |
1961 | ||
e0d19036 NB |
1962 | This usage will allow individual devices in an array to be failed, |
1963 | removed or added. It is possible to perform multiple operations with | |
e0fe762a | 1964 | on command. For example: |
e0d19036 | 1965 | .br |
7e23fc43 | 1966 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
1967 | .br |
1968 | will firstly mark | |
1969 | .B /dev/hda1 | |
1970 | as faulty in | |
1971 | .B /dev/md0 | |
1972 | and will then remove it from the array and finally add it back | |
2d465520 | 1973 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 1974 | command. |
e0d19036 | 1975 | |
e0fe762a N |
1976 | When a device is added to an active array, mdadm checks to see if it |
1977 | has metadata on it which suggests that it was recently a member of the | |
a4e13010 | 1978 | array. If it does, it tries to "re\-add" the device. If there have |
e0fe762a N |
1979 | been no changes since the device was removed, or if the array has a |
1980 | write-intent bitmap which has recorded whatever changes there were, | |
1981 | then the device will immediately become a full member of the array and | |
1982 | those differences recorded in the bitmap will be resolved. | |
1983 | ||
e0d19036 NB |
1984 | .SH MISC MODE |
1985 | .HP 12 | |
1986 | Usage: | |
9a9dab36 | 1987 | .B mdadm |
e0d19036 | 1988 | .I options ... |
e0fe762a | 1989 | .I devices ... |
e0d19036 | 1990 | .PP |
cd29a5c8 | 1991 | |
b5e64645 | 1992 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1993 | operate on distinct devices. The operations are: |
1994 | .TP | |
962a108f | 1995 | .B \-\-query |
e0d19036 NB |
1996 | The device is examined to see if it is |
1997 | (1) an active md array, or | |
1998 | (2) a component of an md array. | |
1999 | The information discovered is reported. | |
2000 | ||
2001 | .TP | |
962a108f | 2002 | .B \-\-detail |
2d465520 | 2003 | The device should be an active md device. |
e0fe762a | 2004 | .B mdadm |
2d465520 | 2005 | will display a detailed description of the array. |
7e23fc43 | 2006 | .B \-\-brief |
2d465520 | 2007 | or |
7e23fc43 | 2008 | .B \-\-scan |
2d465520 | 2009 | will cause the output to be less detailed and the format to be |
e0d19036 | 2010 | suitable for inclusion in |
87eb4fab | 2011 | .BR mdadm.conf . |
feb716e9 NB |
2012 | The exit status of |
2013 | .I mdadm | |
2014 | will normally be 0 unless | |
2015 | .I mdadm | |
93e790af | 2016 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 2017 | .B \-\-test |
feb716e9 NB |
2018 | option is given, then the exit status will be: |
2019 | .RS | |
2020 | .TP | |
2021 | 0 | |
2022 | The array is functioning normally. | |
2023 | .TP | |
2024 | 1 | |
2025 | The array has at least one failed device. | |
2026 | .TP | |
2027 | 2 | |
a77be586 | 2028 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
2029 | .TP |
2030 | 4 | |
2031 | There was an error while trying to get information about the device. | |
2032 | .RE | |
cd29a5c8 | 2033 | |
4cce4069 DW |
2034 | .TP |
2035 | .B \-\-detail\-platform | |
e0fe762a | 2036 | Print detail of the platform's RAID capabilities (firmware / hardware |
4cce4069 DW |
2037 | topology). If the metadata is specified with |
2038 | .B \-e | |
2039 | or | |
2040 | .B \-\-metadata= | |
2041 | then the return status will be: | |
2042 | .RS | |
2043 | .TP | |
2044 | 0 | |
2045 | metadata successfully enumerated its platform components on this system | |
2046 | .TP | |
2047 | 1 | |
2048 | metadata is platform independent | |
2049 | .TP | |
2050 | 2 | |
2051 | metadata failed to find its platform components on this system | |
2052 | .RE | |
2053 | ||
aa534678 DW |
2054 | .TP |
2055 | .B \-\-update\-subarray= | |
2056 | If the device is a container and the argument to \-\-update\-subarray | |
2057 | specifies a subarray in the container, then attempt to update the given | |
2058 | superblock field in the subarray. Similar to updating an array in | |
2059 | "assemble" mode, the field to update is selected by | |
2060 | .B \-U | |
2061 | or | |
2062 | .B \-\-update= | |
2063 | option. Currently only | |
2064 | .B name | |
2065 | is supported. | |
2066 | ||
2067 | The | |
2068 | .B name | |
2069 | option updates the subarray name in the metadata, it may not affect the | |
2070 | device node name or the device node symlink until the subarray is | |
2071 | re\-assembled. If updating | |
2072 | .B name | |
2073 | would change the UUID of an active subarray this operation is blocked, | |
2074 | and the command will end in an error. | |
2075 | ||
e0d19036 | 2076 | .TP |
962a108f | 2077 | .B \-\-examine |
2d465520 | 2078 | The device should be a component of an md array. |
51ac42e3 | 2079 | .I mdadm |
2d465520 | 2080 | will read the md superblock of the device and display the contents. |
e0d19036 | 2081 | If |
7e23fc43 | 2082 | .B \-\-brief |
93e790af | 2083 | or |
7e23fc43 | 2084 | .B \-\-scan |
93e790af | 2085 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
2086 | are grouped together and reported in a single entry suitable |
2087 | for inclusion in | |
87eb4fab | 2088 | .BR mdadm.conf . |
e0d19036 | 2089 | |
2d465520 | 2090 | Having |
7e23fc43 | 2091 | .B \-\-scan |
e0d19036 NB |
2092 | without listing any devices will cause all devices listed in the |
2093 | config file to be examined. | |
2094 | ||
2095 | .TP | |
962a108f | 2096 | .B \-\-stop |
98c6faba NB |
2097 | The devices should be active md arrays which will be deactivated, as |
2098 | long as they are not currently in use. | |
e0d19036 NB |
2099 | |
