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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. | |
7b0bbd0f | 8 | .TH MDADM 8 "" v3.2.1 |
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 , | |
2ae555c3 | 219 | or |
7e23fc43 | 220 | .BR \-\-remove , |
e0fe762a | 221 | then the MANAGE mode is assumed. |
2ae555c3 NB |
222 | Anything other than these will cause the |
223 | .B Misc | |
224 | mode to be assumed. | |
dd0781e5 | 225 | |
2ae555c3 | 226 | .SH Options that are not mode-specific are: |
e793c2e5 | 227 | |
cd29a5c8 | 228 | .TP |
7e23fc43 | 229 | .BR \-h ", " \-\-help |
a9d69660 | 230 | Display general help message or, after one of the above options, a |
93e790af | 231 | mode-specific help message. |
56eedc1a NB |
232 | |
233 | .TP | |
7e23fc43 | 234 | .B \-\-help\-options |
56eedc1a NB |
235 | Display more detailed help about command line parsing and some commonly |
236 | used options. | |
52826846 | 237 | |
cd29a5c8 | 238 | .TP |
7e23fc43 | 239 | .BR \-V ", " \-\-version |
9a9dab36 | 240 | Print version information for mdadm. |
52826846 | 241 | |
cd29a5c8 | 242 | .TP |
7e23fc43 | 243 | .BR \-v ", " \-\-verbose |
22892d56 NB |
244 | Be more verbose about what is happening. This can be used twice to be |
245 | extra-verbose. | |
a9d69660 | 246 | The extra verbosity currently only affects |
7e23fc43 | 247 | .B \-\-detail \-\-scan |
22892d56 | 248 | and |
7e23fc43 | 249 | .BR "\-\-examine \-\-scan" . |
52826846 | 250 | |
dab6685f | 251 | .TP |
7e23fc43 | 252 | .BR \-q ", " \-\-quiet |
dab6685f | 253 | Avoid printing purely informative messages. With this, |
51ac42e3 | 254 | .I mdadm |
dab6685f NB |
255 | will be silent unless there is something really important to report. |
256 | ||
e0d19036 | 257 | .TP |
7e23fc43 | 258 | .BR \-f ", " \-\-force |
93e790af | 259 | Be more forceful about certain operations. See the various modes for |
e0d19036 NB |
260 | the exact meaning of this option in different contexts. |
261 | ||
262 | .TP | |
7e23fc43 | 263 | .BR \-c ", " \-\-config= |
2ae555c3 NB |
264 | Specify the config file. Default is to use |
265 | .BR /etc/mdadm.conf , | |
93e790af | 266 | or if that is missing then |
2ae555c3 | 267 | .BR /etc/mdadm/mdadm.conf . |
5787fa49 | 268 | If the config file given is |
93e790af | 269 | .B "partitions" |
5787fa49 NB |
270 | then nothing will be read, but |
271 | .I mdadm | |
272 | will act as though the config file contained exactly | |
8fd8d9c4 | 273 | .B "DEVICE partitions containers" |
5787fa49 NB |
274 | and will read |
275 | .B /proc/partitions | |
8fd8d9c4 N |
276 | to find a list of devices to scan, and |
277 | .B /proc/mdstat | |
278 | to find a list of containers to examine. | |
d013a55e | 279 | If the word |
93e790af | 280 | .B "none" |
d013a55e NB |
281 | is given for the config file, then |
282 | .I mdadm | |
283 | will act as though the config file were empty. | |
e0d19036 NB |
284 | |
285 | .TP | |
7e23fc43 | 286 | .BR \-s ", " \-\-scan |
93e790af | 287 | Scan config file or |
e0d19036 NB |
288 | .B /proc/mdstat |
289 | for missing information. | |
290 | In general, this option gives | |
51ac42e3 | 291 | .I mdadm |
93e790af SW |
292 | permission to get any missing information (like component devices, |
293 | array devices, array identities, and alert destination) from the | |
294 | configuration file (see previous option); | |
295 | one exception is MISC mode when using | |
7e23fc43 | 296 | .B \-\-detail |
e0d19036 | 297 | or |
93e790af | 298 | .B \-\-stop, |
e0d19036 | 299 | in which case |
7e23fc43 | 300 | .B \-\-scan |
e0d19036 NB |
301 | says to get a list of array devices from |
302 | .BR /proc/mdstat . | |
303 | ||
570c0542 | 304 | .TP |
d16c7af6 | 305 | .BR \-e ", " \-\-metadata= |
e0fe762a | 306 | Declare the style of RAID metadata (superblock) to be used. The |
26f467a9 | 307 | default is {DEFAULT_METADATA} for |
7e23fc43 | 308 | .BR \-\-create , |
53e8b987 | 309 | and to guess for other operations. |
2790ffe3 GB |
310 | The default can be overridden by setting the |
311 | .B metadata | |
312 | value for the | |
313 | .B CREATE | |
314 | keyword in | |
315 | .BR mdadm.conf . | |
570c0542 NB |
316 | |
317 | Options are: | |
318 | .RS | |
26f467a9 | 319 | .ie '{DEFAULT_METADATA}'0.90' |
320 | .IP "0, 0.90, default" | |
321 | .el | |
7d5c3964 | 322 | .IP "0, 0.90" |
26f467a9 | 323 | .. |
570c0542 | 324 | Use the original 0.90 format superblock. This format limits arrays to |
93e790af | 325 | 28 component devices and limits component devices of levels 1 and |
cd19c0cf JR |
326 | greater to 2 terabytes. It is also possible for there to be confusion |
327 | about whether the superblock applies to a whole device or just the | |
328 | last partition, if that partition starts on a 64K boundary. | |
26f467a9 | 329 | .ie '{DEFAULT_METADATA}'0.90' |
330 | .IP "1, 1.0, 1.1, 1.2" | |
331 | .el | |
7d5c3964 | 332 | .IP "1, 1.0, 1.1, 1.2 default" |
26f467a9 | 333 | .. |
cd19c0cf JR |
334 | Use the new version-1 format superblock. This has fewer restrictions. |
335 | It can easily be moved between hosts with different endian-ness, and a | |
336 | recovery operation can be checkpointed and restarted. The different | |
337 | sub-versions store the superblock at different locations on the | |
338 | device, either at the end (for 1.0), at the start (for 1.1) or 4K from | |
339 | the start (for 1.2). "1" is equivalent to "1.0". | |
26f467a9 | 340 | 'if '{DEFAULT_METADATA}'1.2' "default" is equivalent to "1.2". |
8fd8d9c4 | 341 | .IP ddf |
e0fe762a N |
342 | Use the "Industry Standard" DDF (Disk Data Format) format defined by |
343 | SNIA. | |
344 | When creating a DDF array a | |
8fd8d9c4 N |
345 | .B CONTAINER |
346 | will be created, and normal arrays can be created in that container. | |
347 | .IP imsm | |
4cce4069 | 348 | Use the Intel(R) Matrix Storage Manager metadata format. This creates a |
8fd8d9c4 | 349 | .B CONTAINER |
4cce4069 DW |
350 | which is managed in a similar manner to DDF, and is supported by an |
351 | option-rom on some platforms: | |
352 | .IP | |
353 | .B http://www.intel.com/design/chipsets/matrixstorage_sb.htm | |
354 | .PP | |
570c0542 NB |
355 | .RE |
356 | ||
41a3b72a | 357 | .TP |
7e23fc43 | 358 | .B \-\-homehost= |
35cc5be4 | 359 | This will override any |
41a3b72a | 360 | .B HOMEHOST |
93e790af | 361 | setting in the config file and provides the identity of the host which |
41a3b72a NB |
362 | should be considered the home for any arrays. |
363 | ||
364 | When creating an array, the | |
365 | .B homehost | |
e0fe762a | 366 | will be recorded in the metadata. For version-1 superblocks, it will |
93e790af | 367 | be prefixed to the array name. For version-0.90 superblocks, part of |
41a3b72a NB |
368 | the SHA1 hash of the hostname will be stored in the later half of the |
369 | UUID. | |
370 | ||
371 | When reporting information about an array, any array which is tagged | |
372 | for the given homehost will be reported as such. | |
373 | ||
374 | When using Auto-Assemble, only arrays tagged for the given homehost | |
0ac91628 | 375 | will be allowed to use 'local' names (i.e. not ending in '_' followed |
e0fe762a N |
376 | by a digit string). See below under |
377 | .BR "Auto Assembly" . | |
41a3b72a | 378 | |
2ae555c3 NB |
379 | .SH For create, build, or grow: |
380 | ||
381 | .TP | |
7e23fc43 | 382 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
383 | Specify the number of active devices in the array. This, plus the |
384 | number of spare devices (see below) must equal the number of | |
385 | .I component-devices | |
386 | (including "\fBmissing\fP" devices) | |
387 | that are listed on the command line for | |
e0fe762a | 388 | .BR \-\-create . |
2ae555c3 NB |
389 | Setting a value of 1 is probably |
390 | a mistake and so requires that | |
7e23fc43 | 391 | .B \-\-force |
2ae555c3 | 392 | be specified first. A value of 1 will then be allowed for linear, |
e0fe762a | 393 | multipath, RAID0 and RAID1. It is never allowed for RAID4, RAID5 or RAID6. |
2ae555c3 NB |
394 | .br |
395 | This number can only be changed using | |
7e23fc43 | 396 | .B \-\-grow |
e0fe762a N |
397 | for RAID1, RAID4, RAID5 and RAID6 arrays, and only on kernels which provide |
398 | the necessary support. | |
2ae555c3 NB |
399 | |
400 | .TP | |
7e23fc43 | 401 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
402 | Specify the number of spare (eXtra) devices in the initial array. |
403 | Spares can also be added | |
404 | and removed later. The number of component devices listed | |
e0fe762a | 405 | on the command line must equal the number of RAID devices plus the |
2ae555c3 NB |
406 | number of spare devices. |
407 | ||
2ae555c3 | 408 | .TP |
7e23fc43 | 409 | .BR \-z ", " \-\-size= |
e0fe762a | 410 | Amount (in Kibibytes) of space to use from each drive in RAID levels 1/4/5/6. |
2ae555c3 NB |
411 | This must be a multiple of the chunk size, and must leave about 128Kb |
412 | of space at the end of the drive for the RAID superblock. | |
413 | If this is not specified | |
414 | (as it normally is not) the smallest drive (or partition) sets the | |
415 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
416 | issued. | |
417 | ||
36fad8ec N |
418 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
419 | Gigabytes respectively. | |
420 | ||
2ae555c3 | 421 | This value can be set with |
7e23fc43 | 422 | .B \-\-grow |
e0fe762a | 423 | for RAID level 1/4/5/6. If the array was created with a size smaller |
2ae555c3 NB |
424 | than the currently active drives, the extra space can be accessed |
425 | using | |
7e23fc43 | 426 | .BR \-\-grow . |
2ae555c3 NB |
427 | The size can be given as |
428 | .B max | |
429 | which means to choose the largest size that fits on all current drives. | |
52826846 | 430 | |
c26d78fe N |
431 | Before reducing the size of the array (with |
432 | .BR "\-\-grow \-\-size=" ) | |
433 | you should make sure that space isn't needed. If the device holds a | |
434 | filesystem, you would need to resize the filesystem to use less space. | |
435 | ||
436 | After reducing the array size you should check that the data stored in | |
437 | the device is still available. If the device holds a filesystem, then | |
438 | an 'fsck' of the filesystem is a minimum requirement. If there are | |
439 | problems the array can be made bigger again with no loss with another | |
440 | .B "\-\-grow \-\-size=" | |
441 | command. | |
442 | ||
8fd8d9c4 N |
443 | This value can not be used with |
444 | .B CONTAINER | |
445 | metadata such as DDF and IMSM. | |
446 | ||
f24e2d6c | 447 | .TP |
c26d78fe | 448 | .BR \-Z ", " \-\-array\-size= |
f24e2d6c N |
449 | This is only meaningful with |
450 | .B \-\-grow | |
36fad8ec | 451 | and its effect is not persistent: when the array is stopped and |
f24e2d6c N |
452 | restarted the default array size will be restored. |
453 | ||
454 | Setting the array-size causes the array to appear smaller to programs | |
455 | that access the data. This is particularly needed before reshaping an | |
456 | array so that it will be smaller. As the reshape is not reversible, | |
457 | but setting the size with | |
458 | .B \-\-array-size | |
459 | is, it is required that the array size is reduced as appropriate | |
460 | before the number of devices in the array is reduced. | |
461 | ||
c26d78fe N |
462 | Before reducing the size of the array you should make sure that space |
463 | isn't needed. If the device holds a filesystem, you would need to | |
464 | resize the filesystem to use less space. | |
465 | ||
466 | After reducing the array size you should check that the data stored in | |
467 | the device is still available. If the device holds a filesystem, then | |
468 | an 'fsck' of the filesystem is a minimum requirement. If there are | |
469 | problems the array can be made bigger again with no loss with another | |
470 | .B "\-\-grow \-\-array\-size=" | |
471 | command. | |
472 | ||
36fad8ec N |
473 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
474 | Gigabytes respectively. | |
475 | A value of | |
476 | .B max | |
477 | restores the apparent size of the array to be whatever the real | |
478 | amount of available space is. | |
479 | ||
cd29a5c8 | 480 | .TP |
7e23fc43 | 481 | .BR \-c ", " \-\-chunk= |
5f175898 N |
482 | Specify chunk size of kibibytes. The default when creating an |
483 | array is 512KB. To ensure compatibility with earlier versions, the | |
484 | default when Building and array with no persistent metadata is 64KB. | |
e0fe762a | 485 | This is only meaningful for RAID0, RAID4, RAID5, RAID6, and RAID10. |
52826846 | 486 | |
36fad8ec N |
487 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
488 | Gigabytes respectively. | |
489 | ||
cd29a5c8 | 490 | .TP |
7e23fc43 | 491 | .BR \-\-rounding= |
e0fe762a N |
492 | Specify rounding factor for a Linear array. The size of each |
493 | component will be rounded down to a multiple of this size. | |
494 | This is a synonym for | |
495 | .B \-\-chunk | |
496 | but highlights the different meaning for Linear as compared to other | |
5f175898 N |
497 | RAID levels. The default is 64K if a kernel earlier than 2.6.16 is in |
498 | use, and is 0K (i.e. no rounding) in later kernels. | |
52826846 | 499 | |
cd29a5c8 | 500 | .TP |
7e23fc43 | 501 | .BR \-l ", " \-\-level= |
e0fe762a | 502 | Set RAID level. When used with |
7e23fc43 | 503 | .BR \-\-create , |
98c6faba | 504 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
8fd8d9c4 N |
505 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container. |
506 | Obviously some of these are synonymous. | |
507 | ||
508 | When a | |
509 | .B CONTAINER | |
510 | metadata type is requested, only the | |
511 | .B container | |
512 | level is permitted, and it does not need to be explicitly given. | |
aa88f531 NB |
513 | |
514 | When used with | |
7e23fc43 | 515 | .BR \-\-build , |
a9d69660 | 516 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 517 | |
fd547b50 N |
518 | Can be used with |
519 | .B \-\-grow | |
520 | to change the RAID level in some cases. See LEVEL CHANGES below. | |
2ae555c3 | 521 | |
cd29a5c8 | 522 | .TP |
7e23fc43 | 523 | .BR \-p ", " \-\-layout= |
f24e2d6c N |
524 | This option configures the fine details of data layout for RAID5, RAID6, |
525 | and RAID10 arrays, and controls the failure modes for | |
1a7dfc35 NB |
