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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. | |
866d136a | 8 | .TH MDADM 8 "" v2.6.7 |
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 , |
cd29a5c8 | 41 | and |
b5e64645 | 42 | .BR FAULTY . |
d013a55e | 43 | |
a9d69660 NB |
44 | .B MULTIPATH |
45 | is not a Software RAID mechanism, but does involve | |
93e790af | 46 | multiple devices: |
d013a55e NB |
47 | each device is a path to one common physical storage device. |
48 | ||
a9d69660 NB |
49 | .B FAULTY |
50 | is also not true RAID, and it only involves one device. It | |
b5e64645 | 51 | provides a layer over a true device that can be used to inject faults. |
52826846 | 52 | |
51ac42e3 | 53 | .\".I mdadm |
e43d0cda NB |
54 | .\"is a program that can be used to create, manage, and monitor |
55 | .\"MD devices. As | |
56 | .\"such it provides a similar set of functionality to the | |
57 | .\".B raidtools | |
58 | .\"packages. | |
59 | .\"The key differences between | |
51ac42e3 | 60 | .\".I mdadm |
e43d0cda NB |
61 | .\"and |
62 | .\".B raidtools | |
63 | .\"are: | |
64 | .\".IP \(bu 4 | |
51ac42e3 | 65 | .\".I mdadm |
e43d0cda NB |
66 | .\"is a single program and not a collection of programs. |
67 | .\".IP \(bu 4 | |
51ac42e3 | 68 | .\".I mdadm |
e43d0cda NB |
69 | .\"can perform (almost) all of its functions without having a |
70 | .\"configuration file and does not use one by default. Also | |
51ac42e3 | 71 | .\".I mdadm |
e43d0cda NB |
72 | .\"helps with management of the configuration |
73 | .\"file. | |
74 | .\".IP \(bu 4 | |
51ac42e3 | 75 | .\".I mdadm |
e43d0cda NB |
76 | .\"can provide information about your arrays (through Query, Detail, and Examine) |
77 | .\"that | |
78 | .\".B raidtools | |
79 | .\"cannot. | |
80 | .\".P | |
81 | .\".I mdadm | |
82 | .\"does not use | |
83 | .\".IR /etc/raidtab , | |
84 | .\"the | |
85 | .\".B raidtools | |
86 | .\"configuration file, at all. It has a different configuration file | |
87 | .\"with a different format and a different purpose. | |
52826846 NB |
88 | |
89 | .SH MODES | |
8382f19b | 90 | mdadm has several major modes of operation: |
cd29a5c8 NB |
91 | .TP |
92 | .B Assemble | |
93e790af | 93 | Assemble the components of a previously created |
52826846 | 94 | array into an active array. Components can be explicitly given |
2ae555c3 | 95 | or can be searched for. |
51ac42e3 | 96 | .I mdadm |
cd29a5c8 NB |
97 | checks that the components |
98 | do form a bona fide array, and can, on request, fiddle superblock | |
99 | information so as to assemble a faulty array. | |
100 | ||
101 | .TP | |
102 | .B Build | |
a9d69660 NB |
103 | Build an array that doesn't have per-device superblocks. For these |
104 | sorts of arrays, | |
105 | .I mdadm | |
106 | cannot differentiate between initial creation and subsequent assembly | |
107 | of an array. It also cannot perform any checks that appropriate | |
93e790af | 108 | components have been requested. Because of this, the |
a9d69660 NB |
109 | .B Build |
110 | mode should only be used together with a complete understanding of | |
111 | what you are doing. | |
cd29a5c8 NB |
112 | |
113 | .TP | |
114 | .B Create | |
115 | Create a new array with per-device superblocks. | |
e43d0cda NB |
116 | .\"It can progress |
117 | .\"in several step create-add-add-run or it can all happen with one command. | |
cd29a5c8 | 118 | |
cd29a5c8 NB |
119 | .TP |
120 | .B "Follow or Monitor" | |
5787fa49 | 121 | Monitor one or more md devices and act on any state changes. This is |
93e790af | 122 | only meaningful for raid1, 4, 5, 6, 10 or multipath arrays, as |
98c6faba NB |
123 | only these have interesting state. raid0 or linear never have |
124 | missing, spare, or failed drives, so there is nothing to monitor. | |
5787fa49 | 125 | |
dd0781e5 NB |
126 | .TP |
127 | .B "Grow" | |
128 | Grow (or shrink) an array, or otherwise reshape it in some way. | |
129 | Currently supported growth options including changing the active size | |
93e790af SW |
130 | of component devices and changing the number of active devices in RAID |
131 | levels 1/4/5/6, as well as adding or removing a write-intent bitmap. | |
cd29a5c8 | 132 | |
8382f19b NB |
133 | .TP |
134 | .B "Incremental Assembly" | |
135 | Add a single device to an appropriate array. If the addition of the | |
136 | device makes the array runnable, the array will be started. | |
137 | This provides a convenient interface to a | |
138 | .I hot-plug | |
139 | system. As each device is detected, | |
140 | .I mdadm | |
141 | has a chance to include it in some array as appropriate. | |
142 | ||
2ae555c3 NB |
143 | .TP |
144 | .B Manage | |
145 | This is for doing things to specific components of an array such as | |
146 | adding new spares and removing faulty devices. | |
147 | ||
148 | .TP | |
149 | .B Misc | |
150 | This is an 'everything else' mode that supports operations on active | |
151 | arrays, operations on component devices such as erasing old superblocks, and | |
152 | information gathering operations. | |
e43d0cda NB |
153 | .\"This mode allows operations on independent devices such as examine MD |
154 | .\"superblocks, erasing old superblocks and stopping active arrays. | |
2ae555c3 | 155 | |
1f48664b NB |
156 | .TP |
157 | .B Auto-detect | |
158 | This mode does not act on a specific device or array, but rather it | |
159 | requests the Linux Kernel to activate any auto-detected arrays. | |
52826846 NB |
160 | .SH OPTIONS |
161 | ||
2ae555c3 | 162 | .SH Options for selecting a mode are: |
52826846 | 163 | |
cd29a5c8 | 164 | .TP |
7e23fc43 | 165 | .BR \-A ", " \-\-assemble |
2d465520 | 166 | Assemble a pre-existing array. |
52826846 | 167 | |
cd29a5c8 | 168 | .TP |
7e23fc43 | 169 | .BR \-B ", " \-\-build |
cd29a5c8 | 170 | Build a legacy array without superblocks. |
52826846 | 171 | |
cd29a5c8 | 172 | .TP |
7e23fc43 | 173 | .BR \-C ", " \-\-create |
cd29a5c8 | 174 | Create a new array. |
52826846 | 175 | |
cd29a5c8 | 176 | .TP |
7e23fc43 | 177 | .BR \-F ", " \-\-follow ", " \-\-monitor |
cd29a5c8 NB |
178 | Select |
179 | .B Monitor | |
180 | mode. | |
52826846 | 181 | |
dd0781e5 | 182 | .TP |
7e23fc43 | 183 | .BR \-G ", " \-\-grow |
dd0781e5 | 184 | Change the size or shape of an active array. |
8382f19b NB |
185 | |
186 | .TP | |
1f48664b | 187 | .BR \-I ", " \-\-incremental |
8382f19b NB |
188 | Add a single device into an appropriate array, and possibly start the array. |
189 | ||
1f48664b NB |
190 | .TP |
191 | .B \-\-auto-detect | |
192 | Request that the kernel starts any auto-detected arrays. This can only | |
193 | work if | |
194 | .I md | |
195 | is compiled into the kernel \(em not if it is a module. | |
196 | Arrays can be auto-detected by the kernel if all the components are in | |
197 | primary MS-DOS partitions with partition type | |
198 | .BR FD . | |
199 | In-kernel autodetect is not recommended for new installations. Using | |
200 | .I mdadm | |
201 | to detect and assemble arrays \(em possibly in an | |
202 | .I initrd | |
203 | \(em is substantially more flexible and should be preferred. | |
204 | ||
2ae555c3 NB |
205 | .P |
206 | If a device is given before any options, or if the first option is | |
7e23fc43 PS |
207 | .BR \-\-add , |
208 | .BR \-\-fail , | |
2ae555c3 | 209 | or |
7e23fc43 | 210 | .BR \-\-remove , |
2ae555c3 NB |
211 | then the MANAGE mode is assume. |
212 | Anything other than these will cause the | |
213 | .B Misc | |
214 | mode to be assumed. | |
dd0781e5 | 215 | |
2ae555c3 | 216 | .SH Options that are not mode-specific are: |
e793c2e5 | 217 | |
cd29a5c8 | 218 | .TP |
7e23fc43 | 219 | .BR \-h ", " \-\-help |
a9d69660 | 220 | Display general help message or, after one of the above options, a |
93e790af | 221 | mode-specific help message. |
56eedc1a NB |
222 | |
223 | .TP | |
7e23fc43 | 224 | .B \-\-help\-options |
56eedc1a NB |
225 | Display more detailed help about command line parsing and some commonly |
226 | used options. | |
52826846 | 227 | |
cd29a5c8 | 228 | .TP |
7e23fc43 | 229 | .BR \-V ", " \-\-version |
9a9dab36 | 230 | Print version information for mdadm. |
52826846 | 231 | |
cd29a5c8 | 232 | .TP |
7e23fc43 | 233 | .BR \-v ", " \-\-verbose |
22892d56 NB |
234 | Be more verbose about what is happening. This can be used twice to be |
235 | extra-verbose. | |
a9d69660 | 236 | The extra verbosity currently only affects |
7e23fc43 | 237 | .B \-\-detail \-\-scan |
22892d56 | 238 | and |
7e23fc43 | 239 | .BR "\-\-examine \-\-scan" . |
52826846 | 240 | |
dab6685f | 241 | .TP |
7e23fc43 | 242 | .BR \-q ", " \-\-quiet |
dab6685f | 243 | Avoid printing purely informative messages. With this, |
51ac42e3 | 244 | .I mdadm |
dab6685f NB |
245 | will be silent unless there is something really important to report. |
246 | ||
cd29a5c8 | 247 | .TP |
7e23fc43 | 248 | .BR \-b ", " \-\-brief |
cd29a5c8 | 249 | Be less verbose. This is used with |
7e23fc43 | 250 | .B \-\-detail |
cd29a5c8 | 251 | and |
7e23fc43 | 252 | .BR \-\-examine . |
22892d56 | 253 | Using |
7e23fc43 | 254 | .B \-\-brief |
22892d56 | 255 | with |
7e23fc43 | 256 | .B \-\-verbose |
22892d56 | 257 | gives an intermediate level of verbosity. |
52826846 | 258 | |
e0d19036 | 259 | .TP |
7e23fc43 | 260 | .BR \-f ", " \-\-force |
93e790af | 261 | Be more forceful about certain operations. See the various modes for |
e0d19036 NB |
262 | the exact meaning of this option in different contexts. |
263 | ||
264 | .TP | |
7e23fc43 | 265 | .BR \-c ", " \-\-config= |
2ae555c3 NB |
266 | Specify the config file. Default is to use |
267 | .BR /etc/mdadm.conf , | |
93e790af | 268 | or if that is missing then |
2ae555c3 | 269 | .BR /etc/mdadm/mdadm.conf . |
5787fa49 | 270 | If the config file given is |
93e790af | 271 | .B "partitions" |
5787fa49 NB |
272 | then nothing will be read, but |
273 | .I mdadm | |
274 | will act as though the config file contained exactly | |
275 | .B "DEVICE partitions" | |
276 | and will read | |
277 | .B /proc/partitions | |
278 | to find a list of devices to scan. | |
d013a55e | 279 | If the word |
93e790af | 280 | .B "none" |
d013a55e NB |
281 | is given for the config file, then |
282 | .I mdadm | |
283 | will act as though the config file were empty. | |
e0d19036 NB |
284 | |
285 | .TP | |
7e23fc43 | 286 | .BR \-s ", " \-\-scan |
93e790af | 287 | Scan config file or |
e0d19036 NB |
288 | .B /proc/mdstat |
289 | for missing information. | |
290 | In general, this option gives | |
51ac42e3 | 291 | .I mdadm |
93e790af SW |
292 | permission to get any missing information (like component devices, |
293 | array devices, array identities, and alert destination) from the | |
294 | configuration file (see previous option); | |
295 | one exception is MISC mode when using | |
7e23fc43 | 296 | .B \-\-detail |
e0d19036 | 297 | or |
93e790af | 298 | .B \-\-stop, |
e0d19036 | 299 | in which case |
7e23fc43 | 300 | .B \-\-scan |
e0d19036 NB |
301 | says to get a list of array devices from |
302 | .BR /proc/mdstat . | |
303 | ||
570c0542 | 304 | .TP |
7e23fc43 | 305 | .B \-e ", " \-\-metadata= |
570c0542 | 306 | Declare the style of superblock (raid metadata) to be used. The |
53e8b987 | 307 | default is 0.90 for |
7e23fc43 | 308 | .BR \-\-create , |
53e8b987 | 309 | and to guess for other operations. |
2790ffe3 GB |
