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52826846 | 1 | .\" -*- nroff -*- |
e43d0cda NB |
2 | .\" Copyright Neil Brown and others. |
3 | .\" This program is free software; you can redistribute it and/or modify | |
4 | .\" it under the terms of the GNU General Public License as published by | |
5 | .\" the Free Software Foundation; either version 2 of the License, or | |
6 | .\" (at your option) any later version. | |
7 | .\" See file COPYING in distribution for details. | |
1679bef2 | 8 | .TH MDADM 8 "" v3.0-devel2 |
52826846 | 9 | .SH NAME |
9a9dab36 | 10 | mdadm \- manage MD devices |
cd29a5c8 | 11 | .I aka |
93e790af | 12 | Linux Software RAID |
cd29a5c8 | 13 | |
52826846 NB |
14 | .SH SYNOPSIS |
15 | ||
e0d19036 | 16 | .BI mdadm " [mode] <raiddevice> [options] <component-devices>" |
52826846 | 17 | |
2ae555c3 | 18 | .SH DESCRIPTION |
52826846 | 19 | RAID devices are virtual devices created from two or more |
cd29a5c8 | 20 | real block devices. This allows multiple devices (typically disk |
35cc5be4 | 21 | drives or partitions thereof) to be combined into a single device to |
cd29a5c8 | 22 | hold (for example) a single filesystem. |
2d465520 | 23 | Some RAID levels include redundancy and so can survive some degree of |
cd29a5c8 NB |
24 | device failure. |
25 | ||
2d465520 NB |
26 | Linux Software RAID devices are implemented through the md (Multiple |
27 | Devices) device driver. | |
cd29a5c8 NB |
28 | |
29 | Currently, Linux supports | |
30 | .B LINEAR | |
31 | md devices, | |
32 | .B RAID0 | |
33 | (striping), | |
34 | .B RAID1 | |
35 | (mirroring), | |
d013a55e NB |
36 | .BR RAID4 , |
37 | .BR RAID5 , | |
98c6faba | 38 | .BR RAID6 , |
1a7dfc35 | 39 | .BR RAID10 , |
b5e64645 | 40 | .BR MULTIPATH , |
90c8d668 | 41 | .BR FAULTY , |
cd29a5c8 | 42 | and |
90c8d668 | 43 | .BR CONTAINER . |
d013a55e | 44 | |
a9d69660 NB |
45 | .B MULTIPATH |
46 | is not a Software RAID mechanism, but does involve | |
93e790af | 47 | multiple devices: |
d013a55e NB |
48 | each device is a path to one common physical storage device. |
49 | ||
a9d69660 NB |
50 | .B FAULTY |
51 | is also not true RAID, and it only involves one device. It | |
b5e64645 | 52 | provides a layer over a true device that can be used to inject faults. |
52826846 | 53 | |
90c8d668 | 54 | B CONTAINER |
8fd8d9c4 N |
55 | is different again. A |
56 | .B CONTAINER | |
57 | is a collection of devices that are | |
90c8d668 N |
58 | managed as a set. This is similar to the set of devices connected to |
59 | a hardware RAID controller. The set of devices may contain a number | |
60 | of different RAID arrays each utilising some (or all) blocks from a | |
61 | number of the devices in the set. For example, two devices in a 5-device set | |
62 | might form a RAID1 used the whole devices. The remaining three might | |
63 | have a RAID5 over the first half of each device, and a RAID0 over the | |
64 | second half. | |
65 | ||
8fd8d9c4 N |
66 | With a |
67 | .BR CONTAINER , | |
68 | there is one set of metadata that describes all of | |
69 | the arrays in the container. So when | |
70 | .I mdadm | |
71 | creates a | |
72 | .B CONTAINER | |
73 | device, it just represents the metadata. Other normal arrays (RAID1 | |
74 | etc) can be created inside that container. | |
90c8d668 N |
75 | |
76 | ||
51ac42e3 | 77 | .\".I mdadm |
e43d0cda NB |
78 | .\"is a program that can be used to create, manage, and monitor |
79 | .\"MD devices. As | |
80 | .\"such it provides a similar set of functionality to the | |
81 | .\".B raidtools | |
82 | .\"packages. | |
83 | .\"The key differences between | |
51ac42e3 | 84 | .\".I mdadm |
e43d0cda NB |
85 | .\"and |
86 | .\".B raidtools | |
87 | .\"are: | |
88 | .\".IP \(bu 4 | |
51ac42e3 | 89 | .\".I mdadm |
e43d0cda NB |
90 | .\"is a single program and not a collection of programs. |
91 | .\".IP \(bu 4 | |
51ac42e3 | 92 | .\".I mdadm |
e43d0cda NB |
93 | .\"can perform (almost) all of its functions without having a |
94 | .\"configuration file and does not use one by default. Also | |
51ac42e3 | 95 | .\".I mdadm |
e43d0cda NB |
96 | .\"helps with management of the configuration |
97 | .\"file. | |
98 | .\".IP \(bu 4 | |
51ac42e3 | 99 | .\".I mdadm |
e43d0cda NB |
100 | .\"can provide information about your arrays (through Query, Detail, and Examine) |
101 | .\"that | |
102 | .\".B raidtools | |
103 | .\"cannot. | |
104 | .\".P | |
105 | .\".I mdadm | |
106 | .\"does not use | |
107 | .\".IR /etc/raidtab , | |
108 | .\"the | |
109 | .\".B raidtools | |
110 | .\"configuration file, at all. It has a different configuration file | |
111 | .\"with a different format and a different purpose. | |
52826846 NB |
112 | |
113 | .SH MODES | |
8382f19b | 114 | mdadm has several major modes of operation: |
cd29a5c8 NB |
115 | .TP |
116 | .B Assemble | |
93e790af | 117 | Assemble the components of a previously created |
52826846 | 118 | array into an active array. Components can be explicitly given |
2ae555c3 | 119 | or can be searched for. |
51ac42e3 | 120 | .I mdadm |
cd29a5c8 NB |
121 | checks that the components |
122 | do form a bona fide array, and can, on request, fiddle superblock | |
123 | information so as to assemble a faulty array. | |
124 | ||
125 | .TP | |
126 | .B Build | |
a9d69660 NB |
127 | Build an array that doesn't have per-device superblocks. For these |
128 | sorts of arrays, | |
129 | .I mdadm | |
130 | cannot differentiate between initial creation and subsequent assembly | |
131 | of an array. It also cannot perform any checks that appropriate | |
93e790af | 132 | components have been requested. Because of this, the |
a9d69660 NB |
133 | .B Build |
134 | mode should only be used together with a complete understanding of | |
135 | what you are doing. | |
cd29a5c8 NB |
136 | |
137 | .TP | |
138 | .B Create | |
139 | Create a new array with per-device superblocks. | |
e43d0cda NB |
140 | .\"It can progress |
141 | .\"in several step create-add-add-run or it can all happen with one command. | |
cd29a5c8 | 142 | |
cd29a5c8 NB |