2100 | .TP | |
962a108f | 2101 | .B \-\-run |
e0d19036 NB |
2102 | This will fully activate a partially assembled md array. |
2103 | ||
2104 | .TP | |
962a108f | 2105 | .B \-\-readonly |
e0d19036 NB |
2106 | This will mark an active array as read-only, providing that it is |
2107 | not currently being used. | |
2108 | ||
2109 | .TP | |
962a108f | 2110 | .B \-\-readwrite |
e0d19036 NB |
2111 | This will change a |
2112 | .B readonly | |
2113 | array back to being read/write. | |
2114 | ||
2d465520 | 2115 | .TP |
962a108f | 2116 | .B \-\-scan |
2d465520 | 2117 | For all operations except |
7e23fc43 PS |
2118 | .BR \-\-examine , |
2119 | .B \-\-scan | |
2d465520 NB |
2120 | will cause the operation to be applied to all arrays listed in |
2121 | .BR /proc/mdstat . | |
2122 | For | |
7e23fc43 PS |
2123 | .BR \-\-examine, |
2124 | .B \-\-scan | |
2d465520 NB |
2125 | causes all devices listed in the config file to be examined. |
2126 | ||
a1331cc4 N |
2127 | .TP |
2128 | .BR \-b ", " \-\-brief | |
2129 | Be less verbose. This is used with | |
2130 | .B \-\-detail | |
2131 | and | |
2132 | .BR \-\-examine . | |
2133 | Using | |
2134 | .B \-\-brief | |
2135 | with | |
2136 | .B \-\-verbose | |
2137 | gives an intermediate level of verbosity. | |
2138 | ||
e0d19036 NB |
2139 | .SH MONITOR MODE |
2140 | ||
cd29a5c8 NB |
2141 | .HP 12 |
2142 | Usage: | |
7e23fc43 | 2143 | .B mdadm \-\-monitor |
e0d19036 NB |
2144 | .I options... devices... |
2145 | ||
cd29a5c8 | 2146 | .PP |
e0d19036 | 2147 | This usage causes |
51ac42e3 | 2148 | .I mdadm |
e0d19036 NB |
2149 | to periodically poll a number of md arrays and to report on any events |
2150 | noticed. | |
51ac42e3 | 2151 | .I mdadm |
e0d19036 NB |
2152 | will never exit once it decides that there are arrays to be checked, |
2153 | so it should normally be run in the background. | |
2154 | ||
2d465520 | 2155 | As well as reporting events, |
51ac42e3 | 2156 | .I mdadm |
2d465520 NB |
2157 | may move a spare drive from one array to another if they are in the |
2158 | same | |
2159 | .B spare-group | |
210597d1 PC |
2160 | or |
2161 | .B domain | |
a9d69660 | 2162 | and if the destination array has a failed drive but no spares. |
2d465520 | 2163 | |
e0d19036 | 2164 | If any devices are listed on the command line, |
51ac42e3 | 2165 | .I mdadm |
e0fe762a | 2166 | will only monitor those devices. Otherwise all arrays listed in the |
e0d19036 | 2167 | configuration file will be monitored. Further, if |
7e23fc43 | 2168 | .B \-\-scan |
e0d19036 NB |
2169 | is given, then any other md devices that appear in |
2170 | .B /proc/mdstat | |
2171 | will also be monitored. | |
2172 | ||
2173 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 2174 | These events are passed to a separate program (if specified) and may |
2d465520 | 2175 | be mailed to a given E-mail address. |
e0d19036 | 2176 | |
93e790af SW |
2177 | When passing events to a program, the program is run once for each event, |
2178 | and is given 2 or 3 command-line arguments: the first is the | |
2179 | name of the event (see below), the second is the name of the | |
bd526cee | 2180 | md device which is affected, and the third is the name of a related |
93e790af | 2181 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
2182 | |
2183 | If | |
7e23fc43 | 2184 | .B \-\-scan |
e0d19036 NB |
2185 | is given, then a program or an E-mail address must be specified on the |
2186 | command line or in the config file. If neither are available, then | |
51ac42e3 | 2187 | .I mdadm |
e0d19036 NB |
2188 | will not monitor anything. |
2189 | Without | |
93e790af | 2190 | .B \-\-scan, |
51ac42e3 | 2191 | .I mdadm |
2d465520 | 2192 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
2193 | no program or email is given, then each event is reported to |
2194 | .BR stdout . | |
cd29a5c8 | 2195 | |
e0d19036 NB |
2196 | The different events are: |
2197 | ||
2198 | .RS 4 | |
2199 | .TP | |
2200 | .B DeviceDisappeared | |
2d465520 | 2201 | An md array which previously was configured appears to no longer be |
773135f5 | 2202 | configured. (syslog priority: Critical) |
e0d19036 | 2203 | |
b8f72a62 NB |
2204 | If |
2205 | .I mdadm | |
2206 | was told to monitor an array which is RAID0 or Linear, then it will | |
2207 | report | |
2208 | .B DeviceDisappeared | |
2209 | with the extra information | |
2210 | .BR Wrong-Level . | |
2211 | This is because RAID0 and Linear do not support the device-failed, | |
2212 | hot-spare and resync operations which are monitored. | |
2213 | ||
e0d19036 NB |
2214 | .TP |
2215 | .B RebuildStarted | |
773135f5 | 2216 | An md array started reconstruction. (syslog priority: Warning) |
e0d19036 NB |
2217 | |
2218 | .TP | |
2219 | .BI Rebuild NN | |
2220 | Where | |
2221 | .I NN | |
9a36a9b7 ZB |
2222 | is a two-digit number (ie. 05, 48). This indicates that rebuild |
2223 | has passed that many percent of the total. The events are generated | |
2224 | with fixed increment since 0. Increment size may be specified with | |
2225 | a commandline option (default is 20). (syslog priority: Warning) | |
e0d19036 | 2226 | |
98c6faba NB |
2227 | .TP |
2228 | .B RebuildFinished | |
2229 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 2230 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 2231 | |
e0d19036 NB |
2232 | .TP |
2233 | .B Fail | |
773135f5 NB |
2234 | An active component device of an array has been marked as |
2235 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
2236 | |
2237 | .TP | |