310 | The default can be overridden by setting the |
311 | .B metadata | |
312 | value for the | |
313 | .B CREATE | |
314 | keyword in | |
315 | .BR mdadm.conf . | |
570c0542 NB |
316 | |
317 | Options are: | |
318 | .RS | |
319 | .IP "0, 0.90, default" | |
320 | Use the original 0.90 format superblock. This format limits arrays to | |
93e790af | 321 | 28 component devices and limits component devices of levels 1 and |
570c0542 NB |
322 | greater to 2 terabytes. |
323 | .IP "1, 1.0, 1.1, 1.2" | |
324 | Use the new version-1 format superblock. This has few restrictions. | |
93e790af | 325 | The different sub-versions store the superblock at different locations |
570c0542 NB |
326 | on the device, either at the end (for 1.0), at the start (for 1.1) or |
327 | 4K from the start (for 1.2). | |
328 | .RE | |
329 | ||
41a3b72a | 330 | .TP |
7e23fc43 | 331 | .B \-\-homehost= |
35cc5be4 | 332 | This will override any |
41a3b72a | 333 | .B HOMEHOST |
93e790af | 334 | setting in the config file and provides the identity of the host which |
41a3b72a NB |
335 | should be considered the home for any arrays. |
336 | ||
337 | When creating an array, the | |
338 | .B homehost | |
339 | will be recorded in the superblock. For version-1 superblocks, it will | |
93e790af | 340 | be prefixed to the array name. For version-0.90 superblocks, part of |
41a3b72a NB |
341 | the SHA1 hash of the hostname will be stored in the later half of the |
342 | UUID. | |
343 | ||
344 | When reporting information about an array, any array which is tagged | |
345 | for the given homehost will be reported as such. | |
346 | ||
347 | When using Auto-Assemble, only arrays tagged for the given homehost | |
348 | will be assembled. | |
349 | ||
2ae555c3 NB |
350 | .SH For create, build, or grow: |
351 | ||
352 | .TP | |
7e23fc43 | 353 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
354 | Specify the number of active devices in the array. This, plus the |
355 | number of spare devices (see below) must equal the number of | |
356 | .I component-devices | |
357 | (including "\fBmissing\fP" devices) | |
358 | that are listed on the command line for | |
7e23fc43 | 359 | .BR \-\-create . |
2ae555c3 NB |
360 | Setting a value of 1 is probably |
361 | a mistake and so requires that | |
7e23fc43 | 362 | .B \-\-force |
2ae555c3 NB |
363 | be specified first. A value of 1 will then be allowed for linear, |
364 | multipath, raid0 and raid1. It is never allowed for raid4 or raid5. | |
365 | .br | |
366 | This number can only be changed using | |
7e23fc43 | 367 | .B \-\-grow |
00be0b12 NB |
368 | for RAID1, RAID5 and RAID6 arrays, and only on kernels which provide |
369 | necessary support. | |
2ae555c3 NB |
370 | |
371 | .TP | |
7e23fc43 | 372 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
373 | Specify the number of spare (eXtra) devices in the initial array. |
374 | Spares can also be added | |
375 | and removed later. The number of component devices listed | |
376 | on the command line must equal the number of raid devices plus the | |
377 | number of spare devices. | |
378 | ||
379 | ||
380 | .TP | |
7e23fc43 | 381 | .BR \-z ", " \-\-size= |
93e790af | 382 | Amount (in Kibibytes) of space to use from each drive in RAID level 1/4/5/6. |
2ae555c3 NB |
383 | This must be a multiple of the chunk size, and must leave about 128Kb |
384 | of space at the end of the drive for the RAID superblock. | |
385 | If this is not specified | |
386 | (as it normally is not) the smallest drive (or partition) sets the | |
387 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
388 | issued. | |
389 | ||
390 | This value can be set with | |
7e23fc43 | 391 | .B \-\-grow |
2ae555c3 NB |
392 | for RAID level 1/4/5/6. If the array was created with a size smaller |
393 | than the currently active drives, the extra space can be accessed | |
394 | using | |
7e23fc43 | 395 | .BR \-\-grow . |
2ae555c3 NB |
396 | The size can be given as |
397 | .B max | |
398 | which means to choose the largest size that fits on all current drives. | |
52826846 | 399 | |
cd29a5c8 | 400 | .TP |
7e23fc43 | 401 | .BR \-c ", " \-\-chunk= |
cd29a5c8 | 402 | Specify chunk size of kibibytes. The default is 64. |
52826846 | 403 | |
cd29a5c8 | 404 | .TP |
7e23fc43 | 405 | .BR \-\-rounding= |
cd29a5c8 | 406 | Specify rounding factor for linear array (==chunk size) |
52826846 | 407 | |
cd29a5c8 | 408 | .TP |
7e23fc43 | 409 | .BR \-l ", " \-\-level= |
aa88f531 | 410 | Set raid level. When used with |
7e23fc43 | 411 | .BR \-\-create , |
98c6faba | 412 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
2ae555c3 | 413 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty. Obviously some of these are synonymous. |
aa88f531 NB |
414 | |
415 | When used with | |
7e23fc43 | 416 | .BR \-\-build , |
a9d69660 | 417 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 418 | |
2ae555c3 | 419 | Not yet supported with |
7e23fc43 | 420 | .BR \-\-grow . |
2ae555c3 | 421 | |
cd29a5c8 | 422 | .TP |
7e23fc43 | 423 | .BR \-p ", " \-\-layout= |
1a7dfc35 NB |
424 | This option configures the fine details of data layout for raid5, |
425 | and raid10 arrays, and controls the failure modes for | |
426 | .IR faulty . | |
427 | ||
428 | The layout of the raid5 parity block can be one of | |
7e23fc43 PS |
429 | .BR left\-asymmetric , |
430 | .BR left\-symmetric , | |
431 | .BR right\-asymmetric , | |
432 | .BR right\-symmetric , | |
53e8b987 PS |
433 | .BR la ", " ra ", " ls ", " rs . |
434 | The default is | |
7e23fc43 | 435 | .BR left\-symmetric . |
52826846 | 436 | |
93e790af SW |
437 | When setting the failure mode for level |
438 | .I faulty, | |
1a7dfc35 | 439 | the options are: |
7e23fc43 PS |
440 | .BR write\-transient ", " wt , |
441 | .BR read\-transient ", " rt , | |
442 | .BR write\-persistent ", " wp , | |
443 | .BR read\-persistent ", " rp , | |
444 | .BR write\-all , | |
445 | .BR read\-fixable ", " rf , | |
53e8b987 | 446 | .BR clear ", " flush ", " none . |
b5e64645 | 447 | |
93e790af | 448 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
449 | between fault generation. Without a number, the fault is generated |
450 | once on the first relevant request. With a number, the fault will be | |
93e790af | 451 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
452 | every time the period elapses. |
453 | ||
454 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 455 | .B \-\-grow |
53e8b987 | 456 | option to set subsequent failure modes. |
b5e64645 NB |
457 | |
458 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 459 | and "flush" will clear any persistent faults. |
b5e64645 | 460 | |
53e8b987 | 461 | To set the parity with |
7e23fc43 | 462 | .BR \-\-grow , |
53e8b987 | 463 | the level of the array ("faulty") |
b5e64645 NB |
464 | must be specified before the fault mode is specified. |
465 | ||
6f9a21a7 | 466 | Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 467 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 468 | |
93e790af | 469 | .I 'n' |
b578481c NB |
470 | signals 'near' copies. Multiple copies of one data block are at |
471 | similar offsets in different devices. | |
472 | ||
93e790af | 473 | .I 'o' |
b578481c NB |
474 | signals 'offset' copies. Rather than the chunks being duplicated |
475 | within a stripe, whole stripes are duplicated but are rotated by one | |
476 | device so duplicate blocks are on different devices. Thus subsequent | |
477 | copies of a block are in the next drive, and are one chunk further | |
478 | down. | |
479 | ||
93e790af | 480 | .I 'f' |
1a7dfc35 | 481 | signals 'far' copies |
93e790af SW |
482 | (multiple copies have very different offsets). |
483 | See md(4) for more detail about 'near' and 'far'. | |
1a7dfc35 NB |
484 | |
485 | The number is the number of copies of each datablock. 2 is normal, 3 | |
486 | can be useful. This number can be at most equal to the number of | |
487 | devices in the array. It does not need to divide evenly into that | |
488 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
489 | with an odd number of devices). | |
490 | ||
cd29a5c8 | 491 | .TP |
7e23fc43 | 492 | .BR \-\-parity= |
53e8b987 | 493 | same as |
7e23fc43 | 494 | .B \-\-layout |
53e8b987 | 495 | (thus explaining the p of |
7e23fc43 | 496 | .BR \-p ). |
52826846 | 497 | |
e793c2e5 | 498 | .TP |
7e23fc43 | 499 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 500 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 501 | exist unless |
7e23fc43 | 502 | .B \-\-force |
53e8b987 | 503 | is also given. The same file should be provided |
2ae555c3 | 504 | when assembling the array. If the word |
93e790af | 505 | .B "internal" |
2ae555c3 NB |
506 | is given, then the bitmap is stored with the metadata on the array, |
507 | and so is replicated on all devices. If the word | |
93e790af | 508 | .B "none" |
2ae555c3 | 509 | is given with |
7e23fc43 | 510 | .B \-\-grow |
2ae555c3 | 511 | mode, then any bitmap that is present is removed. |
e793c2e5 | 512 | |
2ae555c3 NB |
513 | To help catch typing errors, the filename must contain at least one |
514 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
515 | ||
516 | Note: external bitmaps are only known to work on ext2 and ext3. | |
517 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 518 | |
cd29a5c8 | 519 | .TP |
7e23fc43 | 520 | .BR \-\-bitmap\-chunk= |
2ae555c3 | 521 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
522 | Kilobytes of storage. |
523 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 524 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
525 | When using an |
526 | .B internal | |
527 | bitmap, the chunksize is automatically determined to make best use of | |
528 | available space. | |
5787fa49 | 529 | |
cd29a5c8 NB |
530 | |
531 | .TP | |
7e23fc43 | 532 | .BR \-W ", " \-\-write\-mostly |
2ae555c3 | 533 | subsequent devices lists in a |
7e23fc43 PS |
534 | .BR \-\-build , |
535 | .BR \-\-create , | |
2ae555c3 | 536 | or |
7e23fc43 | 537 | .B \-\-add |
2ae555c3 NB |
538 | command will be flagged as 'write-mostly'. This is valid for RAID1 |
539 | only and means that the 'md' driver will avoid reading from these | |
540 | devices if at all possible. This can be useful if mirroring over a | |
541 | slow link. | |
52826846 | 542 | |
2ae555c3 | 543 | .TP |
7e23fc43 | 544 | .BR \-\-write\-behind= |
2ae555c3 NB |
545 | Specify that write-behind mode should be enabled (valid for RAID1 |
546 | only). If an argument is specified, it will set the maximum number | |
547 | of outstanding writes allowed. The default value is 256. | |
548 | A write-intent bitmap is required in order to use write-behind | |
549 | mode, and write-behind is only attempted on drives marked as | |
550 | .IR write-mostly . | |
dd0781e5 NB |
551 | |
552 | .TP | |
7e23fc43 | 553 | .BR \-\-assume\-clean |
dd0781e5 NB |
554 | Tell |
555 | .I mdadm | |
47d79ef8 NB |
556 | that the array pre-existed and is known to be clean. It can be useful |
557 | when trying to recover from a major failure as you can be sure that no | |
558 | data will be affected unless you actually write to the array. It can | |
559 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 560 | initial resync, however this practice \(em while normally safe \(em is not |