143 | .TP |
144 | .B "Follow or Monitor" | |
5787fa49 | 145 | Monitor one or more md devices and act on any state changes. This is |
93e790af | 146 | only meaningful for raid1, 4, 5, 6, 10 or multipath arrays, as |
98c6faba NB |
147 | only these have interesting state. raid0 or linear never have |
148 | missing, spare, or failed drives, so there is nothing to monitor. | |
5787fa49 | 149 | |
dd0781e5 NB |
150 | .TP |
151 | .B "Grow" | |
152 | Grow (or shrink) an array, or otherwise reshape it in some way. | |
153 | Currently supported growth options including changing the active size | |
93e790af SW |
154 | of component devices and changing the number of active devices in RAID |
155 | levels 1/4/5/6, as well as adding or removing a write-intent bitmap. | |
cd29a5c8 | 156 | |
8382f19b NB |
157 | .TP |
158 | .B "Incremental Assembly" | |
159 | Add a single device to an appropriate array. If the addition of the | |
160 | device makes the array runnable, the array will be started. | |
161 | This provides a convenient interface to a | |
162 | .I hot-plug | |
163 | system. As each device is detected, | |
164 | .I mdadm | |
165 | has a chance to include it in some array as appropriate. | |
8fd8d9c4 N |
166 | .P |
167 | If a | |
168 | .B CONTAINER | |
169 | is passed to | |
170 | .I mdadm | |
171 | in this mode, then any arrays within that container will be assembled | |
172 | and started. | |
8382f19b | 173 | |
2ae555c3 NB |
174 | .TP |
175 | .B Manage | |
176 | This is for doing things to specific components of an array such as | |
177 | adding new spares and removing faulty devices. | |
178 | ||
179 | .TP | |
180 | .B Misc | |
181 | This is an 'everything else' mode that supports operations on active | |
182 | arrays, operations on component devices such as erasing old superblocks, and | |
183 | information gathering operations. | |
e43d0cda NB |
184 | .\"This mode allows operations on independent devices such as examine MD |
185 | .\"superblocks, erasing old superblocks and stopping active arrays. | |
2ae555c3 | 186 | |
1f48664b NB |
187 | .TP |
188 | .B Auto-detect | |
189 | This mode does not act on a specific device or array, but rather it | |
190 | requests the Linux Kernel to activate any auto-detected arrays. | |
52826846 NB |
191 | .SH OPTIONS |
192 | ||
2ae555c3 | 193 | .SH Options for selecting a mode are: |
52826846 | 194 | |
cd29a5c8 | 195 | .TP |
7e23fc43 | 196 | .BR \-A ", " \-\-assemble |
2d465520 | 197 | Assemble a pre-existing array. |
52826846 | 198 | |
cd29a5c8 | 199 | .TP |
7e23fc43 | 200 | .BR \-B ", " \-\-build |
cd29a5c8 | 201 | Build a legacy array without superblocks. |
52826846 | 202 | |
cd29a5c8 | 203 | .TP |
7e23fc43 | 204 | .BR \-C ", " \-\-create |
cd29a5c8 | 205 | Create a new array. |
52826846 | 206 | |
cd29a5c8 | 207 | .TP |
7e23fc43 | 208 | .BR \-F ", " \-\-follow ", " \-\-monitor |
cd29a5c8 NB |
209 | Select |
210 | .B Monitor | |
211 | mode. | |
52826846 | 212 | |
dd0781e5 | 213 | .TP |
7e23fc43 | 214 | .BR \-G ", " \-\-grow |
dd0781e5 | 215 | Change the size or shape of an active array. |
8382f19b NB |
216 | |
217 | .TP | |
1f48664b | 218 | .BR \-I ", " \-\-incremental |
8382f19b NB |
219 | Add a single device into an appropriate array, and possibly start the array. |
220 | ||
1f48664b NB |
221 | .TP |
222 | .B \-\-auto-detect | |
223 | Request that the kernel starts any auto-detected arrays. This can only | |
224 | work if | |
225 | .I md | |
226 | is compiled into the kernel \(em not if it is a module. | |
227 | Arrays can be auto-detected by the kernel if all the components are in | |
228 | primary MS-DOS partitions with partition type | |
229 | .BR FD . | |
230 | In-kernel autodetect is not recommended for new installations. Using | |
231 | .I mdadm | |
232 | to detect and assemble arrays \(em possibly in an | |
233 | .I initrd | |
234 | \(em is substantially more flexible and should be preferred. | |
235 | ||
2ae555c3 NB |
236 | .P |
237 | If a device is given before any options, or if the first option is | |
7e23fc43 PS |
238 | .BR \-\-add , |
239 | .BR \-\-fail , | |
2ae555c3 | 240 | or |
7e23fc43 | 241 | .BR \-\-remove , |
2ae555c3 NB |
242 | then the MANAGE mode is assume. |
243 | Anything other than these will cause the | |
244 | .B Misc | |
245 | mode to be assumed. | |
dd0781e5 | 246 | |
2ae555c3 | 247 | .SH Options that are not mode-specific are: |
e793c2e5 | 248 | |
cd29a5c8 | 249 | .TP |
7e23fc43 | 250 | .BR \-h ", " \-\-help |
a9d69660 | 251 | Display general help message or, after one of the above options, a |
93e790af | 252 | mode-specific help message. |
56eedc1a NB |
253 | |
254 | .TP | |
7e23fc43 | 255 | .B \-\-help\-options |
56eedc1a NB |
256 | Display more detailed help about command line parsing and some commonly |
257 | used options. | |
52826846 | 258 | |
cd29a5c8 | 259 | .TP |
7e23fc43 | 260 | .BR \-V ", " \-\-version |
9a9dab36 | 261 | Print version information for mdadm. |
52826846 | 262 | |
cd29a5c8 | 263 | .TP |
7e23fc43 | 264 | .BR \-v ", " \-\-verbose |
22892d56 NB |
265 | Be more verbose about what is happening. This can be used twice to be |
266 | extra-verbose. | |
a9d69660 | 267 | The extra verbosity currently only affects |
7e23fc43 | 268 | .B \-\-detail \-\-scan |
22892d56 | 269 | and |
7e23fc43 | 270 | .BR "\-\-examine \-\-scan" . |
52826846 | 271 | |
dab6685f | 272 | .TP |
7e23fc43 | 273 | .BR \-q ", " \-\-quiet |
dab6685f | 274 | Avoid printing purely informative messages. With this, |
51ac42e3 | 275 | .I mdadm |
dab6685f NB |
276 | will be silent unless there is something really important to report. |
277 | ||
cd29a5c8 | 278 | .TP |
7e23fc43 | 279 | .BR \-b ", " \-\-brief |
cd29a5c8 | 280 | Be less verbose. This is used with |
7e23fc43 | 281 | .B \-\-detail |
cd29a5c8 | 282 | and |
7e23fc43 | 283 | .BR \-\-examine . |
22892d56 | 284 | Using |
7e23fc43 | 285 | .B \-\-brief |
22892d56 | 286 | with |
7e23fc43 | 287 | .B \-\-verbose |
22892d56 | 288 | gives an intermediate level of verbosity. |
52826846 | 289 | |
e0d19036 | 290 | .TP |