2238 | .B FailSpare | |
2239 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 2240 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
2241 | |
2242 | .TP | |
2243 | .B SpareActive | |
2244 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 2245 | device has been successfully rebuilt and has been made active. |
773135f5 | 2246 | (syslog priority: Info) |
e0d19036 NB |
2247 | |
2248 | .TP | |
2249 | .B NewArray | |
2250 | A new md array has been detected in the | |
2251 | .B /proc/mdstat | |
e0fe762a | 2252 | file. (syslog priority: Info) |
e0d19036 | 2253 | |
aa88f531 NB |
2254 | .TP |
2255 | .B DegradedArray | |
2256 | A newly noticed array appears to be degraded. This message is not | |
2257 | generated when | |
2258 | .I mdadm | |
2259 | notices a drive failure which causes degradation, but only when | |
2260 | .I mdadm | |
2261 | notices that an array is degraded when it first sees the array. | |
93e790af | 2262 | (syslog priority: Critical) |
aa88f531 | 2263 | |
e0d19036 NB |
2264 | .TP |
2265 | .B MoveSpare | |
2266 | A spare drive has been moved from one array in a | |
2267 | .B spare-group | |
210597d1 PC |
2268 | or |
2269 | .B domain | |
e0d19036 | 2270 | to another to allow a failed drive to be replaced. |
773135f5 | 2271 | (syslog priority: Info) |
e0d19036 | 2272 | |
b8f72a62 NB |
2273 | .TP |
2274 | .B SparesMissing | |
2275 | If | |
2276 | .I mdadm | |
2277 | has been told, via the config file, that an array should have a certain | |
2278 | number of spare devices, and | |
2279 | .I mdadm | |
93e790af | 2280 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
2281 | array, it will report a |
2282 | .B SparesMissing | |
2283 | message. | |
d1732eeb | 2284 | (syslog priority: Warning) |
b8f72a62 | 2285 | |
98c6faba NB |
2286 | .TP |
2287 | .B TestMessage | |
2288 | An array was found at startup, and the | |
7e23fc43 | 2289 | .B \-\-test |
98c6faba | 2290 | flag was given. |
773135f5 | 2291 | (syslog priority: Info) |
e0d19036 NB |
2292 | .RE |
2293 | ||
2294 | Only | |
93e790af SW |
2295 | .B Fail, |
2296 | .B FailSpare, | |
2297 | .B DegradedArray, | |
2298 | .B SparesMissing | |
e0d19036 | 2299 | and |
98c6faba | 2300 | .B TestMessage |
e0d19036 | 2301 | cause Email to be sent. All events cause the program to be run. |
93e790af | 2302 | The program is run with two or three arguments: the event |
e0d19036 NB |
2303 | name, the array device and possibly a second device. |
2304 | ||
2305 | Each event has an associated array device (e.g. | |
2306 | .BR /dev/md1 ) | |
2307 | and possibly a second device. For | |
2308 | .BR Fail , | |
2309 | .BR FailSpare , | |
2310 | and | |
2311 | .B SpareActive | |
2312 | the second device is the relevant component device. | |
2313 | For | |
2314 | .B MoveSpare | |
2315 | the second device is the array that the spare was moved from. | |
2316 | ||
2317 | For | |
51ac42e3 | 2318 | .I mdadm |
e0d19036 | 2319 | to move spares from one array to another, the different arrays need to |
93e790af | 2320 | be labeled with the same |
e0d19036 | 2321 | .B spare-group |
210597d1 | 2322 | or the spares must be allowed to migrate through matching POLICY domains |
e0d19036 NB |
2323 | in the configuration file. The |
2324 | .B spare-group | |
93e790af | 2325 | name can be any string; it is only necessary that different spare |
2d465520 | 2326 | groups use different names. |
e0d19036 NB |
2327 | |
2328 | When | |
51ac42e3 | 2329 | .I mdadm |
93e790af | 2330 | detects that an array in a spare group has fewer active |
e0d19036 NB |
2331 | devices than necessary for the complete array, and has no spare |
2332 | devices, it will look for another array in the same spare group that | |
2333 | has a full complement of working drive and a spare. It will then | |
2334 | attempt to remove the spare from the second drive and add it to the | |
2335 | first. | |
2336 | If the removal succeeds but the adding fails, then it is added back to | |
2337 | the original array. | |
2338 | ||
210597d1 PC |
2339 | If the spare group for a degraded array is not defined, |
2340 | .I mdadm | |
2341 | will look at the rules of spare migration specified by POLICY lines in | |
87eb4fab | 2342 | .B mdadm.conf |
210597d1 PC |
2343 | and then follow similar steps as above if a matching spare is found. |
2344 | ||
dd0781e5 NB |
2345 | .SH GROW MODE |
2346 | The GROW mode is used for changing the size or shape of an active | |
2347 | array. | |
2348 | For this to work, the kernel must support the necessary change. | |
c64881d7 | 2349 | Various types of growth are being added during 2.6 development. |
dd0781e5 | 2350 | |
c64881d7 | 2351 | Currently the supported changes include |
dfd4d8ee | 2352 | .IP \(bu 4 |
c64881d7 | 2353 | change the "size" attribute for RAID1, RAID4, RAID5 and RAID6. |
dfd4d8ee | 2354 | .IP \(bu 4 |
c64881d7 N |
2355 | increase or decrease the "raid\-devices" attribute of RAID0, RAID1, RAID4, |
2356 | RAID5, and RAID6. | |
cb77f620 | 2357 | .IP \(bu 4 |
c64881d7 | 2358 | change the chunk-size and layout of RAID0, RAID4, RAID5 and RAID6. |
cb77f620 | 2359 | .IP \(bu 4 |
c64881d7 | 2360 | convert between RAID1 and RAID5, between RAID5 and RAID6, between |
cb77f620 | 2361 | RAID0, RAID4, and RAID5, and between RAID0 and RAID10 (in the near-2 mode). |
dfd4d8ee | 2362 | .IP \(bu 4 |
93e790af | 2363 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 2364 | remove a write-intent bitmap from such an array. |
dfd4d8ee | 2365 | .PP |
dd0781e5 | 2366 | |