93e790af | 561 | recommended. Use this only if you really know what you are doing. |
dd0781e5 | 562 | |
2ae555c3 | 563 | .TP |
7e23fc43 | 564 | .BR \-\-backup\-file= |
53e8b987 | 565 | This is needed when |
7e23fc43 | 566 | .B \-\-grow |
53e8b987 | 567 | is used to increase the number of |
2ae555c3 NB |
568 | raid-devices in a RAID5 if there are no spare devices available. |
569 | See the section below on RAID_DEVICE CHANGES. The file should be | |
570 | stored on a separate device, not on the raid array being reshaped. | |
571 | ||
947fd4dd | 572 | .TP |
7e23fc43 | 573 | .BR \-N ", " \-\-name= |
947fd4dd NB |
574 | Set a |
575 | .B name | |
576 | for the array. This is currently only effective when creating an | |
577 | array with a version-1 superblock. The name is a simple textual | |
578 | string that can be used to identify array components when assembling. | |
579 | ||
dd0781e5 | 580 | .TP |
7e23fc43 | 581 | .BR \-R ", " \-\-run |
dd0781e5 NB |
582 | Insist that |
583 | .I mdadm | |
584 | run the array, even if some of the components | |
585 | appear to be active in another array or filesystem. Normally | |
586 | .I mdadm | |
587 | will ask for confirmation before including such components in an | |
588 | array. This option causes that question to be suppressed. | |
589 | ||
590 | .TP | |
7e23fc43 | 591 | .BR \-f ", " \-\-force |
dd0781e5 NB |
592 | Insist that |
593 | .I mdadm | |
594 | accept the geometry and layout specified without question. Normally | |
595 | .I mdadm | |
596 | will not allow creation of an array with only one device, and will try | |
597 | to create a raid5 array with one missing drive (as this makes the | |
598 | initial resync work faster). With | |
7e23fc43 | 599 | .BR \-\-force , |
dd0781e5 NB |
600 | .I mdadm |
601 | will not try to be so clever. | |
602 | ||
603 | .TP | |
7e23fc43 | 604 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part,p}{NN}" |
48f7b27a NB |
605 | Instruct mdadm to create the device file if needed, possibly allocating |
606 | an unused minor number. "md" causes a non-partitionable array | |
dd0781e5 | 607 | to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and |
2ae555c3 | 608 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 609 | a 'standard' format, and the type and minor number will be determined |
48f7b27a NB |
610 | from this. See DEVICE NAMES below. |
611 | ||
a9d69660 | 612 | The argument can also come immediately after |
7e23fc43 | 613 | "\-a". e.g. "\-ap". |
dd0781e5 | 614 | |
53e8b987 | 615 | If |
7e23fc43 | 616 | .B \-\-auto |
53e8b987 | 617 | is not given on the command line or in the config file, then |
75723446 | 618 | the default will be |
7e23fc43 | 619 | .BR \-\-auto=yes . |
75723446 | 620 | |
1337546d | 621 | If |
7e23fc43 | 622 | .B \-\-scan |
1337546d NB |
623 | is also given, then any |
624 | .I auto= | |
35cc5be4 | 625 | entries in the config file will override the |
7e23fc43 | 626 | .B \-\-auto |
1337546d NB |
627 | instruction given on the command line. |
628 | ||
dd0781e5 NB |
629 | For partitionable arrays, |
630 | .I mdadm | |
631 | will create the device file for the whole array and for the first 4 | |
632 | partitions. A different number of partitions can be specified at the | |
633 | end of this option (e.g. | |
7e23fc43 | 634 | .BR \-\-auto=p7 ). |
2ae555c3 | 635 | If the device name ends with a digit, the partition names add a 'p', |
48f7b27a | 636 | and a number, e.g. "/dev/home1p3". If there is no |
dd0781e5 NB |
637 | trailing digit, then the partition names just have a number added, |
638 | e.g. "/dev/scratch3". | |
639 | ||
48f7b27a NB |
640 | If the md device name is in a 'standard' format as described in DEVICE |
641 | NAMES, then it will be created, if necessary, with the appropriate | |
642 | number based on that name. If the device name is not in one of these | |
a9d69660 | 643 | formats, then a unused minor number will be allocated. The minor |
48f7b27a NB |
644 | number will be considered unused if there is no active array for that |
645 | number, and there is no entry in /dev for that number and with a | |
646 | non-standard name. | |
647 | ||
38098016 | 648 | .TP |
7e23fc43 | 649 | .BR \-\-symlink = no |
38098016 | 650 | Normally when |
7e23fc43 | 651 | .B \-\-auto |
38098016 NB |
652 | causes |
653 | .I mdadm | |
654 | to create devices in | |
655 | .B /dev/md/ | |
656 | it will also create symlinks from | |
657 | .B /dev/ | |
658 | with names starting with | |
659 | .B md | |
660 | or | |
661 | .BR md_ . | |
662 | Use | |
7e23fc43 | 663 | .B \-\-symlink=no |
38098016 | 664 | to suppress this, or |
7e23fc43 | 665 | .B \-\-symlink=yes |
38098016 NB |
666 | to enforce this even if it is suppressing |
667 | .IR mdadm.conf . | |
668 | ||
669 | ||
52826846 NB |
670 | .SH For assemble: |
671 | ||
cd29a5c8 | 672 | .TP |
7e23fc43 | 673 | .BR \-u ", " \-\-uuid= |
cd29a5c8 NB |
674 | uuid of array to assemble. Devices which don't have this uuid are |
675 | excluded | |
676 | ||
677 | .TP | |
7e23fc43 | 678 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
679 | Minor number of device that array was created for. Devices which |
680 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 681 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
682 | the array is later assembled as /dev/md2. |
683 | ||
d013a55e | 684 | Giving the literal word "dev" for |
7e23fc43 | 685 | .B \-\-super\-minor |
d013a55e NB |
686 | will cause |
687 | .I mdadm | |
688 | to use the minor number of the md device that is being assembled. | |
689 | e.g. when assembling | |
690 | .BR /dev/md0 , | |
51ac42e3 | 691 | .B \-\-super\-minor=dev |
d013a55e NB |
692 | will look for super blocks with a minor number of 0. |
693 | ||
947fd4dd | 694 | .TP |
7e23fc43 | 695 | .BR \-N ", " \-\-name= |
947fd4dd | 696 | Specify the name of the array to assemble. This must be the name |
624920bb | 697 | that was specified when creating the array. It must either match |
93e790af | 698 | the name stored in the superblock exactly, or it must match |
41a3b72a | 699 | with the current |
624920bb | 700 | .I homehost |
93e790af | 701 | prefixed to the start of the given name. |
947fd4dd | 702 | |
cd29a5c8 | 703 | .TP |
7e23fc43 | 704 | .BR \-f ", " \-\-force |
52826846 NB |
705 | Assemble the array even if some superblocks appear out-of-date |
706 | ||
cd29a5c8 | 707 | .TP |
7e23fc43 | 708 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
709 | Attempt to start the array even if fewer drives were given than were |
710 | present last time the array was active. Normally if not all the | |
711 | expected drives are found and | |
7e23fc43 | 712 | .B \-\-scan |
cd29a5c8 NB |
713 | is not used, then the array will be assembled but not started. |
714 | With | |
7e23fc43 | 715 | .B \-\-run |
cd29a5c8 | 716 | an attempt will be made to start it anyway. |
52826846 | 717 | |
b8a8ccf9 | 718 | .TP |
7e23fc43 | 719 | .B \-\-no\-degraded |
b8a8ccf9 | 720 | This is the reverse of |
7e23fc43 | 721 | .B \-\-run |
93e790af | 722 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 723 | are present. This is only needed with |
93e790af SW |
724 | .B \-\-scan, |
725 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
726 | not as reliable as you would like. |
727 | ||
dd0781e5 | 728 | .TP |
7e23fc43 | 729 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
730 | See this option under Create and Build options. |
731 | ||
e793c2e5 | 732 | .TP |
7e23fc43 | 733 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
734 | Specify the bitmap file that was given when the array was created. If |
735 | an array has an | |
736 | .B internal | |
737 | bitmap, there is no need to specify this when assembling the array. | |
738 | ||
739 | .TP | |
7e23fc43 | 740 | .BR \-\-backup\-file= |
2ae555c3 | 741 | If |
7e23fc43 | 742 | .B \-\-backup\-file |
2ae555c3 NB |
743 | was used to grow the number of raid-devices in a RAID5, and the system |
744 | crashed during the critical section, then the same | |
7e23fc43 | 745 | .B \-\-backup\-file |
53e8b987 | 746 | must be presented to |
7e23fc43 | 747 | .B \-\-assemble |
53e8b987 | 748 | to allow possibly corrupted data to be restored. |
e793c2e5 | 749 | |
5787fa49 | 750 | .TP |
7e23fc43 | 751 | .BR \-U ", " \-\-update= |
5787fa49 | 752 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
753 | argument given to this flag can be one of |
754 | .BR sparc2.2 , | |
755 | .BR summaries , | |
7d99579f | 756 | .BR uuid , |
c4f12c13 | 757 | .BR name , |
0237e0ca | 758 | .BR homehost , |
e5329c37 | 759 | .BR resync , |
586ed405 | 760 | .BR byteorder , |
bee8ec56 | 761 | .BR devicesize , |
5787fa49 | 762 | or |
7e23fc43 | 763 | .BR super\-minor . |
5787fa49 NB |
764 | |
765 | The | |
766 | .B sparc2.2 | |
7d99579f | 767 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
768 | machine running a patched 2.2 Linux kernel. This kernel got the |
769 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 770 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
771 | option to |
772 | .I mdadm | |
773 | to see what effect this would have. | |
774 | ||
775 | The | |
7e23fc43 | 776 | .B super\-minor |
5787fa49 | 777 | option will update the |
2ae555c3 | 778 | .B "preferred minor" |
5787fa49 | 779 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
780 | assembled. |
781 | This can be useful if | |
7e23fc43 | 782 | .B \-\-examine |
45c073c9 | 783 | reports a different "Preferred Minor" to |
7e23fc43 | 784 | .BR \-\-detail . |
45c073c9 NB |
785 | In some cases this update will be performed automatically |
786 | by the kernel driver. In particular the update happens automatically | |
787 | at the first write to an array with redundancy (RAID level 1 or | |
788 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 789 | |
7d99579f NB |
790 | The |
791 | .B uuid | |
792 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 793 | .B \-\-uuid |
53e8b987 | 794 | option that UUID will be used as a new UUID and will |
7d99579f NB |
795 | .B NOT |
796 | be used to help identify the devices in the array. | |
53e8b987 | 797 | If no |
7e23fc43 | 798 | .B \-\-uuid |
53e8b987 | 799 | is given, a random UUID is chosen. |
7d99579f | 800 | |
c4f12c13 NB |
801 | The |
802 | .B name | |
803 | option will change the | |
804 | .I name | |
805 | of the array as stored in the superblock. This is only supported for | |
806 | version-1 superblocks. | |
807 | ||
0237e0ca NB |
808 | The |
809 | .B homehost | |
810 | option will change the | |
811 | .I homehost | |
812 | as recorded in the superblock. For version-0 superblocks, this is the | |
813 | same as updating the UUID. | |
814 | For version-1 superblocks, this involves updating the name. | |
815 | ||
e5329c37 NB |
816 | The |
817 | .B resync | |
818 | option will cause the array to be marked | |
819 | .I dirty | |
820 | meaning that any redundancy in the array (e.g. parity for raid5, | |
821 | copies for raid1) may be incorrect. This will cause the raid system | |
822 | to perform a "resync" pass to make sure that all redundant information | |
823 | is correct. | |
824 | ||
586ed405 NB |
825 | The |
826 | .B byteorder | |
827 | option allows arrays to be moved between machines with different | |
828 | byte-order. | |
2ae555c3 | 829 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 830 | .B "\-\-update=byteorder" |