7e23fc43 | 291 | .BR \-f ", " \-\-force |
93e790af | 292 | Be more forceful about certain operations. See the various modes for |
e0d19036 NB |
293 | the exact meaning of this option in different contexts. |
294 | ||
295 | .TP | |
7e23fc43 | 296 | .BR \-c ", " \-\-config= |
2ae555c3 NB |
297 | Specify the config file. Default is to use |
298 | .BR /etc/mdadm.conf , | |
93e790af | 299 | or if that is missing then |
2ae555c3 | 300 | .BR /etc/mdadm/mdadm.conf . |
5787fa49 | 301 | If the config file given is |
93e790af | 302 | .B "partitions" |
5787fa49 NB |
303 | then nothing will be read, but |
304 | .I mdadm | |
305 | will act as though the config file contained exactly | |
8fd8d9c4 | 306 | .B "DEVICE partitions containers" |
5787fa49 NB |
307 | and will read |
308 | .B /proc/partitions | |
8fd8d9c4 N |
309 | to find a list of devices to scan, and |
310 | .B /proc/mdstat | |
311 | to find a list of containers to examine. | |
d013a55e | 312 | If the word |
93e790af | 313 | .B "none" |
d013a55e NB |
314 | is given for the config file, then |
315 | .I mdadm | |
316 | will act as though the config file were empty. | |
e0d19036 NB |
317 | |
318 | .TP | |
7e23fc43 | 319 | .BR \-s ", " \-\-scan |
93e790af | 320 | Scan config file or |
e0d19036 NB |
321 | .B /proc/mdstat |
322 | for missing information. | |
323 | In general, this option gives | |
51ac42e3 | 324 | .I mdadm |
93e790af SW |
325 | permission to get any missing information (like component devices, |
326 | array devices, array identities, and alert destination) from the | |
327 | configuration file (see previous option); | |
328 | one exception is MISC mode when using | |
7e23fc43 | 329 | .B \-\-detail |
e0d19036 | 330 | or |
93e790af | 331 | .B \-\-stop, |
e0d19036 | 332 | in which case |
7e23fc43 | 333 | .B \-\-scan |
e0d19036 NB |
334 | says to get a list of array devices from |
335 | .BR /proc/mdstat . | |
336 | ||
570c0542 | 337 | .TP |
7e23fc43 | 338 | .B \-e ", " \-\-metadata= |
570c0542 | 339 | Declare the style of superblock (raid metadata) to be used. The |
53e8b987 | 340 | default is 0.90 for |
7e23fc43 | 341 | .BR \-\-create , |
53e8b987 | 342 | and to guess for other operations. |
2790ffe3 GB |
343 | The default can be overridden by setting the |
344 | .B metadata | |
345 | value for the | |
346 | .B CREATE | |
347 | keyword in | |
348 | .BR mdadm.conf . | |
570c0542 NB |
349 | |
350 | Options are: | |
351 | .RS | |
352 | .IP "0, 0.90, default" | |
353 | Use the original 0.90 format superblock. This format limits arrays to | |
93e790af | 354 | 28 component devices and limits component devices of levels 1 and |
570c0542 NB |
355 | greater to 2 terabytes. |
356 | .IP "1, 1.0, 1.1, 1.2" | |
357 | Use the new version-1 format superblock. This has few restrictions. | |
93e790af | 358 | The different sub-versions store the superblock at different locations |
570c0542 NB |
359 | on the device, either at the end (for 1.0), at the start (for 1.1) or |
360 | 4K from the start (for 1.2). | |
8fd8d9c4 N |
361 | .IP ddf |
362 | Use the "Industry Standard" DDF (Disk Data Format) format. When | |
363 | creating a DDF array a | |
364 | .B CONTAINER | |
365 | will be created, and normal arrays can be created in that container. | |
366 | .IP imsm | |
367 | Use the Intel Matrix Storage Manager metadata format. This creates a | |
368 | .B CONTAINER | |
369 | which is managed in a similar manner to DDF. | |
570c0542 NB |
370 | .RE |
371 | ||
41a3b72a | 372 | .TP |
7e23fc43 | 373 | .B \-\-homehost= |
35cc5be4 | 374 | This will override any |
41a3b72a | 375 | .B HOMEHOST |
93e790af | 376 | setting in the config file and provides the identity of the host which |
41a3b72a NB |
377 | should be considered the home for any arrays. |
378 | ||
379 | When creating an array, the | |
380 | .B homehost | |
381 | will be recorded in the superblock. For version-1 superblocks, it will | |
93e790af | 382 | be prefixed to the array name. For version-0.90 superblocks, part of |
41a3b72a NB |
383 | the SHA1 hash of the hostname will be stored in the later half of the |
384 | UUID. | |
385 | ||
386 | When reporting information about an array, any array which is tagged | |
387 | for the given homehost will be reported as such. | |
388 | ||
389 | When using Auto-Assemble, only arrays tagged for the given homehost | |
390 | will be assembled. | |
391 | ||
2ae555c3 NB |
392 | .SH For create, build, or grow: |
393 | ||
394 | .TP | |
7e23fc43 | 395 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
396 | Specify the number of active devices in the array. This, plus the |
397 | number of spare devices (see below) must equal the number of | |
398 | .I component-devices | |
399 | (including "\fBmissing\fP" devices) | |
400 | that are listed on the command line for | |
7e23fc43 | 401 | .BR \-\-create . |
2ae555c3 NB |
402 | Setting a value of 1 is probably |
403 | a mistake and so requires that | |
7e23fc43 | 404 | .B \-\-force |
2ae555c3 NB |
405 | be specified first. A value of 1 will then be allowed for linear, |
406 | multipath, raid0 and raid1. It is never allowed for raid4 or raid5. | |
407 | .br | |
408 | This number can only be changed using | |
7e23fc43 | 409 | .B \-\-grow |
00be0b12 NB |
410 | for RAID1, RAID5 and RAID6 arrays, and only on kernels which provide |
411 | necessary support. | |
2ae555c3 NB |
412 | |
413 | .TP | |
7e23fc43 | 414 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
415 | Specify the number of spare (eXtra) devices in the initial array. |
416 | Spares can also be added | |
417 | and removed later. The number of component devices listed | |
418 | on the command line must equal the number of raid devices plus the | |
419 | number of spare devices. | |
420 | ||
421 | ||
422 | .TP | |
7e23fc43 | 423 | .BR \-z ", " \-\-size= |
93e790af | 424 | Amount (in Kibibytes) of space to use from each drive in RAID level 1/4/5/6. |
2ae555c3 NB |
425 | This must be a multiple of the chunk size, and must leave about 128Kb |
426 | of space at the end of the drive for the RAID superblock. | |