9ab6e80a | 2367 | Using GROW on containers is currently supported only for Intel's IMSM |
c64881d7 N |
2368 | container format. The number of devices in a container can be |
2369 | increased - which affects all arrays in the container - or an array | |
2370 | in a container can be converted between levels where those levels are | |
2371 | supported by the container, and the conversion is on of those listed | |
9ab6e80a N |
2372 | above. Resizing arrays in an IMSM container with |
2373 | .B "--grow --size" | |
2374 | is not yet supported. | |
8fd8d9c4 | 2375 | |
ca24ddb0 AK |
2376 | Grow functionality (e.g. expand a number of raid devices) for Intel's |
2377 | IMSM container format has an experimental status. It is guarded by the | |
2378 | .B MDADM_EXPERIMENTAL | |
2379 | environment variable which must be set to '1' for a GROW command to | |
2380 | succeed. | |
2381 | This is for the following reasons: | |
2382 | ||
2383 | .IP 1. | |
0de8d44d AK |
2384 | Intel's native IMSM check-pointing is not fully tested yet. |
2385 | This can causes IMSM incompatibility during the grow process: an array | |
ca24ddb0 AK |
2386 | which is growing cannot roam between Microsoft Windows(R) and Linux |
2387 | systems. | |
2388 | ||
2389 | .IP 2. | |
2390 | Interrupting a grow operation is not recommended, because it | |
2391 | has not been fully tested for Intel's IMSM container format yet. | |
2392 | ||
0de8d44d AK |
2393 | .PP |
2394 | Note: Intel's native checkpointing doesn't use | |
2395 | .B --backup-file | |
2396 | option and it is transparent for assembly feature. | |
2397 | ||
2ae555c3 | 2398 | .SS SIZE CHANGES |
c64881d7 | 2399 | Normally when an array is built the "size" is taken from the smallest |
dd0781e5 NB |
2400 | of the drives. If all the small drives in an arrays are, one at a |
2401 | time, removed and replaced with larger drives, then you could have an | |
2402 | array of large drives with only a small amount used. In this | |
2403 | situation, changing the "size" with "GROW" mode will allow the extra | |
2404 | space to start being used. If the size is increased in this way, a | |
2405 | "resync" process will start to make sure the new parts of the array | |
2406 | are synchronised. | |
2407 | ||
2408 | Note that when an array changes size, any filesystem that may be | |
cb77f620 | 2409 | stored in the array will not automatically grow or shrink to use or |
88b496c2 | 2410 | vacate the space. The |
666bba9b N |
2411 | filesystem will need to be explicitly told to use the extra space |
2412 | after growing, or to reduce its size | |
2413 | .B prior | |
2414 | to shrinking the array. | |
dd0781e5 | 2415 | |
e0fe762a N |
2416 | Also the size of an array cannot be changed while it has an active |
2417 | bitmap. If an array has a bitmap, it must be removed before the size | |
cb77f620 | 2418 | can be changed. Once the change is complete a new bitmap can be created. |
e0fe762a N |
2419 | |
2420 | .SS RAID\-DEVICES CHANGES | |
2ae555c3 | 2421 | |
dd0781e5 NB |
2422 | A RAID1 array can work with any number of devices from 1 upwards |
2423 | (though 1 is not very useful). There may be times which you want to | |
2424 | increase or decrease the number of active devices. Note that this is | |
2425 | different to hot-add or hot-remove which changes the number of | |
2426 | inactive devices. | |
2427 | ||
2428 | When reducing the number of devices in a RAID1 array, the slots which | |
2429 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 2430 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
2431 | |
2432 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 2433 | present will be activated immediately. |
dd0781e5 | 2434 | |
f24e2d6c | 2435 | Changing the number of active devices in a RAID5 or RAID6 is much more |
2ae555c3 | 2436 | effort. Every block in the array will need to be read and written |
f24e2d6c | 2437 | back to a new location. From 2.6.17, the Linux Kernel is able to |
ca4f89a3 N |
2438 | increase the number of devices in a RAID5 safely, including restarting |
2439 | an interrupted "reshape". From 2.6.31, the Linux Kernel is able to | |
f24e2d6c N |
2440 | increase or decrease the number of devices in a RAID5 or RAID6. |
2441 | ||
c64881d7 N |
2442 | From 2.6.35, the Linux Kernel is able to convert a RAID0 in to a RAID4 |
2443 | or RAID5. | |
2444 | .I mdadm | |
2445 | uses this functionality and the ability to add | |
2446 | devices to a RAID4 to allow devices to be added to a RAID0. When | |
2447 | requested to do this, | |
2448 | .I mdadm | |
2449 | will convert the RAID0 to a RAID4, add the necessary disks and make | |
2450 | the reshape happen, and then convert the RAID4 back to RAID0. | |
2451 | ||
f24e2d6c N |
2452 | When decreasing the number of devices, the size of the array will also |
2453 | decrease. If there was data in the array, it could get destroyed and | |
666bba9b N |
2454 | this is not reversible, so you should firstly shrink the filesystem on |
2455 | the array to fit within the new size. To help prevent accidents, | |
f24e2d6c N |
2456 | .I mdadm |
2457 | requires that the size of the array be decreased first with | |
2458 | .BR "mdadm --grow --array-size" . | |
2459 | This is a reversible change which simply makes the end of the array | |
2460 | inaccessible. The integrity of any data can then be checked before | |
2461 | the non-reversible reduction in the number of devices is request. | |
2ae555c3 | 2462 | |
cd19c0cf JR |
2463 | When relocating the first few stripes on a RAID5 or RAID6, it is not |