586ed405 NB |
831 | will cause |
832 | .I mdadm | |
833 | to expect superblocks to have their byteorder reversed, and will | |
834 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 835 | with original (Version 0.90) superblocks. |
586ed405 | 836 | |
feb716e9 NB |
837 | The |
838 | .B summaries | |
839 | option will correct the summaries in the superblock. That is the | |
840 | counts of total, working, active, failed, and spare devices. | |
5787fa49 | 841 | |
bee8ec56 NB |
842 | The |
843 | .B devicesize | |
844 | will rarely be of use. It applies to version 1.1 and 1.2 metadata | |
845 | only (where the metadata is at the start of the device) and is only | |
846 | useful when the component device has changed size (typically become | |
847 | larger). The version 1 metadata records the amount of the device that | |
848 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
849 | array becomes larger, the metadata will still be visible, but the | |
850 | extra space will not. In this case it might be useful to assemble the | |
851 | array with | |
7e23fc43 | 852 | .BR \-\-update=devicesize . |
bee8ec56 NB |
853 | This will cause |
854 | .I mdadm | |
855 | to determine the maximum usable amount of space on each device and | |
856 | update the relevant field in the metadata. | |
857 | ||
41a3b72a | 858 | .TP |
7e23fc43 | 859 | .B \-\-auto\-update\-homehost |
93e790af | 860 | This flag is only meaningful with auto-assembly (see discussion below). |
41a3b72a NB |
861 | In that situation, if no suitable arrays are found for this homehost, |
862 | .I mdadm | |
93e790af | 863 | will rescan for any arrays at all and will assemble them and update the |
41a3b72a NB |
864 | homehost to match the current host. |
865 | ||
e0d19036 | 866 | .SH For Manage mode: |
52826846 | 867 | |
cd29a5c8 | 868 | .TP |
7e23fc43 | 869 | .BR \-a ", " \-\-add |
2ae555c3 | 870 | hot-add listed devices. |
52826846 | 871 | |
fe80f49b | 872 | .TP |
7e23fc43 | 873 | .BR \-\-re\-add |
2ae555c3 | 874 | re-add a device that was recently removed from an array. |
fe80f49b | 875 | |
cd29a5c8 | 876 | .TP |
7e23fc43 | 877 | .BR \-r ", " \-\-remove |
2d465520 | 878 | remove listed devices. They must not be active. i.e. they should |
b80da661 NB |
879 | be failed or spare devices. As well as the name of a device file |
880 | (e.g. | |
881 | .BR /dev/sda1 ) | |
882 | the words | |
883 | .B failed | |
884 | and | |
885 | .B detached | |
886 | can be given to | |
887 | .BR \-\-remove . | |
888 | The first causes all failed device to be removed. The second causes | |
93e790af | 889 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
890 | returns |
891 | .BR ENXIO ) | |
892 | to be removed. This will only succeed for devices that are spares or | |
893 | have already been marked as failed. | |
52826846 | 894 | |
cd29a5c8 | 895 | .TP |
7e23fc43 | 896 | .BR \-f ", " \-\-fail |
cd29a5c8 | 897 | mark listed devices as faulty. |
b80da661 NB |
898 | As well as the name of a device file, the word |
899 | .B detached | |
900 | can be given. This will cause any device that has been detached from | |
901 | the system to be marked as failed. It can then be removed. | |
52826846 | 902 | |
cd29a5c8 | 903 | .TP |
7e23fc43 | 904 | .BR \-\-set\-faulty |
53e8b987 | 905 | same as |
7e23fc43 | 906 | .BR \-\-fail . |
52826846 | 907 | |
2ae555c3 | 908 | .P |
93e790af SW |
909 | Each of these options require that the first device listed is the array |
910 | to be acted upon, and the remainder are component devices to be added, | |
911 | removed, or marked as faulty. Several different operations can be | |
2ae555c3 NB |
912 | specified for different devices, e.g. |
913 | .in +5 | |
7e23fc43 | 914 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
915 | .in -5 |
916 | Each operation applies to all devices listed until the next | |
93e790af | 917 | operation. |
2ae555c3 NB |
918 | |
919 | If an array is using a write-intent bitmap, then devices which have | |
920 | been removed can be re-added in a way that avoids a full | |
93e790af | 921 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
922 | since the device was removed. For arrays with persistent metadata |
923 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 924 | .B \-\-build |
2ae555c3 | 925 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 926 | .BR \-\-re\-add . |
2ae555c3 NB |
927 | |
928 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
929 | use, i.e. that must be spares or failed devices. To remove an active |
930 | device, it must first be marked as | |
931 | .B faulty. | |
2ae555c3 NB |
932 | |
933 | .SH For Misc mode: | |
934 | ||
935 | .TP | |
7e23fc43 | 936 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
937 | Examine a device to see |
938 | (1) if it is an md device and (2) if it is a component of an md | |
939 | array. | |
940 | Information about what is discovered is presented. | |
941 | ||
942 | .TP | |
7e23fc43 | 943 | .BR \-D ", " \-\-detail |
2ae555c3 | 944 | Print detail of one or more md devices. |
5787fa49 | 945 | |
54bad364 KS |
946 | .TP |
947 | .BR \-Y ", " \-\-export | |
948 | When used with | |
0d726f17 KS |
949 | .B \-\-detail |
950 | or | |
951 | .BR \-\-examine , | |
54bad364 KS |
952 | output will be formatted as |
953 | .B key=value | |
954 | pairs for easy import into the environment. | |
955 | ||
2ae555c3 | 956 | .TP |
7e23fc43 | 957 | .BR \-E ", " \-\-examine |
2ae555c3 | 958 | Print content of md superblock on device(s). |
5787fa49 | 959 | .TP |
7e23fc43 | 960 | .B \-\-sparc2.2 |
a9d69660 | 961 | If an array was created on a 2.2 Linux kernel patched with RAID |
5787fa49 NB |
962 | support, the superblock will have been created incorrectly, or at |
963 | least incompatibly with 2.4 and later kernels. Using the | |
7e23fc43 | 964 | .B \-\-sparc2.2 |
5787fa49 | 965 | flag with |
7e23fc43 | 966 | .B \-\-examine |
5787fa49 NB |
967 | will fix the superblock before displaying it. If this appears to do |
968 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 969 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 970 | |
2ae555c3 | 971 | .TP |
7e23fc43 | 972 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 973 | Report information about a bitmap file. |
01d9299c NB |
974 | The argument is either an external bitmap file or an array component |
975 | in case of an internal bitmap. | |
e0d19036 | 976 | |
cd29a5c8 | 977 | .TP |
7e23fc43 | 978 | .BR \-R ", " \-\-run |
cd29a5c8 | 979 | start a partially built array. |
52826846 | 980 | |
cd29a5c8 | 981 | .TP |
7e23fc43 | 982 | .BR \-S ", " \-\-stop |
cd29a5c8 | 983 | deactivate array, releasing all resources. |
52826846 | 984 | |
cd29a5c8 | 985 | .TP |
7e23fc43 | 986 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 987 | mark array as readonly. |
52826846 | 988 | |
cd29a5c8 | 989 | .TP |
7e23fc43 | 990 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 991 | mark array as readwrite. |
52826846 | 992 | |
e0d19036 | 993 | .TP |
7e23fc43 | 994 | .B \-\-zero\-superblock |
e0d19036 | 995 | If the device contains a valid md superblock, the block is |
35cc5be4 | 996 | overwritten with zeros. With |
7e23fc43 | 997 | .B \-\-force |
35cc5be4 | 998 | the block where the superblock would be is overwritten even if it |
e0d19036 | 999 | doesn't appear to be valid. |
52826846 | 1000 | |
feb716e9 | 1001 | .TP |
7e23fc43 | 1002 | .BR \-t ", " \-\-test |
feb716e9 | 1003 | When used with |
7e23fc43 | 1004 | .BR \-\-detail , |
feb716e9 NB |
1005 | the exit status of |
1006 | .I mdadm | |
1007 | is set to reflect the status of the device. | |
1008 | ||
b90c0e9a | 1009 | .TP |
7e23fc43 | 1010 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1011 | For each md device given, wait for any resync, recovery, or reshape |
1012 | activity to finish before returning. | |
1013 | .I mdadm | |
1014 | will return with success if it actually waited for every device | |
1015 | listed, otherwise it will return failure. | |
1016 | ||
8382f19b NB |
1017 | .SH For Incremental Assembly mode: |
1018 | .TP | |
7e23fc43 | 1019 | .BR \-\-rebuild\-map ", " \-r |
8382f19b NB |
1020 | Rebuild the map file |
1021 | .RB ( /var/run/mdadm/map ) | |
1022 | that | |
1023 | .I mdadm | |
1024 | uses to help track which arrays are currently being assembled. | |
1025 | ||
1026 | .TP | |
7e23fc43 | 1027 | .BR \-\-run ", " \-R |
8382f19b NB |
1028 | Run any array assembled as soon as a minimal number of devices are |
1029 | available, rather than waiting until all expected devices are present. | |
1030 | ||
1031 | .TP | |
7e23fc43 | 1032 | .BR \-\-scan ", " \-s |
8382f19b | 1033 | Only meaningful with |
7e23fc43 | 1034 | .B \-R |
8382f19b NB |
1035 | this will scan the |
1036 | .B map | |
1037 | file for arrays that are being incrementally assembled and will try to | |
1038 | start any that are not already started. If any such array is listed | |
1039 | in | |
1040 | .B mdadm.conf | |
1041 | as requiring an external bitmap, that bitmap will be attached first. | |
1042 | ||
e0d19036 NB |
1043 | .SH For Monitor mode: |
1044 | .TP | |
7e23fc43 | 1045 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1046 | Give a mail address to send alerts to. |
1047 | ||
1048 | .TP | |
7e23fc43 | 1049 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1050 | Give a program to be run whenever an event is detected. |
1051 | ||
773135f5 | 1052 | .TP |
7e23fc43 | 1053 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1054 | Cause all events to be reported through 'syslog'. The messages have |
1055 | facility of 'daemon' and varying priorities. | |
1056 | ||
e0d19036 | 1057 | .TP |
7e23fc43 | 1058 | .BR \-d ", " \-\-delay |
e0d19036 | 1059 | Give a delay in seconds. |
51ac42e3 | 1060 | .I mdadm |
e0d19036 NB |
1061 | polls the md arrays and then waits this many seconds before polling |
1062 | again. The default is 60 seconds. | |
1063 | ||
d013a55e | 1064 | .TP |
7e23fc43 | 1065 | .BR \-f ", " \-\-daemonise |
d013a55e | 1066 | Tell |
51ac42e3 | 1067 | .I mdadm |
d013a55e NB |
1068 | to run as a background daemon if it decides to monitor anything. This |
1069 | causes it to fork and run in the child, and to disconnect form the | |
1070 | terminal. The process id of the child is written to stdout. | |
1071 | This is useful with | |
7e23fc43 | 1072 | .B \-\-scan |
d013a55e NB |
1073 | which will only continue monitoring if a mail address or alert program |
1074 | is found in the config file. | |
1075 | ||
b5e64645 | 1076 | .TP |
7e23fc43 | 1077 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1078 | When |
51ac42e3 | 1079 | .I mdadm |
b5e64645 NB |
1080 | is running in daemon mode, write the pid of the daemon process to |
1081 | the specified file, instead of printing it on standard output. | |
1082 | ||
aa88f531 | 1083 | .TP |
7e23fc43 | 1084 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1085 | Check arrays only once. This will generate |
1086 | .B NewArray | |
1087 | events and more significantly | |
1088 | .B DegradedArray | |
a9d69660 NB |
1089 | and |
1090 | .B SparesMissing | |
aa88f531 NB |
1091 | events. Running |
1092 | .in +5 | |
7e23fc43 | 1093 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1094 | .in -5 |
1095 | from a cron script will ensure regular notification of any degraded arrays. | |