427 | If this is not specified | |
428 | (as it normally is not) the smallest drive (or partition) sets the | |
429 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
430 | issued. | |
431 | ||
432 | This value can be set with | |
7e23fc43 | 433 | .B \-\-grow |
2ae555c3 NB |
434 | for RAID level 1/4/5/6. If the array was created with a size smaller |
435 | than the currently active drives, the extra space can be accessed | |
436 | using | |
7e23fc43 | 437 | .BR \-\-grow . |
2ae555c3 NB |
438 | The size can be given as |
439 | .B max | |
440 | which means to choose the largest size that fits on all current drives. | |
52826846 | 441 | |
8fd8d9c4 N |
442 | This value can not be used with |
443 | .B CONTAINER | |
444 | metadata such as DDF and IMSM. | |
445 | ||
cd29a5c8 | 446 | .TP |
7e23fc43 | 447 | .BR \-c ", " \-\-chunk= |
cd29a5c8 | 448 | Specify chunk size of kibibytes. The default is 64. |
52826846 | 449 | |
cd29a5c8 | 450 | .TP |
7e23fc43 | 451 | .BR \-\-rounding= |
cd29a5c8 | 452 | Specify rounding factor for linear array (==chunk size) |
52826846 | 453 | |
cd29a5c8 | 454 | .TP |
7e23fc43 | 455 | .BR \-l ", " \-\-level= |
aa88f531 | 456 | Set raid level. When used with |
7e23fc43 | 457 | .BR \-\-create , |
98c6faba | 458 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
8fd8d9c4 N |
459 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container. |
460 | Obviously some of these are synonymous. | |
461 | ||
462 | When a | |
463 | .B CONTAINER | |
464 | metadata type is requested, only the | |
465 | .B container | |
466 | level is permitted, and it does not need to be explicitly given. | |
aa88f531 NB |
467 | |
468 | When used with | |
7e23fc43 | 469 | .BR \-\-build , |
a9d69660 | 470 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 471 | |
2ae555c3 | 472 | Not yet supported with |
7e23fc43 | 473 | .BR \-\-grow . |
2ae555c3 | 474 | |
cd29a5c8 | 475 | .TP |
7e23fc43 | 476 | .BR \-p ", " \-\-layout= |
1a7dfc35 NB |
477 | This option configures the fine details of data layout for raid5, |
478 | and raid10 arrays, and controls the failure modes for | |
479 | .IR faulty . | |
480 | ||
481 | The layout of the raid5 parity block can be one of | |
7e23fc43 PS |
482 | .BR left\-asymmetric , |
483 | .BR left\-symmetric , | |
484 | .BR right\-asymmetric , | |
485 | .BR right\-symmetric , | |
53e8b987 PS |
486 | .BR la ", " ra ", " ls ", " rs . |
487 | The default is | |
7e23fc43 | 488 | .BR left\-symmetric . |
52826846 | 489 | |
93e790af SW |
490 | When setting the failure mode for level |
491 | .I faulty, | |
1a7dfc35 | 492 | the options are: |
7e23fc43 PS |
493 | .BR write\-transient ", " wt , |
494 | .BR read\-transient ", " rt , | |
495 | .BR write\-persistent ", " wp , | |
496 | .BR read\-persistent ", " rp , | |
497 | .BR write\-all , | |
498 | .BR read\-fixable ", " rf , | |
53e8b987 | 499 | .BR clear ", " flush ", " none . |
b5e64645 | 500 | |
93e790af | 501 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
502 | between fault generation. Without a number, the fault is generated |
503 | once on the first relevant request. With a number, the fault will be | |
93e790af | 504 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
505 | every time the period elapses. |
506 | ||
507 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 508 | .B \-\-grow |
53e8b987 | 509 | option to set subsequent failure modes. |
b5e64645 NB |
510 | |
511 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 512 | and "flush" will clear any persistent faults. |
b5e64645 | 513 | |
53e8b987 | 514 | To set the parity with |
7e23fc43 | 515 | .BR \-\-grow , |
53e8b987 | 516 | the level of the array ("faulty") |
b5e64645 NB |
517 | must be specified before the fault mode is specified. |
518 | ||
6f9a21a7 | 519 | Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 520 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 521 | |
93e790af | 522 | .I 'n' |
b578481c NB |
523 | signals 'near' copies. Multiple copies of one data block are at |
524 | similar offsets in different devices. | |
525 | ||
93e790af | 526 | .I 'o' |
b578481c NB |
527 | signals 'offset' copies. Rather than the chunks being duplicated |
528 | within a stripe, whole stripes are duplicated but are rotated by one | |
529 | device so duplicate blocks are on different devices. Thus subsequent | |
530 | copies of a block are in the next drive, and are one chunk further | |
531 | down. | |
532 | ||
93e790af | 533 | .I 'f' |
1a7dfc35 | 534 | signals 'far' copies |
93e790af SW |
535 | (multiple copies have very different offsets). |
536 | See md(4) for more detail about 'near' and 'far'. | |
1a7dfc35 NB |
537 | |
538 | The number is the number of copies of each datablock. 2 is normal, 3 | |
539 | can be useful. This number can be at most equal to the number of | |
540 | devices in the array. It does not need to divide evenly into that | |
541 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
542 | with an odd number of devices). | |
543 | ||
cd29a5c8 | 544 | .TP |
7e23fc43 | 545 | .BR \-\-parity= |
53e8b987 | 546 | same as |
7e23fc43 | 547 | .B \-\-layout |
53e8b987 | 548 | (thus explaining the p of |
7e23fc43 | 549 | .BR \-p ). |
52826846 | 550 | |
e793c2e5 | 551 | .TP |
7e23fc43 | 552 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 553 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 554 | exist unless |
7e23fc43 | 555 | .B \-\-force |
53e8b987 | 556 | is also given. The same file should be provided |
2ae555c3 | 557 | when assembling the array. If the word |
93e790af | 558 | .B "internal" |
2ae555c3 NB |
559 | is given, then the bitmap is stored with the metadata on the array, |
560 | and so is replicated on all devices. If the word | |
93e790af | 561 | .B "none" |
2ae555c3 | 562 | is given with |
7e23fc43 | 563 | .B \-\-grow |
2ae555c3 | 564 | mode, then any bitmap that is present is removed. |
e793c2e5 | 565 | |
2ae555c3 NB |
566 | To help catch typing errors, the filename must contain at least one |
