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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. | |
1679bef2 | 8 | .TH MDADM 8 "" v3.0-devel2 |
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 |
cd29a5c8 | 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 NB |
48 | each device is a path to one common physical storage device. |
49 | ||
a9d69660 NB |
50 | .B FAULTY |
51 | is also not true RAID, and it only involves one device. It | |
b5e64645 | 52 | provides a layer over a true device that can be used to inject faults. |
52826846 | 53 | |
4cce4069 | 54 | .B CONTAINER |
8fd8d9c4 N |
55 | is different again. A |
56 | .B CONTAINER | |
57 | is a collection of devices that are | |
90c8d668 N |
58 | managed as a set. This is similar to the set of devices connected to |
59 | a hardware RAID controller. The set of devices may contain a number | |
60 | of different RAID arrays each utilising some (or all) blocks from a | |
61 | number of the devices in the set. For example, two devices in a 5-device set | |
62 | might form a RAID1 used the whole devices. The remaining three might | |
63 | have a RAID5 over the first half of each device, and a RAID0 over the | |
64 | second half. | |
65 | ||
8fd8d9c4 N |
66 | With a |
67 | .BR CONTAINER , | |
68 | there is one set of metadata that describes all of | |
69 | the arrays in the container. So when | |
70 | .I mdadm | |
71 | creates a | |
72 | .B CONTAINER | |
73 | device, it just represents the metadata. Other normal arrays (RAID1 | |
74 | etc) can be created inside that container. | |
90c8d668 N |
75 | |
76 | ||
51ac42e3 | 77 | .\".I mdadm |
e43d0cda NB |
78 | .\"is a program that can be used to create, manage, and monitor |
79 | .\"MD devices. As | |
80 | .\"such it provides a similar set of functionality to the | |
81 | .\".B raidtools | |
82 | .\"packages. | |
83 | .\"The key differences between | |
51ac42e3 | 84 | .\".I mdadm |
e43d0cda NB |
85 | .\"and |
86 | .\".B raidtools | |
87 | .\"are: | |
88 | .\".IP \(bu 4 | |
51ac42e3 | 89 | .\".I mdadm |
e43d0cda NB |
90 | .\"is a single program and not a collection of programs. |
91 | .\".IP \(bu 4 | |
51ac42e3 | 92 | .\".I mdadm |
e43d0cda NB |
93 | .\"can perform (almost) all of its functions without having a |
94 | .\"configuration file and does not use one by default. Also | |
51ac42e3 | 95 | .\".I mdadm |
e43d0cda NB |
96 | .\"helps with management of the configuration |
97 | .\"file. | |
98 | .\".IP \(bu 4 | |
51ac42e3 | 99 | .\".I mdadm |
e43d0cda NB |
100 | .\"can provide information about your arrays (through Query, Detail, and Examine) |
101 | .\"that | |
102 | .\".B raidtools | |
103 | .\"cannot. | |
104 | .\".P | |
105 | .\".I mdadm | |
106 | .\"does not use | |
107 | .\".IR /etc/raidtab , | |
108 | .\"the | |
109 | .\".B raidtools | |
110 | .\"configuration file, at all. It has a different configuration file | |
111 | .\"with a different format and a different purpose. | |
52826846 NB |
112 | |
113 | .SH MODES | |
8382f19b | 114 | mdadm has several major modes of operation: |
cd29a5c8 NB |
115 | .TP |
116 | .B Assemble | |
93e790af | 117 | Assemble the components of a previously created |
52826846 | 118 | array into an active array. Components can be explicitly given |
2ae555c3 | 119 | or can be searched for. |
51ac42e3 | 120 | .I mdadm |
cd29a5c8 NB |
121 | checks that the components |
122 | do form a bona fide array, and can, on request, fiddle superblock | |
123 | information so as to assemble a faulty array. | |
124 | ||
125 | .TP | |
126 | .B Build | |
a9d69660 NB |
127 | Build an array that doesn't have per-device superblocks. For these |
128 | sorts of arrays, | |
129 | .I mdadm | |
130 | cannot differentiate between initial creation and subsequent assembly | |
131 | of an array. It also cannot perform any checks that appropriate | |
93e790af | 132 | components have been requested. Because of this, the |
a9d69660 NB |
133 | .B Build |
134 | mode should only be used together with a complete understanding of | |
135 | what you are doing. | |
cd29a5c8 NB |
136 | |
137 | .TP | |
138 | .B Create | |
139 | Create a new array with per-device superblocks. | |
e43d0cda NB |
140 | .\"It can progress |
141 | .\"in several step create-add-add-run or it can all happen with one command. | |
cd29a5c8 | 142 | |
cd29a5c8 NB |
143 | .TP |
144 | .B "Follow or Monitor" | |
5787fa49 | 145 | Monitor one or more md devices and act on any state changes. This is |
93e790af | 146 | only meaningful for raid1, 4, 5, 6, 10 or multipath arrays, as |
98c6faba NB |
147 | only these have interesting state. raid0 or linear never have |
148 | missing, spare, or failed drives, so there is nothing to monitor. | |
5787fa49 | 149 | |
dd0781e5 NB |
150 | .TP |
151 | .B "Grow" | |
152 | Grow (or shrink) an array, or otherwise reshape it in some way. | |
153 | Currently supported growth options including changing the active size | |
93e790af SW |
154 | of component devices and changing the number of active devices in RAID |
155 | levels 1/4/5/6, as well as adding or removing a write-intent bitmap. | |
cd29a5c8 | 156 | |
8382f19b NB |
157 | .TP |
158 | .B "Incremental Assembly" | |
159 | Add a single device to an appropriate array. If the addition of the | |
160 | device makes the array runnable, the array will be started. | |
161 | This provides a convenient interface to a | |
162 | .I hot-plug | |
163 | system. As each device is detected, | |
164 | .I mdadm | |
165 | has a chance to include it in some array as appropriate. | |
8fd8d9c4 N |
166 | .P |
167 | If a | |
168 | .B CONTAINER | |
169 | is passed to | |
170 | .I mdadm | |
171 | in this mode, then any arrays within that container will be assembled | |
172 | and started. | |
8382f19b | 173 | |
2ae555c3 NB |
174 | .TP |
175 | .B Manage | |
176 | This is for doing things to specific components of an array such as | |
177 | adding new spares and removing faulty devices. | |
178 | ||
179 | .TP | |
180 | .B Misc | |
181 | This is an 'everything else' mode that supports operations on active | |
182 | arrays, operations on component devices such as erasing old superblocks, and | |
183 | information gathering operations. | |
e43d0cda NB |
184 | .\"This mode allows operations on independent devices such as examine MD |
185 | .\"superblocks, erasing old superblocks and stopping active arrays. | |
2ae555c3 | 186 | |
1f48664b NB |
187 | .TP |
188 | .B Auto-detect | |
189 | This mode does not act on a specific device or array, but rather it | |
190 | requests the Linux Kernel to activate any auto-detected arrays. | |
52826846 NB |
191 | .SH OPTIONS |
192 | ||
2ae555c3 | 193 | .SH Options for selecting a mode are: |
52826846 | 194 | |
cd29a5c8 | 195 | .TP |
7e23fc43 | 196 | .BR \-A ", " \-\-assemble |
2d465520 | 197 | Assemble a pre-existing array. |
52826846 | 198 | |
cd29a5c8 | 199 | .TP |
7e23fc43 | 200 | .BR \-B ", " \-\-build |
cd29a5c8 | 201 | Build a legacy array without superblocks. |
52826846 | 202 | |
cd29a5c8 | 203 | .TP |
7e23fc43 | 204 | .BR \-C ", " \-\-create |
cd29a5c8 | 205 | Create a new array. |
52826846 | 206 | |
cd29a5c8 | 207 | .TP |
7e23fc43 | 208 | .BR \-F ", " \-\-follow ", " \-\-monitor |
cd29a5c8 NB |
209 | Select |
210 | .B Monitor | |
211 | mode. | |
52826846 | 212 | |
dd0781e5 | 213 | .TP |
7e23fc43 | 214 | .BR \-G ", " \-\-grow |
dd0781e5 | 215 | Change the size or shape of an active array. |
8382f19b NB |
216 | |
217 | .TP | |
1f48664b | 218 | .BR \-I ", " \-\-incremental |
8382f19b NB |
219 | Add a single device into an appropriate array, and possibly start the array. |
220 | ||
1f48664b NB |
221 | .TP |
222 | .B \-\-auto-detect | |
223 | Request that the kernel starts any auto-detected arrays. This can only | |
224 | work if | |
225 | .I md | |
226 | is compiled into the kernel \(em not if it is a module. | |
227 | Arrays can be auto-detected by the kernel if all the components are in | |
228 | primary MS-DOS partitions with partition type | |
229 | .BR FD . | |
230 | In-kernel autodetect is not recommended for new installations. Using | |
231 | .I mdadm | |
232 | to detect and assemble arrays \(em possibly in an | |
233 | .I initrd | |
234 | \(em is substantially more flexible and should be preferred. | |
235 | ||
2ae555c3 NB |
236 | .P |
237 | If a device is given before any options, or if the first option is | |
7e23fc43 PS |
238 | .BR \-\-add , |
239 | .BR \-\-fail , | |
2ae555c3 | 240 | or |
7e23fc43 | 241 | .BR \-\-remove , |
2ae555c3 NB |
242 | then the MANAGE mode is assume. |
243 | Anything other than these will cause the | |
244 | .B Misc | |
245 | mode to be assumed. | |
dd0781e5 | 246 | |
2ae555c3 | 247 | .SH Options that are not mode-specific are: |
e793c2e5 | 248 | |
cd29a5c8 | 249 | .TP |
7e23fc43 | 250 | .BR \-h ", " \-\-help |
a9d69660 | 251 | Display general help message or, after one of the above options, a |
93e790af | 252 | mode-specific help message. |
56eedc1a NB |
253 | |
254 | .TP | |
7e23fc43 | 255 | .B \-\-help\-options |
56eedc1a NB |
256 | Display more detailed help about command line parsing and some commonly |
257 | used options. | |
52826846 | 258 | |
cd29a5c8 | 259 | .TP |
7e23fc43 | 260 | .BR \-V ", " \-\-version |
9a9dab36 | 261 | Print version information for mdadm. |
52826846 | 262 | |
cd29a5c8 | 263 | .TP |
7e23fc43 | 264 | .BR \-v ", " \-\-verbose |
22892d56 NB |
265 | Be more verbose about what is happening. This can be used twice to be |
266 | extra-verbose. | |
a9d69660 | 267 | The extra verbosity currently only affects |
7e23fc43 | 268 | .B \-\-detail \-\-scan |
22892d56 | 269 | and |
7e23fc43 | 270 | .BR "\-\-examine \-\-scan" . |
52826846 | 271 | |
dab6685f | 272 | .TP |
7e23fc43 | 273 | .BR \-q ", " \-\-quiet |
dab6685f | 274 | Avoid printing purely informative messages. With this, |
51ac42e3 | 275 | .I mdadm |
dab6685f NB |
276 | will be silent unless there is something really important to report. |
277 | ||
cd29a5c8 | 278 | .TP |
7e23fc43 | 279 | .BR \-b ", " \-\-brief |
cd29a5c8 | 280 | Be less verbose. This is used with |
7e23fc43 | 281 | .B \-\-detail |
cd29a5c8 | 282 | and |
7e23fc43 | 283 | .BR \-\-examine . |
22892d56 | 284 | Using |
7e23fc43 | 285 | .B \-\-brief |
22892d56 | 286 | with |
7e23fc43 | 287 | .B \-\-verbose |
22892d56 | 288 | gives an intermediate level of verbosity. |
52826846 | 289 | |
e0d19036 | 290 | .TP |
7e23fc43 | 291 | .BR \-f ", " \-\-force |
93e790af | 292 | Be more forceful about certain operations. See the various modes for |
e0d19036 NB |
293 | the exact meaning of this option in different contexts. |
294 | ||
295 | .TP | |
7e23fc43 | 296 | .BR \-c ", " \-\-config= |
2ae555c3 NB |
297 | Specify the config file. Default is to use |
298 | .BR /etc/mdadm.conf , | |
93e790af | 299 | or if that is missing then |
2ae555c3 | 300 | .BR /etc/mdadm/mdadm.conf . |
5787fa49 | 301 | If the config file given is |
93e790af | 302 | .B "partitions" |
5787fa49 NB |
303 | then nothing will be read, but |
304 | .I mdadm | |
305 | will act as though the config file contained exactly | |
8fd8d9c4 | 306 | .B "DEVICE partitions containers" |
5787fa49 NB |
307 | and will read |
308 | .B /proc/partitions | |
8fd8d9c4 N |
309 | to find a list of devices to scan, and |
310 | .B /proc/mdstat | |
311 | to find a list of containers to examine. | |
d013a55e | 312 | If the word |
93e790af | 313 | .B "none" |
d013a55e NB |
314 | is given for the config file, then |
315 | .I mdadm | |
316 | will act as though the config file were empty. | |
e0d19036 NB |
317 | |
318 | .TP | |
7e23fc43 | 319 | .BR \-s ", " \-\-scan |
93e790af | 320 | Scan config file or |
e0d19036 NB |
321 | .B /proc/mdstat |
322 | for missing information. | |
323 | In general, this option gives | |
51ac42e3 | 324 | .I mdadm |
93e790af SW |
325 | permission to get any missing information (like component devices, |
326 | array devices, array identities, and alert destination) from the | |
327 | configuration file (see previous option); | |
328 | one exception is MISC mode when using | |
7e23fc43 | 329 | .B \-\-detail |
e0d19036 | 330 | or |
93e790af | 331 | .B \-\-stop, |
e0d19036 | 332 | in which case |
7e23fc43 | 333 | .B \-\-scan |
e0d19036 NB |
334 | says to get a list of array devices from |