1096 | ||
98c6faba | 1097 | .TP |
7e23fc43 | 1098 | .BR \-t ", " \-\-test |
98c6faba NB |
1099 | Generate a |
1100 | .B TestMessage | |
1101 | alert for every array found at startup. This alert gets mailed and | |
1102 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1103 | message do get through successfully. |
98c6faba | 1104 | |
e0d19036 | 1105 | .SH ASSEMBLE MODE |
52826846 | 1106 | |
cd29a5c8 NB |
1107 | .HP 12 |
1108 | Usage: | |
7e23fc43 | 1109 | .B mdadm \-\-assemble |
5787fa49 NB |
1110 | .I md-device options-and-component-devices... |
1111 | .HP 12 | |
1112 | Usage: | |
7e23fc43 | 1113 | .B mdadm \-\-assemble \-\-scan |
5787fa49 | 1114 | .I md-devices-and-options... |
cd29a5c8 NB |
1115 | .HP 12 |
1116 | Usage: | |
7e23fc43 | 1117 | .B mdadm \-\-assemble \-\-scan |
cd29a5c8 | 1118 | .I options... |
52826846 | 1119 | |
cd29a5c8 | 1120 | .PP |
52826846 | 1121 | This usage assembles one or more raid arrays from pre-existing components. |
9a9dab36 | 1122 | For each array, mdadm needs to know the md device, the identity of the |
e0d19036 | 1123 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1124 | |
5787fa49 | 1125 | In the first usage example (without the |
7e23fc43 | 1126 | .BR \-\-scan ) |
5787fa49 NB |
1127 | the first device given is the md device. |
1128 | In the second usage example, all devices listed are treated as md | |
1129 | devices and assembly is attempted. | |
1130 | In the third (where no devices are listed) all md devices that are | |
1131 | listed in the configuration file are assembled. | |
52826846 | 1132 | |
d013a55e | 1133 | If precisely one device is listed, but |
7e23fc43 | 1134 | .B \-\-scan |
dd0781e5 | 1135 | is not given, then |
d013a55e NB |
1136 | .I mdadm |
1137 | acts as though | |
7e23fc43 | 1138 | .B \-\-scan |
93e790af | 1139 | was given and identity information is extracted from the configuration file. |
d013a55e | 1140 | |
2ae555c3 | 1141 | The identity can be given with the |
7e23fc43 | 1142 | .B \-\-uuid |
cd29a5c8 | 1143 | option, with the |
7e23fc43 | 1144 | .B \-\-super\-minor |
93e790af SW |
1145 | option, will be taken from the md-device record in the config file, or |
1146 | will be taken from the super block of the first component-device | |
1147 | listed on the command line. | |
52826846 | 1148 | |
2ae555c3 | 1149 | Devices can be given on the |
7e23fc43 | 1150 | .B \-\-assemble |
5787fa49 NB |
1151 | command line or in the config file. Only devices which have an md |
1152 | superblock which contains the right identity will be considered for | |
1153 | any array. | |
52826846 | 1154 | |
2ae555c3 | 1155 | The config file is only used if explicitly named with |
7e23fc43 | 1156 | .B \-\-config |
d013a55e | 1157 | or requested with (a possibly implicit) |
7e23fc43 | 1158 | .BR \-\-scan . |
52826846 | 1159 | In the later case, |
9a9dab36 | 1160 | .B /etc/mdadm.conf |
52826846 NB |
1161 | is used. |
1162 | ||
2ae555c3 | 1163 | If |
7e23fc43 | 1164 | .B \-\-scan |
cd29a5c8 NB |
1165 | is not given, then the config file will only be used to find the |
1166 | identity of md arrays. | |
52826846 | 1167 | |
2d465520 | 1168 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 1169 | .B \-\-scan |
2d465520 | 1170 | is not given and insufficient drives were listed to start a complete |
cd29a5c8 NB |
1171 | (non-degraded) array, then the array is not started (to guard against |
1172 | usage errors). To insist that the array be started in this case (as | |
1a7dfc35 | 1173 | may work for RAID1, 4, 5, 6, or 10), give the |
7e23fc43 | 1174 | .B \-\-run |
cd29a5c8 | 1175 | flag. |
52826846 | 1176 | |
75723446 NB |
1177 | If the md device does not exist, then it will be created providing the |
1178 | intent is clear. i.e. the name must be in a standard form, or the | |
7e23fc43 | 1179 | .B \-\-auto |
75723446 NB |
1180 | option must be given to clarify how and whether the device should be |
1181 | created. | |
dd0781e5 | 1182 | This can be useful for handling partitioned devices (which don't have |
b3f1c093 | 1183 | a stable device number \(em it can change after a reboot) and when using |
dd0781e5 NB |
1184 | "udev" to manage your |
1185 | .B /dev | |
1186 | tree (udev cannot handle md devices because of the unusual device | |
1187 | initialisation conventions). | |
1188 | ||
1189 | If the option to "auto" is "mdp" or "part" or (on the command line | |
1190 | only) "p", then mdadm will create a partitionable array, using the | |
93e790af | 1191 | first free one that is not in use and does not already have an entry |
dd0781e5 NB |
1192 | in /dev (apart from numeric /dev/md* entries). |
1193 | ||
1194 | If the option to "auto" is "yes" or "md" or (on the command line) | |
1195 | nothing, then mdadm will create a traditional, non-partitionable md | |
1196 | array. | |
1197 | ||
1198 | It is expected that the "auto" functionality will be used to create | |
1199 | device entries with meaningful names such as "/dev/md/home" or | |
1200 | "/dev/md/root", rather than names based on the numerical array number. | |
1201 | ||
93e790af | 1202 | When using option "auto" to create a partitionable array, the device |
dd0781e5 NB |
1203 | files for the first 4 partitions are also created. If a different |
1204 | number is required it can be simply appended to the auto option. | |
1205 | e.g. "auto=part8". Partition names are created by appending a digit | |
a9d69660 | 1206 | string to the device name, with an intervening "p" if the device name |
dd0781e5 NB |
1207 | ends with a digit. |
1208 | ||
1209 | The | |
7e23fc43 | 1210 | .B \-\-auto |
dd0781e5 NB |
1211 | option is also available in Build and Create modes. As those modes do |
1212 | not use a config file, the "auto=" config option does not apply to | |
1213 | these modes. | |
52826846 | 1214 | |
41a3b72a NB |
1215 | .SS Auto Assembly |
1216 | When | |
7e23fc43 | 1217 | .B \-\-assemble |
41a3b72a | 1218 | is used with |
7e23fc43 | 1219 | .B \-\-scan |
41a3b72a NB |
1220 | and no devices are listed, |
1221 | .I mdadm | |
1222 | will first attempt to assemble all the arrays listed in the config | |
1223 | file. | |
1224 | ||
1225 | If a | |
1226 | .B homehost | |
1227 | has been specified (either in the config file or on the command line), | |
1228 | .I mdadm | |
1229 | will look further for possible arrays and will try to assemble | |
1230 | anything that it finds which is tagged as belonging to the given | |
1231 | homehost. This is the only situation where | |
1232 | .I mdadm | |
1233 | will assemble arrays without being given specific device name or | |
93e790af | 1234 | identity information for the array. |
41a3b72a NB |
1235 | |
1236 | If | |
1237 | .I mdadm | |
1238 | finds a consistent set of devices that look like they should comprise | |
1239 | an array, and if the superblock is tagged as belonging to the given | |
1240 | home host, it will automatically choose a device name and try to | |
1241 | assemble the array. If the array uses version-0.90 metadata, then the | |
1242 | .B minor | |
1243 | number as recorded in the superblock is used to create a name in | |
1244 | .B /dev/md/ | |
1245 | so for example | |
1246 | .BR /dev/md/3 . | |
1247 | If the array uses version-1 metadata, then the | |
1248 | .B name | |
1249 | from the superblock is used to similarly create a name in | |
93e790af SW |
1250 | .BR /dev/md |
1251 | (the name will have any 'host' prefix stripped first). | |
41a3b72a NB |
1252 | |
1253 | If | |
1254 | .I mdadm | |
1255 | cannot find any array for the given host at all, and if | |
7e23fc43 | 1256 | .B \-\-auto\-update\-homehost |
41a3b72a NB |
1257 | is given, then |
1258 | .I mdadm | |
1259 | will search again for any array (not just an array created for this | |
1260 | host) and will assemble each assuming | |
7e23fc43 | 1261 | .BR \-\-update=homehost . |
41a3b72a NB |
1262 | This will change the host tag in the superblock so that on the next run, |
1263 | these arrays will be found without the second pass. The intention of | |
1264 | this feature is to support transitioning a set of md arrays to using | |
1265 | homehost tagging. | |
1266 | ||
1267 | The reason for requiring arrays to be tagged with the homehost for | |
1268 | auto assembly is to guard against problems that can arise when moving | |
1269 | devices from one host to another. | |
1270 | ||
cd29a5c8 | 1271 | .SH BUILD MODE |
52826846 | 1272 | |
cd29a5c8 NB |
1273 | .HP 12 |
1274 | Usage: | |
7e23fc43 | 1275 | .B mdadm \-\-build |
93e790af | 1276 | .I md-device |
7e23fc43 PS |
1277 | .BI \-\-chunk= X |
1278 | .BI \-\-level= Y | |
1279 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
1280 | .I devices |
1281 | ||
1282 | .PP | |
2ae555c3 | 1283 | This usage is similar to |
7e23fc43 | 1284 | .BR \-\-create . |
a9d69660 | 1285 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 1286 | these arrays there is no difference between initially creating the array and |
52826846 NB |
1287 | subsequently assembling the array, except that hopefully there is useful |
1288 | data there in the second case. | |
1289 | ||
a9d69660 NB |
1290 | The level may raid0, linear, multipath, or faulty, or one of their |
1291 | synonyms. All devices must be listed and the array will be started | |
1292 | once complete. | |
cd29a5c8 NB |
1293 | |
1294 | .SH CREATE MODE | |
1295 | ||
1296 | .HP 12 | |
1297 | Usage: | |
7e23fc43 | 1298 | .B mdadm \-\-create |
93e790af | 1299 | .I md-device |
7e23fc43 PS |
1300 | .BI \-\-chunk= X |
1301 | .BI \-\-level= Y | |
cd29a5c8 | 1302 | .br |
7e23fc43 | 1303 | .BI \-\-raid\-devices= Z |
cd29a5c8 NB |
1304 | .I devices |
1305 | ||
1306 | .PP | |
1307 | This usage will initialise a new md array, associate some devices with | |
1308 | it, and activate the array. | |
1309 | ||
a9d69660 | 1310 | If the |
7e23fc43 | 1311 | .B \-\-auto |
dd0781e5 NB |
1312 | option is given (as described in more detail in the section on |
1313 | Assemble mode), then the md device will be created with a suitable | |
1314 | device number if necessary. | |
1315 | ||
cd29a5c8 | 1316 | As devices are added, they are checked to see if they contain raid |
2d465520 | 1317 | superblocks or filesystems. They are also checked to see if the variance in |
cd29a5c8 NB |
1318 | device size exceeds 1%. |
1319 | ||
1320 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 1321 | the presence of a |
7e23fc43 | 1322 | .B \-\-run |
cd29a5c8 NB |
1323 | can override this caution. |
1324 | ||
2d465520 | 1325 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 1326 | give the word "\fBmissing\fP" |
2d465520 | 1327 | in place of a device name. This will cause |
51ac42e3 | 1328 | .I mdadm |
2d465520 NB |
1329 | to leave the corresponding slot in the array empty. |
1330 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 1331 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
1332 | For a RAID1 array, only one real device needs to be given. All of the |
1333 | others can be | |
d013a55e | 1334 | "\fBmissing\fP". |
2d465520 | 1335 | |
feb716e9 | 1336 | When creating a RAID5 array, |
51ac42e3 | 1337 | .I mdadm |
feb716e9 NB |
1338 | will automatically create a degraded array with an extra spare drive. |
1339 | This is because building the spare into a degraded array is in general faster than resyncing | |