2464 | possible to keep the data on disk completely consistent and | |
2465 | crash-proof. To provide the required safety, mdadm disables writes to | |
2466 | the array while this "critical section" is reshaped, and takes a | |
2467 | backup of the data that is in that section. For grows, this backup may be | |
2468 | stored in any spare devices that the array has, however it can also be | |
2469 | stored in a separate file specified with the | |
7e23fc43 | 2470 | .B \-\-backup\-file |
cd19c0cf JR |
2471 | option, and is required to be specified for shrinks, RAID level |
2472 | changes and layout changes. If this option is used, and the system | |
2473 | does crash during the critical period, the same file must be passed to | |
7e23fc43 | 2474 | .B \-\-assemble |
cd19c0cf JR |
2475 | to restore the backup and reassemble the array. When shrinking rather |
2476 | than growing the array, the reshape is done from the end towards the | |
2477 | beginning, so the "critical section" is at the end of the reshape. | |
2ae555c3 | 2478 | |
f24e2d6c N |
2479 | .SS LEVEL CHANGES |
2480 | ||
2481 | Changing the RAID level of any array happens instantaneously. However | |
cd19c0cf | 2482 | in the RAID5 to RAID6 case this requires a non-standard layout of the |
f24e2d6c | 2483 | RAID6 data, and in the RAID6 to RAID5 case that non-standard layout is |
cd19c0cf | 2484 | required before the change can be accomplished. So while the level |
f24e2d6c | 2485 | change is instant, the accompanying layout change can take quite a |
cd19c0cf JR |
2486 | long time. A |
2487 | .B \-\-backup\-file | |
2488 | is required. If the array is not simultaneously being grown or | |
2489 | shrunk, so that the array size will remain the same - for example, | |
2490 | reshaping a 3-drive RAID5 into a 4-drive RAID6 - the backup file will | |
2491 | be used not just for a "cricital section" but throughout the reshape | |
2492 | operation, as described below under LAYOUT CHANGES. | |
f24e2d6c N |
2493 | |
2494 | .SS CHUNK-SIZE AND LAYOUT CHANGES | |
2495 | ||
2496 | Changing the chunk-size of layout without also changing the number of | |
2497 | devices as the same time will involve re-writing all blocks in-place. | |
2498 | To ensure against data loss in the case of a crash, a | |
2499 | .B --backup-file | |
2500 | must be provided for these changes. Small sections of the array will | |
cd19c0cf JR |
2501 | be copied to the backup file while they are being rearranged. This |
2502 | means that all the data is copied twice, once to the backup and once | |
2503 | to the new layout on the array, so this type of reshape will go very | |
2504 | slowly. | |
f24e2d6c N |
2505 | |
2506 | If the reshape is interrupted for any reason, this backup file must be | |
cd19c0cf | 2507 | made available to |
f24e2d6c N |
2508 | .B "mdadm --assemble" |
2509 | so the array can be reassembled. Consequently the file cannot be | |
2510 | stored on the device being reshaped. | |
2511 | ||
2512 | ||
2ae555c3 NB |
2513 | .SS BITMAP CHANGES |
2514 | ||
2515 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 2516 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b | 2517 | can be added. Note that if you add a bitmap stored in a file which is |
e0fe762a | 2518 | in a filesystem that is on the RAID array being affected, the system |
fe80f49b NB |
2519 | will deadlock. The bitmap must be on a separate filesystem. |
2520 | ||
8382f19b NB |
2521 | .SH INCREMENTAL MODE |
2522 | ||
2523 | .HP 12 | |
2524 | Usage: | |
7e23fc43 PS |
2525 | .B mdadm \-\-incremental |
2526 | .RB [ \-\-run ] | |
2527 | .RB [ \-\-quiet ] | |
8382f19b NB |
2528 | .I component-device |
2529 | .HP 12 | |
2530 | Usage: | |
29ba4804 N |
2531 | .B mdadm \-\-incremental \-\-fail |
2532 | .I component-device | |
2533 | .HP 12 | |
2534 | Usage: | |
7e6140e6 | 2535 | .B mdadm \-\-incremental \-\-rebuild\-map |
8382f19b NB |
2536 | .HP 12 |
2537 | Usage: | |
7e23fc43 | 2538 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b | 2539 | |
8382f19b NB |
2540 | .PP |
2541 | This mode is designed to be used in conjunction with a device | |
2542 | discovery system. As devices are found in a system, they can be | |
2543 | passed to | |
7e23fc43 | 2544 | .B "mdadm \-\-incremental" |
8382f19b NB |
2545 | to be conditionally added to an appropriate array. |
2546 | ||
29ba4804 N |
2547 | Conversely, it can also be used with the |
2548 | .B \-\-fail | |
2549 | flag to do just the opposite and find whatever array a particular device | |
2550 | is part of and remove the device from that array. | |
2551 | ||
8fd8d9c4 N |
2552 | If the device passed is a |
2553 | .B CONTAINER | |
2554 | device created by a previous call to | |
2555 | .IR mdadm , | |
2556 | then rather than trying to add that device to an array, all the arrays | |
2557 | described by the metadata of the container will be started. | |
2558 | ||
8382f19b NB |
2559 | .I mdadm |
2560 | performs a number of tests to determine if the device is part of an | |
93e790af | 2561 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
2562 | is found, or can be created, |
2563 | .I mdadm | |
2564 | adds the device to the array and conditionally starts the array. | |
2565 | ||
2566 | Note that | |
2567 | .I mdadm | |
87eb4fab N |
2568 | will normally only add devices to an array which were previously working |
2569 | (active or spare) parts of that array. The support for automatic | |
210597d1 PC |
2570 | inclusion of a new drive as a spare in some array requires |