335 | .BR /proc/mdstat . | |
336 | ||
570c0542 | 337 | .TP |
7e23fc43 | 338 | .B \-e ", " \-\-metadata= |
570c0542 | 339 | Declare the style of superblock (raid metadata) to be used. The |
53e8b987 | 340 | default is 0.90 for |
7e23fc43 | 341 | .BR \-\-create , |
53e8b987 | 342 | and to guess for other operations. |
2790ffe3 GB |
343 | The default can be overridden by setting the |
344 | .B metadata | |
345 | value for the | |
346 | .B CREATE | |
347 | keyword in | |
348 | .BR mdadm.conf . | |
570c0542 NB |
349 | |
350 | Options are: | |
351 | .RS | |
352 | .IP "0, 0.90, default" | |
353 | Use the original 0.90 format superblock. This format limits arrays to | |
93e790af | 354 | 28 component devices and limits component devices of levels 1 and |
570c0542 NB |
355 | greater to 2 terabytes. |
356 | .IP "1, 1.0, 1.1, 1.2" | |
357 | Use the new version-1 format superblock. This has few restrictions. | |
93e790af | 358 | The different sub-versions store the superblock at different locations |
570c0542 NB |
359 | on the device, either at the end (for 1.0), at the start (for 1.1) or |
360 | 4K from the start (for 1.2). | |
8fd8d9c4 N |
361 | .IP ddf |
362 | Use the "Industry Standard" DDF (Disk Data Format) format. When | |
363 | creating a DDF array a | |
364 | .B CONTAINER | |
365 | will be created, and normal arrays can be created in that container. | |
366 | .IP imsm | |
4cce4069 | 367 | Use the Intel(R) Matrix Storage Manager metadata format. This creates a |
8fd8d9c4 | 368 | .B CONTAINER |
4cce4069 DW |
369 | which is managed in a similar manner to DDF, and is supported by an |
370 | option-rom on some platforms: | |
371 | .IP | |
372 | .B http://www.intel.com/design/chipsets/matrixstorage_sb.htm | |
373 | .PP | |
570c0542 NB |
374 | .RE |
375 | ||
41a3b72a | 376 | .TP |
7e23fc43 | 377 | .B \-\-homehost= |
35cc5be4 | 378 | This will override any |
41a3b72a | 379 | .B HOMEHOST |
93e790af | 380 | setting in the config file and provides the identity of the host which |
41a3b72a NB |
381 | should be considered the home for any arrays. |
382 | ||
383 | When creating an array, the | |
384 | .B homehost | |
385 | will be recorded in the superblock. For version-1 superblocks, it will | |
93e790af | 386 | be prefixed to the array name. For version-0.90 superblocks, part of |
41a3b72a NB |
387 | the SHA1 hash of the hostname will be stored in the later half of the |
388 | UUID. | |
389 | ||
390 | When reporting information about an array, any array which is tagged | |
391 | for the given homehost will be reported as such. | |
392 | ||
393 | When using Auto-Assemble, only arrays tagged for the given homehost | |
394 | will be assembled. | |
395 | ||
2ae555c3 NB |
396 | .SH For create, build, or grow: |
397 | ||
398 | .TP | |
7e23fc43 | 399 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
400 | Specify the number of active devices in the array. This, plus the |
401 | number of spare devices (see below) must equal the number of | |
402 | .I component-devices | |
403 | (including "\fBmissing\fP" devices) | |
404 | that are listed on the command line for | |
7e23fc43 | 405 | .BR \-\-create . |
2ae555c3 NB |
406 | Setting a value of 1 is probably |
407 | a mistake and so requires that | |
7e23fc43 | 408 | .B \-\-force |
2ae555c3 NB |
409 | be specified first. A value of 1 will then be allowed for linear, |
410 | multipath, raid0 and raid1. It is never allowed for raid4 or raid5. | |
411 | .br | |
412 | This number can only be changed using | |
7e23fc43 | 413 | .B \-\-grow |
00be0b12 NB |
414 | for RAID1, RAID5 and RAID6 arrays, and only on kernels which provide |
415 | necessary support. | |
2ae555c3 NB |
416 | |
417 | .TP | |
7e23fc43 | 418 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
419 | Specify the number of spare (eXtra) devices in the initial array. |
420 | Spares can also be added | |
421 | and removed later. The number of component devices listed | |
422 | on the command line must equal the number of raid devices plus the | |
423 | number of spare devices. | |
424 | ||
425 | ||
426 | .TP | |
7e23fc43 | 427 | .BR \-z ", " \-\-size= |
93e790af | 428 | Amount (in Kibibytes) of space to use from each drive in RAID level 1/4/5/6. |
2ae555c3 NB |
429 | This must be a multiple of the chunk size, and must leave about 128Kb |
430 | of space at the end of the drive for the RAID superblock. | |
431 | If this is not specified | |
432 | (as it normally is not) the smallest drive (or partition) sets the | |
433 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
434 | issued. | |
435 | ||
436 | This value can be set with | |
7e23fc43 | 437 | .B \-\-grow |
2ae555c3 NB |
438 | for RAID level 1/4/5/6. If the array was created with a size smaller |
439 | than the currently active drives, the extra space can be accessed | |
440 | using | |
7e23fc43 | 441 | .BR \-\-grow . |
2ae555c3 NB |
442 | The size can be given as |
443 | .B max | |
444 | which means to choose the largest size that fits on all current drives. | |
52826846 | 445 | |
8fd8d9c4 N |
446 | This value can not be used with |
447 | .B CONTAINER | |
448 | metadata such as DDF and IMSM. | |
449 | ||
cd29a5c8 | 450 | .TP |
7e23fc43 | 451 | .BR \-c ", " \-\-chunk= |
cd29a5c8 | 452 | Specify chunk size of kibibytes. The default is 64. |
52826846 | 453 | |
cd29a5c8 | 454 | .TP |
7e23fc43 | 455 | .BR \-\-rounding= |
cd29a5c8 | 456 | Specify rounding factor for linear array (==chunk size) |
52826846 | 457 | |
cd29a5c8 | 458 | .TP |
7e23fc43 | 459 | .BR \-l ", " \-\-level= |
aa88f531 | 460 | Set raid level. When used with |
7e23fc43 | 461 | .BR \-\-create , |
98c6faba | 462 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
8fd8d9c4 N |
463 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container. |
464 | Obviously some of these are synonymous. | |
465 | ||
466 | When a | |
467 | .B CONTAINER | |
468 | metadata type is requested, only the | |
469 | .B container | |
470 | level is permitted, and it does not need to be explicitly given. | |
aa88f531 NB |
471 | |
472 | When used with | |
7e23fc43 | 473 | .BR \-\-build , |
a9d69660 | 474 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 475 | |
2ae555c3 | 476 | Not yet supported with |
7e23fc43 | 477 | .BR \-\-grow . |
2ae555c3 | 478 | |
cd29a5c8 | 479 | .TP |
7e23fc43 | 480 | .BR \-p ", " \-\-layout= |
1a7dfc35 NB |
481 | This option configures the fine details of data layout for raid5, |
482 | and raid10 arrays, and controls the failure modes for | |
483 | .IR faulty . | |
484 | ||
485 | The layout of the raid5 parity block can be one of | |
7e23fc43 PS |
486 | .BR left\-asymmetric , |
487 | .BR left\-symmetric , | |
488 | .BR right\-asymmetric , | |
489 | .BR right\-symmetric , | |
53e8b987 PS |
490 | .BR la ", " ra ", " ls ", " rs . |
491 | The default is | |
7e23fc43 | 492 | .BR left\-symmetric . |
52826846 | 493 | |
93e790af SW |
494 | When setting the failure mode for level |
495 | .I faulty, | |
1a7dfc35 | 496 | the options are: |
7e23fc43 PS |
497 | .BR write\-transient ", " wt , |
498 | .BR read\-transient ", " rt , | |
499 | .BR write\-persistent ", " wp , | |
500 | .BR read\-persistent ", " rp , | |
501 | .BR write\-all , | |
502 | .BR read\-fixable ", " rf , | |
53e8b987 | 503 | .BR clear ", " flush ", " none . |
b5e64645 | 504 | |
93e790af | 505 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
506 | between fault generation. Without a number, the fault is generated |
507 | once on the first relevant request. With a number, the fault will be | |
93e790af | 508 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
509 | every time the period elapses. |
510 | ||
511 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 512 | .B \-\-grow |
53e8b987 | 513 | option to set subsequent failure modes. |
b5e64645 NB |
514 | |
515 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 516 | and "flush" will clear any persistent faults. |
b5e64645 | 517 | |
53e8b987 | 518 | To set the parity with |
7e23fc43 | 519 | .BR \-\-grow , |
53e8b987 | 520 | the level of the array ("faulty") |
b5e64645 NB |
521 | must be specified before the fault mode is specified. |
522 | ||
6f9a21a7 | 523 | Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 524 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 525 | |
93e790af | 526 | .I 'n' |
b578481c NB |
527 | signals 'near' copies. Multiple copies of one data block are at |
528 | similar offsets in different devices. | |
529 | ||
93e790af | 530 | .I 'o' |
b578481c NB |
531 | signals 'offset' copies. Rather than the chunks being duplicated |
532 | within a stripe, whole stripes are duplicated but are rotated by one | |
533 | device so duplicate blocks are on different devices. Thus subsequent | |
534 | copies of a block are in the next drive, and are one chunk further | |
535 | down. | |
536 | ||
93e790af | 537 | .I 'f' |
1a7dfc35 | 538 | signals 'far' copies |
93e790af SW |
539 | (multiple copies have very different offsets). |
540 | See md(4) for more detail about 'near' and 'far'. | |
1a7dfc35 NB |
541 | |
542 | The number is the number of copies of each datablock. 2 is normal, 3 | |
543 | can be useful. This number can be at most equal to the number of | |
544 | devices in the array. It does not need to divide evenly into that | |
545 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
546 | with an odd number of devices). | |
547 | ||
cd29a5c8 | 548 | .TP |
7e23fc43 | 549 | .BR \-\-parity= |
53e8b987 | 550 | same as |
7e23fc43 | 551 | .B \-\-layout |
53e8b987 | 552 | (thus explaining the p of |
7e23fc43 | 553 | .BR \-p ). |
52826846 | 554 | |
e793c2e5 | 555 | .TP |
7e23fc43 | 556 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 557 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 558 | exist unless |
7e23fc43 | 559 | .B \-\-force |
53e8b987 | 560 | is also given. The same file should be provided |
2ae555c3 | 561 | when assembling the array. If the word |
93e790af | 562 | .B "internal" |
2ae555c3 NB |
563 | is given, then the bitmap is stored with the metadata on the array, |
564 | and so is replicated on all devices. If the word | |
93e790af | 565 | .B "none" |
2ae555c3 | 566 | is given with |
7e23fc43 | 567 | .B \-\-grow |
2ae555c3 | 568 | mode, then any bitmap that is present is removed. |
e793c2e5 | 569 | |
2ae555c3 NB |
570 | To help catch typing errors, the filename must contain at least one |
571 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
572 | ||
573 | Note: external bitmaps are only known to work on ext2 and ext3. | |
574 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 575 | |
cd29a5c8 | 576 | .TP |
7e23fc43 | 577 | .BR \-\-bitmap\-chunk= |
2ae555c3 | 578 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
579 | Kilobytes of storage. |
580 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 581 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
582 | When using an |
583 | .B internal | |
584 | bitmap, the chunksize is automatically determined to make best use of | |
585 | available space. | |
5787fa49 | 586 | |
cd29a5c8 NB |
587 | |
588 | .TP | |
7e23fc43 | 589 | .BR \-W ", " \-\-write\-mostly |
2ae555c3 | 590 | subsequent devices lists in a |
7e23fc43 PS |
591 | .BR \-\-build , |
592 | .BR \-\-create , | |
2ae555c3 | 593 | or |
7e23fc43 | 594 | .B \-\-add |
2ae555c3 NB |
595 | command will be flagged as 'write-mostly'. This is valid for RAID1 |
596 | only and means that the 'md' driver will avoid reading from these | |
597 | devices if at all possible. This can be useful if mirroring over a | |
598 | slow link. | |
52826846 | 599 | |
2ae555c3 | 600 | .TP |
7e23fc43 | 601 | .BR \-\-write\-behind= |
2ae555c3 NB |
602 | Specify that write-behind mode should be enabled (valid for RAID1 |
603 | only). If an argument is specified, it will set the maximum number | |
604 | of outstanding writes allowed. The default value is 256. | |
605 | A write-intent bitmap is required in order to use write-behind | |
606 | mode, and write-behind is only attempted on drives marked as | |
607 | .IR write-mostly . | |
dd0781e5 NB |
608 | |
609 | .TP | |
7e23fc43 | 610 | .BR \-\-assume\-clean |
dd0781e5 NB |
611 | Tell |
612 | .I mdadm | |
47d79ef8 NB |
613 | that the array pre-existed and is known to be clean. It can be useful |