567 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
568 | ||
569 | Note: external bitmaps are only known to work on ext2 and ext3. | |
570 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 571 | |
cd29a5c8 | 572 | .TP |
7e23fc43 | 573 | .BR \-\-bitmap\-chunk= |
2ae555c3 | 574 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
575 | Kilobytes of storage. |
576 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 577 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
578 | When using an |
579 | .B internal | |
580 | bitmap, the chunksize is automatically determined to make best use of | |
581 | available space. | |
5787fa49 | 582 | |
cd29a5c8 NB |
583 | |
584 | .TP | |
7e23fc43 | 585 | .BR \-W ", " \-\-write\-mostly |
2ae555c3 | 586 | subsequent devices lists in a |
7e23fc43 PS |
587 | .BR \-\-build , |
588 | .BR \-\-create , | |
2ae555c3 | 589 | or |
7e23fc43 | 590 | .B \-\-add |
2ae555c3 NB |
591 | command will be flagged as 'write-mostly'. This is valid for RAID1 |
592 | only and means that the 'md' driver will avoid reading from these | |
593 | devices if at all possible. This can be useful if mirroring over a | |
594 | slow link. | |
52826846 | 595 | |
2ae555c3 | 596 | .TP |
7e23fc43 | 597 | .BR \-\-write\-behind= |
2ae555c3 NB |
598 | Specify that write-behind mode should be enabled (valid for RAID1 |
599 | only). If an argument is specified, it will set the maximum number | |
600 | of outstanding writes allowed. The default value is 256. | |
601 | A write-intent bitmap is required in order to use write-behind | |
602 | mode, and write-behind is only attempted on drives marked as | |
603 | .IR write-mostly . | |
dd0781e5 NB |
604 | |
605 | .TP | |
7e23fc43 | 606 | .BR \-\-assume\-clean |
dd0781e5 NB |
607 | Tell |
608 | .I mdadm | |
47d79ef8 NB |
609 | that the array pre-existed and is known to be clean. It can be useful |
610 | when trying to recover from a major failure as you can be sure that no | |
611 | data will be affected unless you actually write to the array. It can | |
612 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 613 | initial resync, however this practice \(em while normally safe \(em is not |
93e790af | 614 | recommended. Use this only if you really know what you are doing. |
dd0781e5 | 615 | |
2ae555c3 | 616 | .TP |
7e23fc43 | 617 | .BR \-\-backup\-file= |
53e8b987 | 618 | This is needed when |
7e23fc43 | 619 | .B \-\-grow |
53e8b987 | 620 | is used to increase the number of |
2ae555c3 NB |
621 | raid-devices in a RAID5 if there are no spare devices available. |
622 | See the section below on RAID_DEVICE CHANGES. The file should be | |
623 | stored on a separate device, not on the raid array being reshaped. | |
624 | ||
947fd4dd | 625 | .TP |
7e23fc43 | 626 | .BR \-N ", " \-\-name= |
947fd4dd NB |
627 | Set a |
628 | .B name | |
629 | for the array. This is currently only effective when creating an | |
630 | array with a version-1 superblock. The name is a simple textual | |
631 | string that can be used to identify array components when assembling. | |
632 | ||
dd0781e5 | 633 | .TP |
7e23fc43 | 634 | .BR \-R ", " \-\-run |
dd0781e5 NB |
635 | Insist that |
636 | .I mdadm | |
637 | run the array, even if some of the components | |
638 | appear to be active in another array or filesystem. Normally | |
639 | .I mdadm | |
640 | will ask for confirmation before including such components in an | |
641 | array. This option causes that question to be suppressed. | |
642 | ||
643 | .TP | |
7e23fc43 | 644 | .BR \-f ", " \-\-force |
dd0781e5 NB |
645 | Insist that |
646 | .I mdadm | |
647 | accept the geometry and layout specified without question. Normally | |
648 | .I mdadm | |
649 | will not allow creation of an array with only one device, and will try | |
650 | to create a raid5 array with one missing drive (as this makes the | |
651 | initial resync work faster). With | |
7e23fc43 | 652 | .BR \-\-force , |
dd0781e5 NB |
653 | .I mdadm |
654 | will not try to be so clever. | |
655 | ||
656 | .TP | |
7e23fc43 | 657 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part,p}{NN}" |
48f7b27a NB |
658 | Instruct mdadm to create the device file if needed, possibly allocating |
659 | an unused minor number. "md" causes a non-partitionable array | |
dd0781e5 | 660 | to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and |
2ae555c3 | 661 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 662 | a 'standard' format, and the type and minor number will be determined |
48f7b27a NB |
663 | from this. See DEVICE NAMES below. |
664 | ||
a9d69660 | 665 | The argument can also come immediately after |
7e23fc43 | 666 | "\-a". e.g. "\-ap". |
dd0781e5 | 667 | |
53e8b987 | 668 | If |
7e23fc43 | 669 | .B \-\-auto |
53e8b987 | 670 | is not given on the command line or in the config file, then |
75723446 | 671 | the default will be |
7e23fc43 | 672 | .BR \-\-auto=yes . |
75723446 | 673 | |
1337546d | 674 | If |
7e23fc43 | 675 | .B \-\-scan |
1337546d NB |
676 | is also given, then any |
677 | .I auto= | |
35cc5be4 | 678 | entries in the config file will override the |
7e23fc43 | 679 | .B \-\-auto |
1337546d NB |
680 | instruction given on the command line. |
681 | ||
dd0781e5 NB |
682 | For partitionable arrays, |
683 | .I mdadm | |
684 | will create the device file for the whole array and for the first 4 | |
685 | partitions. A different number of partitions can be specified at the | |
686 | end of this option (e.g. | |
7e23fc43 | 687 | .BR \-\-auto=p7 ). |
2ae555c3 | 688 | If the device name ends with a digit, the partition names add a 'p', |
8fd8d9c4 | 689 | and a number, e.g. "/dev/md/home1p3". If there is no |
dd0781e5 | 690 | trailing digit, then the partition names just have a number added, |
8fd8d9c4 | 691 | e.g. "/dev/md/scratch3". |
dd0781e5 | 692 | |
48f7b27a NB |
693 | If the md device name is in a 'standard' format as described in DEVICE |
694 | NAMES, then it will be created, if necessary, with the appropriate | |
695 | number based on that name. If the device name is not in one of these | |