526 | .IR faulty . |
527 | ||
e0fe762a | 528 | The layout of the RAID5 parity block can be one of |
7e23fc43 PS |
529 | .BR left\-asymmetric , |
530 | .BR left\-symmetric , | |
531 | .BR right\-asymmetric , | |
532 | .BR right\-symmetric , | |
53e8b987 PS |
533 | .BR la ", " ra ", " ls ", " rs . |
534 | The default is | |
7e23fc43 | 535 | .BR left\-symmetric . |
52826846 | 536 | |
cd19c0cf | 537 | It is also possible to cause RAID5 to use a RAID4-like layout by |
e0fe762a N |
538 | choosing |
539 | .BR parity\-first , | |
540 | or | |
541 | .BR parity\-last . | |
542 | ||
543 | Finally for RAID5 there are DDF\-compatible layouts, | |
544 | .BR ddf\-zero\-restart , | |
545 | .BR ddf\-N\-restart , | |
546 | and | |
547 | .BR ddf\-N\-continue . | |
548 | ||
549 | These same layouts are available for RAID6. There are also 4 layouts | |
550 | that will provide an intermediate stage for converting between RAID5 | |
551 | and RAID6. These provide a layout which is identical to the | |
552 | corresponding RAID5 layout on the first N\-1 devices, and has the 'Q' | |
553 | syndrome (the second 'parity' block used by RAID6) on the last device. | |
554 | These layouts are: | |
555 | .BR left\-symmetric\-6 , | |
556 | .BR right\-symmetric\-6 , | |
557 | .BR left\-asymmetric\-6 , | |
558 | .BR right\-asymmetric\-6 , | |
559 | and | |
10adfe9a | 560 | .BR parity\-first\-6 . |
e0fe762a | 561 | |
93e790af SW |
562 | When setting the failure mode for level |
563 | .I faulty, | |
1a7dfc35 | 564 | the options are: |
7e23fc43 PS |
565 | .BR write\-transient ", " wt , |
566 | .BR read\-transient ", " rt , | |
567 | .BR write\-persistent ", " wp , | |
568 | .BR read\-persistent ", " rp , | |
569 | .BR write\-all , | |
570 | .BR read\-fixable ", " rf , | |
53e8b987 | 571 | .BR clear ", " flush ", " none . |
b5e64645 | 572 | |
93e790af | 573 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
574 | between fault generation. Without a number, the fault is generated |
575 | once on the first relevant request. With a number, the fault will be | |
93e790af | 576 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
577 | every time the period elapses. |
578 | ||
579 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 580 | .B \-\-grow |
53e8b987 | 581 | option to set subsequent failure modes. |
b5e64645 NB |
582 | |
583 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 584 | and "flush" will clear any persistent faults. |
b5e64645 | 585 | |
6f9a21a7 | 586 | Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 587 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 588 | |
93e790af | 589 | .I 'n' |
e0fe762a | 590 | signals 'near' copies. Multiple copies of one data block are at |
b578481c NB |
591 | similar offsets in different devices. |
592 | ||
93e790af | 593 | .I 'o' |
b578481c NB |
594 | signals 'offset' copies. Rather than the chunks being duplicated |
595 | within a stripe, whole stripes are duplicated but are rotated by one | |
596 | device so duplicate blocks are on different devices. Thus subsequent | |
597 | copies of a block are in the next drive, and are one chunk further | |
598 | down. | |
599 | ||
93e790af | 600 | .I 'f' |
1a7dfc35 | 601 | signals 'far' copies |
93e790af | 602 | (multiple copies have very different offsets). |
e0fe762a | 603 | See md(4) for more detail about 'near', 'offset', and 'far'. |
1a7dfc35 NB |
604 | |
605 | The number is the number of copies of each datablock. 2 is normal, 3 | |
606 | can be useful. This number can be at most equal to the number of | |
607 | devices in the array. It does not need to divide evenly into that | |
608 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
609 | with an odd number of devices). | |
610 | ||
f24e2d6c N |
611 | When an array is converted between RAID5 and RAID6 an intermediate |
612 | RAID6 layout is used in which the second parity block (Q) is always on | |
613 | the last device. To convert a RAID5 to RAID6 and leave it in this new | |
614 | layout (which does not require re-striping) use | |
615 | .BR \-\-layout=preserve . | |
616 | This will try to avoid any restriping. | |
617 | ||
618 | The converse of this is | |
619 | .B \-\-layout=normalise | |
620 | which will change a non-standard RAID6 layout into a more standard | |
621 | arrangement. | |
622 | ||
cd29a5c8 | 623 | .TP |
7e23fc43 | 624 | .BR \-\-parity= |
53e8b987 | 625 | same as |
7e23fc43 | 626 | .B \-\-layout |
53e8b987 | 627 | (thus explaining the p of |
7e23fc43 | 628 | .BR \-p ). |
52826846 | 629 | |
e793c2e5 | 630 | .TP |
7e23fc43 | 631 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 632 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 633 | exist unless |
7e23fc43 | 634 | .B \-\-force |
53e8b987 | 635 | is also given. The same file should be provided |
2ae555c3 | 636 | when assembling the array. If the word |
93e790af | 637 | .B "internal" |
2ae555c3 NB |
638 | is given, then the bitmap is stored with the metadata on the array, |
639 | and so is replicated on all devices. If the word | |
93e790af | 640 | .B "none" |
2ae555c3 | 641 | is given with |
7e23fc43 | 642 | .B \-\-grow |
2ae555c3 | 643 | mode, then any bitmap that is present is removed. |
e793c2e5 | 644 | |
2ae555c3 NB |
645 | To help catch typing errors, the filename must contain at least one |
646 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
647 | ||
648 | Note: external bitmaps are only known to work on ext2 and ext3. | |
649 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 650 | |
cd29a5c8 | 651 | .TP |
7e23fc43 | 652 | .BR \-\-bitmap\-chunk= |
e0fe762a | 653 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
654 | Kilobytes of storage. |
655 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 656 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
657 | When using an |
658 | .B internal | |
b8ab2a50 N |
659 | bitmap, the chunksize defaults to 64Meg, or larger if necessary to |
660 | fit the bitmap into the available space. | |
5787fa49 | 661 | |
36fad8ec N |
662 | A suffix of 'M' or 'G' can be given to indicate Megabytes or |
663 | Gigabytes respectively. | |
664 | ||
cd29a5c8 | 665 | .TP |
7e23fc43 | 666 | .BR \-W ", " \-\-write\-mostly |
e0fe762a | 667 | subsequent devices listed in a |
7e23fc43 PS |
668 | .BR \-\-build , |
669 | .BR \-\-create , | |
2ae555c3 | 670 | or |
7e23fc43 | 671 | .B \-\-add |
2ae555c3 NB |
672 | command will be flagged as 'write-mostly'. This is valid for RAID1 |
673 | only and means that the 'md' driver will avoid reading from these | |
674 | devices if at all possible. This can be useful if mirroring over a | |
675 | slow link. | |
52826846 | 676 | |
2ae555c3 | 677 | .TP |
7e23fc43 | 678 | .BR \-\-write\-behind= |
2ae555c3 | 679 | Specify that write-behind mode should be enabled (valid for RAID1 |
e0fe762a N |
680 | only). If an argument is specified, it will set the maximum number |
681 | of outstanding writes allowed. The default value is 256. | |
2ae555c3 NB |
682 | A write-intent bitmap is required in order to use write-behind |
683 | mode, and write-behind is only attempted on drives marked as | |
684 | .IR write-mostly . | |
dd0781e5 NB |
685 | |
686 | .TP | |
7e23fc43 | 687 | .BR \-\-assume\-clean |
dd0781e5 NB |
688 | Tell |
689 | .I mdadm | |
47d79ef8 NB |
690 | that the array pre-existed and is known to be clean. It can be useful |
691 | when trying to recover from a major failure as you can be sure that no | |
692 | data will be affected unless you actually write to the array. It can | |
693 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 694 | initial resync, however this practice \(em while normally safe \(em is not |
e0fe762a | 695 | recommended. Use this only if you really know what you are doing. |
6acad481 ME |
696 | .IP |
697 | When the devices that will be part of a new array were filled | |
698 | with zeros before creation the operator knows the array is | |
699 | actually clean. If that is the case, such as after running | |
700 | badblocks, this argument can be used to tell mdadm the | |
701 | facts the operator knows. | |
dd0781e5 | 702 | |
2ae555c3 | 703 | .TP |
7e23fc43 | 704 | .BR \-\-backup\-file= |
53e8b987 | 705 | This is needed when |
7e23fc43 | 706 | .B \-\-grow |
cd19c0cf JR |
707 | is used to increase the number of raid-devices in a RAID5 or RAID6 if |
708 | there are no spare devices available, or to shrink, change RAID level | |
709 | or layout. See the GROW MODE section below on RAID\-DEVICES CHANGES. | |
710 | The file must be stored on a separate device, not on the RAID array | |
711 | being reshaped. | |
2ae555c3 | 712 | |
947fd4dd | 713 | .TP |
7e23fc43 | 714 | .BR \-N ", " \-\-name= |
947fd4dd NB |
715 | Set a |
716 | .B name | |
717 | for the array. This is currently only effective when creating an | |
e0fe762a N |
718 | array with a version-1 superblock, or an array in a DDF container. |
719 | The name is a simple textual string that can be used to identify array | |
720 | components when assembling. If name is needed but not specified, it | |
721 | is taken from the basename of the device that is being created. | |
722 | e.g. when creating | |
723 | .I /dev/md/home | |
724 | the | |
725 | .B name | |
726 | will default to | |
727 | .IR home . | |
947fd4dd | 728 | |
dd0781e5 | 729 | .TP |
7e23fc43 | 730 | .BR \-R ", " \-\-run |
dd0781e5 NB |
731 | Insist that |
732 | .I mdadm | |
733 | run the array, even if some of the components | |
734 | appear to be active in another array or filesystem. Normally | |
735 | .I mdadm | |
736 | will ask for confirmation before including such components in an | |
737 | array. This option causes that question to be suppressed. | |
738 | ||
739 | .TP | |
7e23fc43 | 740 | .BR \-f ", " \-\-force |
dd0781e5 NB |
741 | Insist that |
742 | .I mdadm | |
743 | accept the geometry and layout specified without question. Normally | |
744 | .I mdadm | |
745 | will not allow creation of an array with only one device, and will try | |
e0fe762a | 746 | to create a RAID5 array with one missing drive (as this makes the |
dd0781e5 | 747 | initial resync work faster). With |
7e23fc43 | 748 | .BR \-\-force , |
dd0781e5 NB |
749 | .I mdadm |
750 | will not try to be so clever. | |
751 | ||
752 | .TP | |
257c1dc2 N |
753 | .BR \-a ", " "\-\-auto{=yes,md,mdp,part,p}{NN}" |
754 | Instruct mdadm how to create the device file if needed, possibly allocating | |
48f7b27a | 755 | an unused minor number. "md" causes a non-partitionable array |
257c1dc2 N |
756 | to be used (though since Linux 2.6.28, these array devices are in fact |
757 | partitionable). "mdp", "part" or "p" causes a partitionable array (2.6 and | |
2ae555c3 | 758 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 759 | a 'standard' format, and the type and minor number will be determined |
257c1dc2 N |
760 | from this. With mdadm 3.0, device creation is normally left up to |
761 | .I udev | |
762 | so this option is unlikely to be needed. | |
763 | See DEVICE NAMES below. | |
48f7b27a | 764 | |
a9d69660 | 765 | The argument can also come immediately after |
7e23fc43 | 766 | "\-a". e.g. "\-ap". |
dd0781e5 | 767 | |
53e8b987 | 768 | If |
7e23fc43 | 769 | .B \-\-auto |
53e8b987 | 770 | is not given on the command line or in the config file, then |
75723446 | 771 | the default will be |
7e23fc43 | 772 | .BR \-\-auto=yes . |
75723446 | 773 | |
1337546d | 774 | If |
7e23fc43 | 775 | .B \-\-scan |
1337546d NB |
776 | is also given, then any |
777 | .I auto= | |
35cc5be4 | 778 | entries in the config file will override the |
7e23fc43 | 779 | .B \-\-auto |
1337546d NB |
780 | instruction given on the command line. |
781 | ||
dd0781e5 NB |
782 | For partitionable arrays, |
783 | .I mdadm | |
784 | will create the device file for the whole array and for the first 4 | |
785 | partitions. A different number of partitions can be specified at the | |
786 | end of this option (e.g. | |
7e23fc43 | 787 | .BR \-\-auto=p7 ). |
2ae555c3 | 788 | If the device name ends with a digit, the partition names add a 'p', |
e0fe762a N |
789 | and a number, e.g. |
790 | .IR /dev/md/home1p3 . | |
791 | If there is no trailing digit, then the partition names just have a | |
792 | number added, e.g. | |
793 | .IR /dev/md/scratch3 . | |
dd0781e5 | 794 | |
48f7b27a NB |
795 | If the md device name is in a 'standard' format as described in DEVICE |
796 | NAMES, then it will be created, if necessary, with the appropriate | |
e0fe762a N |
797 | device number based on that name. If the device name is not in one of these |
798 | formats, then a unused device number will be allocated. The device | |
48f7b27a NB |
799 | number will be considered unused if there is no active array for that |
800 | number, and there is no entry in /dev for that number and with a | |
e0fe762a | 801 | non-standard name. Names that are not in 'standard' format are only |
8fd8d9c4 N |
802 | allowed in "/dev/md/". |
803 | ||
f24e2d6c | 804 | .ig XX |
e0fe762a N |
805 | .\".TP |
806 | .\".BR \-\-symlink = no | |
807 | .\"Normally when | |
808 | .\".B \-\-auto | |
809 | .\"causes | |
810 | .\".I mdadm | |
811 | .\"to create devices in | |
812 | .\".B /dev/md/ | |
813 | .\"it will also create symlinks from | |
814 | .\".B /dev/ | |
815 | .\"with names starting with | |
816 | .\".B md | |
817 | .\"or | |
818 | .\".BR md_ . | |
819 | .\"Use | |
820 | .\".B \-\-symlink=no | |
821 | .\"to suppress this, or | |
822 | .\".B \-\-symlink=yes | |
823 | .\"to enforce this even if it is suppressing | |
824 | .\".IR mdadm.conf . | |
825 | .\" | |
f24e2d6c | 826 | .XX |
38098016 | 827 | |
52826846 NB |
828 | .SH For assemble: |
829 | ||
cd29a5c8 | 830 | .TP |
7e23fc43 | 831 | .BR \-u ", " \-\-uuid= |
e0fe762a | 832 | uuid of array to assemble. Devices which don't have this uuid are |
cd29a5c8 NB |
833 | excluded |
834 | ||
835 | .TP | |
7e23fc43 | 836 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
837 | Minor number of device that array was created for. Devices which |
838 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 839 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
840 | the array is later assembled as /dev/md2. |
841 | ||
d013a55e | 842 | Giving the literal word "dev" for |
7e23fc43 | 843 | .B \-\-super\-minor |
d013a55e NB |
844 | will cause |
845 | .I mdadm | |
846 | to use the minor number of the md device that is being assembled. | |