614 | when trying to recover from a major failure as you can be sure that no | |
615 | data will be affected unless you actually write to the array. It can | |
616 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 617 | initial resync, however this practice \(em while normally safe \(em is not |
93e790af | 618 | recommended. Use this only if you really know what you are doing. |
dd0781e5 | 619 | |
2ae555c3 | 620 | .TP |
7e23fc43 | 621 | .BR \-\-backup\-file= |
53e8b987 | 622 | This is needed when |
7e23fc43 | 623 | .B \-\-grow |
53e8b987 | 624 | is used to increase the number of |
2ae555c3 NB |
625 | raid-devices in a RAID5 if there are no spare devices available. |
626 | See the section below on RAID_DEVICE CHANGES. The file should be | |
627 | stored on a separate device, not on the raid array being reshaped. | |
628 | ||
947fd4dd | 629 | .TP |
7e23fc43 | 630 | .BR \-N ", " \-\-name= |
947fd4dd NB |
631 | Set a |
632 | .B name | |
633 | for the array. This is currently only effective when creating an | |
634 | array with a version-1 superblock. The name is a simple textual | |
635 | string that can be used to identify array components when assembling. | |
636 | ||
dd0781e5 | 637 | .TP |
7e23fc43 | 638 | .BR \-R ", " \-\-run |
dd0781e5 NB |
639 | Insist that |
640 | .I mdadm | |
641 | run the array, even if some of the components | |
642 | appear to be active in another array or filesystem. Normally | |
643 | .I mdadm | |
644 | will ask for confirmation before including such components in an | |
645 | array. This option causes that question to be suppressed. | |
646 | ||
647 | .TP | |
7e23fc43 | 648 | .BR \-f ", " \-\-force |
dd0781e5 NB |
649 | Insist that |
650 | .I mdadm | |
651 | accept the geometry and layout specified without question. Normally | |
652 | .I mdadm | |
653 | will not allow creation of an array with only one device, and will try | |
654 | to create a raid5 array with one missing drive (as this makes the | |
655 | initial resync work faster). With | |
7e23fc43 | 656 | .BR \-\-force , |
dd0781e5 NB |
657 | .I mdadm |
658 | will not try to be so clever. | |
659 | ||
660 | .TP | |
7e23fc43 | 661 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part,p}{NN}" |
48f7b27a NB |
662 | Instruct mdadm to create the device file if needed, possibly allocating |
663 | an unused minor number. "md" causes a non-partitionable array | |
dd0781e5 | 664 | to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and |
2ae555c3 | 665 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 666 | a 'standard' format, and the type and minor number will be determined |
48f7b27a NB |
667 | from this. See DEVICE NAMES below. |
668 | ||
a9d69660 | 669 | The argument can also come immediately after |
7e23fc43 | 670 | "\-a". e.g. "\-ap". |
dd0781e5 | 671 | |
53e8b987 | 672 | If |
7e23fc43 | 673 | .B \-\-auto |
53e8b987 | 674 | is not given on the command line or in the config file, then |
75723446 | 675 | the default will be |
7e23fc43 | 676 | .BR \-\-auto=yes . |
75723446 | 677 | |
1337546d | 678 | If |
7e23fc43 | 679 | .B \-\-scan |
1337546d NB |
680 | is also given, then any |
681 | .I auto= | |
35cc5be4 | 682 | entries in the config file will override the |
7e23fc43 | 683 | .B \-\-auto |
1337546d NB |
684 | instruction given on the command line. |
685 | ||
dd0781e5 NB |
686 | For partitionable arrays, |
687 | .I mdadm | |
688 | will create the device file for the whole array and for the first 4 | |
689 | partitions. A different number of partitions can be specified at the | |
690 | end of this option (e.g. | |
7e23fc43 | 691 | .BR \-\-auto=p7 ). |
2ae555c3 | 692 | If the device name ends with a digit, the partition names add a 'p', |
8fd8d9c4 | 693 | and a number, e.g. "/dev/md/home1p3". If there is no |
dd0781e5 | 694 | trailing digit, then the partition names just have a number added, |
8fd8d9c4 | 695 | e.g. "/dev/md/scratch3". |
dd0781e5 | 696 | |
48f7b27a NB |
697 | If the md device name is in a 'standard' format as described in DEVICE |
698 | NAMES, then it will be created, if necessary, with the appropriate | |
699 | number based on that name. If the device name is not in one of these | |
a9d69660 | 700 | formats, then a unused minor number will be allocated. The minor |
48f7b27a NB |
701 | number will be considered unused if there is no active array for that |
702 | number, and there is no entry in /dev for that number and with a | |
8fd8d9c4 N |
703 | non-standard name. Name that are not in 'standard' format are only |
704 | allowed in "/dev/md/". | |
705 | ||
706 | \".TP | |
707 | \".BR \-\-symlink = no | |
708 | \"Normally when | |
709 | \".B \-\-auto | |
710 | \"causes | |
711 | \".I mdadm | |
712 | \"to create devices in | |
713 | \".B /dev/md/ | |
714 | \"it will also create symlinks from | |
715 | \".B /dev/ | |
716 | \"with names starting with | |
717 | \".B md | |
718 | \"or | |
719 | \".BR md_ . | |
720 | \"Use | |
721 | \".B \-\-symlink=no | |
722 | \"to suppress this, or | |
723 | \".B \-\-symlink=yes | |
724 | \"to enforce this even if it is suppressing | |
725 | \".IR mdadm.conf . | |
726 | \" | |
38098016 | 727 | |
52826846 NB |
728 | .SH For assemble: |
729 | ||
cd29a5c8 | 730 | .TP |
7e23fc43 | 731 | .BR \-u ", " \-\-uuid= |
cd29a5c8 NB |
732 | uuid of array to assemble. Devices which don't have this uuid are |
733 | excluded | |
734 | ||
735 | .TP | |
7e23fc43 | 736 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
737 | Minor number of device that array was created for. Devices which |
738 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 739 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
740 | the array is later assembled as /dev/md2. |
741 | ||
d013a55e | 742 | Giving the literal word "dev" for |
7e23fc43 | 743 | .B \-\-super\-minor |
d013a55e NB |
744 | will cause |
745 | .I mdadm | |
746 | to use the minor number of the md device that is being assembled. | |
747 | e.g. when assembling | |
748 | .BR /dev/md0 , | |
51ac42e3 | 749 | .B \-\-super\-minor=dev |
d013a55e NB |
750 | will look for super blocks with a minor number of 0. |
751 | ||
947fd4dd | 752 | .TP |
7e23fc43 | 753 | .BR \-N ", " \-\-name= |
947fd4dd | 754 | Specify the name of the array to assemble. This must be the name |
624920bb | 755 | that was specified when creating the array. It must either match |
93e790af | 756 | the name stored in the superblock exactly, or it must match |
41a3b72a | 757 | with the current |
624920bb | 758 | .I homehost |
93e790af | 759 | prefixed to the start of the given name. |
947fd4dd | 760 | |
cd29a5c8 | 761 | .TP |
7e23fc43 | 762 | .BR \-f ", " \-\-force |
52826846 NB |
763 | Assemble the array even if some superblocks appear out-of-date |
764 | ||
cd29a5c8 | 765 | .TP |
7e23fc43 | 766 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
767 | Attempt to start the array even if fewer drives were given than were |
768 | present last time the array was active. Normally if not all the | |
769 | expected drives are found and | |
7e23fc43 | 770 | .B \-\-scan |
cd29a5c8 NB |
771 | is not used, then the array will be assembled but not started. |
772 | With | |
7e23fc43 | 773 | .B \-\-run |
cd29a5c8 | 774 | an attempt will be made to start it anyway. |
52826846 | 775 | |
b8a8ccf9 | 776 | .TP |
7e23fc43 | 777 | .B \-\-no\-degraded |
b8a8ccf9 | 778 | This is the reverse of |
7e23fc43 | 779 | .B \-\-run |
93e790af | 780 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 781 | are present. This is only needed with |
93e790af SW |
782 | .B \-\-scan, |
783 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
784 | not as reliable as you would like. |
785 | ||
dd0781e5 | 786 | .TP |
7e23fc43 | 787 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
788 | See this option under Create and Build options. |
789 | ||
e793c2e5 | 790 | .TP |
7e23fc43 | 791 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
792 | Specify the bitmap file that was given when the array was created. If |
793 | an array has an | |
794 | .B internal | |
795 | bitmap, there is no need to specify this when assembling the array. | |
796 | ||
797 | .TP | |
7e23fc43 | 798 | .BR \-\-backup\-file= |
2ae555c3 | 799 | If |
7e23fc43 | 800 | .B \-\-backup\-file |
2ae555c3 NB |
801 | was used to grow the number of raid-devices in a RAID5, and the system |
802 | crashed during the critical section, then the same | |
7e23fc43 | 803 | .B \-\-backup\-file |
53e8b987 | 804 | must be presented to |
7e23fc43 | 805 | .B \-\-assemble |
53e8b987 | 806 | to allow possibly corrupted data to be restored. |
e793c2e5 | 807 | |
5787fa49 | 808 | .TP |
7e23fc43 | 809 | .BR \-U ", " \-\-update= |
5787fa49 | 810 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
811 | argument given to this flag can be one of |
812 | .BR sparc2.2 , | |
813 | .BR summaries , | |
7d99579f | 814 | .BR uuid , |
c4f12c13 | 815 | .BR name , |
0237e0ca | 816 | .BR homehost , |
e5329c37 | 817 | .BR resync , |
586ed405 | 818 | .BR byteorder , |
bee8ec56 | 819 | .BR devicesize , |
5787fa49 | 820 | or |
7e23fc43 | 821 | .BR super\-minor . |
5787fa49 NB |
822 | |
823 | The | |
824 | .B sparc2.2 | |
7d99579f | 825 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
826 | machine running a patched 2.2 Linux kernel. This kernel got the |
827 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 828 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
829 | option to |
830 | .I mdadm | |
831 | to see what effect this would have. | |
832 | ||
833 | The | |
7e23fc43 | 834 | .B super\-minor |
5787fa49 | 835 | option will update the |
2ae555c3 | 836 | .B "preferred minor" |
5787fa49 | 837 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
838 | assembled. |
839 | This can be useful if | |
7e23fc43 | 840 | .B \-\-examine |
45c073c9 | 841 | reports a different "Preferred Minor" to |
7e23fc43 | 842 | .BR \-\-detail . |
45c073c9 NB |
843 | In some cases this update will be performed automatically |
844 | by the kernel driver. In particular the update happens automatically | |
845 | at the first write to an array with redundancy (RAID level 1 or | |
846 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 847 | |
7d99579f NB |
848 | The |
849 | .B uuid | |
850 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 851 | .B \-\-uuid |
53e8b987 | 852 | option that UUID will be used as a new UUID and will |
7d99579f NB |
853 | .B NOT |
854 | be used to help identify the devices in the array. | |
53e8b987 | 855 | If no |
7e23fc43 | 856 | .B \-\-uuid |
53e8b987 | 857 | is given, a random UUID is chosen. |
7d99579f | 858 | |
c4f12c13 NB |
859 | The |
860 | .B name | |
861 | option will change the | |
862 | .I name | |
863 | of the array as stored in the superblock. This is only supported for | |
864 | version-1 superblocks. | |
865 | ||
0237e0ca NB |
866 | The |
867 | .B homehost | |
868 | option will change the | |
869 | .I homehost | |
870 | as recorded in the superblock. For version-0 superblocks, this is the | |
871 | same as updating the UUID. | |
872 | For version-1 superblocks, this involves updating the name. | |
873 | ||
e5329c37 NB |
874 | The |
875 | .B resync | |
876 | option will cause the array to be marked | |
877 | .I dirty | |
878 | meaning that any redundancy in the array (e.g. parity for raid5, | |
879 | copies for raid1) may be incorrect. This will cause the raid system | |
880 | to perform a "resync" pass to make sure that all redundant information | |
881 | is correct. | |
882 | ||
586ed405 NB |
883 | The |
884 | .B byteorder | |
885 | option allows arrays to be moved between machines with different | |
886 | byte-order. | |
2ae555c3 | 887 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 888 | .B "\-\-update=byteorder" |
586ed405 NB |
889 | will cause |
890 | .I mdadm | |
891 | to expect superblocks to have their byteorder reversed, and will | |
892 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 893 | with original (Version 0.90) superblocks. |
586ed405 | 894 | |
feb716e9 NB |
895 | The |
896 | .B summaries | |
897 | option will correct the summaries in the superblock. That is the | |
898 | counts of total, working, active, failed, and spare devices. | |
5787fa49 | 899 | |