2571 | a configuration through POLICY in config file. | |
8382f19b | 2572 | |
8382f19b NB |
2573 | The tests that |
2574 | .I mdadm | |
2575 | makes are as follow: | |
2576 | .IP + | |
2577 | Is the device permitted by | |
2578 | .BR mdadm.conf ? | |
2579 | That is, is it listed in a | |
2580 | .B DEVICES | |
2581 | line in that file. If | |
2582 | .B DEVICES | |
2583 | is absent then the default it to allow any device. Similar if | |
2584 | .B DEVICES | |
2585 | contains the special word | |
2586 | .B partitions | |
2587 | then any device is allowed. Otherwise the device name given to | |
2588 | .I mdadm | |
2589 | must match one of the names or patterns in a | |
2590 | .B DEVICES | |
2591 | line. | |
2592 | ||
2593 | .IP + | |
cb77f620 NK |
2594 | Does the device have a valid md superblock? If a specific metadata |
2595 | version is requested with | |
7e23fc43 | 2596 | .B \-\-metadata |
8382f19b | 2597 | or |
7e23fc43 | 2598 | .B \-e |
8382f19b NB |
2599 | then only that style of metadata is accepted, otherwise |
2600 | .I mdadm | |
2601 | finds any known version of metadata. If no | |
2602 | .I md | |
210597d1 PC |
2603 | metadata is found, the device may be still added to an array |
2604 | as a spare if POLICY allows. | |
8382f19b | 2605 | |
d1302dd8 | 2606 | .ig |
8382f19b NB |
2607 | .IP + |
2608 | Does the metadata match an expected array? | |
2609 | The metadata can match in two ways. Either there is an array listed | |
2610 | in | |
2611 | .B mdadm.conf | |
2612 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 2613 | or by minor-number), or the array was created with a |
8382f19b | 2614 | .B homehost |
93e790af | 2615 | specified and that |
8382f19b | 2616 | .B homehost |
93e790af | 2617 | matches the one in |
8382f19b NB |
2618 | .B mdadm.conf |
2619 | or on the command line. | |
2620 | If | |
2621 | .I mdadm | |
2622 | is not able to positively identify the array as belonging to the | |
2623 | current host, the device will be rejected. | |
d1302dd8 | 2624 | .. |
8382f19b | 2625 | |
cb77f620 | 2626 | .PP |
8382f19b | 2627 | .I mdadm |
93e790af | 2628 | keeps a list of arrays that it has partially assembled in |
96fd06ed | 2629 | .BR {MAP_PATH} . |
e0fe762a | 2630 | If no array exists which matches |
8382f19b NB |
2631 | the metadata on the new device, |
2632 | .I mdadm | |
2633 | must choose a device name and unit number. It does this based on any | |
2634 | name given in | |
2635 | .B mdadm.conf | |
2636 | or any name information stored in the metadata. If this name | |
2637 | suggests a unit number, that number will be used, otherwise a free | |
2638 | unit number will be chosen. Normally | |
2639 | .I mdadm | |
2640 | will prefer to create a partitionable array, however if the | |
2641 | .B CREATE | |
2642 | line in | |
2643 | .B mdadm.conf | |
2644 | suggests that a non-partitionable array is preferred, that will be | |
2645 | honoured. | |
2646 | ||
e0fe762a N |
2647 | If the array is not found in the config file and its metadata does not |
2648 | identify it as belonging to the "homehost", then | |
2649 | .I mdadm | |
2650 | will choose a name for the array which is certain not to conflict with | |
2651 | any array which does belong to this host. It does this be adding an | |
2652 | underscore and a small number to the name preferred by the metadata. | |
2653 | ||
8382f19b NB |
2654 | Once an appropriate array is found or created and the device is added, |
2655 | .I mdadm | |
2656 | must decide if the array is ready to be started. It will | |
2657 | normally compare the number of available (non-spare) devices to the | |
2658 | number of devices that the metadata suggests need to be active. If | |
2659 | there are at least that many, the array will be started. This means | |
2660 | that if any devices are missing the array will not be restarted. | |
2661 | ||
2662 | As an alternative, | |
7e23fc43 | 2663 | .B \-\-run |
8382f19b | 2664 | may be passed to |
51ac42e3 | 2665 | .I mdadm |
8382f19b | 2666 | in which case the array will be run as soon as there are enough |
e0fe762a N |
2667 | devices present for the data to be accessible. For a RAID1, that |
2668 | means one device will start the array. For a clean RAID5, the array | |
8382f19b NB |
2669 | will be started as soon as all but one drive is present. |
2670 | ||
93e790af | 2671 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
2672 | be known that all device discovery has completed, then |
2673 | .br | |
7e23fc43 | 2674 | .B " mdadm \-IRs" |
8382f19b NB |
2675 | .br |
2676 | can be run which will try to start all arrays that are being | |
2677 | incrementally assembled. They are started in "read-auto" mode in | |
2678 | which they are read-only until the first write request. This means | |
2679 | that no metadata updates are made and no attempt at resync or recovery | |
2680 | happens. Further devices that are found before the first write can | |
2681 | still be added safely. | |
2682 | ||
5545fa6d DW |
2683 | .SH ENVIRONMENT |
2684 | This section describes environment variables that affect how mdadm | |
2685 | operates. | |
2686 | ||
2687 | .TP | |
2688 | .B MDADM_NO_MDMON | |
2689 | Setting this value to 1 will prevent mdadm from automatically launching | |
2690 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
2691 | ||
8fd8d9c4 N |
2692 | .TP |
2693 | .B MDADM_NO_UDEV | |
2694 | Normally, | |
2695 | .I mdadm | |
2696 | does not create any device nodes in /dev, but leaves that task to | |