847 | e.g. when assembling | |
848 | .BR /dev/md0 , | |
51ac42e3 | 849 | .B \-\-super\-minor=dev |
d013a55e NB |
850 | will look for super blocks with a minor number of 0. |
851 | ||
e0fe762a N |
852 | .B \-\-super\-minor |
853 | is only relevant for v0.90 metadata, and should not normally be used. | |
854 | Using | |
855 | .B \-\-uuid | |
856 | is much safer. | |
857 | ||
947fd4dd | 858 | .TP |
7e23fc43 | 859 | .BR \-N ", " \-\-name= |
947fd4dd | 860 | Specify the name of the array to assemble. This must be the name |
624920bb | 861 | that was specified when creating the array. It must either match |
93e790af | 862 | the name stored in the superblock exactly, or it must match |
41a3b72a | 863 | with the current |
624920bb | 864 | .I homehost |
93e790af | 865 | prefixed to the start of the given name. |
947fd4dd | 866 | |
cd29a5c8 | 867 | .TP |
7e23fc43 | 868 | .BR \-f ", " \-\-force |
e0fe762a N |
869 | Assemble the array even if the metadata on some devices appears to be |
870 | out-of-date. If | |
871 | .I mdadm | |
872 | cannot find enough working devices to start the array, but can find | |
873 | some devices that are recorded as having failed, then it will mark | |
874 | those devices as working so that the array can be started. | |
875 | An array which requires | |
876 | .B \-\-force | |
877 | to be started may contain data corruption. Use it carefully. | |
52826846 | 878 | |
cd29a5c8 | 879 | .TP |
7e23fc43 | 880 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
881 | Attempt to start the array even if fewer drives were given than were |
882 | present last time the array was active. Normally if not all the | |
883 | expected drives are found and | |
7e23fc43 | 884 | .B \-\-scan |
cd29a5c8 NB |
885 | is not used, then the array will be assembled but not started. |
886 | With | |
7e23fc43 | 887 | .B \-\-run |
cd29a5c8 | 888 | an attempt will be made to start it anyway. |
52826846 | 889 | |
b8a8ccf9 | 890 | .TP |
7e23fc43 | 891 | .B \-\-no\-degraded |
b8a8ccf9 | 892 | This is the reverse of |
7e23fc43 | 893 | .B \-\-run |
93e790af | 894 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 895 | are present. This is only needed with |
93e790af SW |
896 | .B \-\-scan, |
897 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
898 | not as reliable as you would like. |
899 | ||
dd0781e5 | 900 | .TP |
7e23fc43 | 901 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
902 | See this option under Create and Build options. |
903 | ||
c64881d7 N |
904 | .TP |
905 | .BR \-a ", " "\-\-add" | |
906 | This option can be used in Grow mode in two cases. | |
907 | ||
908 | If the target array is a Linear array, then | |
909 | .B \-\-add | |
910 | can be used to add one or more devices to the array. They | |
911 | are simply catenated on to the end of the array. Once added, the | |
912 | devices cannot be removed. | |
913 | ||
914 | If the | |
915 | .B \-\-raid\-disks | |
916 | option is being used to increase the number of devices in an array, | |
917 | then | |
918 | .B \-\-add | |
919 | can be used to add some extra devices to be included in the array. | |
920 | In most cases this is not needed as the extra devices can be added as | |
921 | spares first, and then the number of raid-disks can be changed. | |
922 | However for RAID0, it is not possible to add spares. So to increase | |
923 | the number of devices in a RAID0, it is necessary to set the new | |
924 | number of devices, and to add the new devices, in the same command. | |
925 | ||
e793c2e5 | 926 | .TP |
7e23fc43 | 927 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
928 | Specify the bitmap file that was given when the array was created. If |
929 | an array has an | |
930 | .B internal | |
931 | bitmap, there is no need to specify this when assembling the array. | |
932 | ||
933 | .TP | |
7e23fc43 | 934 | .BR \-\-backup\-file= |
2ae555c3 | 935 | If |
7e23fc43 | 936 | .B \-\-backup\-file |
87f26d14 N |
937 | was used while reshaping an array (e.g. changing number of devices or |
938 | chunk size) and the system crashed during the critical section, then the same | |
7e23fc43 | 939 | .B \-\-backup\-file |
53e8b987 | 940 | must be presented to |
7e23fc43 | 941 | .B \-\-assemble |
cd19c0cf JR |
942 | to allow possibly corrupted data to be restored, and the reshape |
943 | to be completed. | |
e793c2e5 | 944 | |
87f26d14 N |
945 | .TP |
946 | .BR \-\-invalid\-backup | |
947 | If the file needed for the above option is not available for any | |
948 | reason an empty file can be given together with this option to | |
949 | indicate that the backup file is invalid. In this case the data that | |
950 | was being rearranged at the time of the crash could be irrecoverably | |
951 | lost, but the rest of the array may still be recoverable. This option | |
952 | should only be used as a last resort if there is no way to recover the | |
953 | backup file. | |
954 | ||
955 | ||
5787fa49 | 956 | .TP |
7e23fc43 | 957 | .BR \-U ", " \-\-update= |
5787fa49 | 958 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
959 | argument given to this flag can be one of |
960 | .BR sparc2.2 , | |
961 | .BR summaries , | |
7d99579f | 962 | .BR uuid , |
c4f12c13 | 963 | .BR name , |
0237e0ca | 964 | .BR homehost , |
e5329c37 | 965 | .BR resync , |
586ed405 | 966 | .BR byteorder , |
bee8ec56 | 967 | .BR devicesize , |
5a31170d | 968 | .BR no\-bitmap , |
5787fa49 | 969 | or |
7e23fc43 | 970 | .BR super\-minor . |
5787fa49 NB |
971 | |
972 | The | |
973 | .B sparc2.2 | |
7d99579f | 974 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
975 | machine running a patched 2.2 Linux kernel. This kernel got the |
976 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 977 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
978 | option to |
979 | .I mdadm | |
980 | to see what effect this would have. | |
981 | ||
982 | The | |
7e23fc43 | 983 | .B super\-minor |
5787fa49 | 984 | option will update the |
2ae555c3 | 985 | .B "preferred minor" |
5787fa49 | 986 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
987 | assembled. |
988 | This can be useful if | |
7e23fc43 | 989 | .B \-\-examine |
45c073c9 | 990 | reports a different "Preferred Minor" to |
7e23fc43 | 991 | .BR \-\-detail . |
45c073c9 | 992 | In some cases this update will be performed automatically |
e0fe762a | 993 | by the kernel driver. In particular the update happens automatically |
45c073c9 NB |
994 | at the first write to an array with redundancy (RAID level 1 or |
995 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 996 | |
7d99579f NB |
997 | The |
998 | .B uuid | |
999 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 1000 | .B \-\-uuid |
53e8b987 | 1001 | option that UUID will be used as a new UUID and will |
7d99579f NB |
1002 | .B NOT |
1003 | be used to help identify the devices in the array. | |
53e8b987 | 1004 | If no |
7e23fc43 | 1005 | .B \-\-uuid |
53e8b987 | 1006 | is given, a random UUID is chosen. |
7d99579f | 1007 | |
c4f12c13 NB |
1008 | The |
1009 | .B name | |
1010 | option will change the | |
1011 | .I name | |
1012 | of the array as stored in the superblock. This is only supported for | |
1013 | version-1 superblocks. | |
1014 | ||
0237e0ca NB |
1015 | The |
1016 | .B homehost | |
1017 | option will change the | |
1018 | .I homehost | |
1019 | as recorded in the superblock. For version-0 superblocks, this is the | |
1020 | same as updating the UUID. | |
1021 | For version-1 superblocks, this involves updating the name. | |
1022 | ||
e5329c37 NB |
1023 | The |
1024 | .B resync | |
1025 | option will cause the array to be marked | |
1026 | .I dirty | |
e0fe762a N |
1027 | meaning that any redundancy in the array (e.g. parity for RAID5, |
1028 | copies for RAID1) may be incorrect. This will cause the RAID system | |
e5329c37 NB |
1029 | to perform a "resync" pass to make sure that all redundant information |
1030 | is correct. | |
1031 | ||
586ed405 NB |
1032 | The |
1033 | .B byteorder | |
1034 | option allows arrays to be moved between machines with different | |
1035 | byte-order. | |
2ae555c3 | 1036 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 1037 | .B "\-\-update=byteorder" |
586ed405 NB |
1038 | will cause |
1039 | .I mdadm | |
1040 | to expect superblocks to have their byteorder reversed, and will | |
1041 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 1042 | with original (Version 0.90) superblocks. |
586ed405 | 1043 | |
feb716e9 NB |
1044 | The |
1045 | .B summaries | |
e0fe762a | 1046 | option will correct the summaries in the superblock. That is the |
feb716e9 | 1047 | counts of total, working, active, failed, and spare devices. |
5787fa49 | 1048 | |
bee8ec56 NB |
1049 | The |
1050 | .B devicesize | |
5a31170d | 1051 | option will rarely be of use. It applies to version 1.1 and 1.2 metadata |
bee8ec56 NB |
1052 | only (where the metadata is at the start of the device) and is only |
1053 | useful when the component device has changed size (typically become | |
1054 | larger). The version 1 metadata records the amount of the device that | |
1055 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
1056 | array becomes larger, the metadata will still be visible, but the | |
1057 | extra space will not. In this case it might be useful to assemble the | |
1058 | array with | |
7e23fc43 | 1059 | .BR \-\-update=devicesize . |
bee8ec56 NB |
1060 | This will cause |
1061 | .I mdadm | |
1062 | to determine the maximum usable amount of space on each device and | |
1063 | update the relevant field in the metadata. | |
1064 | ||
5a31170d N |
1065 | The |
1066 | .B no\-bitmap | |
1067 | option can be used when an array has an internal bitmap which is | |
1068 | corrupt in some way so that assembling the array normally fails. It | |
1069 | will cause any internal bitmap to be ignored. | |
1070 | ||
e0d19036 | 1071 | .SH For Manage mode: |
52826846 | 1072 | |
3d5279b0 N |
1073 | .TP |
1074 | .BR \-t ", " \-\-test | |
1075 | Unless a more serious error occurred, | |
1076 | .I mdadm | |
1077 | will exit with a status of 2 if no changes were made to the array and | |
1078 | 0 if at least one change was made. | |
1079 | This can be useful when an indirect specifier such as | |
1080 | .BR missing , | |
1081 | .B detached | |
1082 | or | |
1083 | .B faulty | |
1084 | is used in requesting an operation on the array. | |
1085 | .B \-\-test | |
1086 | will report failure if these specifiers didn't find any match. | |
1087 | ||
cd29a5c8 | 1088 | .TP |
7e23fc43 | 1089 | .BR \-a ", " \-\-add |
3d5279b0 N |
1090 | hot-add listed devices. |
1091 | If a device appears to have recently been part of the array | |
833bb0f8 | 1092 | (possibly it failed or was removed) the device is re\-added as describe |
3d5279b0 N |
1093 | in the next point. |
1094 | If that fails or the device was never part of the array, the device is | |
1095 | added as a hot-spare. | |
1096 | If the array is degraded, it will immediately start to rebuild data | |
1097 | onto that spare. | |
1098 | ||
1099 | Note that this and the following options are only meaningful on array | |
1100 | with redundancy. They don't apply to RAID0 or Linear. | |
52826846 | 1101 | |
fe80f49b | 1102 | .TP |
7e23fc43 | 1103 | .BR \-\-re\-add |
3d5279b0 N |
1104 | re\-add a device that was previous removed from an array. |
1105 | If the metadata on the device reports that it is a member of the | |
1106 | array, and the slot that it used is still vacant, then the device will | |
1107 | be added back to the array in the same position. This will normally | |
1108 | cause the data for that device to be recovered. However based on the | |
1109 | event count on the device, the recovery may only require sections that | |
1110 | are flagged a write-intent bitmap to be recovered or may not require | |
1111 | any recovery at all. | |
1112 | ||
1113 | When used on an array that has no metadata (i.e. it was built with | |
1114 | .BR \-\-build) | |
1115 | it will be assumed that bitmap-based recovery is enough to make the | |
1116 | device fully consistent with the array. | |
fe80f49b | 1117 | |
833bb0f8 N |
1118 | When |
1119 | .B \-\-re\-add | |
1120 | can be accompanied by | |
1121 | .BR \-\-update=devicesize . | |
1122 | See the description of this option when used in Assemble mode for an | |
1123 | explanation of its use. | |
1124 | ||
a4e13010 N |
1125 | If the device name given is |
1126 | .B missing | |
1127 | then mdadm will try to find any device that looks like it should be | |
1128 | part of the array but isn't and will try to re\-add all such devices. | |
1129 | ||
cd29a5c8 | 1130 | .TP |
7e23fc43 | 1131 | .BR \-r ", " \-\-remove |
2d465520 | 1132 | remove listed devices. They must not be active. i.e. they should |
b80da661 NB |
1133 | be failed or spare devices. As well as the name of a device file |
1134 | (e.g. | |
1135 | .BR /dev/sda1 ) | |
1136 | the words | |
1137 | .B failed | |
1138 | and | |
1139 | .B detached | |
1140 | can be given to | |
1141 | .BR \-\-remove . | |
1142 | The first causes all failed device to be removed. The second causes | |
93e790af | 1143 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
1144 | returns |
1145 | .BR ENXIO ) | |
1146 | to be removed. This will only succeed for devices that are spares or | |
1147 | have already been marked as failed. | |
52826846 | 1148 | |
cd29a5c8 | 1149 | .TP |
7e23fc43 | 1150 | .BR \-f ", " \-\-fail |
cd29a5c8 | 1151 | mark listed devices as faulty. |
b80da661 NB |
1152 | As well as the name of a device file, the word |
1153 | .B detached | |
1154 | can be given. This will cause any device that has been detached from | |
1155 | the system to be marked as failed. It can then be removed. | |
52826846 | 1156 | |
cd29a5c8 | 1157 | .TP |
7e23fc43 | 1158 | .BR \-\-set\-faulty |
53e8b987 | 1159 | same as |
7e23fc43 | 1160 | .BR \-\-fail . |
52826846 | 1161 | |
b3d31955 N |
1162 | .TP |
1163 | .BR \-\-write\-mostly | |
a4e13010 | 1164 | Subsequent devices that are added or re\-added will have the 'write-mostly' |
e0fe762a | 1165 | flag set. This is only valid for RAID1 and means that the 'md' driver |
b3d31955 N |
1166 | will avoid reading from these devices if possible. |
1167 | .TP | |
1168 | .BR \-\-readwrite | |
a4e13010 | 1169 | Subsequent devices that are added or re\-added will have the 'write-mostly' |