a9d69660 | 696 | formats, then a unused minor number will be allocated. The minor |
48f7b27a NB |
697 | number will be considered unused if there is no active array for that |
698 | number, and there is no entry in /dev for that number and with a | |
8fd8d9c4 N |
699 | non-standard name. Name that are not in 'standard' format are only |
700 | allowed in "/dev/md/". | |
701 | ||
702 | \".TP | |
703 | \".BR \-\-symlink = no | |
704 | \"Normally when | |
705 | \".B \-\-auto | |
706 | \"causes | |
707 | \".I mdadm | |
708 | \"to create devices in | |
709 | \".B /dev/md/ | |
710 | \"it will also create symlinks from | |
711 | \".B /dev/ | |
712 | \"with names starting with | |
713 | \".B md | |
714 | \"or | |
715 | \".BR md_ . | |
716 | \"Use | |
717 | \".B \-\-symlink=no | |
718 | \"to suppress this, or | |
719 | \".B \-\-symlink=yes | |
720 | \"to enforce this even if it is suppressing | |
721 | \".IR mdadm.conf . | |
722 | \" | |
38098016 | 723 | |
52826846 NB |
724 | .SH For assemble: |
725 | ||
cd29a5c8 | 726 | .TP |
7e23fc43 | 727 | .BR \-u ", " \-\-uuid= |
cd29a5c8 NB |
728 | uuid of array to assemble. Devices which don't have this uuid are |
729 | excluded | |
730 | ||
731 | .TP | |
7e23fc43 | 732 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
733 | Minor number of device that array was created for. Devices which |
734 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 735 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
736 | the array is later assembled as /dev/md2. |
737 | ||
d013a55e | 738 | Giving the literal word "dev" for |
7e23fc43 | 739 | .B \-\-super\-minor |
d013a55e NB |
740 | will cause |
741 | .I mdadm | |
742 | to use the minor number of the md device that is being assembled. | |
743 | e.g. when assembling | |
744 | .BR /dev/md0 , | |
51ac42e3 | 745 | .B \-\-super\-minor=dev |
d013a55e NB |
746 | will look for super blocks with a minor number of 0. |
747 | ||
947fd4dd | 748 | .TP |
7e23fc43 | 749 | .BR \-N ", " \-\-name= |
947fd4dd | 750 | Specify the name of the array to assemble. This must be the name |
624920bb | 751 | that was specified when creating the array. It must either match |
93e790af | 752 | the name stored in the superblock exactly, or it must match |
41a3b72a | 753 | with the current |
624920bb | 754 | .I homehost |
93e790af | 755 | prefixed to the start of the given name. |
947fd4dd | 756 | |
cd29a5c8 | 757 | .TP |
7e23fc43 | 758 | .BR \-f ", " \-\-force |
52826846 NB |
759 | Assemble the array even if some superblocks appear out-of-date |
760 | ||
cd29a5c8 | 761 | .TP |
7e23fc43 | 762 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
763 | Attempt to start the array even if fewer drives were given than were |
764 | present last time the array was active. Normally if not all the | |
765 | expected drives are found and | |
7e23fc43 | 766 | .B \-\-scan |
cd29a5c8 NB |
767 | is not used, then the array will be assembled but not started. |
768 | With | |
7e23fc43 | 769 | .B \-\-run |
cd29a5c8 | 770 | an attempt will be made to start it anyway. |
52826846 | 771 | |
b8a8ccf9 | 772 | .TP |
7e23fc43 | 773 | .B \-\-no\-degraded |
b8a8ccf9 | 774 | This is the reverse of |
7e23fc43 | 775 | .B \-\-run |
93e790af | 776 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 777 | are present. This is only needed with |
93e790af SW |
778 | .B \-\-scan, |
779 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
780 | not as reliable as you would like. |
781 | ||
dd0781e5 | 782 | .TP |
7e23fc43 | 783 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
784 | See this option under Create and Build options. |
785 | ||
e793c2e5 | 786 | .TP |
7e23fc43 | 787 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
788 | Specify the bitmap file that was given when the array was created. If |
789 | an array has an | |
790 | .B internal | |
791 | bitmap, there is no need to specify this when assembling the array. | |
792 | ||
793 | .TP | |
7e23fc43 | 794 | .BR \-\-backup\-file= |
2ae555c3 | 795 | If |
7e23fc43 | 796 | .B \-\-backup\-file |
2ae555c3 NB |
797 | was used to grow the number of raid-devices in a RAID5, and the system |
798 | crashed during the critical section, then the same | |
7e23fc43 | 799 | .B \-\-backup\-file |
53e8b987 | 800 | must be presented to |
7e23fc43 | 801 | .B \-\-assemble |
53e8b987 | 802 | to allow possibly corrupted data to be restored. |
e793c2e5 | 803 | |
5787fa49 | 804 | .TP |
7e23fc43 | 805 | .BR \-U ", " \-\-update= |
5787fa49 | 806 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
807 | argument given to this flag can be one of |
808 | .BR sparc2.2 , | |
809 | .BR summaries , | |
7d99579f | 810 | .BR uuid , |
c4f12c13 | 811 | .BR name , |
0237e0ca | 812 | .BR homehost , |
e5329c37 | 813 | .BR resync , |
586ed405 | 814 | .BR byteorder , |
bee8ec56 | 815 | .BR devicesize , |
5787fa49 | 816 | or |
7e23fc43 | 817 | .BR super\-minor . |
5787fa49 NB |
818 | |
819 | The | |
820 | .B sparc2.2 | |
7d99579f | 821 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
822 | machine running a patched 2.2 Linux kernel. This kernel got the |
823 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 824 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
825 | option to |
826 | .I mdadm | |
827 | to see what effect this would have. | |
828 | ||
829 | The | |
7e23fc43 | 830 | .B super\-minor |
5787fa49 | 831 | option will update the |
2ae555c3 | 832 | .B "preferred minor" |
5787fa49 | 833 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
834 | assembled. |
835 | This can be useful if | |
7e23fc43 | 836 | .B \-\-examine |
45c073c9 | 837 | reports a different "Preferred Minor" to |
7e23fc43 | 838 | .BR \-\-detail . |
45c073c9 NB |
839 | In some cases this update will be performed automatically |
840 | by the kernel driver. In particular the update happens automatically | |
841 | at the first write to an array with redundancy (RAID level 1 or | |
842 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 843 | |
7d99579f NB |
844 | The |