bee8ec56 NB |
900 | The |
901 | .B devicesize | |
902 | will rarely be of use. It applies to version 1.1 and 1.2 metadata | |
903 | only (where the metadata is at the start of the device) and is only | |
904 | useful when the component device has changed size (typically become | |
905 | larger). The version 1 metadata records the amount of the device that | |
906 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
907 | array becomes larger, the metadata will still be visible, but the | |
908 | extra space will not. In this case it might be useful to assemble the | |
909 | array with | |
7e23fc43 | 910 | .BR \-\-update=devicesize . |
bee8ec56 NB |
911 | This will cause |
912 | .I mdadm | |
913 | to determine the maximum usable amount of space on each device and | |
914 | update the relevant field in the metadata. | |
915 | ||
41a3b72a | 916 | .TP |
7e23fc43 | 917 | .B \-\-auto\-update\-homehost |
93e790af | 918 | This flag is only meaningful with auto-assembly (see discussion below). |
41a3b72a NB |
919 | In that situation, if no suitable arrays are found for this homehost, |
920 | .I mdadm | |
93e790af | 921 | will rescan for any arrays at all and will assemble them and update the |
41a3b72a NB |
922 | homehost to match the current host. |
923 | ||
e0d19036 | 924 | .SH For Manage mode: |
52826846 | 925 | |
cd29a5c8 | 926 | .TP |
7e23fc43 | 927 | .BR \-a ", " \-\-add |
2ae555c3 | 928 | hot-add listed devices. |
52826846 | 929 | |
fe80f49b | 930 | .TP |
7e23fc43 | 931 | .BR \-\-re\-add |
2ae555c3 | 932 | re-add a device that was recently removed from an array. |
fe80f49b | 933 | |
cd29a5c8 | 934 | .TP |
7e23fc43 | 935 | .BR \-r ", " \-\-remove |
2d465520 | 936 | remove listed devices. They must not be active. i.e. they should |
b80da661 NB |
937 | be failed or spare devices. As well as the name of a device file |
938 | (e.g. | |
939 | .BR /dev/sda1 ) | |
940 | the words | |
941 | .B failed | |
942 | and | |
943 | .B detached | |
944 | can be given to | |
945 | .BR \-\-remove . | |
946 | The first causes all failed device to be removed. The second causes | |
93e790af | 947 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
948 | returns |
949 | .BR ENXIO ) | |
950 | to be removed. This will only succeed for devices that are spares or | |
951 | have already been marked as failed. | |
52826846 | 952 | |
cd29a5c8 | 953 | .TP |
7e23fc43 | 954 | .BR \-f ", " \-\-fail |
cd29a5c8 | 955 | mark listed devices as faulty. |
b80da661 NB |
956 | As well as the name of a device file, the word |
957 | .B detached | |
958 | can be given. This will cause any device that has been detached from | |
959 | the system to be marked as failed. It can then be removed. | |
52826846 | 960 | |
cd29a5c8 | 961 | .TP |
7e23fc43 | 962 | .BR \-\-set\-faulty |
53e8b987 | 963 | same as |
7e23fc43 | 964 | .BR \-\-fail . |
52826846 | 965 | |
b3d31955 N |
966 | .TP |
967 | .BR \-\-write\-mostly | |
968 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
969 | flag set. This is only valid for RAID! and means that the 'md' driver | |
970 | will avoid reading from these devices if possible. | |
971 | .TP | |
972 | .BR \-\-readwrite | |
973 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
974 | flag cleared. | |
975 | ||
976 | ||
2ae555c3 | 977 | .P |
93e790af SW |
978 | Each of these options require that the first device listed is the array |
979 | to be acted upon, and the remainder are component devices to be added, | |
980 | removed, or marked as faulty. Several different operations can be | |
2ae555c3 NB |
981 | specified for different devices, e.g. |
982 | .in +5 | |
7e23fc43 | 983 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
984 | .in -5 |
985 | Each operation applies to all devices listed until the next | |
93e790af | 986 | operation. |
2ae555c3 NB |
987 | |
988 | If an array is using a write-intent bitmap, then devices which have | |
989 | been removed can be re-added in a way that avoids a full | |
93e790af | 990 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
991 | since the device was removed. For arrays with persistent metadata |
992 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 993 | .B \-\-build |
2ae555c3 | 994 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 995 | .BR \-\-re\-add . |
2ae555c3 NB |
996 | |
997 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
998 | use, i.e. that must be spares or failed devices. To remove an active |
999 | device, it must first be marked as | |
1000 | .B faulty. | |
2ae555c3 NB |
1001 | |
1002 | .SH For Misc mode: | |
1003 | ||
1004 | .TP | |
7e23fc43 | 1005 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
1006 | Examine a device to see |
1007 | (1) if it is an md device and (2) if it is a component of an md | |
1008 | array. | |
1009 | Information about what is discovered is presented. | |
1010 | ||
1011 | .TP | |
7e23fc43 | 1012 | .BR \-D ", " \-\-detail |
2ae555c3 | 1013 | Print detail of one or more md devices. |
5787fa49 | 1014 | |
4cce4069 DW |
1015 | .TP |
1016 | .BR \-\-detail\-platform | |
1017 | Print detail of the platform's raid capabilities (firmware / hardware | |
1018 | topology) for a given metadata format. | |
1019 | ||
54bad364 KS |
1020 | .TP |
1021 | .BR \-Y ", " \-\-export | |
1022 | When used with | |
0d726f17 KS |
1023 | .B \-\-detail |
1024 | or | |
1025 | .BR \-\-examine , | |
54bad364 KS |
1026 | output will be formatted as |
1027 | .B key=value | |
1028 | pairs for easy import into the environment. | |
1029 | ||
2ae555c3 | 1030 | .TP |
7e23fc43 | 1031 | .BR \-E ", " \-\-examine |
2ae555c3 | 1032 | Print content of md superblock on device(s). |
5787fa49 | 1033 | .TP |
7e23fc43 | 1034 | .B \-\-sparc2.2 |
a9d69660 | 1035 | If an array was created on a 2.2 Linux kernel patched with RAID |
5787fa49 NB |
1036 | support, the superblock will have been created incorrectly, or at |
1037 | least incompatibly with 2.4 and later kernels. Using the | |
7e23fc43 | 1038 | .B \-\-sparc2.2 |
5787fa49 | 1039 | flag with |
7e23fc43 | 1040 | .B \-\-examine |
5787fa49 NB |
1041 | will fix the superblock before displaying it. If this appears to do |
1042 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 1043 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 1044 | |
2ae555c3 | 1045 | .TP |
7e23fc43 | 1046 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 1047 | Report information about a bitmap file. |
01d9299c NB |
1048 | The argument is either an external bitmap file or an array component |
1049 | in case of an internal bitmap. | |
e0d19036 | 1050 | |
cd29a5c8 | 1051 | .TP |
7e23fc43 | 1052 | .BR \-R ", " \-\-run |
cd29a5c8 | 1053 | start a partially built array. |
52826846 | 1054 | |
cd29a5c8 | 1055 | .TP |
7e23fc43 | 1056 | .BR \-S ", " \-\-stop |
cd29a5c8 | 1057 | deactivate array, releasing all resources. |
52826846 | 1058 | |
cd29a5c8 | 1059 | .TP |
7e23fc43 | 1060 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 1061 | mark array as readonly. |
52826846 | 1062 | |
cd29a5c8 | 1063 | .TP |
7e23fc43 | 1064 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 1065 | mark array as readwrite. |
52826846 | 1066 | |
e0d19036 | 1067 | .TP |
7e23fc43 | 1068 | .B \-\-zero\-superblock |
e0d19036 | 1069 | If the device contains a valid md superblock, the block is |
35cc5be4 | 1070 | overwritten with zeros. With |
7e23fc43 | 1071 | .B \-\-force |
35cc5be4 | 1072 | the block where the superblock would be is overwritten even if it |
e0d19036 | 1073 | doesn't appear to be valid. |
52826846 | 1074 | |
feb716e9 | 1075 | .TP |
7e23fc43 | 1076 | .BR \-t ", " \-\-test |
feb716e9 | 1077 | When used with |
7e23fc43 | 1078 | .BR \-\-detail , |
feb716e9 NB |
1079 | the exit status of |
1080 | .I mdadm | |
1081 | is set to reflect the status of the device. | |
1082 | ||
b90c0e9a | 1083 | .TP |
7e23fc43 | 1084 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1085 | For each md device given, wait for any resync, recovery, or reshape |
1086 | activity to finish before returning. | |
1087 | .I mdadm | |
1088 | will return with success if it actually waited for every device | |
1089 | listed, otherwise it will return failure. | |
1090 | ||
1770662b DW |
1091 | .TP |
1092 | .BR \-\-wait\-clean | |
fabbfd48 DW |
1093 | For each md device given, or each device in /proc/mdstat if |
1094 | .B \-\-scan | |
1095 | is given, arrange for the array to be marked clean as soon as possible. | |
1096 | Also, quiesce resync so that the monitor for external metadata arrays | |
1097 | (mdmon) has an opportunity to checkpoint the resync position. | |
7146ec6a DW |
1098 | .I mdadm |
1099 | will return with success if the array uses external metadata and we | |
1100 | successfully waited. For native arrays this returns immediately as the | |
1101 | kernel handles both dirty-clean transitions and resync checkpointing in | |
1102 | the kernel at shutdown. No action is taken if safe-mode handling is | |
1103 | disabled. | |
1770662b | 1104 | |
8382f19b NB |
1105 | .SH For Incremental Assembly mode: |
1106 | .TP | |
7e23fc43 | 1107 | .BR \-\-rebuild\-map ", " \-r |
8382f19b NB |
1108 | Rebuild the map file |
1109 | .RB ( /var/run/mdadm/map ) | |
1110 | that | |
1111 | .I mdadm | |
1112 | uses to help track which arrays are currently being assembled. | |
1113 | ||
1114 | .TP | |
7e23fc43 | 1115 | .BR \-\-run ", " \-R |
8382f19b NB |
1116 | Run any array assembled as soon as a minimal number of devices are |
1117 | available, rather than waiting until all expected devices are present. | |
1118 | ||
fdb482f9 DW |
1119 | .TP |
1120 | .B \-\-no\-degraded | |
1121 | This allows the hot-plug system to prevent arrays from running when it knows | |
1122 | that more disks may arrive later in the discovery process. | |
1123 | ||
8382f19b | 1124 | .TP |
7e23fc43 | 1125 | .BR \-\-scan ", " \-s |
8382f19b | 1126 | Only meaningful with |
7e23fc43 | 1127 | .B \-R |
8382f19b NB |
1128 | this will scan the |
1129 | .B map | |
1130 | file for arrays that are being incrementally assembled and will try to | |
1131 | start any that are not already started. If any such array is listed | |
1132 | in | |
1133 | .B mdadm.conf | |
1134 | as requiring an external bitmap, that bitmap will be attached first. | |
1135 | ||
e0d19036 NB |
1136 | .SH For Monitor mode: |
1137 | .TP | |
7e23fc43 | 1138 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1139 | Give a mail address to send alerts to. |
1140 | ||
1141 | .TP | |
7e23fc43 | 1142 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1143 | Give a program to be run whenever an event is detected. |
1144 | ||
773135f5 | 1145 | .TP |
7e23fc43 | 1146 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1147 | Cause all events to be reported through 'syslog'. The messages have |
1148 | facility of 'daemon' and varying priorities. | |
1149 | ||
e0d19036 | 1150 | .TP |
7e23fc43 | 1151 | .BR \-d ", " \-\-delay |
e0d19036 | 1152 | Give a delay in seconds. |
51ac42e3 | 1153 | .I mdadm |
e0d19036 NB |
1154 | polls the md arrays and then waits this many seconds before polling |
1155 | again. The default is 60 seconds. | |
1156 | ||
d013a55e | 1157 | .TP |
7e23fc43 | 1158 | .BR \-f ", " \-\-daemonise |
d013a55e | 1159 | Tell |
51ac42e3 | 1160 | .I mdadm |
d013a55e NB |
1161 | to run as a background daemon if it decides to monitor anything. This |
1162 | causes it to fork and run in the child, and to disconnect form the | |
1163 | terminal. The process id of the child is written to stdout. | |
1164 | This is useful with | |
7e23fc43 | 1165 | .B \-\-scan |
d013a55e NB |
1166 | which will only continue monitoring if a mail address or alert program |
1167 | is found in the config file. | |
1168 | ||
b5e64645 | 1169 | .TP |
7e23fc43 | 1170 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1171 | When |
51ac42e3 | 1172 | .I mdadm |
b5e64645 NB |
1173 | is running in daemon mode, write the pid of the daemon process to |
1174 | the specified file, instead of printing it on standard output. | |
1175 | ||
aa88f531 | 1176 | .TP |
7e23fc43 | 1177 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1178 | Check arrays only once. This will generate |
1179 | .B NewArray | |
1180 | events and more significantly | |
1181 | .B DegradedArray | |