b3d31955 N |
1170 | flag cleared. |
1171 | ||
2ae555c3 | 1172 | .P |
e0fe762a | 1173 | Each of these options requires that the first device listed is the array |
93e790af | 1174 | to be acted upon, and the remainder are component devices to be added, |
e0fe762a | 1175 | removed, marked as faulty, etc. Several different operations can be |
2ae555c3 NB |
1176 | specified for different devices, e.g. |
1177 | .in +5 | |
7e23fc43 | 1178 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
1179 | .in -5 |
1180 | Each operation applies to all devices listed until the next | |
93e790af | 1181 | operation. |
2ae555c3 NB |
1182 | |
1183 | If an array is using a write-intent bitmap, then devices which have | |
a4e13010 | 1184 | been removed can be re\-added in a way that avoids a full |
93e790af | 1185 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
1186 | since the device was removed. For arrays with persistent metadata |
1187 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 1188 | .B \-\-build |
2ae555c3 | 1189 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 1190 | .BR \-\-re\-add . |
2ae555c3 NB |
1191 | |
1192 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
1193 | use, i.e. that must be spares or failed devices. To remove an active |
1194 | device, it must first be marked as | |
1195 | .B faulty. | |
2ae555c3 NB |
1196 | |
1197 | .SH For Misc mode: | |
1198 | ||
1199 | .TP | |
7e23fc43 | 1200 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
1201 | Examine a device to see |
1202 | (1) if it is an md device and (2) if it is a component of an md | |
1203 | array. | |
1204 | Information about what is discovered is presented. | |
1205 | ||
1206 | .TP | |
7e23fc43 | 1207 | .BR \-D ", " \-\-detail |
e0fe762a | 1208 | Print details of one or more md devices. |
5787fa49 | 1209 | |
4cce4069 DW |
1210 | .TP |
1211 | .BR \-\-detail\-platform | |
e0fe762a | 1212 | Print details of the platform's RAID capabilities (firmware / hardware |
4cce4069 DW |
1213 | topology) for a given metadata format. |
1214 | ||
54bad364 KS |
1215 | .TP |
1216 | .BR \-Y ", " \-\-export | |
1217 | When used with | |
0d726f17 KS |
1218 | .B \-\-detail |
1219 | or | |
1220 | .BR \-\-examine , | |
54bad364 KS |
1221 | output will be formatted as |
1222 | .B key=value | |
1223 | pairs for easy import into the environment. | |
1224 | ||
2ae555c3 | 1225 | .TP |
7e23fc43 | 1226 | .BR \-E ", " \-\-examine |
e0fe762a N |
1227 | Print contents of the metadata stored on the named device(s). |
1228 | Note the contrast between | |
1229 | .B \-\-examine | |
1230 | and | |
1231 | .BR \-\-detail . | |
1232 | .B \-\-examine | |
1233 | applies to devices which are components of an array, while | |
1234 | .B \-\-detail | |
1235 | applies to a whole array which is currently active. | |
5787fa49 | 1236 | .TP |
7e23fc43 | 1237 | .B \-\-sparc2.2 |
e0fe762a N |
1238 | If an array was created on a SPARC machine with a 2.2 Linux kernel |
1239 | patched with RAID support, the superblock will have been created | |
1240 | incorrectly, or at least incompatibly with 2.4 and later kernels. | |
1241 | Using the | |
7e23fc43 | 1242 | .B \-\-sparc2.2 |
5787fa49 | 1243 | flag with |
7e23fc43 | 1244 | .B \-\-examine |
5787fa49 NB |
1245 | will fix the superblock before displaying it. If this appears to do |
1246 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 1247 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 1248 | |
2ae555c3 | 1249 | .TP |
7e23fc43 | 1250 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 1251 | Report information about a bitmap file. |
01d9299c | 1252 | The argument is either an external bitmap file or an array component |
e0fe762a N |
1253 | in case of an internal bitmap. Note that running this on an array |
1254 | device (e.g. | |
1255 | .BR /dev/md0 ) | |
1256 | does not report the bitmap for that array. | |
e0d19036 | 1257 | |
cd29a5c8 | 1258 | .TP |
7e23fc43 | 1259 | .BR \-R ", " \-\-run |
e0fe762a N |
1260 | start a partially assembled array. If |
1261 | .B \-\-assemble | |
1262 | did not find enough devices to fully start the array, it might leaving | |
1263 | it partially assembled. If you wish, you can then use | |
1264 | .B \-\-run | |
1265 | to start the array in degraded mode. | |
52826846 | 1266 | |
cd29a5c8 | 1267 | .TP |
7e23fc43 | 1268 | .BR \-S ", " \-\-stop |
cd29a5c8 | 1269 | deactivate array, releasing all resources. |
52826846 | 1270 | |
cd29a5c8 | 1271 | .TP |
7e23fc43 | 1272 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 1273 | mark array as readonly. |
52826846 | 1274 | |
cd29a5c8 | 1275 | .TP |
7e23fc43 | 1276 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 1277 | mark array as readwrite. |
52826846 | 1278 | |
e0d19036 | 1279 | .TP |
7e23fc43 | 1280 | .B \-\-zero\-superblock |
e0d19036 | 1281 | If the device contains a valid md superblock, the block is |
35cc5be4 | 1282 | overwritten with zeros. With |
7e23fc43 | 1283 | .B \-\-force |
35cc5be4 | 1284 | the block where the superblock would be is overwritten even if it |
e0d19036 | 1285 | doesn't appear to be valid. |
52826846 | 1286 | |
33414a01 DW |
1287 | .TP |
1288 | .B \-\-kill\-subarray= | |
1289 | If the device is a container and the argument to \-\-kill\-subarray | |
1290 | specifies an inactive subarray in the container, then the subarray is | |
1291 | deleted. Deleting all subarrays will leave an 'empty-container' or | |
1292 | spare superblock on the drives. See \-\-zero\-superblock for completely | |
1293 | removing a superblock. Note that some formats depend on the subarray | |
1294 | index for generating a UUID, this command will fail if it would change | |
1295 | the UUID of an active subarray. | |
1296 | ||
aa534678 DW |
1297 | .TP |
1298 | .B \-\-update\-subarray= | |
1299 | If the device is a container and the argument to \-\-update\-subarray | |
1300 | specifies a subarray in the container, then attempt to update the given | |
1301 | superblock field in the subarray. See below in | |
1302 | .B MISC MODE | |
1303 | for details. | |
1304 | ||
feb716e9 | 1305 | .TP |
7e23fc43 | 1306 | .BR \-t ", " \-\-test |
feb716e9 | 1307 | When used with |
7e23fc43 | 1308 | .BR \-\-detail , |
feb716e9 NB |
1309 | the exit status of |
1310 | .I mdadm | |
e0fe762a N |
1311 | is set to reflect the status of the device. See below in |
1312 | .B MISC MODE | |
1313 | for details. | |
feb716e9 | 1314 | |
b90c0e9a | 1315 | .TP |
7e23fc43 | 1316 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1317 | For each md device given, wait for any resync, recovery, or reshape |
1318 | activity to finish before returning. | |
1319 | .I mdadm | |
1320 | will return with success if it actually waited for every device | |
1321 | listed, otherwise it will return failure. | |
1322 | ||
1770662b DW |
1323 | .TP |
1324 | .BR \-\-wait\-clean | |
fabbfd48 DW |
1325 | For each md device given, or each device in /proc/mdstat if |
1326 | .B \-\-scan | |
1327 | is given, arrange for the array to be marked clean as soon as possible. | |
7146ec6a DW |
1328 | .I mdadm |
1329 | will return with success if the array uses external metadata and we | |
1330 | successfully waited. For native arrays this returns immediately as the | |
6a0ee6a0 DW |
1331 | kernel handles dirty-clean transitions at shutdown. No action is taken |
1332 | if safe-mode handling is disabled. | |
1770662b | 1333 | |
8382f19b NB |
1334 | .SH For Incremental Assembly mode: |
1335 | .TP | |
7e23fc43 | 1336 | .BR \-\-rebuild\-map ", " \-r |
8382f19b NB |
1337 | Rebuild the map file |
1338 | .RB ( /var/run/mdadm/map ) | |
1339 | that | |
1340 | .I mdadm | |
1341 | uses to help track which arrays are currently being assembled. | |
1342 | ||
1343 | .TP | |
7e23fc43 | 1344 | .BR \-\-run ", " \-R |
8382f19b NB |
1345 | Run any array assembled as soon as a minimal number of devices are |
1346 | available, rather than waiting until all expected devices are present. | |
1347 | ||
1348 | .TP | |
7e23fc43 | 1349 | .BR \-\-scan ", " \-s |
8382f19b | 1350 | Only meaningful with |
7e23fc43 | 1351 | .B \-R |
8382f19b NB |
1352 | this will scan the |
1353 | .B map | |
1354 | file for arrays that are being incrementally assembled and will try to | |
1355 | start any that are not already started. If any such array is listed | |
1356 | in | |
1357 | .B mdadm.conf | |
1358 | as requiring an external bitmap, that bitmap will be attached first. | |
1359 | ||
29ba4804 N |
1360 | .TP |
1361 | .BR \-\-fail ", " \-f | |
1362 | This allows the hot-plug system to remove devices that have fully disappeared | |
1363 | from the kernel. It will first fail and then remove the device from any | |
1364 | array it belongs to. | |
1365 | The device name given should be a kernel device name such as "sda", | |
1366 | not a name in | |
1367 | .IR /dev . | |
1368 | ||
210597d1 PC |
1369 | .TP |
1370 | .BR \-\-path= | |
87eb4fab N |
1371 | Only used with \-\-fail. The 'path' given will be recorded so that if |
1372 | a new device appears at the same location it can be automatically | |
1373 | added to the same array. This allows the failed device to be | |
1374 | automatically replaced by a new device without metadata if it appears | |
1375 | at specified path. This option is normally only set by a | |
1376 | .I udev | |
1377 | script. | |
210597d1 | 1378 | |
e0d19036 NB |
1379 | .SH For Monitor mode: |
1380 | .TP | |
7e23fc43 | 1381 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1382 | Give a mail address to send alerts to. |
1383 | ||
1384 | .TP | |
7e23fc43 | 1385 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1386 | Give a program to be run whenever an event is detected. |
1387 | ||
773135f5 | 1388 | .TP |
7e23fc43 | 1389 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1390 | Cause all events to be reported through 'syslog'. The messages have |
1391 | facility of 'daemon' and varying priorities. | |
1392 | ||
e0d19036 | 1393 | .TP |
7e23fc43 | 1394 | .BR \-d ", " \-\-delay |
e0d19036 | 1395 | Give a delay in seconds. |
51ac42e3 | 1396 | .I mdadm |
e0d19036 | 1397 | polls the md arrays and then waits this many seconds before polling |
e0fe762a N |
1398 | again. The default is 60 seconds. Since 2.6.16, there is no need to |
1399 | reduce this as the kernel alerts | |
1400 | .I mdadm | |
1401 | immediately when there is any change. | |
e0d19036 | 1402 | |
9a36a9b7 ZB |
1403 | .TP |
1404 | .BR \-r ", " \-\-increment | |
1405 | Give a percentage increment. | |
1406 | .I mdadm | |
1407 | will generate RebuildNN events with the given percentage increment. | |
1408 | ||
d013a55e | 1409 | .TP |
7e23fc43 | 1410 | .BR \-f ", " \-\-daemonise |
d013a55e | 1411 | Tell |
51ac42e3 | 1412 | .I mdadm |
d013a55e | 1413 | to run as a background daemon if it decides to monitor anything. This |
e0fe762a | 1414 | causes it to fork and run in the child, and to disconnect from the |
d013a55e NB |
1415 | terminal. The process id of the child is written to stdout. |
1416 | This is useful with | |
7e23fc43 | 1417 | .B \-\-scan |
d013a55e NB |
1418 | which will only continue monitoring if a mail address or alert program |
1419 | is found in the config file. | |
1420 | ||
b5e64645 | 1421 | .TP |
7e23fc43 | 1422 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1423 | When |
51ac42e3 | 1424 | .I mdadm |
b5e64645 NB |
1425 | is running in daemon mode, write the pid of the daemon process to |
1426 | the specified file, instead of printing it on standard output. | |
1427 | ||
aa88f531 | 1428 | .TP |
7e23fc43 | 1429 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1430 | Check arrays only once. This will generate |
1431 | .B NewArray | |
1432 | events and more significantly | |
1433 | .B DegradedArray | |
a9d69660 NB |
1434 | and |
1435 | .B SparesMissing | |
aa88f531 NB |
1436 | events. Running |
1437 | .in +5 | |
7e23fc43 | 1438 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1439 | .in -5 |
1440 | from a cron script will ensure regular notification of any degraded arrays. | |
1441 | ||
98c6faba | 1442 | .TP |
7e23fc43 | 1443 | .BR \-t ", " \-\-test |
98c6faba NB |
1444 | Generate a |
1445 | .B TestMessage | |
1446 | alert for every array found at startup. This alert gets mailed and | |
1447 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1448 | message do get through successfully. |
98c6faba | 1449 | |
210597d1 PC |
1450 | .TP |
1451 | .BR \-\-no\-sharing | |
87eb4fab | 1452 | This inhibits the functionality for moving spares between arrays. |
210597d1 PC |
1453 | Only one monitoring process started with |
1454 | .B \-\-scan | |
87eb4fab N |
1455 | but without this flag is allowed, otherwise the two could interfere |
1456 | with each other. | |
210597d1 | 1457 | |
e0d19036 | 1458 | .SH ASSEMBLE MODE |
52826846 | 1459 | |
cd29a5c8 NB |
1460 | .HP 12 |
1461 | Usage: | |
7e23fc43 | 1462 | .B mdadm \-\-assemble |
5787fa49 NB |
1463 | .I md-device options-and-component-devices... |
1464 | .HP 12 | |
1465 | Usage: | |
7e23fc43 | 1466 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1467 | .I md-devices-and-options... |
cd29a5c8 NB |
1468 | .HP 12 |
1469 | Usage: | |
7e23fc43 | 1470 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1471 | .I options... |
52826846 | 1472 | |
cd29a5c8 | 1473 | .PP |
e0fe762a | 1474 | This usage assembles one or more RAID arrays from pre-existing components. |
9a9dab36 | 1475 | For each array, mdadm needs to know the md device, the identity of the |
e0fe762a | 1476 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1477 | |
5787fa49 | 1478 | In the first usage example (without the |
7e23fc43 | 1479 | .BR \-\-scan ) |
5787fa49 NB |
1480 | the first device given is the md device. |
1481 | In the second usage example, all devices listed are treated as md | |
1482 | devices and assembly is attempted. | |
1483 | In the third (where no devices are listed) all md devices that are | |
e0fe762a N |
1484 | listed in the configuration file are assembled. If not arrays are |
1485 | described by the configuration file, then any arrays that | |
1486 | can be found on unused devices will be assembled. | |
52826846 | 1487 | |
d013a55e | 1488 | If precisely one device is listed, but |
7e23fc43 | 1489 | .B \-\-scan |
dd0781e5 | 1490 | is not given, then |
d013a55e NB |
1491 | .I mdadm |
1492 | acts as though | |