1340 | the parity on a non-degraded, but not clean, array. This feature can | |
35cc5be4 | 1341 | be overridden with the |
7e23fc43 | 1342 | .B \-\-force |
feb716e9 NB |
1343 | option. |
1344 | ||
0ee4da98 | 1345 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
1346 | required. |
1347 | If this is not given with the | |
7e23fc43 | 1348 | .B \-\-name |
41a3b72a NB |
1349 | option, |
1350 | .I mdadm | |
0ee4da98 | 1351 | will choose a name based on the last component of the name of the |
41a3b72a NB |
1352 | device being created. So if |
1353 | .B /dev/md3 | |
1354 | is being created, then the name | |
1355 | .B 3 | |
1356 | will be chosen. | |
1357 | If | |
1358 | .B /dev/md/home | |
1359 | is being created, then the name | |
1360 | .B home | |
1361 | will be used. | |
1362 | ||
e0f31f50 PC |
1363 | When creating a partition based array, using |
1364 | .I mdadm | |
1365 | with version-1.x metadata, the partition type should be set to | |
1366 | .B 0xDA | |
1367 | (non fs-data). This type selection allows for greater precision since | |
1368 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], | |
1369 | might create problems in the event of array recovery through a live cdrom. | |
1370 | ||
3d3dd91e NB |
1371 | A new array will normally get a randomly assigned 128bit UUID which is |
1372 | very likely to be unique. If you have a specific need, you can choose | |
1373 | a UUID for the array by giving the | |
7e23fc43 | 1374 | .B \-\-uuid= |
3d3dd91e NB |
1375 | option. Be warned that creating two arrays with the same UUID is a |
1376 | recipe for disaster. Also, using | |
7e23fc43 | 1377 | .B \-\-uuid= |
3d3dd91e | 1378 | when creating a v0.90 array will silently override any |
7e23fc43 | 1379 | .B \-\-homehost= |
3d3dd91e | 1380 | setting. |
e43d0cda NB |
1381 | .\"If the |
1382 | .\".B \-\-size | |
1383 | .\"option is given, it is not necessary to list any component-devices in this command. | |
1384 | .\"They can be added later, before a | |
1385 | .\".B \-\-run. | |
1386 | .\"If no | |
1387 | .\".B \-\-size | |
1388 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 1389 | |
53e8b987 | 1390 | The General Management options that are valid with |
7e23fc43 | 1391 | .B \-\-create |
53e8b987 | 1392 | are: |
cd29a5c8 | 1393 | .TP |
7e23fc43 | 1394 | .B \-\-run |
dd0781e5 | 1395 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
1396 | be in use. |
1397 | ||
1398 | .TP | |
7e23fc43 | 1399 | .B \-\-readonly |
b3f1c093 | 1400 | start the array readonly \(em not supported yet. |
52826846 | 1401 | |
2ae555c3 | 1402 | |
e0d19036 | 1403 | .SH MANAGE MODE |
cd29a5c8 NB |
1404 | .HP 12 |
1405 | Usage: | |
e0d19036 NB |
1406 | .B mdadm |
1407 | .I device | |
1408 | .I options... devices... | |
cd29a5c8 NB |
1409 | .PP |
1410 | ||
e0d19036 NB |
1411 | This usage will allow individual devices in an array to be failed, |
1412 | removed or added. It is possible to perform multiple operations with | |
1413 | on command. For example: | |
1414 | .br | |
7e23fc43 | 1415 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
1416 | .br |
1417 | will firstly mark | |
1418 | .B /dev/hda1 | |
1419 | as faulty in | |
1420 | .B /dev/md0 | |
1421 | and will then remove it from the array and finally add it back | |
2d465520 | 1422 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 1423 | command. |
e0d19036 NB |
1424 | |
1425 | .SH MISC MODE | |
1426 | .HP 12 | |
1427 | Usage: | |
9a9dab36 | 1428 | .B mdadm |
e0d19036 NB |
1429 | .I options ... |
1430 | .I devices ... | |
1431 | .PP | |
cd29a5c8 | 1432 | |
b5e64645 | 1433 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1434 | operate on distinct devices. The operations are: |
1435 | .TP | |
962a108f | 1436 | .B \-\-query |
e0d19036 NB |
1437 | The device is examined to see if it is |
1438 | (1) an active md array, or | |
1439 | (2) a component of an md array. | |
1440 | The information discovered is reported. | |
1441 | ||
1442 | .TP | |
962a108f | 1443 | .B \-\-detail |
2d465520 NB |
1444 | The device should be an active md device. |
1445 | .B mdadm | |
1446 | will display a detailed description of the array. | |
7e23fc43 | 1447 | .B \-\-brief |
2d465520 | 1448 | or |
7e23fc43 | 1449 | .B \-\-scan |
2d465520 | 1450 | will cause the output to be less detailed and the format to be |
e0d19036 | 1451 | suitable for inclusion in |
9a9dab36 | 1452 | .BR /etc/mdadm.conf . |
feb716e9 NB |
1453 | The exit status of |
1454 | .I mdadm | |
1455 | will normally be 0 unless | |
1456 | .I mdadm | |
93e790af | 1457 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 1458 | .B \-\-test |
feb716e9 NB |
1459 | option is given, then the exit status will be: |
1460 | .RS | |
1461 | .TP | |
1462 | 0 | |
1463 | The array is functioning normally. | |
1464 | .TP | |
1465 | 1 | |
1466 | The array has at least one failed device. | |
1467 | .TP | |
1468 | 2 | |
a77be586 | 1469 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
1470 | .TP |
1471 | 4 | |
1472 | There was an error while trying to get information about the device. | |
1473 | .RE | |
cd29a5c8 | 1474 | |
e0d19036 | 1475 | .TP |
962a108f | 1476 | .B \-\-examine |
2d465520 | 1477 | The device should be a component of an md array. |
51ac42e3 | 1478 | .I mdadm |
2d465520 | 1479 | will read the md superblock of the device and display the contents. |
e0d19036 | 1480 | If |
7e23fc43 | 1481 | .B \-\-brief |
93e790af | 1482 | or |
7e23fc43 | 1483 | .B \-\-scan |
93e790af | 1484 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
1485 | are grouped together and reported in a single entry suitable |
1486 | for inclusion in | |
1487 | .BR /etc/mdadm.conf . | |
1488 | ||
2d465520 | 1489 | Having |
7e23fc43 | 1490 | .B \-\-scan |
e0d19036 NB |
1491 | without listing any devices will cause all devices listed in the |
1492 | config file to be examined. | |
1493 | ||
1494 | .TP | |
962a108f | 1495 | .B \-\-stop |
98c6faba NB |
1496 | The devices should be active md arrays which will be deactivated, as |
1497 | long as they are not currently in use. | |
e0d19036 NB |
1498 | |
1499 | .TP | |
962a108f | 1500 | .B \-\-run |
e0d19036 NB |
1501 | This will fully activate a partially assembled md array. |
1502 | ||
1503 | .TP | |
962a108f | 1504 | .B \-\-readonly |
e0d19036 NB |
1505 | This will mark an active array as read-only, providing that it is |
1506 | not currently being used. | |
1507 | ||
1508 | .TP | |
962a108f | 1509 | .B \-\-readwrite |
e0d19036 NB |
1510 | This will change a |
1511 | .B readonly | |
1512 | array back to being read/write. | |
1513 | ||
2d465520 | 1514 | .TP |
962a108f | 1515 | .B \-\-scan |
2d465520 | 1516 | For all operations except |
7e23fc43 PS |
1517 | .BR \-\-examine , |
1518 | .B \-\-scan | |
2d465520 NB |
1519 | will cause the operation to be applied to all arrays listed in |
1520 | .BR /proc/mdstat . | |
1521 | For | |
7e23fc43 PS |
1522 | .BR \-\-examine, |
1523 | .B \-\-scan | |
2d465520 NB |
1524 | causes all devices listed in the config file to be examined. |
1525 | ||
1526 | ||
e0d19036 NB |
1527 | .SH MONITOR MODE |
1528 | ||
cd29a5c8 NB |
1529 | .HP 12 |
1530 | Usage: | |
7e23fc43 | 1531 | .B mdadm \-\-monitor |
e0d19036 NB |
1532 | .I options... devices... |
1533 | ||
cd29a5c8 | 1534 | .PP |
e0d19036 | 1535 | This usage causes |
51ac42e3 | 1536 | .I mdadm |
e0d19036 NB |
1537 | to periodically poll a number of md arrays and to report on any events |
1538 | noticed. | |
51ac42e3 | 1539 | .I mdadm |
e0d19036 NB |
1540 | will never exit once it decides that there are arrays to be checked, |
1541 | so it should normally be run in the background. | |
1542 | ||
2d465520 | 1543 | As well as reporting events, |
51ac42e3 | 1544 | .I mdadm |
2d465520 NB |
1545 | may move a spare drive from one array to another if they are in the |
1546 | same | |
1547 | .B spare-group | |
a9d69660 | 1548 | and if the destination array has a failed drive but no spares. |
2d465520 | 1549 | |
e0d19036 | 1550 | If any devices are listed on the command line, |
51ac42e3 | 1551 | .I mdadm |
e0d19036 NB |
1552 | will only monitor those devices. Otherwise all arrays listed in the |
1553 | configuration file will be monitored. Further, if | |
7e23fc43 | 1554 | .B \-\-scan |
e0d19036 NB |
1555 | is given, then any other md devices that appear in |
1556 | .B /proc/mdstat | |
1557 | will also be monitored. | |
1558 | ||
1559 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 1560 | These events are passed to a separate program (if specified) and may |
2d465520 | 1561 | be mailed to a given E-mail address. |
e0d19036 | 1562 | |
93e790af SW |
1563 | When passing events to a program, the program is run once for each event, |
1564 | and is given 2 or 3 command-line arguments: the first is the | |
1565 | name of the event (see below), the second is the name of the | |
bd526cee | 1566 | md device which is affected, and the third is the name of a related |
93e790af | 1567 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
1568 | |
1569 | If | |
7e23fc43 | 1570 | .B \-\-scan |
e0d19036 NB |
1571 | is given, then a program or an E-mail address must be specified on the |
1572 | command line or in the config file. If neither are available, then | |
51ac42e3 | 1573 | .I mdadm |
e0d19036 NB |
1574 | will not monitor anything. |
1575 | Without | |
93e790af | 1576 | .B \-\-scan, |
51ac42e3 | 1577 | .I mdadm |
2d465520 | 1578 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
1579 | no program or email is given, then each event is reported to |
1580 | .BR stdout . | |
cd29a5c8 | 1581 | |
e0d19036 NB |
1582 | The different events are: |
1583 | ||
1584 | .RS 4 | |
1585 | .TP | |
1586 | .B DeviceDisappeared | |
2d465520 | 1587 | An md array which previously was configured appears to no longer be |
773135f5 | 1588 | configured. (syslog priority: Critical) |
e0d19036 | 1589 | |
b8f72a62 NB |
1590 | If |
1591 | .I mdadm | |
1592 | was told to monitor an array which is RAID0 or Linear, then it will | |
1593 | report | |
1594 | .B DeviceDisappeared | |
1595 | with the extra information | |
1596 | .BR Wrong-Level . | |
1597 | This is because RAID0 and Linear do not support the device-failed, | |
1598 | hot-spare and resync operations which are monitored. | |
1599 | ||
e0d19036 NB |
1600 | .TP |
1601 | .B RebuildStarted | |
773135f5 | 1602 | An md array started reconstruction. (syslog priority: Warning) |
e0d19036 NB |
1603 | |
1604 | .TP | |
1605 | .BI Rebuild NN | |
1606 | Where | |
1607 | .I NN | |
1608 | is 20, 40, 60, or 80, this indicates that rebuild has passed that many | |
773135f5 | 1609 | percentage of the total. (syslog priority: Warning) |
e0d19036 | 1610 | |
98c6faba NB |
1611 | .TP |
1612 | .B RebuildFinished | |
1613 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 1614 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 1615 | |
e0d19036 NB |
1616 | .TP |
1617 | .B Fail | |
773135f5 NB |
1618 | An active component device of an array has been marked as |
1619 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
1620 | |
1621 | .TP | |
1622 | .B FailSpare | |
1623 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 1624 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
1625 | |
1626 | .TP | |
1627 | .B SpareActive | |