a9d69660 NB |
1182 | and |
1183 | .B SparesMissing | |
aa88f531 NB |
1184 | events. Running |
1185 | .in +5 | |
7e23fc43 | 1186 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1187 | .in -5 |
1188 | from a cron script will ensure regular notification of any degraded arrays. | |
1189 | ||
98c6faba | 1190 | .TP |
7e23fc43 | 1191 | .BR \-t ", " \-\-test |
98c6faba NB |
1192 | Generate a |
1193 | .B TestMessage | |
1194 | alert for every array found at startup. This alert gets mailed and | |
1195 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1196 | message do get through successfully. |
98c6faba | 1197 | |
e0d19036 | 1198 | .SH ASSEMBLE MODE |
52826846 | 1199 | |
cd29a5c8 NB |
1200 | .HP 12 |
1201 | Usage: | |
7e23fc43 | 1202 | .B mdadm \-\-assemble |
5787fa49 NB |
1203 | .I md-device options-and-component-devices... |
1204 | .HP 12 | |
1205 | Usage: | |
7e23fc43 | 1206 | .B mdadm \-\-assemble \-\-scan |
5787fa49 | 1207 | .I md-devices-and-options... |
cd29a5c8 NB |
1208 | .HP 12 |
1209 | Usage: | |
7e23fc43 | 1210 | .B mdadm \-\-assemble \-\-scan |
cd29a5c8 | 1211 | .I options... |
52826846 | 1212 | |
cd29a5c8 | 1213 | .PP |
52826846 | 1214 | This usage assembles one or more raid arrays from pre-existing components. |
9a9dab36 | 1215 | For each array, mdadm needs to know the md device, the identity of the |
e0d19036 | 1216 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1217 | |
5787fa49 | 1218 | In the first usage example (without the |
7e23fc43 | 1219 | .BR \-\-scan ) |
5787fa49 NB |
1220 | the first device given is the md device. |
1221 | In the second usage example, all devices listed are treated as md | |
1222 | devices and assembly is attempted. | |
1223 | In the third (where no devices are listed) all md devices that are | |
8fd8d9c4 N |
1224 | listed in the configuration file are assembled. Then any arrays that |
1225 | can be found on unused devices will also be assembled. | |
52826846 | 1226 | |
d013a55e | 1227 | If precisely one device is listed, but |
7e23fc43 | 1228 | .B \-\-scan |
dd0781e5 | 1229 | is not given, then |
d013a55e NB |
1230 | .I mdadm |
1231 | acts as though | |
7e23fc43 | 1232 | .B \-\-scan |
93e790af | 1233 | was given and identity information is extracted from the configuration file. |
d013a55e | 1234 | |
2ae555c3 | 1235 | The identity can be given with the |
7e23fc43 | 1236 | .B \-\-uuid |
cd29a5c8 | 1237 | option, with the |
7e23fc43 | 1238 | .B \-\-super\-minor |
93e790af SW |
1239 | option, will be taken from the md-device record in the config file, or |
1240 | will be taken from the super block of the first component-device | |
1241 | listed on the command line. | |
52826846 | 1242 | |
2ae555c3 | 1243 | Devices can be given on the |
7e23fc43 | 1244 | .B \-\-assemble |
5787fa49 NB |
1245 | command line or in the config file. Only devices which have an md |
1246 | superblock which contains the right identity will be considered for | |
1247 | any array. | |
52826846 | 1248 | |
2ae555c3 | 1249 | The config file is only used if explicitly named with |
7e23fc43 | 1250 | .B \-\-config |
d013a55e | 1251 | or requested with (a possibly implicit) |
7e23fc43 | 1252 | .BR \-\-scan . |
52826846 | 1253 | In the later case, |
9a9dab36 | 1254 | .B /etc/mdadm.conf |
8fd8d9c4 N |
1255 | or |
1256 | .B /etc/mdadm/mdadm.conf | |
52826846 NB |
1257 | is used. |
1258 | ||
2ae555c3 | 1259 | If |
7e23fc43 | 1260 | .B \-\-scan |
cd29a5c8 NB |
1261 | is not given, then the config file will only be used to find the |
1262 | identity of md arrays. | |
52826846 | 1263 | |
2d465520 | 1264 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 1265 | .B \-\-scan |
2d465520 | 1266 | is not given and insufficient drives were listed to start a complete |
cd29a5c8 NB |
1267 | (non-degraded) array, then the array is not started (to guard against |
1268 | usage errors). To insist that the array be started in this case (as | |
1a7dfc35 | 1269 | may work for RAID1, 4, 5, 6, or 10), give the |
7e23fc43 | 1270 | .B \-\-run |
cd29a5c8 | 1271 | flag. |
52826846 | 1272 | |
75723446 NB |
1273 | If the md device does not exist, then it will be created providing the |
1274 | intent is clear. i.e. the name must be in a standard form, or the | |
7e23fc43 | 1275 | .B \-\-auto |
75723446 NB |
1276 | option must be given to clarify how and whether the device should be |
1277 | created. | |
dd0781e5 | 1278 | This can be useful for handling partitioned devices (which don't have |
b3f1c093 | 1279 | a stable device number \(em it can change after a reboot) and when using |
dd0781e5 NB |
1280 | "udev" to manage your |
1281 | .B /dev | |
1282 | tree (udev cannot handle md devices because of the unusual device | |
1283 | initialisation conventions). | |
1284 | ||
1285 | If the option to "auto" is "mdp" or "part" or (on the command line | |
1286 | only) "p", then mdadm will create a partitionable array, using the | |
93e790af | 1287 | first free one that is not in use and does not already have an entry |
dd0781e5 NB |
1288 | in /dev (apart from numeric /dev/md* entries). |
1289 | ||
1290 | If the option to "auto" is "yes" or "md" or (on the command line) | |
1291 | nothing, then mdadm will create a traditional, non-partitionable md | |
1292 | array. | |
1293 | ||
1294 | It is expected that the "auto" functionality will be used to create | |
1295 | device entries with meaningful names such as "/dev/md/home" or | |
1296 | "/dev/md/root", rather than names based on the numerical array number. | |
1297 | ||
93e790af | 1298 | When using option "auto" to create a partitionable array, the device |
dd0781e5 NB |
1299 | files for the first 4 partitions are also created. If a different |
1300 | number is required it can be simply appended to the auto option. | |
1301 | e.g. "auto=part8". Partition names are created by appending a digit | |
a9d69660 | 1302 | string to the device name, with an intervening "p" if the device name |
dd0781e5 NB |
1303 | ends with a digit. |
1304 | ||
1305 | The | |
7e23fc43 | 1306 | .B \-\-auto |
dd0781e5 NB |
1307 | option is also available in Build and Create modes. As those modes do |
1308 | not use a config file, the "auto=" config option does not apply to | |
1309 | these modes. | |
52826846 | 1310 | |
41a3b72a NB |
1311 | .SS Auto Assembly |
1312 | When | |
7e23fc43 | 1313 | .B \-\-assemble |
41a3b72a | 1314 | is used with |
7e23fc43 | 1315 | .B \-\-scan |
41a3b72a NB |
1316 | and no devices are listed, |
1317 | .I mdadm | |
1318 | will first attempt to assemble all the arrays listed in the config | |
1319 | file. | |
1320 | ||
8fd8d9c4 N |
1321 | It will then look further for possible arrays and will try to assemble |
1322 | anything that it finds. Arrays which are tagged as belonging to the given | |
1323 | homehost will be assembled and started normally. Arrays which do not | |
1324 | obviously belong to this host are given names that are expected not to | |
1325 | conflict with anything local, and are started "read-auto" so that | |
1326 | nothing is written to any device until the array is written to. i.e. | |
1327 | automatic resync etc is delayed. | |
41a3b72a NB |
1328 | |
1329 | If | |
1330 | .I mdadm | |
1331 | finds a consistent set of devices that look like they should comprise | |
1332 | an array, and if the superblock is tagged as belonging to the given | |
1333 | home host, it will automatically choose a device name and try to | |
1334 | assemble the array. If the array uses version-0.90 metadata, then the | |
1335 | .B minor | |
1336 | number as recorded in the superblock is used to create a name in | |
1337 | .B /dev/md/ | |
1338 | so for example | |
1339 | .BR /dev/md/3 . | |
1340 | If the array uses version-1 metadata, then the | |
1341 | .B name | |
1342 | from the superblock is used to similarly create a name in | |
93e790af SW |
1343 | .BR /dev/md |
1344 | (the name will have any 'host' prefix stripped first). | |
41a3b72a NB |
1345 | |
1346 | If | |
1347 | .I mdadm | |
1348 | cannot find any array for the given host at all, and if | |
7e23fc43 | 1349 | .B \-\-auto\-update\-homehost |
41a3b72a NB |
1350 | is given, then |
1351 | .I mdadm | |
1352 | will search again for any array (not just an array created for this | |
1353 | host) and will assemble each assuming | |
7e23fc43 | 1354 | .BR \-\-update=homehost . |
41a3b72a NB |
1355 | This will change the host tag in the superblock so that on the next run, |
1356 | these arrays will be found without the second pass. The intention of | |
1357 | this feature is to support transitioning a set of md arrays to using | |
1358 | homehost tagging. | |
1359 | ||
1360 | The reason for requiring arrays to be tagged with the homehost for | |
1361 | auto assembly is to guard against problems that can arise when moving | |
1362 | devices from one host to another. | |
1363 | ||
cd29a5c8 | 1364 | .SH BUILD MODE |
52826846 | 1365 | |
cd29a5c8 NB |
1366 | .HP 12 |
1367 | Usage: | |
7e23fc43 | 1368 | .B mdadm \-\-build |
93e790af | 1369 | .I md-device |
7e23fc43 PS |
1370 | .BI \-\-chunk= X |
1371 | .BI \-\-level= Y | |
1372 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
1373 | .I devices |
1374 | ||
1375 | .PP | |
2ae555c3 | 1376 | This usage is similar to |
7e23fc43 | 1377 | .BR \-\-create . |
a9d69660 | 1378 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 1379 | these arrays there is no difference between initially creating the array and |
52826846 NB |
1380 | subsequently assembling the array, except that hopefully there is useful |
1381 | data there in the second case. | |
1382 | ||
a9d69660 NB |
1383 | The level may raid0, linear, multipath, or faulty, or one of their |
1384 | synonyms. All devices must be listed and the array will be started | |
1385 | once complete. | |
cd29a5c8 NB |
1386 | |
1387 | .SH CREATE MODE | |
1388 | ||
1389 | .HP 12 | |
1390 | Usage: | |
7e23fc43 | 1391 | .B mdadm \-\-create |
93e790af | 1392 | .I md-device |
7e23fc43 PS |
1393 | .BI \-\-chunk= X |
1394 | .BI \-\-level= Y | |
cd29a5c8 | 1395 | .br |
7e23fc43 | 1396 | .BI \-\-raid\-devices= Z |
cd29a5c8 NB |
1397 | .I devices |
1398 | ||
1399 | .PP | |
1400 | This usage will initialise a new md array, associate some devices with | |
1401 | it, and activate the array. | |
1402 | ||
a9d69660 | 1403 | If the |
7e23fc43 | 1404 | .B \-\-auto |
dd0781e5 NB |
1405 | option is given (as described in more detail in the section on |
1406 | Assemble mode), then the md device will be created with a suitable | |
1407 | device number if necessary. | |
1408 | ||
cd29a5c8 | 1409 | As devices are added, they are checked to see if they contain raid |
2d465520 | 1410 | superblocks or filesystems. They are also checked to see if the variance in |
cd29a5c8 NB |
1411 | device size exceeds 1%. |
1412 | ||
1413 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 1414 | the presence of a |
7e23fc43 | 1415 | .B \-\-run |
cd29a5c8 NB |
1416 | can override this caution. |
1417 | ||
2d465520 | 1418 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 1419 | give the word "\fBmissing\fP" |
2d465520 | 1420 | in place of a device name. This will cause |
51ac42e3 | 1421 | .I mdadm |
2d465520 NB |
1422 | to leave the corresponding slot in the array empty. |
1423 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 1424 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
1425 | For a RAID1 array, only one real device needs to be given. All of the |
1426 | others can be | |
d013a55e | 1427 | "\fBmissing\fP". |
2d465520 | 1428 | |
feb716e9 | 1429 | When creating a RAID5 array, |
51ac42e3 | 1430 | .I mdadm |
feb716e9 NB |
1431 | will automatically create a degraded array with an extra spare drive. |
1432 | This is because building the spare into a degraded array is in general faster than resyncing | |
1433 | the parity on a non-degraded, but not clean, array. This feature can | |
35cc5be4 | 1434 | be overridden with the |
7e23fc43 | 1435 | .B \-\-force |
feb716e9 NB |
1436 | option. |
1437 | ||
0ee4da98 | 1438 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
1439 | required. |
1440 | If this is not given with the | |
7e23fc43 | 1441 | .B \-\-name |
41a3b72a NB |
1442 | option, |
1443 | .I mdadm | |