7e23fc43 | 1493 | .B \-\-scan |
93e790af | 1494 | was given and identity information is extracted from the configuration file. |
d013a55e | 1495 | |
2ae555c3 | 1496 | The identity can be given with the |
7e23fc43 | 1497 | .B \-\-uuid |
e0fe762a N |
1498 | option, the |
1499 | .B \-\-name | |
1500 | option, or the | |
7e23fc43 | 1501 | .B \-\-super\-minor |
93e790af SW |
1502 | option, will be taken from the md-device record in the config file, or |
1503 | will be taken from the super block of the first component-device | |
1504 | listed on the command line. | |
52826846 | 1505 | |
2ae555c3 | 1506 | Devices can be given on the |
7e23fc43 | 1507 | .B \-\-assemble |
e0fe762a | 1508 | command line or in the config file. Only devices which have an md |
5787fa49 NB |
1509 | superblock which contains the right identity will be considered for |
1510 | any array. | |
52826846 | 1511 | |
2ae555c3 | 1512 | The config file is only used if explicitly named with |
7e23fc43 | 1513 | .B \-\-config |
d013a55e | 1514 | or requested with (a possibly implicit) |
7e23fc43 | 1515 | .BR \-\-scan . |
52826846 | 1516 | In the later case, |
9a9dab36 | 1517 | .B /etc/mdadm.conf |
8fd8d9c4 N |
1518 | or |
1519 | .B /etc/mdadm/mdadm.conf | |
52826846 NB |
1520 | is used. |
1521 | ||
2ae555c3 | 1522 | If |
7e23fc43 | 1523 | .B \-\-scan |
cd29a5c8 NB |
1524 | is not given, then the config file will only be used to find the |
1525 | identity of md arrays. | |
52826846 | 1526 | |
2d465520 | 1527 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 1528 | .B \-\-scan |
e0fe762a N |
1529 | is not given and not all expected drives were listed, then the array |
1530 | is not started (to guard against usage errors). To insist that the | |
1531 | array be started in this case (as may work for RAID1, 4, 5, 6, or 10), | |
1532 | give the | |
7e23fc43 | 1533 | .B \-\-run |
cd29a5c8 | 1534 | flag. |
52826846 | 1535 | |
e0fe762a N |
1536 | If |
1537 | .I udev | |
1538 | is active, | |
1539 | .I mdadm | |
1540 | does not create any entries in | |
dd0781e5 | 1541 | .B /dev |
e0fe762a N |
1542 | but leaves that to |
1543 | .IR udev . | |
1544 | It does record information in | |
1545 | .B /var/run/mdadm/map | |
1546 | which will allow | |
1547 | .I udev | |
1548 | to choose the correct name. | |
dd0781e5 | 1549 | |
e0fe762a N |
1550 | If |
1551 | .I mdadm | |
1552 | detects that udev is not configured, it will create the devices in | |
1553 | .B /dev | |
1554 | itself. | |
dd0781e5 | 1555 | |
e0fe762a N |
1556 | In Linux kernels prior to version 2.6.28 there were two distinctly |
1557 | different types of md devices that could be created: one that could be | |
1558 | partitioned using standard partitioning tools and one that could not. | |
1559 | Since 2.6.28 that distinction is no longer relevant as both type of | |
1560 | devices can be partitioned. | |
1561 | .I mdadm | |
1562 | will normally create the type that originally could not be partitioned | |
1563 | as it has a well defined major number (9). | |
dd0781e5 | 1564 | |
e0fe762a N |
1565 | Prior to 2.6.28, it is important that mdadm chooses the correct type |
1566 | of array device to use. This can be controlled with the | |
1567 | .B \-\-auto | |
1568 | option. In particular, a value of "mdp" or "part" or "p" tells mdadm | |
1569 | to use a partitionable device rather than the default. | |
dd0781e5 | 1570 | |
e0fe762a N |
1571 | In the no-udev case, the value given to |
1572 | .B \-\-auto | |
1573 | can be suffixed by a number. This tells | |
1574 | .I mdadm | |
1575 | to create that number of partition devices rather than the default of 4. | |
dd0781e5 | 1576 | |
e0fe762a | 1577 | The value given to |
7e23fc43 | 1578 | .B \-\-auto |
e0fe762a N |
1579 | can also be given in the configuration file as a word starting |
1580 | .B auto= | |
1581 | on the ARRAY line for the relevant array. | |
52826846 | 1582 | |
41a3b72a NB |
1583 | .SS Auto Assembly |
1584 | When | |
7e23fc43 | 1585 | .B \-\-assemble |
41a3b72a | 1586 | is used with |
7e23fc43 | 1587 | .B \-\-scan |
41a3b72a NB |
1588 | and no devices are listed, |
1589 | .I mdadm | |
1590 | will first attempt to assemble all the arrays listed in the config | |
1591 | file. | |
1592 | ||
e0fe762a N |
1593 | In no array at listed in the config (other than those marked |
1594 | .BR <ignore> ) | |
1595 | it will look through the available devices for possible arrays and | |
1596 | will try to assemble anything that it finds. Arrays which are tagged | |
1597 | as belonging to the given homehost will be assembled and started | |
1598 | normally. Arrays which do not obviously belong to this host are given | |
1599 | names that are expected not to conflict with anything local, and are | |
1600 | started "read-auto" so that nothing is written to any device until the | |
1601 | array is written to. i.e. automatic resync etc is delayed. | |
41a3b72a NB |
1602 | |
1603 | If | |
1604 | .I mdadm | |
1605 | finds a consistent set of devices that look like they should comprise | |
1606 | an array, and if the superblock is tagged as belonging to the given | |
1607 | home host, it will automatically choose a device name and try to | |
1608 | assemble the array. If the array uses version-0.90 metadata, then the | |
1609 | .B minor | |
1610 | number as recorded in the superblock is used to create a name in | |
1611 | .B /dev/md/ | |
1612 | so for example | |
1613 | .BR /dev/md/3 . | |
1614 | If the array uses version-1 metadata, then the | |
1615 | .B name | |
1616 | from the superblock is used to similarly create a name in | |
e0fe762a | 1617 | .B /dev/md/ |
93e790af | 1618 | (the name will have any 'host' prefix stripped first). |
41a3b72a | 1619 | |
c64ba03a N |
1620 | This behaviour can be modified by the |
1621 | .I AUTO | |
1622 | line in the | |
1623 | .I mdadm.conf | |
1624 | configuration file. This line can indicate that specific metadata | |
1625 | type should, or should not, be automatically assembled. If an array | |
1626 | is found which is not listed in | |
1627 | .I mdadm.conf | |
1628 | and has a metadata format that is denied by the | |
1629 | .I AUTO | |
1630 | line, then it will not be assembled. | |
1631 | The | |
1632 | .I AUTO | |
1633 | line can also request that all arrays identified as being for this | |
1634 | homehost should be assembled regardless of their metadata type. | |
1635 | See | |
1636 | .IR mdadm.conf (5) | |
1637 | for further details. | |
1638 | ||
246cebdb AK |
1639 | Note: Auto assembly cannot be used for assembling and activating some |
1640 | arrays which are undergoing reshape. In particular as the | |
1641 | .B backup\-file | |
1642 | cannot be given, any reshape which requires a backup-file to continue | |
1643 | cannot be started by auto assembly. An array which is growing to more | |
1644 | devices and has passed the critical section can be assembled using | |
1645 | auto-assembly. | |
41a3b72a | 1646 | |
cd29a5c8 | 1647 | .SH BUILD MODE |
52826846 | 1648 | |
cd29a5c8 NB |
1649 | .HP 12 |
1650 | Usage: | |
7e23fc43 | 1651 | .B mdadm \-\-build |
93e790af | 1652 | .I md-device |
7e23fc43 PS |
1653 | .BI \-\-chunk= X |
1654 | .BI \-\-level= Y | |
1655 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
1656 | .I devices |
1657 | ||
1658 | .PP | |
2ae555c3 | 1659 | This usage is similar to |
7e23fc43 | 1660 | .BR \-\-create . |
e0fe762a | 1661 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 1662 | these arrays there is no difference between initially creating the array and |
52826846 NB |
1663 | subsequently assembling the array, except that hopefully there is useful |
1664 | data there in the second case. | |
1665 | ||
e0fe762a N |
1666 | The level may raid0, linear, raid1, raid10, multipath, or faulty, or |
1667 | one of their synonyms. All devices must be listed and the array will | |
1668 | be started once complete. It will often be appropriate to use | |
1669 | .B \-\-assume\-clean | |
1670 | with levels raid1 or raid10. | |
cd29a5c8 NB |
1671 | |
1672 | .SH CREATE MODE | |
1673 | ||
1674 | .HP 12 | |
1675 | Usage: | |
7e23fc43 | 1676 | .B mdadm \-\-create |
93e790af | 1677 | .I md-device |
7e23fc43 PS |
1678 | .BI \-\-chunk= X |
1679 | .BI \-\-level= Y | |
cd29a5c8 | 1680 | .br |
7e23fc43 | 1681 | .BI \-\-raid\-devices= Z |
e0fe762a | 1682 | .I devices |
cd29a5c8 NB |
1683 | |
1684 | .PP | |
1685 | This usage will initialise a new md array, associate some devices with | |
1686 | it, and activate the array. | |
1687 | ||
e0fe762a N |
1688 | The named device will normally not exist when |
1689 | .I "mdadm \-\-create" | |
1690 | is run, but will be created by | |
1691 | .I udev | |
1692 | once the array becomes active. | |
dd0781e5 | 1693 | |
e0fe762a N |
1694 | As devices are added, they are checked to see if they contain RAID |
1695 | superblocks or filesystems. They are also checked to see if the variance in | |
cd29a5c8 NB |
1696 | device size exceeds 1%. |
1697 | ||
1698 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 1699 | the presence of a |
7e23fc43 | 1700 | .B \-\-run |
cd29a5c8 NB |
1701 | can override this caution. |
1702 | ||
2d465520 | 1703 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 1704 | give the word "\fBmissing\fP" |
2d465520 | 1705 | in place of a device name. This will cause |
51ac42e3 | 1706 | .I mdadm |
2d465520 NB |
1707 | to leave the corresponding slot in the array empty. |
1708 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 1709 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
1710 | For a RAID1 array, only one real device needs to be given. All of the |
1711 | others can be | |
d013a55e | 1712 | "\fBmissing\fP". |
2d465520 | 1713 | |
feb716e9 | 1714 | When creating a RAID5 array, |
51ac42e3 | 1715 | .I mdadm |
feb716e9 | 1716 | will automatically create a degraded array with an extra spare drive. |
e0fe762a N |
1717 | This is because building the spare into a degraded array is in general |
1718 | faster than resyncing the parity on a non-degraded, but not clean, | |
1719 | array. This feature can be overridden with the | |
7e23fc43 | 1720 | .B \-\-force |
feb716e9 NB |
1721 | option. |
1722 | ||
0ee4da98 | 1723 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
1724 | required. |
1725 | If this is not given with the | |
7e23fc43 | 1726 | .B \-\-name |
41a3b72a NB |
1727 | option, |
1728 | .I mdadm | |
0ee4da98 | 1729 | will choose a name based on the last component of the name of the |
41a3b72a NB |
1730 | device being created. So if |
1731 | .B /dev/md3 | |
1732 | is being created, then the name | |
1733 | .B 3 | |
1734 | will be chosen. | |
1735 | If | |
1736 | .B /dev/md/home | |
1737 | is being created, then the name | |
1738 | .B home | |
1739 | will be used. | |
1740 | ||
e0fe762a N |
1741 | When creating a partition based array, using |
1742 | .I mdadm | |
1743 | with version-1.x metadata, the partition type should be set to | |
e0f31f50 | 1744 | .B 0xDA |
e0fe762a | 1745 | (non fs-data). This type selection allows for greater precision since |
e0f31f50 PC |
1746 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], |
1747 | might create problems in the event of array recovery through a live cdrom. | |
1748 | ||
3d3dd91e NB |
1749 | A new array will normally get a randomly assigned 128bit UUID which is |
1750 | very likely to be unique. If you have a specific need, you can choose | |
1751 | a UUID for the array by giving the | |
7e23fc43 | 1752 | .B \-\-uuid= |
3d3dd91e NB |
1753 | option. Be warned that creating two arrays with the same UUID is a |
1754 | recipe for disaster. Also, using | |
7e23fc43 | 1755 | .B \-\-uuid= |
3d3dd91e | 1756 | when creating a v0.90 array will silently override any |
7e23fc43 | 1757 | .B \-\-homehost= |
3d3dd91e | 1758 | setting. |
e43d0cda NB |
1759 | .\"If the |
1760 | .\".B \-\-size | |
1761 | .\"option is given, it is not necessary to list any component-devices in this command. | |
1762 | .\"They can be added later, before a | |
1763 | .\".B \-\-run. | |
1764 | .\"If no | |
1765 | .\".B \-\-size | |
1766 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 1767 | |
8fd8d9c4 N |
1768 | When creating an array within a |
1769 | .B CONTAINER | |
1770 | .I mdadm | |
1771 | can be given either the list of devices to use, or simply the name of | |
1772 | the container. The former case gives control over which devices in | |
1773 | the container will be used for the array. The latter case allows | |
1774 | .I mdadm | |
1775 | to automatically choose which devices to use based on how much spare | |
1776 | space is available. | |
1777 | ||
53e8b987 | 1778 | The General Management options that are valid with |
7e23fc43 | 1779 | .B \-\-create |
53e8b987 | 1780 | are: |
cd29a5c8 | 1781 | .TP |
7e23fc43 | 1782 | .B \-\-run |
dd0781e5 | 1783 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
1784 | be in use. |
1785 | ||
1786 | .TP | |
7e23fc43 | 1787 | .B \-\-readonly |
b3f1c093 | 1788 | start the array readonly \(em not supported yet. |
52826846 | 1789 | |
e0d19036 | 1790 | .SH MANAGE MODE |
cd29a5c8 NB |
1791 | .HP 12 |
1792 | Usage: | |
e0d19036 NB |
1793 | .B mdadm |
1794 | .I device | |
1795 | .I options... devices... | |
cd29a5c8 NB |
1796 | .PP |
1797 | ||
e0d19036 NB |
1798 | This usage will allow individual devices in an array to be failed, |
1799 | removed or added. It is possible to perform multiple operations with | |
e0fe762a | 1800 | on command. For example: |
e0d19036 | 1801 | .br |
7e23fc43 | 1802 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
1803 | .br |
1804 | will firstly mark | |
1805 | .B /dev/hda1 | |
1806 | as faulty in | |
1807 | .B /dev/md0 | |
1808 | and will then remove it from the array and finally add it back | |
2d465520 | 1809 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 1810 | command. |
e0d19036 | 1811 | |
e0fe762a N |
1812 | When a device is added to an active array, mdadm checks to see if it |
1813 | has metadata on it which suggests that it was recently a member of the | |
a4e13010 | 1814 | array. If it does, it tries to "re\-add" the device. If there have |
e0fe762a N |
1815 | been no changes since the device was removed, or if the array has a |
1816 | write-intent bitmap which has recorded whatever changes there were, | |
1817 | then the device will immediately become a full member of the array and | |