1628 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 1629 | device has been successfully rebuilt and has been made active. |
773135f5 | 1630 | (syslog priority: Info) |
e0d19036 NB |
1631 | |
1632 | .TP | |
1633 | .B NewArray | |
1634 | A new md array has been detected in the | |
1635 | .B /proc/mdstat | |
773135f5 | 1636 | file. (syslog priority: Info) |
e0d19036 | 1637 | |
aa88f531 NB |
1638 | .TP |
1639 | .B DegradedArray | |
1640 | A newly noticed array appears to be degraded. This message is not | |
1641 | generated when | |
1642 | .I mdadm | |
1643 | notices a drive failure which causes degradation, but only when | |
1644 | .I mdadm | |
1645 | notices that an array is degraded when it first sees the array. | |
93e790af | 1646 | (syslog priority: Critical) |
aa88f531 | 1647 | |
e0d19036 NB |
1648 | .TP |
1649 | .B MoveSpare | |
1650 | A spare drive has been moved from one array in a | |
1651 | .B spare-group | |
1652 | to another to allow a failed drive to be replaced. | |
773135f5 | 1653 | (syslog priority: Info) |
e0d19036 | 1654 | |
b8f72a62 NB |
1655 | .TP |
1656 | .B SparesMissing | |
1657 | If | |
1658 | .I mdadm | |
1659 | has been told, via the config file, that an array should have a certain | |
1660 | number of spare devices, and | |
1661 | .I mdadm | |
93e790af | 1662 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
1663 | array, it will report a |
1664 | .B SparesMissing | |
1665 | message. | |
d1732eeb | 1666 | (syslog priority: Warning) |
b8f72a62 | 1667 | |
98c6faba NB |
1668 | .TP |
1669 | .B TestMessage | |
1670 | An array was found at startup, and the | |
7e23fc43 | 1671 | .B \-\-test |
98c6faba | 1672 | flag was given. |
773135f5 | 1673 | (syslog priority: Info) |
e0d19036 NB |
1674 | .RE |
1675 | ||
1676 | Only | |
93e790af SW |
1677 | .B Fail, |
1678 | .B FailSpare, | |
1679 | .B DegradedArray, | |
1680 | .B SparesMissing | |
e0d19036 | 1681 | and |
98c6faba | 1682 | .B TestMessage |
e0d19036 | 1683 | cause Email to be sent. All events cause the program to be run. |
93e790af | 1684 | The program is run with two or three arguments: the event |
e0d19036 NB |
1685 | name, the array device and possibly a second device. |
1686 | ||
1687 | Each event has an associated array device (e.g. | |
1688 | .BR /dev/md1 ) | |
1689 | and possibly a second device. For | |
1690 | .BR Fail , | |
1691 | .BR FailSpare , | |
1692 | and | |
1693 | .B SpareActive | |
1694 | the second device is the relevant component device. | |
1695 | For | |
1696 | .B MoveSpare | |
1697 | the second device is the array that the spare was moved from. | |
1698 | ||
1699 | For | |
51ac42e3 | 1700 | .I mdadm |
e0d19036 | 1701 | to move spares from one array to another, the different arrays need to |
93e790af | 1702 | be labeled with the same |
e0d19036 NB |
1703 | .B spare-group |
1704 | in the configuration file. The | |
1705 | .B spare-group | |
93e790af | 1706 | name can be any string; it is only necessary that different spare |
2d465520 | 1707 | groups use different names. |
e0d19036 NB |
1708 | |
1709 | When | |
51ac42e3 | 1710 | .I mdadm |
93e790af | 1711 | detects that an array in a spare group has fewer active |
e0d19036 NB |
1712 | devices than necessary for the complete array, and has no spare |
1713 | devices, it will look for another array in the same spare group that | |
1714 | has a full complement of working drive and a spare. It will then | |
1715 | attempt to remove the spare from the second drive and add it to the | |
1716 | first. | |
1717 | If the removal succeeds but the adding fails, then it is added back to | |
1718 | the original array. | |
1719 | ||
dd0781e5 NB |
1720 | .SH GROW MODE |
1721 | The GROW mode is used for changing the size or shape of an active | |
1722 | array. | |
1723 | For this to work, the kernel must support the necessary change. | |
2ae555c3 | 1724 | Various types of growth are being added during 2.6 development, |
dd0781e5 NB |
1725 | including restructuring a raid5 array to have more active devices. |
1726 | ||
dfd4d8ee NB |
1727 | Currently the only support available is to |
1728 | .IP \(bu 4 | |
1729 | change the "size" attribute | |
1730 | for RAID1, RAID5 and RAID6. | |
1731 | .IP \(bu 4 | |
e5669f40 | 1732 | increase the "raid\-devices" attribute of RAID1, RAID5, and RAID6. |
dfd4d8ee | 1733 | .IP \(bu 4 |
93e790af | 1734 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 1735 | remove a write-intent bitmap from such an array. |
dfd4d8ee | 1736 | .PP |
dd0781e5 | 1737 | |
2ae555c3 | 1738 | .SS SIZE CHANGES |
fe80f49b | 1739 | Normally when an array is built the "size" it taken from the smallest |
dd0781e5 NB |
1740 | of the drives. If all the small drives in an arrays are, one at a |
1741 | time, removed and replaced with larger drives, then you could have an | |
1742 | array of large drives with only a small amount used. In this | |
1743 | situation, changing the "size" with "GROW" mode will allow the extra | |
1744 | space to start being used. If the size is increased in this way, a | |
1745 | "resync" process will start to make sure the new parts of the array | |
1746 | are synchronised. | |
1747 | ||
1748 | Note that when an array changes size, any filesystem that may be | |
1749 | stored in the array will not automatically grow to use the space. The | |
1750 | filesystem will need to be explicitly told to use the extra space. | |
1751 | ||
2ae555c3 NB |
1752 | .SS RAID-DEVICES CHANGES |
1753 | ||
dd0781e5 NB |
1754 | A RAID1 array can work with any number of devices from 1 upwards |
1755 | (though 1 is not very useful). There may be times which you want to | |
1756 | increase or decrease the number of active devices. Note that this is | |
1757 | different to hot-add or hot-remove which changes the number of | |
1758 | inactive devices. | |
1759 | ||
1760 | When reducing the number of devices in a RAID1 array, the slots which | |
1761 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 1762 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
1763 | |
1764 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 1765 | present will be activated immediately. |
dd0781e5 | 1766 | |
2ae555c3 NB |
1767 | Increasing the number of active devices in a RAID5 is much more |
1768 | effort. Every block in the array will need to be read and written | |
1769 | back to a new location. From 2.6.17, the Linux Kernel is able to do | |
1770 | this safely, including restart and interrupted "reshape". | |
1771 | ||
1772 | When relocating the first few stripes on a raid5, it is not possible | |
1773 | to keep the data on disk completely consistent and crash-proof. To | |
1774 | provide the required safety, mdadm disables writes to the array while | |
1775 | this "critical section" is reshaped, and takes a backup of the data | |
1776 | that is in that section. This backup is normally stored in any spare | |
1777 | devices that the array has, however it can also be stored in a | |
1778 | separate file specified with the | |
7e23fc43 | 1779 | .B \-\-backup\-file |
2ae555c3 NB |
1780 | option. If this option is used, and the system does crash during the |
1781 | critical period, the same file must be passed to | |
7e23fc43 | 1782 | .B \-\-assemble |
2ae555c3 NB |
1783 | to restore the backup and reassemble the array. |
1784 | ||
1785 | .SS BITMAP CHANGES | |
1786 | ||
1787 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 1788 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b NB |
1789 | can be added. Note that if you add a bitmap stored in a file which is |
1790 | in a filesystem that is on the raid array being affected, the system | |
1791 | will deadlock. The bitmap must be on a separate filesystem. | |
1792 | ||
8382f19b NB |
1793 | .SH INCREMENTAL MODE |
1794 | ||
1795 | .HP 12 | |
1796 | Usage: | |
7e23fc43 PS |
1797 | .B mdadm \-\-incremental |
1798 | .RB [ \-\-run ] | |
1799 | .RB [ \-\-quiet ] | |
8382f19b NB |
1800 | .I component-device |
1801 | .HP 12 | |
1802 | Usage: | |
7e23fc43 | 1803 | .B mdadm \-\-incremental \-\-rebuild |
8382f19b NB |
1804 | .HP 12 |
1805 | Usage: | |
7e23fc43 | 1806 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b NB |
1807 | |
1808 | ||
1809 | .PP | |
1810 | This mode is designed to be used in conjunction with a device | |
1811 | discovery system. As devices are found in a system, they can be | |
1812 | passed to | |
7e23fc43 | 1813 | .B "mdadm \-\-incremental" |
8382f19b NB |
1814 | to be conditionally added to an appropriate array. |
1815 | ||
1816 | .I mdadm | |
1817 | performs a number of tests to determine if the device is part of an | |
93e790af | 1818 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
1819 | is found, or can be created, |
1820 | .I mdadm | |
1821 | adds the device to the array and conditionally starts the array. | |
1822 | ||
1823 | Note that | |
1824 | .I mdadm | |
1825 | will only add devices to an array which were previously working | |
1826 | (active or spare) parts of that array. It does not currently support | |
1827 | automatic inclusion of a new drive as a spare in some array. | |
1828 | ||
7e23fc43 | 1829 | .B "mdadm \-\-incremental" |
93e790af SW |
1830 | requires a bug-fix in all kernels through 2.6.19. |
1831 | Hopefully, this will be fixed in 2.6.20; alternately, apply the patch | |
8382f19b NB |
1832 | which is included with the mdadm source distribution. If |
1833 | .I mdadm | |
1834 | detects that this bug is present, it will abort any attempt to use | |
7e23fc43 | 1835 | .BR \-\-incremental . |
8382f19b NB |
1836 | |
1837 | The tests that | |
1838 | .I mdadm | |
1839 | makes are as follow: | |
1840 | .IP + | |
1841 | Is the device permitted by | |
1842 | .BR mdadm.conf ? | |
1843 | That is, is it listed in a | |
1844 | .B DEVICES | |
1845 | line in that file. If | |
1846 | .B DEVICES | |
1847 | is absent then the default it to allow any device. Similar if | |
1848 | .B DEVICES | |
1849 | contains the special word | |
1850 | .B partitions | |
1851 | then any device is allowed. Otherwise the device name given to | |
1852 | .I mdadm | |
1853 | must match one of the names or patterns in a | |
1854 | .B DEVICES | |
1855 | line. | |
1856 | ||
1857 | .IP + | |
1858 | Does the device have a valid md superblock. If a specific metadata | |
1859 | version is request with | |
7e23fc43 | 1860 | .B \-\-metadata |
8382f19b | 1861 | or |
7e23fc43 | 1862 | .B \-e |
8382f19b NB |
1863 | then only that style of metadata is accepted, otherwise |
1864 | .I mdadm | |
1865 | finds any known version of metadata. If no | |
1866 | .I md | |
1867 | metadata is found, the device is rejected. | |
1868 | ||
1869 | .IP + | |
1870 | Does the metadata match an expected array? | |
1871 | The metadata can match in two ways. Either there is an array listed | |
1872 | in | |
1873 | .B mdadm.conf | |
1874 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 1875 | or by minor-number), or the array was created with a |
8382f19b | 1876 | .B homehost |
93e790af | 1877 | specified and that |
8382f19b | 1878 | .B homehost |
93e790af | 1879 | matches the one in |
8382f19b NB |
1880 | .B mdadm.conf |
1881 | or on the command line. | |
1882 | If | |
1883 | .I mdadm | |
1884 | is not able to positively identify the array as belonging to the | |
1885 | current host, the device will be rejected. | |
1886 | ||
1887 | .IP + | |