0ee4da98 | 1444 | will choose a name based on the last component of the name of the |
41a3b72a NB |
1445 | device being created. So if |
1446 | .B /dev/md3 | |
1447 | is being created, then the name | |
1448 | .B 3 | |
1449 | will be chosen. | |
1450 | If | |
1451 | .B /dev/md/home | |
1452 | is being created, then the name | |
1453 | .B home | |
1454 | will be used. | |
1455 | ||
e0f31f50 PC |
1456 | When creating a partition based array, using |
1457 | .I mdadm | |
1458 | with version-1.x metadata, the partition type should be set to | |
1459 | .B 0xDA | |
1460 | (non fs-data). This type selection allows for greater precision since | |
1461 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], | |
1462 | might create problems in the event of array recovery through a live cdrom. | |
1463 | ||
3d3dd91e NB |
1464 | A new array will normally get a randomly assigned 128bit UUID which is |
1465 | very likely to be unique. If you have a specific need, you can choose | |
1466 | a UUID for the array by giving the | |
7e23fc43 | 1467 | .B \-\-uuid= |
3d3dd91e NB |
1468 | option. Be warned that creating two arrays with the same UUID is a |
1469 | recipe for disaster. Also, using | |
7e23fc43 | 1470 | .B \-\-uuid= |
3d3dd91e | 1471 | when creating a v0.90 array will silently override any |
7e23fc43 | 1472 | .B \-\-homehost= |
3d3dd91e | 1473 | setting. |
e43d0cda NB |
1474 | .\"If the |
1475 | .\".B \-\-size | |
1476 | .\"option is given, it is not necessary to list any component-devices in this command. | |
1477 | .\"They can be added later, before a | |
1478 | .\".B \-\-run. | |
1479 | .\"If no | |
1480 | .\".B \-\-size | |
1481 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 1482 | |
8fd8d9c4 N |
1483 | When creating an array within a |
1484 | .B CONTAINER | |
1485 | .I mdadm | |
1486 | can be given either the list of devices to use, or simply the name of | |
1487 | the container. The former case gives control over which devices in | |
1488 | the container will be used for the array. The latter case allows | |
1489 | .I mdadm | |
1490 | to automatically choose which devices to use based on how much spare | |
1491 | space is available. | |
1492 | ||
53e8b987 | 1493 | The General Management options that are valid with |
7e23fc43 | 1494 | .B \-\-create |
53e8b987 | 1495 | are: |
cd29a5c8 | 1496 | .TP |
7e23fc43 | 1497 | .B \-\-run |
dd0781e5 | 1498 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
1499 | be in use. |
1500 | ||
1501 | .TP | |
7e23fc43 | 1502 | .B \-\-readonly |
b3f1c093 | 1503 | start the array readonly \(em not supported yet. |
52826846 | 1504 | |
2ae555c3 | 1505 | |
e0d19036 | 1506 | .SH MANAGE MODE |
cd29a5c8 NB |
1507 | .HP 12 |
1508 | Usage: | |
e0d19036 NB |
1509 | .B mdadm |
1510 | .I device | |
1511 | .I options... devices... | |
cd29a5c8 NB |
1512 | .PP |
1513 | ||
e0d19036 NB |
1514 | This usage will allow individual devices in an array to be failed, |
1515 | removed or added. It is possible to perform multiple operations with | |
1516 | on command. For example: | |
1517 | .br | |
7e23fc43 | 1518 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
1519 | .br |
1520 | will firstly mark | |
1521 | .B /dev/hda1 | |
1522 | as faulty in | |
1523 | .B /dev/md0 | |
1524 | and will then remove it from the array and finally add it back | |
2d465520 | 1525 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 1526 | command. |
e0d19036 NB |
1527 | |
1528 | .SH MISC MODE | |
1529 | .HP 12 | |
1530 | Usage: | |
9a9dab36 | 1531 | .B mdadm |
e0d19036 NB |
1532 | .I options ... |
1533 | .I devices ... | |
1534 | .PP | |
cd29a5c8 | 1535 | |
b5e64645 | 1536 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1537 | operate on distinct devices. The operations are: |
1538 | .TP | |
962a108f | 1539 | .B \-\-query |
e0d19036 NB |
1540 | The device is examined to see if it is |
1541 | (1) an active md array, or | |
1542 | (2) a component of an md array. | |
1543 | The information discovered is reported. | |
1544 | ||
1545 | .TP | |
962a108f | 1546 | .B \-\-detail |
2d465520 NB |
1547 | The device should be an active md device. |
1548 | .B mdadm | |
1549 | will display a detailed description of the array. | |
7e23fc43 | 1550 | .B \-\-brief |
2d465520 | 1551 | or |
7e23fc43 | 1552 | .B \-\-scan |
2d465520 | 1553 | will cause the output to be less detailed and the format to be |
e0d19036 | 1554 | suitable for inclusion in |
9a9dab36 | 1555 | .BR /etc/mdadm.conf . |
feb716e9 NB |
1556 | The exit status of |
1557 | .I mdadm | |
1558 | will normally be 0 unless | |
1559 | .I mdadm | |
93e790af | 1560 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 1561 | .B \-\-test |
feb716e9 NB |
1562 | option is given, then the exit status will be: |
1563 | .RS | |
1564 | .TP | |
1565 | 0 | |
1566 | The array is functioning normally. | |
1567 | .TP | |
1568 | 1 | |
1569 | The array has at least one failed device. | |
1570 | .TP | |
1571 | 2 | |
a77be586 | 1572 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
1573 | .TP |
1574 | 4 | |
1575 | There was an error while trying to get information about the device. | |
1576 | .RE | |
cd29a5c8 | 1577 | |
4cce4069 DW |
1578 | .TP |
1579 | .B \-\-detail\-platform | |
1580 | Print detail of the platform's raid capabilities (firmware / hardware | |
1581 | topology). If the metadata is specified with | |
1582 | .B \-e | |
1583 | or | |
1584 | .B \-\-metadata= | |
1585 | then the return status will be: | |
1586 | .RS | |
1587 | .TP | |
1588 | 0 | |
1589 | metadata successfully enumerated its platform components on this system | |
1590 | .TP | |
1591 | 1 | |
1592 | metadata is platform independent | |
1593 | .TP | |
1594 | 2 | |
1595 | metadata failed to find its platform components on this system | |
1596 | .RE | |
1597 | ||
e0d19036 | 1598 | .TP |
962a108f | 1599 | .B \-\-examine |
2d465520 | 1600 | The device should be a component of an md array. |
51ac42e3 | 1601 | .I mdadm |
2d465520 | 1602 | will read the md superblock of the device and display the contents. |
e0d19036 | 1603 | If |
7e23fc43 | 1604 | .B \-\-brief |
93e790af | 1605 | or |
7e23fc43 | 1606 | .B \-\-scan |
93e790af | 1607 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
1608 | are grouped together and reported in a single entry suitable |
1609 | for inclusion in | |
1610 | .BR /etc/mdadm.conf . | |
1611 | ||
2d465520 | 1612 | Having |
7e23fc43 | 1613 | .B \-\-scan |
e0d19036 NB |
1614 | without listing any devices will cause all devices listed in the |
1615 | config file to be examined. | |
1616 | ||
1617 | .TP | |
962a108f | 1618 | .B \-\-stop |
98c6faba NB |
1619 | The devices should be active md arrays which will be deactivated, as |
1620 | long as they are not currently in use. | |
e0d19036 NB |
1621 | |
1622 | .TP | |
962a108f | 1623 | .B \-\-run |
e0d19036 NB |
1624 | This will fully activate a partially assembled md array. |
1625 | ||
1626 | .TP | |
962a108f | 1627 | .B \-\-readonly |
e0d19036 NB |
1628 | This will mark an active array as read-only, providing that it is |
1629 | not currently being used. | |
1630 | ||
1631 | .TP | |
962a108f | 1632 | .B \-\-readwrite |
e0d19036 NB |
1633 | This will change a |
1634 | .B readonly | |
1635 | array back to being read/write. | |
1636 | ||
2d465520 | 1637 | .TP |
962a108f | 1638 | .B \-\-scan |
2d465520 | 1639 | For all operations except |
7e23fc43 PS |
1640 | .BR \-\-examine , |
1641 | .B \-\-scan | |
2d465520 NB |
1642 | will cause the operation to be applied to all arrays listed in |
1643 | .BR /proc/mdstat . | |
1644 | For | |
7e23fc43 PS |
1645 | .BR \-\-examine, |
1646 | .B \-\-scan | |
2d465520 NB |
1647 | causes all devices listed in the config file to be examined. |
1648 | ||
1649 | ||
e0d19036 NB |
1650 | .SH MONITOR MODE |
1651 | ||
cd29a5c8 NB |
1652 | .HP 12 |
1653 | Usage: | |
7e23fc43 | 1654 | .B mdadm \-\-monitor |
e0d19036 NB |
1655 | .I options... devices... |
1656 | ||
cd29a5c8 | 1657 | .PP |
e0d19036 | 1658 | This usage causes |
51ac42e3 | 1659 | .I mdadm |
e0d19036 NB |
1660 | to periodically poll a number of md arrays and to report on any events |
1661 | noticed. | |
51ac42e3 | 1662 | .I mdadm |
e0d19036 NB |
1663 | will never exit once it decides that there are arrays to be checked, |
1664 | so it should normally be run in the background. | |
1665 | ||
2d465520 | 1666 | As well as reporting events, |
51ac42e3 | 1667 | .I mdadm |
2d465520 NB |
1668 | may move a spare drive from one array to another if they are in the |
1669 | same | |
1670 | .B spare-group | |
a9d69660 | 1671 | and if the destination array has a failed drive but no spares. |
2d465520 | 1672 | |
e0d19036 | 1673 | If any devices are listed on the command line, |
51ac42e3 | 1674 | .I mdadm |
e0d19036 NB |
1675 | will only monitor those devices. Otherwise all arrays listed in the |
1676 | configuration file will be monitored. Further, if | |
7e23fc43 | 1677 | .B \-\-scan |
e0d19036 NB |
1678 | is given, then any other md devices that appear in |
1679 | .B /proc/mdstat | |
1680 | will also be monitored. | |
1681 | ||
1682 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 1683 | These events are passed to a separate program (if specified) and may |
2d465520 | 1684 | be mailed to a given E-mail address. |
e0d19036 | 1685 | |
93e790af SW |
1686 | When passing events to a program, the program is run once for each event, |
1687 | and is given 2 or 3 command-line arguments: the first is the | |
1688 | name of the event (see below), the second is the name of the | |
bd526cee | 1689 | md device which is affected, and the third is the name of a related |
93e790af | 1690 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
1691 | |
1692 | If | |
7e23fc43 | 1693 | .B \-\-scan |
e0d19036 NB |
1694 | is given, then a program or an E-mail address must be specified on the |
1695 | command line or in the config file. If neither are available, then | |
51ac42e3 | 1696 | .I mdadm |
e0d19036 NB |
1697 | will not monitor anything. |
1698 | Without | |
93e790af | 1699 | .B \-\-scan, |
51ac42e3 | 1700 | .I mdadm |
2d465520 | 1701 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
1702 | no program or email is given, then each event is reported to |
1703 | .BR stdout . | |
cd29a5c8 | 1704 | |
e0d19036 NB |
1705 | The different events are: |
1706 | ||
1707 | .RS 4 | |
1708 | .TP | |
1709 | .B DeviceDisappeared | |
2d465520 | 1710 | An md array which previously was configured appears to no longer be |
773135f5 | 1711 | configured. (syslog priority: Critical) |
e0d19036 | 1712 | |
b8f72a62 NB |
1713 | If |
1714 | .I mdadm | |
1715 | was told to monitor an array which is RAID0 or Linear, then it will | |
1716 | report | |
1717 | .B DeviceDisappeared | |
1718 | with the extra information | |
1719 | .BR Wrong-Level . | |
1720 | This is because RAID0 and Linear do not support the device-failed, | |
1721 | hot-spare and resync operations which are monitored. | |
1722 | ||
e0d19036 NB |
1723 | .TP |
1724 | .B RebuildStarted | |
773135f5 | 1725 | An md array started reconstruction. (syslog priority: Warning) |
e0d19036 NB |
1726 | |
1727 | .TP | |
1728 | .BI Rebuild NN | |
1729 | Where | |
1730 | .I NN | |
1731 | is 20, 40, 60, or 80, this indicates that rebuild has passed that many | |
773135f5 | 1732 | percentage of the total. (syslog priority: Warning) |
e0d19036 | 1733 | |
98c6faba NB |
1734 | .TP |
1735 | .B RebuildFinished | |
1736 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 1737 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 1738 | |
e0d19036 NB |
1739 | .TP |
1740 | .B Fail | |
773135f5 NB |
1741 | An active component device of an array has been marked as |
1742 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
1743 | |
1744 | .TP | |
1745 | .B FailSpare | |
1746 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 1747 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
1748 | |
1749 | .TP | |
1750 | .B SpareActive | |
1751 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 1752 | device has been successfully rebuilt and has been made active. |
773135f5 | 1753 | (syslog priority: Info) |
e0d19036 NB |
1754 | |
1755 | .TP | |
1756 | .B NewArray | |
1757 | A new md array has been detected in the | |
1758 | .B /proc/mdstat | |