2697 | .IR udev . | |
2698 | If | |
2699 | .I udev | |
2700 | appears not to be configured, or if this environment variable is set | |
2701 | to '1', the | |
2702 | .I mdadm | |
2703 | will create and devices that are needed. | |
2704 | ||
2d465520 NB |
2705 | .SH EXAMPLES |
2706 | ||
7e23fc43 | 2707 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 2708 | .br |
e0fe762a | 2709 | This will find out if a given device is a RAID array, or is part of |
5787fa49 | 2710 | one, and will provide brief information about the device. |
2d465520 | 2711 | |
7e23fc43 | 2712 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 2713 | .br |
93e790af | 2714 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 2715 | file. This command will typically go in a system startup file. |
2d465520 | 2716 | |
7e23fc43 | 2717 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 2718 | .br |
93e790af | 2719 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 2720 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 2721 | |
7e23fc43 | 2722 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 2723 | .br |
5787fa49 NB |
2724 | If (and only if) there is an Email address or program given in the |
2725 | standard config file, then | |
2726 | monitor the status of all arrays listed in that file by | |
2727 | polling them ever 2 minutes. | |
2d465520 | 2728 | |
7e23fc43 | 2729 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 2730 | .br |
5787fa49 | 2731 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 2732 | |
2d465520 | 2733 | .br |
7e23fc43 | 2734 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 2735 | .br |
7e23fc43 | 2736 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 2737 | .br |
5787fa49 NB |
2738 | This will create a prototype config file that describes currently |
2739 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
2740 | This file should be reviewed before being used as it may |
2741 | contain unwanted detail. | |
2742 | ||
7e23fc43 | 2743 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 2744 | .br |
7e23fc43 | 2745 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
2746 | .br |
2747 | This will find arrays which could be assembled from existing IDE and | |
2748 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 2749 | format of a config file. |
2d465520 NB |
2750 | This file is very likely to contain unwanted detail, particularly |
2751 | the | |
2752 | .B devices= | |
5787fa49 NB |
2753 | entries. It should be reviewed and edited before being used as an |
2754 | actual config file. | |
2d465520 | 2755 | |
7e23fc43 | 2756 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 2757 | .br |
7e23fc43 | 2758 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
2759 | .br |
2760 | Create a list of devices by reading | |
2761 | .BR /proc/partitions , | |
2762 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 2763 | that were found. |
2d465520 | 2764 | |
7e23fc43 | 2765 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 2766 | .br |
5787fa49 NB |
2767 | Scan all partitions and devices listed in |
2768 | .BR /proc/partitions | |
2769 | and assemble | |
2770 | .B /dev/md0 | |
2771 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 2772 | |
96fd06ed | 2773 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /run/mdadm/mon.pid" |
d013a55e NB |
2774 | .br |
2775 | If config file contains a mail address or alert program, run mdadm in | |
2776 | the background in monitor mode monitoring all md devices. Also write | |
2777 | pid of mdadm daemon to | |
96fd06ed | 2778 | .BR /run/mdadm/mon.pid . |
d013a55e | 2779 | |
7e23fc43 | 2780 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
2781 | .br |
2782 | Try to incorporate newly discovered device into some array as | |
2783 | appropriate. | |
2784 | ||
7e6140e6 | 2785 | .B " mdadm \-\-incremental \-\-rebuild\-map \-\-run \-\-scan" |
8382f19b NB |
2786 | .br |
2787 | Rebuild the array map from any current arrays, and then start any that | |
2788 | can be started. | |
2789 | ||
b80da661 NB |
2790 | .B " mdadm /dev/md4 --fail detached --remove detached" |
2791 | .br | |
2792 | Any devices which are components of /dev/md4 will be marked as faulty | |
2793 | and then remove from the array. | |
2794 | ||
cb77f620 | 2795 | .B " mdadm --grow /dev/md4 --level=6 --backup-file=/root/backup-md4" |
f24e2d6c N |
2796 | .br |
2797 | The array | |
2798 | .B /dev/md4 | |
2799 | which is currently a RAID5 array will be converted to RAID6. There | |
2800 | should normally already be a spare drive attached to the array as a | |
2801 | RAID6 needs one more drive than a matching RAID5. | |
2802 | ||
8fd8d9c4 N |
2803 | .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]" |
2804 | .br | |
2805 | Create a DDF array over 6 devices. | |
2806 | ||
2807 | .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf" | |
2808 | .br | |
e0fe762a | 2809 | Create a RAID5 array over any 3 devices in the given DDF set. Use |
8fd8d9c4 N |
2810 | only 30 gigabytes of each device. |
2811 | ||
2812 | .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]" | |
2813 | .br | |
2814 | Assemble a pre-exist ddf array. | |
2815 | ||
2816 | .B " mdadm -I /dev/md/ddf1" | |
2817 | .br | |
2818 | Assemble all arrays contained in the ddf array, assigning names as | |
2819 | appropriate. | |
2820 | ||
7e23fc43 | 2821 | .B " mdadm \-\-create \-\-help" |
2d465520 | 2822 | .br |
2ae555c3 | 2823 | Provide help about the Create mode. |
2d465520 | 2824 | |