845 | .B uuid | |
846 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 847 | .B \-\-uuid |
53e8b987 | 848 | option that UUID will be used as a new UUID and will |
7d99579f NB |
849 | .B NOT |
850 | be used to help identify the devices in the array. | |
53e8b987 | 851 | If no |
7e23fc43 | 852 | .B \-\-uuid |
53e8b987 | 853 | is given, a random UUID is chosen. |
7d99579f | 854 | |
c4f12c13 NB |
855 | The |
856 | .B name | |
857 | option will change the | |
858 | .I name | |
859 | of the array as stored in the superblock. This is only supported for | |
860 | version-1 superblocks. | |
861 | ||
0237e0ca NB |
862 | The |
863 | .B homehost | |
864 | option will change the | |
865 | .I homehost | |
866 | as recorded in the superblock. For version-0 superblocks, this is the | |
867 | same as updating the UUID. | |
868 | For version-1 superblocks, this involves updating the name. | |
869 | ||
e5329c37 NB |
870 | The |
871 | .B resync | |
872 | option will cause the array to be marked | |
873 | .I dirty | |
874 | meaning that any redundancy in the array (e.g. parity for raid5, | |
875 | copies for raid1) may be incorrect. This will cause the raid system | |
876 | to perform a "resync" pass to make sure that all redundant information | |
877 | is correct. | |
878 | ||
586ed405 NB |
879 | The |
880 | .B byteorder | |
881 | option allows arrays to be moved between machines with different | |
882 | byte-order. | |
2ae555c3 | 883 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 884 | .B "\-\-update=byteorder" |
586ed405 NB |
885 | will cause |
886 | .I mdadm | |
887 | to expect superblocks to have their byteorder reversed, and will | |
888 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 889 | with original (Version 0.90) superblocks. |
586ed405 | 890 | |
feb716e9 NB |
891 | The |
892 | .B summaries | |
893 | option will correct the summaries in the superblock. That is the | |
894 | counts of total, working, active, failed, and spare devices. | |
5787fa49 | 895 | |
bee8ec56 NB |
896 | The |
897 | .B devicesize | |
898 | will rarely be of use. It applies to version 1.1 and 1.2 metadata | |
899 | only (where the metadata is at the start of the device) and is only | |
900 | useful when the component device has changed size (typically become | |
901 | larger). The version 1 metadata records the amount of the device that | |
902 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
903 | array becomes larger, the metadata will still be visible, but the | |
904 | extra space will not. In this case it might be useful to assemble the | |
905 | array with | |
7e23fc43 | 906 | .BR \-\-update=devicesize . |
bee8ec56 NB |
907 | This will cause |
908 | .I mdadm | |
909 | to determine the maximum usable amount of space on each device and | |
910 | update the relevant field in the metadata. | |
911 | ||
41a3b72a | 912 | .TP |
7e23fc43 | 913 | .B \-\-auto\-update\-homehost |
93e790af | 914 | This flag is only meaningful with auto-assembly (see discussion below). |
41a3b72a NB |
915 | In that situation, if no suitable arrays are found for this homehost, |
916 | .I mdadm | |
93e790af | 917 | will rescan for any arrays at all and will assemble them and update the |
41a3b72a NB |
918 | homehost to match the current host. |
919 | ||
e0d19036 | 920 | .SH For Manage mode: |
52826846 | 921 | |
cd29a5c8 | 922 | .TP |
7e23fc43 | 923 | .BR \-a ", " \-\-add |
2ae555c3 | 924 | hot-add listed devices. |
52826846 | 925 | |
fe80f49b | 926 | .TP |
7e23fc43 | 927 | .BR \-\-re\-add |
2ae555c3 | 928 | re-add a device that was recently removed from an array. |
fe80f49b | 929 | |
cd29a5c8 | 930 | .TP |
7e23fc43 | 931 | .BR \-r ", " \-\-remove |
2d465520 | 932 | remove listed devices. They must not be active. i.e. they should |
b80da661 NB |
933 | be failed or spare devices. As well as the name of a device file |
934 | (e.g. | |
935 | .BR /dev/sda1 ) | |
936 | the words | |
937 | .B failed | |
938 | and | |
939 | .B detached | |
940 | can be given to | |
941 | .BR \-\-remove . | |
942 | The first causes all failed device to be removed. The second causes | |
93e790af | 943 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
944 | returns |
945 | .BR ENXIO ) | |
946 | to be removed. This will only succeed for devices that are spares or | |
947 | have already been marked as failed. | |
52826846 | 948 | |
cd29a5c8 | 949 | .TP |
7e23fc43 | 950 | .BR \-f ", " \-\-fail |
cd29a5c8 | 951 | mark listed devices as faulty. |
b80da661 NB |
952 | As well as the name of a device file, the word |
953 | .B detached | |
954 | can be given. This will cause any device that has been detached from | |
955 | the system to be marked as failed. It can then be removed. | |
52826846 | 956 | |
cd29a5c8 | 957 | .TP |
7e23fc43 | 958 | .BR \-\-set\-faulty |
53e8b987 | 959 | same as |
7e23fc43 | 960 | .BR \-\-fail . |
52826846 | 961 | |
b3d31955 N |
962 | .TP |
963 | .BR \-\-write\-mostly | |
964 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
965 | flag set. This is only valid for RAID! and means that the 'md' driver | |
966 | will avoid reading from these devices if possible. | |
967 | .TP | |
968 | .BR \-\-readwrite | |
969 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
970 | flag cleared. | |
971 | ||
972 | ||
2ae555c3 | 973 | .P |
93e790af SW |
974 | Each of these options require that the first device listed is the array |
975 | to be acted upon, and the remainder are component devices to be added, | |
976 | removed, or marked as faulty. Several different operations can be | |
2ae555c3 NB |
977 | specified for different devices, e.g. |
978 | .in +5 | |
7e23fc43 | 979 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
980 | .in -5 |
981 | Each operation applies to all devices listed until the next | |
93e790af | 982 | operation. |
2ae555c3 NB |
983 | |
984 | If an array is using a write-intent bitmap, then devices which have | |
985 | been removed can be re-added in a way that avoids a full | |
93e790af | 986 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