773135f5 | 1759 | file. (syslog priority: Info) |
e0d19036 | 1760 | |
aa88f531 NB |
1761 | .TP |
1762 | .B DegradedArray | |
1763 | A newly noticed array appears to be degraded. This message is not | |
1764 | generated when | |
1765 | .I mdadm | |
1766 | notices a drive failure which causes degradation, but only when | |
1767 | .I mdadm | |
1768 | notices that an array is degraded when it first sees the array. | |
93e790af | 1769 | (syslog priority: Critical) |
aa88f531 | 1770 | |
e0d19036 NB |
1771 | .TP |
1772 | .B MoveSpare | |
1773 | A spare drive has been moved from one array in a | |
1774 | .B spare-group | |
1775 | to another to allow a failed drive to be replaced. | |
773135f5 | 1776 | (syslog priority: Info) |
e0d19036 | 1777 | |
b8f72a62 NB |
1778 | .TP |
1779 | .B SparesMissing | |
1780 | If | |
1781 | .I mdadm | |
1782 | has been told, via the config file, that an array should have a certain | |
1783 | number of spare devices, and | |
1784 | .I mdadm | |
93e790af | 1785 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
1786 | array, it will report a |
1787 | .B SparesMissing | |
1788 | message. | |
d1732eeb | 1789 | (syslog priority: Warning) |
b8f72a62 | 1790 | |
98c6faba NB |
1791 | .TP |
1792 | .B TestMessage | |
1793 | An array was found at startup, and the | |
7e23fc43 | 1794 | .B \-\-test |
98c6faba | 1795 | flag was given. |
773135f5 | 1796 | (syslog priority: Info) |
e0d19036 NB |
1797 | .RE |
1798 | ||
1799 | Only | |
93e790af SW |
1800 | .B Fail, |
1801 | .B FailSpare, | |
1802 | .B DegradedArray, | |
1803 | .B SparesMissing | |
e0d19036 | 1804 | and |
98c6faba | 1805 | .B TestMessage |
e0d19036 | 1806 | cause Email to be sent. All events cause the program to be run. |
93e790af | 1807 | The program is run with two or three arguments: the event |
e0d19036 NB |
1808 | name, the array device and possibly a second device. |
1809 | ||
1810 | Each event has an associated array device (e.g. | |
1811 | .BR /dev/md1 ) | |
1812 | and possibly a second device. For | |
1813 | .BR Fail , | |
1814 | .BR FailSpare , | |
1815 | and | |
1816 | .B SpareActive | |
1817 | the second device is the relevant component device. | |
1818 | For | |
1819 | .B MoveSpare | |
1820 | the second device is the array that the spare was moved from. | |
1821 | ||
1822 | For | |
51ac42e3 | 1823 | .I mdadm |
e0d19036 | 1824 | to move spares from one array to another, the different arrays need to |
93e790af | 1825 | be labeled with the same |
e0d19036 NB |
1826 | .B spare-group |
1827 | in the configuration file. The | |
1828 | .B spare-group | |
93e790af | 1829 | name can be any string; it is only necessary that different spare |
2d465520 | 1830 | groups use different names. |
e0d19036 NB |
1831 | |
1832 | When | |
51ac42e3 | 1833 | .I mdadm |
93e790af | 1834 | detects that an array in a spare group has fewer active |
e0d19036 NB |
1835 | devices than necessary for the complete array, and has no spare |
1836 | devices, it will look for another array in the same spare group that | |
1837 | has a full complement of working drive and a spare. It will then | |
1838 | attempt to remove the spare from the second drive and add it to the | |
1839 | first. | |
1840 | If the removal succeeds but the adding fails, then it is added back to | |
1841 | the original array. | |
1842 | ||
dd0781e5 NB |
1843 | .SH GROW MODE |
1844 | The GROW mode is used for changing the size or shape of an active | |
1845 | array. | |
1846 | For this to work, the kernel must support the necessary change. | |
2ae555c3 | 1847 | Various types of growth are being added during 2.6 development, |
dd0781e5 NB |
1848 | including restructuring a raid5 array to have more active devices. |
1849 | ||
dfd4d8ee NB |
1850 | Currently the only support available is to |
1851 | .IP \(bu 4 | |
1852 | change the "size" attribute | |
1853 | for RAID1, RAID5 and RAID6. | |
1854 | .IP \(bu 4 | |
e5669f40 | 1855 | increase the "raid\-devices" attribute of RAID1, RAID5, and RAID6. |
dfd4d8ee | 1856 | .IP \(bu 4 |
93e790af | 1857 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 1858 | remove a write-intent bitmap from such an array. |
dfd4d8ee | 1859 | .PP |
dd0781e5 | 1860 | |
8fd8d9c4 N |
1861 | GROW mode is not currently supported for |
1862 | .B CONTAINERS | |
1863 | or arrays inside containers. | |
1864 | ||
2ae555c3 | 1865 | .SS SIZE CHANGES |
fe80f49b | 1866 | Normally when an array is built the "size" it taken from the smallest |
dd0781e5 NB |
1867 | of the drives. If all the small drives in an arrays are, one at a |
1868 | time, removed and replaced with larger drives, then you could have an | |
1869 | array of large drives with only a small amount used. In this | |
1870 | situation, changing the "size" with "GROW" mode will allow the extra | |
1871 | space to start being used. If the size is increased in this way, a | |
1872 | "resync" process will start to make sure the new parts of the array | |
1873 | are synchronised. | |
1874 | ||
1875 | Note that when an array changes size, any filesystem that may be | |
1876 | stored in the array will not automatically grow to use the space. The | |
1877 | filesystem will need to be explicitly told to use the extra space. | |
1878 | ||
2ae555c3 NB |
1879 | .SS RAID-DEVICES CHANGES |
1880 | ||
dd0781e5 NB |
1881 | A RAID1 array can work with any number of devices from 1 upwards |
1882 | (though 1 is not very useful). There may be times which you want to | |
1883 | increase or decrease the number of active devices. Note that this is | |
1884 | different to hot-add or hot-remove which changes the number of | |
1885 | inactive devices. | |
1886 | ||
1887 | When reducing the number of devices in a RAID1 array, the slots which | |
1888 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 1889 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
1890 | |
1891 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 1892 | present will be activated immediately. |
dd0781e5 | 1893 | |
2ae555c3 NB |
1894 | Increasing the number of active devices in a RAID5 is much more |
1895 | effort. Every block in the array will need to be read and written | |
1896 | back to a new location. From 2.6.17, the Linux Kernel is able to do | |
1897 | this safely, including restart and interrupted "reshape". | |
1898 | ||
1899 | When relocating the first few stripes on a raid5, it is not possible | |
1900 | to keep the data on disk completely consistent and crash-proof. To | |
1901 | provide the required safety, mdadm disables writes to the array while | |
1902 | this "critical section" is reshaped, and takes a backup of the data | |
1903 | that is in that section. This backup is normally stored in any spare | |
1904 | devices that the array has, however it can also be stored in a | |
1905 | separate file specified with the | |
7e23fc43 | 1906 | .B \-\-backup\-file |
2ae555c3 NB |
1907 | option. If this option is used, and the system does crash during the |
1908 | critical period, the same file must be passed to | |
7e23fc43 | 1909 | .B \-\-assemble |
2ae555c3 NB |
1910 | to restore the backup and reassemble the array. |
1911 | ||
1912 | .SS BITMAP CHANGES | |
1913 | ||
1914 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 1915 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b NB |
1916 | can be added. Note that if you add a bitmap stored in a file which is |
1917 | in a filesystem that is on the raid array being affected, the system | |
1918 | will deadlock. The bitmap must be on a separate filesystem. | |
1919 | ||
8382f19b NB |
1920 | .SH INCREMENTAL MODE |
1921 | ||
1922 | .HP 12 | |
1923 | Usage: | |
7e23fc43 PS |
1924 | .B mdadm \-\-incremental |
1925 | .RB [ \-\-run ] | |
1926 | .RB [ \-\-quiet ] | |
8382f19b NB |
1927 | .I component-device |
1928 | .HP 12 | |
1929 | Usage: | |
7e23fc43 | 1930 | .B mdadm \-\-incremental \-\-rebuild |
8382f19b NB |
1931 | .HP 12 |
1932 | Usage: | |
7e23fc43 | 1933 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b NB |
1934 | |
1935 | ||
1936 | .PP | |
1937 | This mode is designed to be used in conjunction with a device | |
1938 | discovery system. As devices are found in a system, they can be | |
1939 | passed to | |
7e23fc43 | 1940 | .B "mdadm \-\-incremental" |
8382f19b NB |
1941 | to be conditionally added to an appropriate array. |
1942 | ||
8fd8d9c4 N |
1943 | If the device passed is a |
1944 | .B CONTAINER | |
1945 | device created by a previous call to | |
1946 | .IR mdadm , | |
1947 | then rather than trying to add that device to an array, all the arrays | |
1948 | described by the metadata of the container will be started. | |
1949 | ||
8382f19b NB |
1950 | .I mdadm |
1951 | performs a number of tests to determine if the device is part of an | |
93e790af | 1952 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
1953 | is found, or can be created, |
1954 | .I mdadm | |
1955 | adds the device to the array and conditionally starts the array. | |
1956 | ||
1957 | Note that | |
1958 | .I mdadm | |
1959 | will only add devices to an array which were previously working | |
1960 | (active or spare) parts of that array. It does not currently support | |
1961 | automatic inclusion of a new drive as a spare in some array. | |
1962 | ||
8382f19b NB |
1963 | The tests that |
1964 | .I mdadm | |
1965 | makes are as follow: | |
1966 | .IP + | |
1967 | Is the device permitted by | |
1968 | .BR mdadm.conf ? | |
1969 | That is, is it listed in a | |
1970 | .B DEVICES | |
1971 | line in that file. If | |
1972 | .B DEVICES | |
1973 | is absent then the default it to allow any device. Similar if | |
1974 | .B DEVICES | |
1975 | contains the special word | |
1976 | .B partitions | |
1977 | then any device is allowed. Otherwise the device name given to | |
1978 | .I mdadm | |
1979 | must match one of the names or patterns in a | |
1980 | .B DEVICES | |
1981 | line. | |
1982 | ||
1983 | .IP + | |
1984 | Does the device have a valid md superblock. If a specific metadata | |
1985 | version is request with | |
7e23fc43 | 1986 | .B \-\-metadata |
8382f19b | 1987 | or |
7e23fc43 | 1988 | .B \-e |
8382f19b NB |
1989 | then only that style of metadata is accepted, otherwise |
1990 | .I mdadm | |
1991 | finds any known version of metadata. If no | |
1992 | .I md | |
1993 | metadata is found, the device is rejected. | |
1994 | ||
1995 | .IP + | |
1996 | Does the metadata match an expected array? | |
1997 | The metadata can match in two ways. Either there is an array listed | |
1998 | in | |
1999 | .B mdadm.conf | |
2000 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 2001 | or by minor-number), or the array was created with a |
8382f19b | 2002 | .B homehost |
93e790af | 2003 | specified and that |
8382f19b | 2004 | .B homehost |
93e790af | 2005 | matches the one in |
8382f19b NB |
2006 | .B mdadm.conf |
2007 | or on the command line. | |
2008 | If | |
2009 | .I mdadm | |
2010 | is not able to positively identify the array as belonging to the | |
2011 | current host, the device will be rejected. | |
2012 | ||
2013 | .IP + | |
2014 | .I mdadm | |
93e790af | 2015 | keeps a list of arrays that it has partially assembled in |
8382f19b NB |
2016 | .B /var/run/mdadm/map |
2017 | (or | |
2018 | .B /var/run/mdadm.map | |
2019 | if the directory doesn't exist). If no array exists which matches | |
2020 | the metadata on the new device, | |
2021 | .I mdadm | |
2022 | must choose a device name and unit number. It does this based on any | |
2023 | name given in | |
2024 | .B mdadm.conf | |
2025 | or any name information stored in the metadata. If this name | |
2026 | suggests a unit number, that number will be used, otherwise a free | |
2027 | unit number will be chosen. Normally | |
2028 | .I mdadm | |
2029 | will prefer to create a partitionable array, however if the | |
2030 | .B CREATE | |
2031 | line in | |
2032 | .B mdadm.conf | |
2033 | suggests that a non-partitionable array is preferred, that will be | |
2034 | honoured. | |
2035 | ||
2036 | .IP + | |
2037 | Once an appropriate array is found or created and the device is added, | |
2038 | .I mdadm | |
2039 | must decide if the array is ready to be started. It will | |
2040 | normally compare the number of available (non-spare) devices to the | |