1818 | those differences recorded in the bitmap will be resolved. | |
1819 | ||
e0d19036 NB |
1820 | .SH MISC MODE |
1821 | .HP 12 | |
1822 | Usage: | |
9a9dab36 | 1823 | .B mdadm |
e0d19036 | 1824 | .I options ... |
e0fe762a | 1825 | .I devices ... |
e0d19036 | 1826 | .PP |
cd29a5c8 | 1827 | |
b5e64645 | 1828 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1829 | operate on distinct devices. The operations are: |
1830 | .TP | |
962a108f | 1831 | .B \-\-query |
e0d19036 NB |
1832 | The device is examined to see if it is |
1833 | (1) an active md array, or | |
1834 | (2) a component of an md array. | |
1835 | The information discovered is reported. | |
1836 | ||
1837 | .TP | |
962a108f | 1838 | .B \-\-detail |
2d465520 | 1839 | The device should be an active md device. |
e0fe762a | 1840 | .B mdadm |
2d465520 | 1841 | will display a detailed description of the array. |
7e23fc43 | 1842 | .B \-\-brief |
2d465520 | 1843 | or |
7e23fc43 | 1844 | .B \-\-scan |
2d465520 | 1845 | will cause the output to be less detailed and the format to be |
e0d19036 | 1846 | suitable for inclusion in |
87eb4fab | 1847 | .BR mdadm.conf . |
feb716e9 NB |
1848 | The exit status of |
1849 | .I mdadm | |
1850 | will normally be 0 unless | |
1851 | .I mdadm | |
93e790af | 1852 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 1853 | .B \-\-test |
feb716e9 NB |
1854 | option is given, then the exit status will be: |
1855 | .RS | |
1856 | .TP | |
1857 | 0 | |
1858 | The array is functioning normally. | |
1859 | .TP | |
1860 | 1 | |
1861 | The array has at least one failed device. | |
1862 | .TP | |
1863 | 2 | |
a77be586 | 1864 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
1865 | .TP |
1866 | 4 | |
1867 | There was an error while trying to get information about the device. | |
1868 | .RE | |
cd29a5c8 | 1869 | |
4cce4069 DW |
1870 | .TP |
1871 | .B \-\-detail\-platform | |
e0fe762a | 1872 | Print detail of the platform's RAID capabilities (firmware / hardware |
4cce4069 DW |
1873 | topology). If the metadata is specified with |
1874 | .B \-e | |
1875 | or | |
1876 | .B \-\-metadata= | |
1877 | then the return status will be: | |
1878 | .RS | |
1879 | .TP | |
1880 | 0 | |
1881 | metadata successfully enumerated its platform components on this system | |
1882 | .TP | |
1883 | 1 | |
1884 | metadata is platform independent | |
1885 | .TP | |
1886 | 2 | |
1887 | metadata failed to find its platform components on this system | |
1888 | .RE | |
1889 | ||
aa534678 DW |
1890 | .TP |
1891 | .B \-\-update\-subarray= | |
1892 | If the device is a container and the argument to \-\-update\-subarray | |
1893 | specifies a subarray in the container, then attempt to update the given | |
1894 | superblock field in the subarray. Similar to updating an array in | |
1895 | "assemble" mode, the field to update is selected by | |
1896 | .B \-U | |
1897 | or | |
1898 | .B \-\-update= | |
1899 | option. Currently only | |
1900 | .B name | |
1901 | is supported. | |
1902 | ||
1903 | The | |
1904 | .B name | |
1905 | option updates the subarray name in the metadata, it may not affect the | |
1906 | device node name or the device node symlink until the subarray is | |
1907 | re\-assembled. If updating | |
1908 | .B name | |
1909 | would change the UUID of an active subarray this operation is blocked, | |
1910 | and the command will end in an error. | |
1911 | ||
e0d19036 | 1912 | .TP |
962a108f | 1913 | .B \-\-examine |
2d465520 | 1914 | The device should be a component of an md array. |
51ac42e3 | 1915 | .I mdadm |
2d465520 | 1916 | will read the md superblock of the device and display the contents. |
e0d19036 | 1917 | If |
7e23fc43 | 1918 | .B \-\-brief |
93e790af | 1919 | or |
7e23fc43 | 1920 | .B \-\-scan |
93e790af | 1921 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
1922 | are grouped together and reported in a single entry suitable |
1923 | for inclusion in | |
87eb4fab | 1924 | .BR mdadm.conf . |
e0d19036 | 1925 | |
2d465520 | 1926 | Having |
7e23fc43 | 1927 | .B \-\-scan |
e0d19036 NB |
1928 | without listing any devices will cause all devices listed in the |
1929 | config file to be examined. | |
1930 | ||
1931 | .TP | |
962a108f | 1932 | .B \-\-stop |
98c6faba NB |
1933 | The devices should be active md arrays which will be deactivated, as |
1934 | long as they are not currently in use. | |
e0d19036 NB |
1935 | |
1936 | .TP | |
962a108f | 1937 | .B \-\-run |
e0d19036 NB |
1938 | This will fully activate a partially assembled md array. |
1939 | ||
1940 | .TP | |
962a108f | 1941 | .B \-\-readonly |
e0d19036 NB |
1942 | This will mark an active array as read-only, providing that it is |
1943 | not currently being used. | |
1944 | ||
1945 | .TP | |
962a108f | 1946 | .B \-\-readwrite |
e0d19036 NB |
1947 | This will change a |
1948 | .B readonly | |
1949 | array back to being read/write. | |
1950 | ||
2d465520 | 1951 | .TP |
962a108f | 1952 | .B \-\-scan |
2d465520 | 1953 | For all operations except |
7e23fc43 PS |
1954 | .BR \-\-examine , |
1955 | .B \-\-scan | |
2d465520 NB |
1956 | will cause the operation to be applied to all arrays listed in |
1957 | .BR /proc/mdstat . | |
1958 | For | |
7e23fc43 PS |
1959 | .BR \-\-examine, |
1960 | .B \-\-scan | |
2d465520 NB |
1961 | causes all devices listed in the config file to be examined. |
1962 | ||
a1331cc4 N |
1963 | .TP |
1964 | .BR \-b ", " \-\-brief | |
1965 | Be less verbose. This is used with | |
1966 | .B \-\-detail | |
1967 | and | |
1968 | .BR \-\-examine . | |
1969 | Using | |
1970 | .B \-\-brief | |
1971 | with | |
1972 | .B \-\-verbose | |
1973 | gives an intermediate level of verbosity. | |
1974 | ||
e0d19036 NB |
1975 | .SH MONITOR MODE |
1976 | ||
cd29a5c8 NB |
1977 | .HP 12 |
1978 | Usage: | |
7e23fc43 | 1979 | .B mdadm \-\-monitor |
e0d19036 NB |
1980 | .I options... devices... |
1981 | ||
cd29a5c8 | 1982 | .PP |
e0d19036 | 1983 | This usage causes |
51ac42e3 | 1984 | .I mdadm |
e0d19036 NB |
1985 | to periodically poll a number of md arrays and to report on any events |
1986 | noticed. | |
51ac42e3 | 1987 | .I mdadm |
e0d19036 NB |
1988 | will never exit once it decides that there are arrays to be checked, |
1989 | so it should normally be run in the background. | |
1990 | ||
2d465520 | 1991 | As well as reporting events, |
51ac42e3 | 1992 | .I mdadm |
2d465520 NB |
1993 | may move a spare drive from one array to another if they are in the |
1994 | same | |
1995 | .B spare-group | |
210597d1 PC |
1996 | or |
1997 | .B domain | |
a9d69660 | 1998 | and if the destination array has a failed drive but no spares. |
2d465520 | 1999 | |
e0d19036 | 2000 | If any devices are listed on the command line, |
51ac42e3 | 2001 | .I mdadm |
e0fe762a | 2002 | will only monitor those devices. Otherwise all arrays listed in the |
e0d19036 | 2003 | configuration file will be monitored. Further, if |
7e23fc43 | 2004 | .B \-\-scan |
e0d19036 NB |
2005 | is given, then any other md devices that appear in |
2006 | .B /proc/mdstat | |
2007 | will also be monitored. | |
2008 | ||
2009 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 2010 | These events are passed to a separate program (if specified) and may |
2d465520 | 2011 | be mailed to a given E-mail address. |
e0d19036 | 2012 | |
93e790af SW |
2013 | When passing events to a program, the program is run once for each event, |
2014 | and is given 2 or 3 command-line arguments: the first is the | |
2015 | name of the event (see below), the second is the name of the | |
bd526cee | 2016 | md device which is affected, and the third is the name of a related |
93e790af | 2017 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
2018 | |
2019 | If | |
7e23fc43 | 2020 | .B \-\-scan |
e0d19036 NB |
2021 | is given, then a program or an E-mail address must be specified on the |
2022 | command line or in the config file. If neither are available, then | |
51ac42e3 | 2023 | .I mdadm |
e0d19036 NB |
2024 | will not monitor anything. |
2025 | Without | |
93e790af | 2026 | .B \-\-scan, |
51ac42e3 | 2027 | .I mdadm |
2d465520 | 2028 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
2029 | no program or email is given, then each event is reported to |
2030 | .BR stdout . | |
cd29a5c8 | 2031 | |
e0d19036 NB |
2032 | The different events are: |
2033 | ||
2034 | .RS 4 | |
2035 | .TP | |
2036 | .B DeviceDisappeared | |
2d465520 | 2037 | An md array which previously was configured appears to no longer be |
773135f5 | 2038 | configured. (syslog priority: Critical) |
e0d19036 | 2039 | |
b8f72a62 NB |
2040 | If |
2041 | .I mdadm | |
2042 | was told to monitor an array which is RAID0 or Linear, then it will | |
2043 | report | |
2044 | .B DeviceDisappeared | |
2045 | with the extra information | |
2046 | .BR Wrong-Level . | |
2047 | This is because RAID0 and Linear do not support the device-failed, | |
2048 | hot-spare and resync operations which are monitored. | |
2049 | ||
e0d19036 NB |
2050 | .TP |
2051 | .B RebuildStarted | |
773135f5 | 2052 | An md array started reconstruction. (syslog priority: Warning) |
e0d19036 NB |
2053 | |
2054 | .TP | |
2055 | .BI Rebuild NN | |
2056 | Where | |
2057 | .I NN | |
9a36a9b7 ZB |
2058 | is a two-digit number (ie. 05, 48). This indicates that rebuild |
2059 | has passed that many percent of the total. The events are generated | |
2060 | with fixed increment since 0. Increment size may be specified with | |
2061 | a commandline option (default is 20). (syslog priority: Warning) | |
e0d19036 | 2062 | |
98c6faba NB |
2063 | .TP |
2064 | .B RebuildFinished | |
2065 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 2066 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 2067 | |
e0d19036 NB |
2068 | .TP |
2069 | .B Fail | |
773135f5 NB |
2070 | An active component device of an array has been marked as |
2071 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
2072 | |
2073 | .TP | |
2074 | .B FailSpare | |
2075 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 2076 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
2077 | |
2078 | .TP | |
2079 | .B SpareActive | |
2080 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 2081 | device has been successfully rebuilt and has been made active. |
773135f5 | 2082 | (syslog priority: Info) |
e0d19036 NB |
2083 | |
2084 | .TP | |
2085 | .B NewArray | |
2086 | A new md array has been detected in the | |
2087 | .B /proc/mdstat | |
e0fe762a | 2088 | file. (syslog priority: Info) |
e0d19036 | 2089 | |
aa88f531 NB |
2090 | .TP |
2091 | .B DegradedArray | |
2092 | A newly noticed array appears to be degraded. This message is not | |
2093 | generated when | |
2094 | .I mdadm | |
2095 | notices a drive failure which causes degradation, but only when | |
2096 | .I mdadm | |
2097 | notices that an array is degraded when it first sees the array. | |
93e790af | 2098 | (syslog priority: Critical) |
aa88f531 | 2099 | |
e0d19036 NB |
2100 | .TP |
2101 | .B MoveSpare | |
2102 | A spare drive has been moved from one array in a | |
2103 | .B spare-group | |
210597d1 PC |
2104 | or |
2105 | .B domain | |
e0d19036 | 2106 | to another to allow a failed drive to be replaced. |
773135f5 | 2107 | (syslog priority: Info) |
e0d19036 | 2108 | |
b8f72a62 NB |
2109 | .TP |
2110 | .B SparesMissing | |
2111 | If | |
2112 | .I mdadm | |
2113 | has been told, via the config file, that an array should have a certain | |
2114 | number of spare devices, and | |
2115 | .I mdadm | |
93e790af | 2116 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
2117 | array, it will report a |
2118 | .B SparesMissing | |
2119 | message. | |
d1732eeb | 2120 | (syslog priority: Warning) |
b8f72a62 | 2121 | |
98c6faba NB |
2122 | .TP |
2123 | .B TestMessage | |
2124 | An array was found at startup, and the | |
7e23fc43 | 2125 | .B \-\-test |
98c6faba | 2126 | flag was given. |
773135f5 | 2127 | (syslog priority: Info) |
e0d19036 NB |
2128 | .RE |
2129 | ||
2130 | Only | |
93e790af SW |
2131 | .B Fail, |
2132 | .B FailSpare, | |
2133 | .B DegradedArray, | |
2134 | .B SparesMissing | |
e0d19036 | 2135 | and |
98c6faba | 2136 | .B TestMessage |
e0d19036 | 2137 | cause Email to be sent. All events cause the program to be run. |
93e790af | 2138 | The program is run with two or three arguments: the event |
e0d19036 NB |
2139 | name, the array device and possibly a second device. |
2140 | ||
2141 | Each event has an associated array device (e.g. | |
2142 | .BR /dev/md1 ) | |
2143 | and possibly a second device. For | |
2144 | .BR Fail , | |
2145 | .BR FailSpare , | |
2146 | and | |
2147 | .B SpareActive | |
2148 | the second device is the relevant component device. | |
2149 | For | |
2150 | .B MoveSpare | |
2151 | the second device is the array that the spare was moved from. | |
2152 | ||
2153 | For | |
51ac42e3 | 2154 | .I mdadm |
e0d19036 | 2155 | to move spares from one array to another, the different arrays need to |
93e790af | 2156 | be labeled with the same |
e0d19036 | 2157 | .B spare-group |
210597d1 | 2158 | or the spares must be allowed to migrate through matching POLICY domains |
e0d19036 NB |
2159 | in the configuration file. The |
2160 | .B spare-group | |
93e790af | 2161 | name can be any string; it is only necessary that different spare |
2d465520 | 2162 | groups use different names. |
e0d19036 NB |
2163 | |
2164 | When | |
51ac42e3 | 2165 | .I mdadm |
93e790af | 2166 | detects that an array in a spare group has fewer active |
e0d19036 NB |
2167 | devices than necessary for the complete array, and has no spare |
2168 | devices, it will look for another array in the same spare group that | |
2169 | has a full complement of working drive and a spare. It will then | |
2170 | attempt to remove the spare from the second drive and add it to the | |
2171 | first. | |
2172 | If the removal succeeds but the adding fails, then it is added back to | |
2173 | the original array. | |
2174 | ||
210597d1 PC |
2175 | If the spare group for a degraded array is not defined, |
2176 | .I mdadm | |
2177 | will look at the rules of spare migration specified by POLICY lines in | |
87eb4fab | 2178 | .B mdadm.conf |
210597d1 PC |
2179 | and then follow similar steps as above if a matching spare is found. |
2180 | ||
dd0781e5 NB |
2181 | .SH GROW MODE |
2182 | The GROW mode is used for changing the size or shape of an active | |
2183 | array. | |