1888 | .I mdadm | |
93e790af | 1889 | keeps a list of arrays that it has partially assembled in |
8382f19b NB |
1890 | .B /var/run/mdadm/map |
1891 | (or | |
1892 | .B /var/run/mdadm.map | |
1893 | if the directory doesn't exist). If no array exists which matches | |
1894 | the metadata on the new device, | |
1895 | .I mdadm | |
1896 | must choose a device name and unit number. It does this based on any | |
1897 | name given in | |
1898 | .B mdadm.conf | |
1899 | or any name information stored in the metadata. If this name | |
1900 | suggests a unit number, that number will be used, otherwise a free | |
1901 | unit number will be chosen. Normally | |
1902 | .I mdadm | |
1903 | will prefer to create a partitionable array, however if the | |
1904 | .B CREATE | |
1905 | line in | |
1906 | .B mdadm.conf | |
1907 | suggests that a non-partitionable array is preferred, that will be | |
1908 | honoured. | |
1909 | ||
1910 | .IP + | |
1911 | Once an appropriate array is found or created and the device is added, | |
1912 | .I mdadm | |
1913 | must decide if the array is ready to be started. It will | |
1914 | normally compare the number of available (non-spare) devices to the | |
1915 | number of devices that the metadata suggests need to be active. If | |
1916 | there are at least that many, the array will be started. This means | |
1917 | that if any devices are missing the array will not be restarted. | |
1918 | ||
1919 | As an alternative, | |
7e23fc43 | 1920 | .B \-\-run |
8382f19b | 1921 | may be passed to |
51ac42e3 | 1922 | .I mdadm |
8382f19b NB |
1923 | in which case the array will be run as soon as there are enough |
1924 | devices present for the data to be accessible. For a raid1, that | |
1925 | means one device will start the array. For a clean raid5, the array | |
1926 | will be started as soon as all but one drive is present. | |
1927 | ||
93e790af | 1928 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
1929 | be known that all device discovery has completed, then |
1930 | .br | |
7e23fc43 | 1931 | .B " mdadm \-IRs" |
8382f19b NB |
1932 | .br |
1933 | can be run which will try to start all arrays that are being | |
1934 | incrementally assembled. They are started in "read-auto" mode in | |
1935 | which they are read-only until the first write request. This means | |
1936 | that no metadata updates are made and no attempt at resync or recovery | |
1937 | happens. Further devices that are found before the first write can | |
1938 | still be added safely. | |
1939 | ||
5545fa6d DW |
1940 | |
1941 | .SH ENVIRONMENT | |
1942 | This section describes environment variables that affect how mdadm | |
1943 | operates. | |
1944 | ||
1945 | .TP | |
1946 | .B MDADM_NO_MDMON | |
1947 | Setting this value to 1 will prevent mdadm from automatically launching | |
1948 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
1949 | ||
2d465520 NB |
1950 | .SH EXAMPLES |
1951 | ||
7e23fc43 | 1952 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 1953 | .br |
5787fa49 NB |
1954 | This will find out if a given device is a raid array, or is part of |
1955 | one, and will provide brief information about the device. | |
2d465520 | 1956 | |
7e23fc43 | 1957 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 1958 | .br |
93e790af | 1959 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 1960 | file. This command will typically go in a system startup file. |
2d465520 | 1961 | |
7e23fc43 | 1962 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 1963 | .br |
93e790af | 1964 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 1965 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 1966 | |
7e23fc43 | 1967 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 1968 | .br |
5787fa49 NB |
1969 | If (and only if) there is an Email address or program given in the |
1970 | standard config file, then | |
1971 | monitor the status of all arrays listed in that file by | |
1972 | polling them ever 2 minutes. | |
2d465520 | 1973 | |
7e23fc43 | 1974 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 1975 | .br |
5787fa49 | 1976 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 1977 | |
2d465520 | 1978 | .br |
7e23fc43 | 1979 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 1980 | .br |
7e23fc43 | 1981 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 1982 | .br |
5787fa49 NB |
1983 | This will create a prototype config file that describes currently |
1984 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
1985 | This file should be reviewed before being used as it may |
1986 | contain unwanted detail. | |
1987 | ||
7e23fc43 | 1988 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 1989 | .br |
7e23fc43 | 1990 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
1991 | .br |
1992 | This will find arrays which could be assembled from existing IDE and | |
1993 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 1994 | format of a config file. |
2d465520 NB |
1995 | This file is very likely to contain unwanted detail, particularly |
1996 | the | |
1997 | .B devices= | |
5787fa49 NB |
1998 | entries. It should be reviewed and edited before being used as an |
1999 | actual config file. | |
2d465520 | 2000 | |
7e23fc43 | 2001 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 2002 | .br |
7e23fc43 | 2003 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
2004 | .br |
2005 | Create a list of devices by reading | |
2006 | .BR /proc/partitions , | |
2007 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 2008 | that were found. |
2d465520 | 2009 | |
7e23fc43 | 2010 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 2011 | .br |
5787fa49 NB |
2012 | Scan all partitions and devices listed in |
2013 | .BR /proc/partitions | |
2014 | and assemble | |
2015 | .B /dev/md0 | |
2016 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 2017 | |
7e23fc43 | 2018 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm" |
d013a55e NB |
2019 | .br |
2020 | If config file contains a mail address or alert program, run mdadm in | |
2021 | the background in monitor mode monitoring all md devices. Also write | |
2022 | pid of mdadm daemon to | |
2023 | .BR /var/run/mdadm . | |
2024 | ||
7e23fc43 | 2025 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
2026 | .br |
2027 | Try to incorporate newly discovered device into some array as | |
2028 | appropriate. | |
2029 | ||
7e23fc43 | 2030 | .B " mdadm \-\-incremental \-\-rebuild \-\-run \-\-scan" |
8382f19b NB |
2031 | .br |
2032 | Rebuild the array map from any current arrays, and then start any that | |
2033 | can be started. | |
2034 | ||
b80da661 NB |
2035 | .B " mdadm /dev/md4 --fail detached --remove detached" |
2036 | .br | |
2037 | Any devices which are components of /dev/md4 will be marked as faulty | |
2038 | and then remove from the array. | |
2039 | ||
7e23fc43 | 2040 | .B " mdadm \-\-create \-\-help" |
2d465520 | 2041 | .br |
2ae555c3 | 2042 | Provide help about the Create mode. |
2d465520 | 2043 | |
7e23fc43 | 2044 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
2045 | .br |
2046 | Provide help about the format of the config file. | |
2d465520 | 2047 | |
7e23fc43 | 2048 | .B " mdadm \-\-help" |
5787fa49 NB |
2049 | .br |
2050 | Provide general help. | |
cd29a5c8 | 2051 | |
cd29a5c8 NB |
2052 | |
2053 | .SH FILES | |
2054 | ||
2055 | .SS /proc/mdstat | |
2056 | ||
2ae555c3 NB |
2057 | If you're using the |
2058 | .B /proc | |
cd29a5c8 NB |
2059 | filesystem, |
2060 | .B /proc/mdstat | |
2d465520 | 2061 | lists all active md devices with information about them. |
51ac42e3 | 2062 | .I mdadm |
2d465520 | 2063 | uses this to find arrays when |
7e23fc43 | 2064 | .B \-\-scan |
2d465520 NB |
2065 | is given in Misc mode, and to monitor array reconstruction |
2066 | on Monitor mode. | |
2067 | ||
cd29a5c8 | 2068 | |
9a9dab36 | 2069 | .SS /etc/mdadm.conf |
cd29a5c8 | 2070 | |
11a3e71d NB |
2071 | The config file lists which devices may be scanned to see if |
2072 | they contain MD super block, and gives identifying information | |
2073 | (e.g. UUID) about known MD arrays. See | |
2074 | .BR mdadm.conf (5) | |
2075 | for more details. | |
cd29a5c8 | 2076 | |
8382f19b NB |
2077 | .SS /var/run/mdadm/map |
2078 | When | |
7e23fc43 | 2079 | .B \-\-incremental |
93e790af | 2080 | mode is used, this file gets a list of arrays currently being created. |
8382f19b NB |
2081 | If |
2082 | .B /var/run/mdadm | |
2083 | does not exist as a directory, then | |
2084 | .B /var/run/mdadm.map | |
2085 | is used instead. | |
2086 | ||
48f7b27a NB |
2087 | .SH DEVICE NAMES |
2088 | ||
2089 | While entries in the /dev directory can have any format you like, | |
2090 | .I mdadm | |
2091 | has an understanding of 'standard' formats which it uses to guide its | |
2092 | behaviour when creating device files via the | |
7e23fc43 | 2093 | .B \-\-auto |
48f7b27a NB |
2094 | option. |
2095 | ||
2096 | The standard names for non-partitioned arrays (the only sort of md | |
93e790af | 2097 | array available in 2.4 and earlier) are either of |
48f7b27a NB |
2098 | .IP |
2099 | /dev/mdNN | |
2100 | .br | |
2101 | /dev/md/NN | |
2102 | .PP | |
2103 | where NN is a number. | |
2104 | The standard names for partitionable arrays (as available from 2.6 | |
93e790af | 2105 | onwards) are either of |
48f7b27a NB |
2106 | .IP |
2107 | /dev/md/dNN | |
2108 | .br | |
2109 | /dev/md_dNN | |
2110 | .PP | |
2111 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
52826846 | 2112 | |
2d465520 | 2113 | .SH NOTE |
51ac42e3 | 2114 | .I mdadm |
2d465520 | 2115 | was previously known as |
51ac42e3 | 2116 | .IR mdctl . |
a9d69660 | 2117 | .P |
51ac42e3 | 2118 | .I mdadm |
a9d69660 | 2119 | is completely separate from the |
51ac42e3 | 2120 | .I raidtools |
a9d69660 NB |
2121 | package, and does not use the |
2122 | .I /etc/raidtab | |
2123 | configuration file at all. | |
2124 | ||
52826846 | 2125 | .SH SEE ALSO |
75f74377 | 2126 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 2127 | RAID, see: |
cd29a5c8 | 2128 | |
3cdfb6a7 NB |
2129 | .IP |
2130 | .UR http://linux-raid.osdl.org/ | |
2131 | http://linux\-raid.osdl.org/ | |
cd29a5c8 | 2132 | .UE |
75f74377 DG |
2133 | .PP |
2134 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
e43d0cda NB |
2135 | .\".PP |
2136 | .\"for new releases of the RAID driver check out: | |
2137 | .\" | |
2138 | .\".IP | |
2139 | .\".UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
2140 | .\"ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
2141 | .\".UE | |
2142 | .\".PP | |
2143 | .\"or | |
2144 | .\".IP | |
2145 | .\".UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2146 | .\"http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2147 | .\".UE | |
cd29a5c8 | 2148 | .PP |
2ae555c3 | 2149 | The latest version of |
a9d69660 NB |
2150 | .I mdadm |
2151 | should always be available from | |
cd29a5c8 | 2152 | .IP |
a9d69660 NB |
2153 | .UR http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
2154 | http://www.kernel.org/pub/linux/utils/raid/mdadm/ | |
cd29a5c8 NB |
2155 | .UE |
2156 | .PP | |
a9d69660 NB |
2157 | .IR mdadm.conf (5), |
2158 | .IR md (4). | |
56eb10c0 | 2159 | .PP |
52826846 NB |
2160 | .IR raidtab (5), |
2161 | .IR raid0run (8), | |
2162 | .IR raidstop (8), | |
a9d69660 | 2163 | .IR mkraid (8). |