2041 | number of devices that the metadata suggests need to be active. If | |
2042 | there are at least that many, the array will be started. This means | |
2043 | that if any devices are missing the array will not be restarted. | |
2044 | ||
2045 | As an alternative, | |
7e23fc43 | 2046 | .B \-\-run |
8382f19b | 2047 | may be passed to |
51ac42e3 | 2048 | .I mdadm |
8382f19b NB |
2049 | in which case the array will be run as soon as there are enough |
2050 | devices present for the data to be accessible. For a raid1, that | |
2051 | means one device will start the array. For a clean raid5, the array | |
2052 | will be started as soon as all but one drive is present. | |
2053 | ||
93e790af | 2054 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
2055 | be known that all device discovery has completed, then |
2056 | .br | |
7e23fc43 | 2057 | .B " mdadm \-IRs" |
8382f19b NB |
2058 | .br |
2059 | can be run which will try to start all arrays that are being | |
2060 | incrementally assembled. They are started in "read-auto" mode in | |
2061 | which they are read-only until the first write request. This means | |
2062 | that no metadata updates are made and no attempt at resync or recovery | |
2063 | happens. Further devices that are found before the first write can | |
2064 | still be added safely. | |
2065 | ||
5545fa6d DW |
2066 | |
2067 | .SH ENVIRONMENT | |
2068 | This section describes environment variables that affect how mdadm | |
2069 | operates. | |
2070 | ||
2071 | .TP | |
2072 | .B MDADM_NO_MDMON | |
2073 | Setting this value to 1 will prevent mdadm from automatically launching | |
2074 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
2075 | ||
8fd8d9c4 N |
2076 | .TP |
2077 | .B MDADM_NO_UDEV | |
2078 | Normally, | |
2079 | .I mdadm | |
2080 | does not create any device nodes in /dev, but leaves that task to | |
2081 | .IR udev . | |
2082 | If | |
2083 | .I udev | |
2084 | appears not to be configured, or if this environment variable is set | |
2085 | to '1', the | |
2086 | .I mdadm | |
2087 | will create and devices that are needed. | |
2088 | ||
2d465520 NB |
2089 | .SH EXAMPLES |
2090 | ||
7e23fc43 | 2091 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 2092 | .br |
5787fa49 NB |
2093 | This will find out if a given device is a raid array, or is part of |
2094 | one, and will provide brief information about the device. | |
2d465520 | 2095 | |
7e23fc43 | 2096 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 2097 | .br |
93e790af | 2098 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 2099 | file. This command will typically go in a system startup file. |
2d465520 | 2100 | |
7e23fc43 | 2101 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 2102 | .br |
93e790af | 2103 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 2104 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 2105 | |
7e23fc43 | 2106 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 2107 | .br |
5787fa49 NB |
2108 | If (and only if) there is an Email address or program given in the |
2109 | standard config file, then | |
2110 | monitor the status of all arrays listed in that file by | |
2111 | polling them ever 2 minutes. | |
2d465520 | 2112 | |
7e23fc43 | 2113 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 2114 | .br |
5787fa49 | 2115 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 2116 | |
2d465520 | 2117 | .br |
7e23fc43 | 2118 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 2119 | .br |
7e23fc43 | 2120 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 2121 | .br |
5787fa49 NB |
2122 | This will create a prototype config file that describes currently |
2123 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
2124 | This file should be reviewed before being used as it may |
2125 | contain unwanted detail. | |
2126 | ||
7e23fc43 | 2127 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 2128 | .br |
7e23fc43 | 2129 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
2130 | .br |
2131 | This will find arrays which could be assembled from existing IDE and | |
2132 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 2133 | format of a config file. |
2d465520 NB |
2134 | This file is very likely to contain unwanted detail, particularly |
2135 | the | |
2136 | .B devices= | |
5787fa49 NB |
2137 | entries. It should be reviewed and edited before being used as an |
2138 | actual config file. | |
2d465520 | 2139 | |
7e23fc43 | 2140 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 2141 | .br |
7e23fc43 | 2142 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
2143 | .br |
2144 | Create a list of devices by reading | |
2145 | .BR /proc/partitions , | |
2146 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 2147 | that were found. |
2d465520 | 2148 | |
7e23fc43 | 2149 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 2150 | .br |
5787fa49 NB |
2151 | Scan all partitions and devices listed in |
2152 | .BR /proc/partitions | |
2153 | and assemble | |
2154 | .B /dev/md0 | |
2155 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 2156 | |
7e23fc43 | 2157 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm" |
d013a55e NB |
2158 | .br |
2159 | If config file contains a mail address or alert program, run mdadm in | |
2160 | the background in monitor mode monitoring all md devices. Also write | |
2161 | pid of mdadm daemon to | |
2162 | .BR /var/run/mdadm . | |
2163 | ||
7e23fc43 | 2164 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
2165 | .br |
2166 | Try to incorporate newly discovered device into some array as | |
2167 | appropriate. | |
2168 | ||
7e23fc43 | 2169 | .B " mdadm \-\-incremental \-\-rebuild \-\-run \-\-scan" |
8382f19b NB |
2170 | .br |
2171 | Rebuild the array map from any current arrays, and then start any that | |
2172 | can be started. | |
2173 | ||
b80da661 NB |
2174 | .B " mdadm /dev/md4 --fail detached --remove detached" |
2175 | .br | |
2176 | Any devices which are components of /dev/md4 will be marked as faulty | |
2177 | and then remove from the array. | |
2178 | ||
8fd8d9c4 N |
2179 | .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]" |
2180 | .br | |
2181 | Create a DDF array over 6 devices. | |
2182 | ||
2183 | .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf" | |
2184 | .br | |
2185 | Create a raid5 array over any 3 devices in the given DDF set. Use | |
2186 | only 30 gigabytes of each device. | |
2187 | ||
2188 | .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]" | |
2189 | .br | |
2190 | Assemble a pre-exist ddf array. | |
2191 | ||
2192 | .B " mdadm -I /dev/md/ddf1" | |
2193 | .br | |
2194 | Assemble all arrays contained in the ddf array, assigning names as | |
2195 | appropriate. | |
2196 | ||
7e23fc43 | 2197 | .B " mdadm \-\-create \-\-help" |
2d465520 | 2198 | .br |
2ae555c3 | 2199 | Provide help about the Create mode. |
2d465520 | 2200 | |
7e23fc43 | 2201 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
2202 | .br |
2203 | Provide help about the format of the config file. | |
2d465520 | 2204 | |
7e23fc43 | 2205 | .B " mdadm \-\-help" |
5787fa49 NB |
2206 | .br |
2207 | Provide general help. | |
cd29a5c8 | 2208 | |
cd29a5c8 NB |
2209 | |
2210 | .SH FILES | |
2211 | ||
2212 | .SS /proc/mdstat | |
2213 | ||
2ae555c3 NB |
2214 | If you're using the |
2215 | .B /proc | |
cd29a5c8 NB |
2216 | filesystem, |
2217 | .B /proc/mdstat | |
2d465520 | 2218 | lists all active md devices with information about them. |
51ac42e3 | 2219 | .I mdadm |
2d465520 | 2220 | uses this to find arrays when |
7e23fc43 | 2221 | .B \-\-scan |
2d465520 NB |
2222 | is given in Misc mode, and to monitor array reconstruction |
2223 | on Monitor mode. | |
2224 | ||
cd29a5c8 | 2225 | |
9a9dab36 | 2226 | .SS /etc/mdadm.conf |
cd29a5c8 | 2227 | |
11a3e71d NB |
2228 | The config file lists which devices may be scanned to see if |
2229 | they contain MD super block, and gives identifying information | |
2230 | (e.g. UUID) about known MD arrays. See | |
2231 | .BR mdadm.conf (5) | |
2232 | for more details. | |
cd29a5c8 | 2233 | |
8382f19b NB |
2234 | .SS /var/run/mdadm/map |
2235 | When | |
7e23fc43 | 2236 | .B \-\-incremental |
93e790af | 2237 | mode is used, this file gets a list of arrays currently being created. |
8382f19b NB |
2238 | If |
2239 | .B /var/run/mdadm | |
2240 | does not exist as a directory, then | |
2241 | .B /var/run/mdadm.map | |
2242 | is used instead. | |
2243 | ||
48f7b27a NB |
2244 | .SH DEVICE NAMES |
2245 | ||
48f7b27a | 2246 | .I mdadm |
8fd8d9c4 N |
2247 | understand two sorts of names for array devices. |
2248 | ||
2249 | The first is the so-called 'standard' format name, which matches the | |
2250 | names used by the kernel and which appear in | |
2251 | .IR /proc/mdstat . | |
2252 | ||
2253 | The second sort can be freely chosen, but must reside in | |
2254 | .IR /dev/md/ . | |
2255 | When giving a device name to | |
2256 | .I mdadm | |
2257 | to create or assemble an array, either full path name such as | |
2258 | .I /dev/md0 | |
2259 | or | |
2260 | .I /dev/md/home | |
2261 | can be given, or just the suffix of the second sort of name, such as | |
2262 | .I home | |
2263 | can be given. | |
2264 | ||
2265 | When | |
2266 | .I mdadm | |
2267 | chooses device names during auto-assembly, it will normally add a | |
2268 | small sequence number to the end of the name to avoid conflicted | |
2269 | between multiple arrays that have the same name. If | |
2270 | .I mdadm | |
2271 | can reasonably determine that the array really is meant for this host, | |
2272 | either by a hostname in the metadata, or by the presence of the array | |
2273 | in /etc/mdadm.conf, then it will leave of the suffix if possible. | |
48f7b27a NB |
2274 | |
2275 | The standard names for non-partitioned arrays (the only sort of md | |
8fd8d9c4 | 2276 | array available in 2.4 and earlier) are of the form |
48f7b27a NB |
2277 | .IP |
2278 | /dev/mdNN | |
48f7b27a NB |
2279 | .PP |
2280 | where NN is a number. | |
2281 | The standard names for partitionable arrays (as available from 2.6 | |
8fd8d9c4 | 2282 | onwards) are of the form |
48f7b27a | 2283 | .IP |
48f7b27a NB |
2284 | /dev/md_dNN |
2285 | .PP | |
2286 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
8fd8d9c4 N |
2287 | .PP |
2288 | From kernel version, 2.6.28 the "non-partitioned array" can actually | |
2289 | be partitioned. So the "md_dNN" names are no longer needed, and | |
2290 | partitions such as "/dev/mdNNpXX" are possible. | |
52826846 | 2291 | |
2d465520 | 2292 | .SH NOTE |
51ac42e3 | 2293 | .I mdadm |
2d465520 | 2294 | was previously known as |
51ac42e3 | 2295 | .IR mdctl . |
a9d69660 | 2296 | .P |
51ac42e3 | 2297 | .I mdadm |
a9d69660 | 2298 | is completely separate from the |
51ac42e3 | 2299 | .I raidtools |
a9d69660 NB |
2300 | package, and does not use the |
2301 | .I /etc/raidtab | |
2302 | configuration file at all. | |
2303 | ||
52826846 | 2304 | .SH SEE ALSO |
75f74377 | 2305 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 2306 | RAID, see: |
3cdfb6a7 | 2307 | .IP |
11cd8b79 | 2308 | .B http://linux\-raid.osdl.org/ |
75f74377 DG |
2309 | .PP |
2310 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
e43d0cda NB |
2311 | .\".PP |
2312 | .\"for new releases of the RAID driver check out: | |
2313 | .\" | |
2314 | .\".IP | |
2315 | .\".UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
2316 | .\"ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
2317 | .\".UE | |
2318 | .\".PP | |
2319 | .\"or | |
2320 | .\".IP | |
2321 | .\".UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2322 | .\"http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2323 | .\".UE | |
cd29a5c8 | 2324 | .PP |
2ae555c3 | 2325 | The latest version of |
a9d69660 NB |
2326 | .I mdadm |
2327 | should always be available from | |
cd29a5c8 | 2328 | .IP |
11cd8b79 N |
2329 | .B http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
2330 | .PP | |
2331 | Related man pages: | |
cd29a5c8 | 2332 | .PP |
a9d69660 NB |
2333 | .IR mdadm.conf (5), |
2334 | .IR md (4). | |
56eb10c0 | 2335 | .PP |
52826846 NB |
2336 | .IR raidtab (5), |
2337 | .IR raid0run (8), | |
2338 | .IR raidstop (8), | |
a9d69660 | 2339 | .IR mkraid (8). |