2184 | For this to work, the kernel must support the necessary change. | |
c64881d7 | 2185 | Various types of growth are being added during 2.6 development. |
dd0781e5 | 2186 | |
c64881d7 | 2187 | Currently the supported changes include |
dfd4d8ee | 2188 | .IP \(bu 4 |
c64881d7 | 2189 | change the "size" attribute for RAID1, RAID4, RAID5 and RAID6. |
dfd4d8ee | 2190 | .IP \(bu 4 |
c64881d7 N |
2191 | increase or decrease the "raid\-devices" attribute of RAID0, RAID1, RAID4, |
2192 | RAID5, and RAID6. | |
f24e2d6c | 2193 | .IP \bu 4 |
c64881d7 | 2194 | change the chunk-size and layout of RAID0, RAID4, RAID5 and RAID6. |
f24e2d6c | 2195 | .IP \bu 4 |
c64881d7 N |
2196 | convert between RAID1 and RAID5, between RAID5 and RAID6, between |
2197 | RAID0, RAID5, and RAID5, and between RAID0 and RAID10 (in the near-2 mode). | |
dfd4d8ee | 2198 | .IP \(bu 4 |
93e790af | 2199 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 2200 | remove a write-intent bitmap from such an array. |
dfd4d8ee | 2201 | .PP |
dd0781e5 | 2202 | |
c64881d7 N |
2203 | Using GROW on containers is currently only support for Intel's IMSM |
2204 | container format. The number of devices in a container can be | |
2205 | increased - which affects all arrays in the container - or an array | |
2206 | in a container can be converted between levels where those levels are | |
2207 | supported by the container, and the conversion is on of those listed | |
2208 | above. | |
8fd8d9c4 | 2209 | |
ca24ddb0 AK |
2210 | Grow functionality (e.g. expand a number of raid devices) for Intel's |
2211 | IMSM container format has an experimental status. It is guarded by the | |
2212 | .B MDADM_EXPERIMENTAL | |
2213 | environment variable which must be set to '1' for a GROW command to | |
2214 | succeed. | |
2215 | This is for the following reasons: | |
2216 | ||
2217 | .IP 1. | |
2218 | Intel's native IMSM check-pointing is not fully implemented yet. | |
2219 | This causes IMSM incompatibility during the grow process: an array | |
2220 | which is growing cannot roam between Microsoft Windows(R) and Linux | |
2221 | systems. | |
2222 | ||
2223 | .IP 2. | |
2224 | Interrupting a grow operation is not recommended, because it | |
2225 | has not been fully tested for Intel's IMSM container format yet. | |
2226 | ||
2ae555c3 | 2227 | .SS SIZE CHANGES |
c64881d7 | 2228 | Normally when an array is built the "size" is taken from the smallest |
dd0781e5 NB |
2229 | of the drives. If all the small drives in an arrays are, one at a |
2230 | time, removed and replaced with larger drives, then you could have an | |
2231 | array of large drives with only a small amount used. In this | |
2232 | situation, changing the "size" with "GROW" mode will allow the extra | |
2233 | space to start being used. If the size is increased in this way, a | |
2234 | "resync" process will start to make sure the new parts of the array | |
2235 | are synchronised. | |
2236 | ||
2237 | Note that when an array changes size, any filesystem that may be | |
666bba9b | 2238 | stored in the array will not automatically grow for shrink to use or |
88b496c2 | 2239 | vacate the space. The |
666bba9b N |
2240 | filesystem will need to be explicitly told to use the extra space |
2241 | after growing, or to reduce its size | |
2242 | .B prior | |
2243 | to shrinking the array. | |
dd0781e5 | 2244 | |
e0fe762a N |
2245 | Also the size of an array cannot be changed while it has an active |
2246 | bitmap. If an array has a bitmap, it must be removed before the size | |
2247 | can be changed. Once the change it complete a new bitmap can be created. | |
2248 | ||
2249 | .SS RAID\-DEVICES CHANGES | |
2ae555c3 | 2250 | |
dd0781e5 NB |
2251 | A RAID1 array can work with any number of devices from 1 upwards |
2252 | (though 1 is not very useful). There may be times which you want to | |
2253 | increase or decrease the number of active devices. Note that this is | |
2254 | different to hot-add or hot-remove which changes the number of | |
2255 | inactive devices. | |
2256 | ||
2257 | When reducing the number of devices in a RAID1 array, the slots which | |
2258 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 2259 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
2260 | |
2261 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 2262 | present will be activated immediately. |
dd0781e5 | 2263 | |
f24e2d6c | 2264 | Changing the number of active devices in a RAID5 or RAID6 is much more |
2ae555c3 | 2265 | effort. Every block in the array will need to be read and written |
f24e2d6c | 2266 | back to a new location. From 2.6.17, the Linux Kernel is able to |
ca4f89a3 N |
2267 | increase the number of devices in a RAID5 safely, including restarting |
2268 | an interrupted "reshape". From 2.6.31, the Linux Kernel is able to | |
f24e2d6c N |
2269 | increase or decrease the number of devices in a RAID5 or RAID6. |
2270 | ||
c64881d7 N |
2271 | From 2.6.35, the Linux Kernel is able to convert a RAID0 in to a RAID4 |
2272 | or RAID5. | |
2273 | .I mdadm | |
2274 | uses this functionality and the ability to add | |
2275 | devices to a RAID4 to allow devices to be added to a RAID0. When | |
2276 | requested to do this, | |
2277 | .I mdadm | |
2278 | will convert the RAID0 to a RAID4, add the necessary disks and make | |
2279 | the reshape happen, and then convert the RAID4 back to RAID0. | |
2280 | ||
f24e2d6c N |
2281 | When decreasing the number of devices, the size of the array will also |
2282 | decrease. If there was data in the array, it could get destroyed and | |
666bba9b N |
2283 | this is not reversible, so you should firstly shrink the filesystem on |
2284 | the array to fit within the new size. To help prevent accidents, | |
f24e2d6c N |
2285 | .I mdadm |
2286 | requires that the size of the array be decreased first with | |
2287 | .BR "mdadm --grow --array-size" . | |
2288 | This is a reversible change which simply makes the end of the array | |
2289 | inaccessible. The integrity of any data can then be checked before | |
2290 | the non-reversible reduction in the number of devices is request. | |
2ae555c3 | 2291 | |
cd19c0cf JR |
2292 | When relocating the first few stripes on a RAID5 or RAID6, it is not |
2293 | possible to keep the data on disk completely consistent and | |
2294 | crash-proof. To provide the required safety, mdadm disables writes to | |
2295 | the array while this "critical section" is reshaped, and takes a | |
2296 | backup of the data that is in that section. For grows, this backup may be | |
2297 | stored in any spare devices that the array has, however it can also be | |
2298 | stored in a separate file specified with the | |
7e23fc43 | 2299 | .B \-\-backup\-file |
cd19c0cf JR |
2300 | option, and is required to be specified for shrinks, RAID level |
2301 | changes and layout changes. If this option is used, and the system | |
2302 | does crash during the critical period, the same file must be passed to | |
7e23fc43 | 2303 | .B \-\-assemble |
cd19c0cf JR |
2304 | to restore the backup and reassemble the array. When shrinking rather |
2305 | than growing the array, the reshape is done from the end towards the | |
2306 | beginning, so the "critical section" is at the end of the reshape. | |
2ae555c3 | 2307 | |
f24e2d6c N |
2308 | .SS LEVEL CHANGES |
2309 | ||
2310 | Changing the RAID level of any array happens instantaneously. However | |
cd19c0cf | 2311 | in the RAID5 to RAID6 case this requires a non-standard layout of the |
f24e2d6c | 2312 | RAID6 data, and in the RAID6 to RAID5 case that non-standard layout is |
cd19c0cf | 2313 | required before the change can be accomplished. So while the level |
f24e2d6c | 2314 | change is instant, the accompanying layout change can take quite a |
cd19c0cf JR |
2315 | long time. A |
2316 | .B \-\-backup\-file | |
2317 | is required. If the array is not simultaneously being grown or | |
2318 | shrunk, so that the array size will remain the same - for example, | |
2319 | reshaping a 3-drive RAID5 into a 4-drive RAID6 - the backup file will | |
2320 | be used not just for a "cricital section" but throughout the reshape | |
2321 | operation, as described below under LAYOUT CHANGES. | |
f24e2d6c N |
2322 | |
2323 | .SS CHUNK-SIZE AND LAYOUT CHANGES | |
2324 | ||
2325 | Changing the chunk-size of layout without also changing the number of | |
2326 | devices as the same time will involve re-writing all blocks in-place. | |
2327 | To ensure against data loss in the case of a crash, a | |
2328 | .B --backup-file | |
2329 | must be provided for these changes. Small sections of the array will | |
cd19c0cf JR |
2330 | be copied to the backup file while they are being rearranged. This |
2331 | means that all the data is copied twice, once to the backup and once | |
2332 | to the new layout on the array, so this type of reshape will go very | |
2333 | slowly. | |
f24e2d6c N |
2334 | |
2335 | If the reshape is interrupted for any reason, this backup file must be | |
cd19c0cf | 2336 | made available to |
f24e2d6c N |
2337 | .B "mdadm --assemble" |
2338 | so the array can be reassembled. Consequently the file cannot be | |
2339 | stored on the device being reshaped. | |
2340 | ||
2341 | ||
2ae555c3 NB |
2342 | .SS BITMAP CHANGES |
2343 | ||
2344 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 2345 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b | 2346 | can be added. Note that if you add a bitmap stored in a file which is |
e0fe762a | 2347 | in a filesystem that is on the RAID array being affected, the system |
fe80f49b NB |
2348 | will deadlock. The bitmap must be on a separate filesystem. |
2349 | ||
8382f19b NB |
2350 | .SH INCREMENTAL MODE |
2351 | ||
2352 | .HP 12 | |
2353 | Usage: | |
7e23fc43 PS |
2354 | .B mdadm \-\-incremental |
2355 | .RB [ \-\-run ] | |
2356 | .RB [ \-\-quiet ] | |
8382f19b NB |
2357 | .I component-device |
2358 | .HP 12 | |
2359 | Usage: | |
29ba4804 N |
2360 | .B mdadm \-\-incremental \-\-fail |
2361 | .I component-device | |
2362 | .HP 12 | |
2363 | Usage: | |
7e6140e6 | 2364 | .B mdadm \-\-incremental \-\-rebuild\-map |
8382f19b NB |
2365 | .HP 12 |
2366 | Usage: | |
7e23fc43 | 2367 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b | 2368 | |
8382f19b NB |
2369 | .PP |
2370 | This mode is designed to be used in conjunction with a device | |
2371 | discovery system. As devices are found in a system, they can be | |
2372 | passed to | |
7e23fc43 | 2373 | .B "mdadm \-\-incremental" |
8382f19b NB |
2374 | to be conditionally added to an appropriate array. |
2375 | ||
29ba4804 N |
2376 | Conversely, it can also be used with the |
2377 | .B \-\-fail | |
2378 | flag to do just the opposite and find whatever array a particular device | |
2379 | is part of and remove the device from that array. | |
2380 | ||
8fd8d9c4 N |
2381 | If the device passed is a |
2382 | .B CONTAINER | |
2383 | device created by a previous call to | |
2384 | .IR mdadm , | |
2385 | then rather than trying to add that device to an array, all the arrays | |
2386 | described by the metadata of the container will be started. | |
2387 | ||
8382f19b NB |
2388 | .I mdadm |
2389 | performs a number of tests to determine if the device is part of an | |
93e790af | 2390 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
2391 | is found, or can be created, |
2392 | .I mdadm | |
2393 | adds the device to the array and conditionally starts the array. | |
2394 | ||
2395 | Note that | |
2396 | .I mdadm | |
87eb4fab N |
2397 | will normally only add devices to an array which were previously working |
2398 | (active or spare) parts of that array. The support for automatic | |
210597d1 PC |
2399 | inclusion of a new drive as a spare in some array requires |
2400 | a configuration through POLICY in config file. | |
8382f19b | 2401 | |
8382f19b NB |
2402 | The tests that |
2403 | .I mdadm | |
2404 | makes are as follow: | |
2405 | .IP + | |
2406 | Is the device permitted by | |
2407 | .BR mdadm.conf ? | |
2408 | That is, is it listed in a | |
2409 | .B DEVICES | |
2410 | line in that file. If | |
2411 | .B DEVICES | |
2412 | is absent then the default it to allow any device. Similar if | |
2413 | .B DEVICES | |
2414 | contains the special word | |
2415 | .B partitions | |
2416 | then any device is allowed. Otherwise the device name given to | |
2417 | .I mdadm | |
2418 | must match one of the names or patterns in a | |
2419 | .B DEVICES | |
2420 | line. | |
2421 | ||
2422 | .IP + | |
2423 | Does the device have a valid md superblock. If a specific metadata | |
2424 | version is request with | |
7e23fc43 | 2425 | .B \-\-metadata |
8382f19b | 2426 | or |
7e23fc43 | 2427 | .B \-e |
8382f19b NB |
2428 | then only that style of metadata is accepted, otherwise |
2429 | .I mdadm | |
2430 | finds any known version of metadata. If no | |
2431 | .I md | |
210597d1 PC |
2432 | metadata is found, the device may be still added to an array |
2433 | as a spare if POLICY allows. | |
8382f19b | 2434 | |
d1302dd8 | 2435 | .ig |
8382f19b NB |
2436 | .IP + |
2437 | Does the metadata match an expected array? | |
2438 | The metadata can match in two ways. Either there is an array listed | |
2439 | in | |
2440 | .B mdadm.conf | |
2441 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 2442 | or by minor-number), or the array was created with a |
8382f19b | 2443 | .B homehost |
93e790af | 2444 | specified and that |
8382f19b | 2445 | .B homehost |
93e790af | 2446 | matches the one in |
8382f19b NB |
2447 | .B mdadm.conf |
2448 | or on the command line. | |
2449 | If | |
2450 | .I mdadm | |
2451 | is not able to positively identify the array as belonging to the | |
2452 | current host, the device will be rejected. | |
d1302dd8 | 2453 | .. |
8382f19b | 2454 | |
8382f19b | 2455 | .I mdadm |
93e790af | 2456 | keeps a list of arrays that it has partially assembled in |
8382f19b NB |
2457 | .B /var/run/mdadm/map |
2458 | (or | |
2459 | .B /var/run/mdadm.map | |
e0fe762a N |
2460 | if the directory doesn't exist. Or maybe even |
2461 | .BR /dev/.mdadm.map ). | |
2462 | If no array exists which matches | |
8382f19b NB |
2463 | the metadata on the new device, |
2464 | .I mdadm | |
2465 | must choose a device name and unit number. It does this based on any | |
2466 | name given in | |
2467 | .B mdadm.conf | |
2468 | or any name information stored in the metadata. If this name | |