7e23fc43 | 2825 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
2826 | .br |
2827 | Provide help about the format of the config file. | |
2d465520 | 2828 | |
7e23fc43 | 2829 | .B " mdadm \-\-help" |
5787fa49 NB |
2830 | .br |
2831 | Provide general help. | |
cd29a5c8 | 2832 | |
cd29a5c8 NB |
2833 | .SH FILES |
2834 | ||
2835 | .SS /proc/mdstat | |
2836 | ||
2ae555c3 NB |
2837 | If you're using the |
2838 | .B /proc | |
cd29a5c8 NB |
2839 | filesystem, |
2840 | .B /proc/mdstat | |
2d465520 | 2841 | lists all active md devices with information about them. |
51ac42e3 | 2842 | .I mdadm |
2d465520 | 2843 | uses this to find arrays when |
7e23fc43 | 2844 | .B \-\-scan |
2d465520 NB |
2845 | is given in Misc mode, and to monitor array reconstruction |
2846 | on Monitor mode. | |
2847 | ||
9a9dab36 | 2848 | .SS /etc/mdadm.conf |
cd29a5c8 | 2849 | |
11a3e71d NB |
2850 | The config file lists which devices may be scanned to see if |
2851 | they contain MD super block, and gives identifying information | |
2852 | (e.g. UUID) about known MD arrays. See | |
2853 | .BR mdadm.conf (5) | |
2854 | for more details. | |
cd29a5c8 | 2855 | |
96fd06ed | 2856 | .SS {MAP_PATH} |
8382f19b | 2857 | When |
7e23fc43 | 2858 | .B \-\-incremental |
93e790af | 2859 | mode is used, this file gets a list of arrays currently being created. |
8382f19b | 2860 | |
48f7b27a NB |
2861 | .SH DEVICE NAMES |
2862 | ||
48f7b27a | 2863 | .I mdadm |
8fd8d9c4 N |
2864 | understand two sorts of names for array devices. |
2865 | ||
2866 | The first is the so-called 'standard' format name, which matches the | |
2867 | names used by the kernel and which appear in | |
2868 | .IR /proc/mdstat . | |
2869 | ||
2870 | The second sort can be freely chosen, but must reside in | |
2871 | .IR /dev/md/ . | |
2872 | When giving a device name to | |
2873 | .I mdadm | |
2874 | to create or assemble an array, either full path name such as | |
2875 | .I /dev/md0 | |
2876 | or | |
2877 | .I /dev/md/home | |
2878 | can be given, or just the suffix of the second sort of name, such as | |
2879 | .I home | |
2880 | can be given. | |
2881 | ||
2882 | When | |
2883 | .I mdadm | |
e0fe762a N |
2884 | chooses device names during auto-assembly or incremental assembly, it |
2885 | will sometimes add a small sequence number to the end of the name to | |
2886 | avoid conflicted between multiple arrays that have the same name. If | |
8fd8d9c4 N |
2887 | .I mdadm |
2888 | can reasonably determine that the array really is meant for this host, | |
2889 | either by a hostname in the metadata, or by the presence of the array | |
87eb4fab N |
2890 | in |
2891 | .BR mdadm.conf , | |
2892 | then it will leave off the suffix if possible. | |
e0fe762a N |
2893 | Also if the homehost is specified as |
2894 | .B <ignore> | |
2895 | .I mdadm | |
2896 | will only use a suffix if a different array of the same name already | |
2897 | exists or is listed in the config file. | |
48f7b27a NB |
2898 | |
2899 | The standard names for non-partitioned arrays (the only sort of md | |
8fd8d9c4 | 2900 | array available in 2.4 and earlier) are of the form |
48f7b27a NB |
2901 | .IP |
2902 | /dev/mdNN | |
48f7b27a NB |
2903 | .PP |
2904 | where NN is a number. | |
2905 | The standard names for partitionable arrays (as available from 2.6 | |
8fd8d9c4 | 2906 | onwards) are of the form |
48f7b27a | 2907 | .IP |
48f7b27a NB |
2908 | /dev/md_dNN |
2909 | .PP | |
2910 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
8fd8d9c4 N |
2911 | .PP |
2912 | From kernel version, 2.6.28 the "non-partitioned array" can actually | |
2913 | be partitioned. So the "md_dNN" names are no longer needed, and | |
2914 | partitions such as "/dev/mdNNpXX" are possible. | |
52826846 | 2915 | |
2d465520 | 2916 | .SH NOTE |
51ac42e3 | 2917 | .I mdadm |
2d465520 | 2918 | was previously known as |
51ac42e3 | 2919 | .IR mdctl . |
a9d69660 | 2920 | .P |
51ac42e3 | 2921 | .I mdadm |
a9d69660 | 2922 | is completely separate from the |
51ac42e3 | 2923 | .I raidtools |
a9d69660 NB |
2924 | package, and does not use the |
2925 | .I /etc/raidtab | |
2926 | configuration file at all. | |
2927 | ||
52826846 | 2928 | .SH SEE ALSO |
75f74377 | 2929 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 2930 | RAID, see: |
3cdfb6a7 | 2931 | .IP |
cb77f620 | 2932 | .B http://raid.wiki.kernel.org/ |
75f74377 DG |
2933 | .PP |
2934 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
e43d0cda NB |
2935 | .\".PP |
2936 | .\"for new releases of the RAID driver check out: | |
2937 | .\" | |
2938 | .\".IP | |
e0fe762a | 2939 | .\".UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches |
e43d0cda NB |
2940 | .\"ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches |
2941 | .\".UE | |
2942 | .\".PP | |
2943 | .\"or | |
2944 | .\".IP | |
2945 | .\".UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2946 | .\"http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2947 | .\".UE | |
cd29a5c8 | 2948 | .PP |
2ae555c3 | 2949 | The latest version of |
a9d69660 NB |
2950 | .I mdadm |
2951 | should always be available from | |
cd29a5c8 | 2952 | .IP |
11cd8b79 N |
2953 | .B http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
2954 | .PP | |
2955 | Related man pages: | |
cd29a5c8 | 2956 | .PP |
e0fe762a | 2957 | .IR mdmon (8), |
a9d69660 NB |
2958 | .IR mdadm.conf (5), |
2959 | .IR md (4). | |
56eb10c0 | 2960 | .PP |
52826846 NB |
2961 | .IR raidtab (5), |
2962 | .IR raid0run (8), | |
2963 | .IR raidstop (8), | |
a9d69660 | 2964 | .IR mkraid (8). |