2469 | suggests a unit number, that number will be used, otherwise a free | |
2470 | unit number will be chosen. Normally | |
2471 | .I mdadm | |
2472 | will prefer to create a partitionable array, however if the | |
2473 | .B CREATE | |
2474 | line in | |
2475 | .B mdadm.conf | |
2476 | suggests that a non-partitionable array is preferred, that will be | |
2477 | honoured. | |
2478 | ||
e0fe762a N |
2479 | If the array is not found in the config file and its metadata does not |
2480 | identify it as belonging to the "homehost", then | |
2481 | .I mdadm | |
2482 | will choose a name for the array which is certain not to conflict with | |
2483 | any array which does belong to this host. It does this be adding an | |
2484 | underscore and a small number to the name preferred by the metadata. | |
2485 | ||
8382f19b NB |
2486 | Once an appropriate array is found or created and the device is added, |
2487 | .I mdadm | |
2488 | must decide if the array is ready to be started. It will | |
2489 | normally compare the number of available (non-spare) devices to the | |
2490 | number of devices that the metadata suggests need to be active. If | |
2491 | there are at least that many, the array will be started. This means | |
2492 | that if any devices are missing the array will not be restarted. | |
2493 | ||
2494 | As an alternative, | |
7e23fc43 | 2495 | .B \-\-run |
8382f19b | 2496 | may be passed to |
51ac42e3 | 2497 | .I mdadm |
8382f19b | 2498 | in which case the array will be run as soon as there are enough |
e0fe762a N |
2499 | devices present for the data to be accessible. For a RAID1, that |
2500 | means one device will start the array. For a clean RAID5, the array | |
8382f19b NB |
2501 | will be started as soon as all but one drive is present. |
2502 | ||
93e790af | 2503 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
2504 | be known that all device discovery has completed, then |
2505 | .br | |
7e23fc43 | 2506 | .B " mdadm \-IRs" |
8382f19b NB |
2507 | .br |
2508 | can be run which will try to start all arrays that are being | |
2509 | incrementally assembled. They are started in "read-auto" mode in | |
2510 | which they are read-only until the first write request. This means | |
2511 | that no metadata updates are made and no attempt at resync or recovery | |
2512 | happens. Further devices that are found before the first write can | |
2513 | still be added safely. | |
2514 | ||
5545fa6d DW |
2515 | .SH ENVIRONMENT |
2516 | This section describes environment variables that affect how mdadm | |
2517 | operates. | |
2518 | ||
2519 | .TP | |
2520 | .B MDADM_NO_MDMON | |
2521 | Setting this value to 1 will prevent mdadm from automatically launching | |
2522 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
2523 | ||
8fd8d9c4 N |
2524 | .TP |
2525 | .B MDADM_NO_UDEV | |
2526 | Normally, | |
2527 | .I mdadm | |
2528 | does not create any device nodes in /dev, but leaves that task to | |
2529 | .IR udev . | |
2530 | If | |
2531 | .I udev | |
2532 | appears not to be configured, or if this environment variable is set | |
2533 | to '1', the | |
2534 | .I mdadm | |
2535 | will create and devices that are needed. | |
2536 | ||
2d465520 NB |
2537 | .SH EXAMPLES |
2538 | ||
7e23fc43 | 2539 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 2540 | .br |
e0fe762a | 2541 | This will find out if a given device is a RAID array, or is part of |
5787fa49 | 2542 | one, and will provide brief information about the device. |
2d465520 | 2543 | |
7e23fc43 | 2544 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 2545 | .br |
93e790af | 2546 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 2547 | file. This command will typically go in a system startup file. |
2d465520 | 2548 | |
7e23fc43 | 2549 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 2550 | .br |
93e790af | 2551 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 2552 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 2553 | |
7e23fc43 | 2554 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 2555 | .br |
5787fa49 NB |
2556 | If (and only if) there is an Email address or program given in the |
2557 | standard config file, then | |
2558 | monitor the status of all arrays listed in that file by | |
2559 | polling them ever 2 minutes. | |
2d465520 | 2560 | |
7e23fc43 | 2561 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 2562 | .br |
5787fa49 | 2563 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 2564 | |
2d465520 | 2565 | .br |
7e23fc43 | 2566 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 2567 | .br |
7e23fc43 | 2568 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 2569 | .br |
5787fa49 NB |
2570 | This will create a prototype config file that describes currently |
2571 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
2572 | This file should be reviewed before being used as it may |
2573 | contain unwanted detail. | |
2574 | ||
7e23fc43 | 2575 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 2576 | .br |
7e23fc43 | 2577 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
2578 | .br |
2579 | This will find arrays which could be assembled from existing IDE and | |
2580 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 2581 | format of a config file. |
2d465520 NB |
2582 | This file is very likely to contain unwanted detail, particularly |
2583 | the | |
2584 | .B devices= | |
5787fa49 NB |
2585 | entries. It should be reviewed and edited before being used as an |
2586 | actual config file. | |
2d465520 | 2587 | |
7e23fc43 | 2588 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 2589 | .br |
7e23fc43 | 2590 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
2591 | .br |
2592 | Create a list of devices by reading | |
2593 | .BR /proc/partitions , | |
2594 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 2595 | that were found. |
2d465520 | 2596 | |
7e23fc43 | 2597 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 2598 | .br |
5787fa49 NB |
2599 | Scan all partitions and devices listed in |
2600 | .BR /proc/partitions | |
2601 | and assemble | |
2602 | .B /dev/md0 | |
2603 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 2604 | |
7e23fc43 | 2605 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm" |
d013a55e NB |
2606 | .br |
2607 | If config file contains a mail address or alert program, run mdadm in | |
2608 | the background in monitor mode monitoring all md devices. Also write | |
2609 | pid of mdadm daemon to | |
2610 | .BR /var/run/mdadm . | |
2611 | ||
7e23fc43 | 2612 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
2613 | .br |
2614 | Try to incorporate newly discovered device into some array as | |
2615 | appropriate. | |
2616 | ||
7e6140e6 | 2617 | .B " mdadm \-\-incremental \-\-rebuild\-map \-\-run \-\-scan" |
8382f19b NB |
2618 | .br |
2619 | Rebuild the array map from any current arrays, and then start any that | |
2620 | can be started. | |
2621 | ||
b80da661 NB |
2622 | .B " mdadm /dev/md4 --fail detached --remove detached" |
2623 | .br | |
2624 | Any devices which are components of /dev/md4 will be marked as faulty | |
2625 | and then remove from the array. | |
2626 | ||
f24e2d6c N |
2627 | .B " mdadm --grow /dev/md4 --level=6 --backup-file=/root/backup-md4 |
2628 | .br | |
2629 | The array | |
2630 | .B /dev/md4 | |
2631 | which is currently a RAID5 array will be converted to RAID6. There | |
2632 | should normally already be a spare drive attached to the array as a | |
2633 | RAID6 needs one more drive than a matching RAID5. | |
2634 | ||
8fd8d9c4 N |
2635 | .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]" |
2636 | .br | |
2637 | Create a DDF array over 6 devices. | |
2638 | ||
2639 | .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf" | |
2640 | .br | |
e0fe762a | 2641 | Create a RAID5 array over any 3 devices in the given DDF set. Use |
8fd8d9c4 N |
2642 | only 30 gigabytes of each device. |
2643 | ||
2644 | .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]" | |
2645 | .br | |
2646 | Assemble a pre-exist ddf array. | |
2647 | ||
2648 | .B " mdadm -I /dev/md/ddf1" | |
2649 | .br | |
2650 | Assemble all arrays contained in the ddf array, assigning names as | |
2651 | appropriate. | |
2652 | ||
7e23fc43 | 2653 | .B " mdadm \-\-create \-\-help" |
2d465520 | 2654 | .br |
2ae555c3 | 2655 | Provide help about the Create mode. |
2d465520 | 2656 | |
7e23fc43 | 2657 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
2658 | .br |
2659 | Provide help about the format of the config file. | |
2d465520 | 2660 | |
7e23fc43 | 2661 | .B " mdadm \-\-help" |
5787fa49 NB |
2662 | .br |
2663 | Provide general help. | |
cd29a5c8 | 2664 | |
cd29a5c8 NB |
2665 | .SH FILES |
2666 | ||
2667 | .SS /proc/mdstat | |
2668 | ||
2ae555c3 NB |
2669 | If you're using the |
2670 | .B /proc | |
cd29a5c8 NB |
2671 | filesystem, |
2672 | .B /proc/mdstat | |
2d465520 | 2673 | lists all active md devices with information about them. |
51ac42e3 | 2674 | .I mdadm |
2d465520 | 2675 | uses this to find arrays when |
7e23fc43 | 2676 | .B \-\-scan |
2d465520 NB |
2677 | is given in Misc mode, and to monitor array reconstruction |
2678 | on Monitor mode. | |
2679 | ||
9a9dab36 | 2680 | .SS /etc/mdadm.conf |
cd29a5c8 | 2681 | |
11a3e71d NB |
2682 | The config file lists which devices may be scanned to see if |
2683 | they contain MD super block, and gives identifying information | |
2684 | (e.g. UUID) about known MD arrays. See | |
2685 | .BR mdadm.conf (5) | |
2686 | for more details. | |
cd29a5c8 | 2687 | |
8382f19b NB |
2688 | .SS /var/run/mdadm/map |
2689 | When | |
7e23fc43 | 2690 | .B \-\-incremental |
93e790af | 2691 | mode is used, this file gets a list of arrays currently being created. |
8382f19b NB |
2692 | If |
2693 | .B /var/run/mdadm | |
2694 | does not exist as a directory, then | |
2695 | .B /var/run/mdadm.map | |
e0fe762a N |
2696 | is used instead. If |
2697 | .B /var/run | |
2698 | is not available (as may be the case during early boot), | |
2699 | .B /dev/.mdadm.map | |
2700 | is used on the basis that | |
2701 | .B /dev | |
2702 | is usually available very early in boot. | |
8382f19b | 2703 | |
48f7b27a NB |
2704 | .SH DEVICE NAMES |
2705 | ||
48f7b27a | 2706 | .I mdadm |
8fd8d9c4 N |
2707 | understand two sorts of names for array devices. |
2708 | ||
2709 | The first is the so-called 'standard' format name, which matches the | |
2710 | names used by the kernel and which appear in | |
2711 | .IR /proc/mdstat . | |
2712 | ||
2713 | The second sort can be freely chosen, but must reside in | |
2714 | .IR /dev/md/ . | |
2715 | When giving a device name to | |
2716 | .I mdadm | |
2717 | to create or assemble an array, either full path name such as | |
2718 | .I /dev/md0 | |
2719 | or | |
2720 | .I /dev/md/home | |
2721 | can be given, or just the suffix of the second sort of name, such as | |
2722 | .I home | |
2723 | can be given. | |
2724 | ||
2725 | When | |
2726 | .I mdadm | |
e0fe762a N |
2727 | chooses device names during auto-assembly or incremental assembly, it |
2728 | will sometimes add a small sequence number to the end of the name to | |
2729 | avoid conflicted between multiple arrays that have the same name. If | |
8fd8d9c4 N |
2730 | .I mdadm |
2731 | can reasonably determine that the array really is meant for this host, | |
2732 | either by a hostname in the metadata, or by the presence of the array | |
87eb4fab N |
2733 | in |
2734 | .BR mdadm.conf , | |
2735 | then it will leave off the suffix if possible. | |
e0fe762a N |
2736 | Also if the homehost is specified as |
2737 | .B <ignore> | |
2738 | .I mdadm | |
2739 | will only use a suffix if a different array of the same name already | |
2740 | exists or is listed in the config file. | |
48f7b27a NB |
2741 | |
2742 | The standard names for non-partitioned arrays (the only sort of md | |
8fd8d9c4 | 2743 | array available in 2.4 and earlier) are of the form |
48f7b27a NB |
2744 | .IP |
2745 | /dev/mdNN | |
48f7b27a NB |
2746 | .PP |
2747 | where NN is a number. | |
2748 | The standard names for partitionable arrays (as available from 2.6 | |
8fd8d9c4 | 2749 | onwards) are of the form |
48f7b27a | 2750 | .IP |
48f7b27a NB |
2751 | /dev/md_dNN |
2752 | .PP | |
2753 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
8fd8d9c4 N |
2754 | .PP |
2755 | From kernel version, 2.6.28 the "non-partitioned array" can actually | |
2756 | be partitioned. So the "md_dNN" names are no longer needed, and | |
2757 | partitions such as "/dev/mdNNpXX" are possible. | |
52826846 | 2758 | |
2d465520 | 2759 | .SH NOTE |
51ac42e3 | 2760 | .I mdadm |
2d465520 | 2761 | was previously known as |
51ac42e3 | 2762 | .IR mdctl . |
a9d69660 | 2763 | .P |
51ac42e3 | 2764 | .I mdadm |
a9d69660 | 2765 | is completely separate from the |
51ac42e3 | 2766 | .I raidtools |
a9d69660 NB |
2767 | package, and does not use the |
2768 | .I /etc/raidtab | |
2769 | configuration file at all. | |
2770 | ||
52826846 | 2771 | .SH SEE ALSO |
75f74377 | 2772 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 2773 | RAID, see: |
3cdfb6a7 | 2774 | .IP |
11cd8b79 | 2775 | .B http://linux\-raid.osdl.org/ |
75f74377 DG |
2776 | .PP |
2777 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
e43d0cda NB |
2778 | .\".PP |
2779 | .\"for new releases of the RAID driver check out: | |
2780 | .\" | |
2781 | .\".IP | |
e0fe762a | 2782 | .\".UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches |
e43d0cda NB |
2783 | .\"ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches |
2784 | .\".UE | |
2785 | .\".PP | |
2786 | .\"or | |
2787 | .\".IP | |
2788 | .\".UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2789 | .\"http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2790 | .\".UE | |
cd29a5c8 | 2791 | .PP |
2ae555c3 | 2792 | The latest version of |
a9d69660 NB |
2793 | .I mdadm |
2794 | should always be available from | |
cd29a5c8 | 2795 | .IP |
11cd8b79 N |
2796 | .B http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
2797 | .PP | |
2798 | Related man pages: | |
cd29a5c8 | 2799 | .PP |
e0fe762a | 2800 | .IR mdmon (8), |
a9d69660 NB |
2801 | .IR mdadm.conf (5), |
2802 | .IR md (4). | |
56eb10c0 | 2803 | .PP |
52826846 NB |
2804 | .IR raidtab (5), |
2805 | .IR raid0run (8), | |
2806 | .IR raidstop (8), | |
a9d69660 | 2807 | .IR mkraid (8). |