987 | since the device was removed. For arrays with persistent metadata |
988 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 989 | .B \-\-build |
2ae555c3 | 990 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 991 | .BR \-\-re\-add . |
2ae555c3 NB |
992 | |
993 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
994 | use, i.e. that must be spares or failed devices. To remove an active |
995 | device, it must first be marked as | |
996 | .B faulty. | |
2ae555c3 NB |
997 | |
998 | .SH For Misc mode: | |
999 | ||
1000 | .TP | |
7e23fc43 | 1001 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
1002 | Examine a device to see |
1003 | (1) if it is an md device and (2) if it is a component of an md | |
1004 | array. | |
1005 | Information about what is discovered is presented. | |
1006 | ||
1007 | .TP | |
7e23fc43 | 1008 | .BR \-D ", " \-\-detail |
2ae555c3 | 1009 | Print detail of one or more md devices. |
5787fa49 | 1010 | |
54bad364 KS |
1011 | .TP |
1012 | .BR \-Y ", " \-\-export | |
1013 | When used with | |
0d726f17 KS |
1014 | .B \-\-detail |
1015 | or | |
1016 | .BR \-\-examine , | |
54bad364 KS |
1017 | output will be formatted as |
1018 | .B key=value | |
1019 | pairs for easy import into the environment. | |
1020 | ||
2ae555c3 | 1021 | .TP |
7e23fc43 | 1022 | .BR \-E ", " \-\-examine |
2ae555c3 | 1023 | Print content of md superblock on device(s). |
5787fa49 | 1024 | .TP |
7e23fc43 | 1025 | .B \-\-sparc2.2 |
a9d69660 | 1026 | If an array was created on a 2.2 Linux kernel patched with RAID |
5787fa49 NB |
1027 | support, the superblock will have been created incorrectly, or at |
1028 | least incompatibly with 2.4 and later kernels. Using the | |
7e23fc43 | 1029 | .B \-\-sparc2.2 |
5787fa49 | 1030 | flag with |
7e23fc43 | 1031 | .B \-\-examine |
5787fa49 NB |
1032 | will fix the superblock before displaying it. If this appears to do |
1033 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 1034 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 1035 | |
2ae555c3 | 1036 | .TP |
7e23fc43 | 1037 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 1038 | Report information about a bitmap file. |
01d9299c NB |
1039 | The argument is either an external bitmap file or an array component |
1040 | in case of an internal bitmap. | |
e0d19036 | 1041 | |
cd29a5c8 | 1042 | .TP |
7e23fc43 | 1043 | .BR \-R ", " \-\-run |
cd29a5c8 | 1044 | start a partially built array. |
52826846 | 1045 | |
cd29a5c8 | 1046 | .TP |
7e23fc43 | 1047 | .BR \-S ", " \-\-stop |
cd29a5c8 | 1048 | deactivate array, releasing all resources. |
52826846 | 1049 | |
cd29a5c8 | 1050 | .TP |
7e23fc43 | 1051 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 1052 | mark array as readonly. |
52826846 | 1053 | |
cd29a5c8 | 1054 | .TP |
7e23fc43 | 1055 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 1056 | mark array as readwrite. |
52826846 | 1057 | |
e0d19036 | 1058 | .TP |
7e23fc43 | 1059 | .B \-\-zero\-superblock |
e0d19036 | 1060 | If the device contains a valid md superblock, the block is |
35cc5be4 | 1061 | overwritten with zeros. With |
7e23fc43 | 1062 | .B \-\-force |
35cc5be4 | 1063 | the block where the superblock would be is overwritten even if it |
e0d19036 | 1064 | doesn't appear to be valid. |
52826846 | 1065 | |
feb716e9 | 1066 | .TP |
7e23fc43 | 1067 | .BR \-t ", " \-\-test |
feb716e9 | 1068 | When used with |
7e23fc43 | 1069 | .BR \-\-detail , |
feb716e9 NB |
1070 | the exit status of |
1071 | .I mdadm | |
1072 | is set to reflect the status of the device. | |
1073 | ||
b90c0e9a | 1074 | .TP |
7e23fc43 | 1075 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1076 | For each md device given, wait for any resync, recovery, or reshape |
1077 | activity to finish before returning. | |
1078 | .I mdadm | |
1079 | will return with success if it actually waited for every device | |
1080 | listed, otherwise it will return failure. | |
1081 | ||
1770662b DW |
1082 | .TP |
1083 | .BR \-\-wait\-clean | |
7146ec6a DW |
1084 | For each md device given, arrange for the array to be marked clean as |
1085 | soon as possible. Also, quiesce resync so that the monitor for external | |
1086 | metadata arrays (mdmon) has an opportunity to checkpoint the resync | |
1087 | position. | |
1088 | .I mdadm | |
1089 | will return with success if the array uses external metadata and we | |
1090 | successfully waited. For native arrays this returns immediately as the | |
1091 | kernel handles both dirty-clean transitions and resync checkpointing in | |
1092 | the kernel at shutdown. No action is taken if safe-mode handling is | |
1093 | disabled. | |
1770662b | 1094 | |
8382f19b NB |
1095 | .SH For Incremental Assembly mode: |
1096 | .TP | |
7e23fc43 | 1097 | .BR \-\-rebuild\-map ", " \-r |
8382f19b NB |
1098 | Rebuild the map file |
1099 | .RB ( /var/run/mdadm/map ) | |
1100 | that | |
1101 | .I mdadm | |
1102 | uses to help track which arrays are currently being assembled. | |
1103 | ||
1104 | .TP | |
7e23fc43 | 1105 | .BR \-\-run ", " \-R |
8382f19b NB |
1106 | Run any array assembled as soon as a minimal number of devices are |
1107 | available, rather than waiting until all expected devices are present. | |
1108 | ||
1109 | .TP | |
7e23fc43 | 1110 | .BR \-\-scan ", " \-s |
8382f19b | 1111 | Only meaningful with |
7e23fc43 | 1112 | .B \-R |
8382f19b NB |
1113 | this will scan the |
1114 | .B map | |
1115 | file for arrays that are being incrementally assembled and will try to | |
1116 | start any that are not already started. If any such array is listed | |
1117 | in | |
1118 | .B mdadm.conf | |
1119 | as requiring an external bitmap, that bitmap will be attached first. | |
1120 | ||
e0d19036 NB |
1121 | .SH For Monitor mode: |
1122 | .TP | |
7e23fc43 | 1123 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1124 | Give a mail address to send alerts to. |
1125 | ||
1126 | .TP | |
7e23fc43 | 1127 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1128 | Give a program to be run whenever an event is detected. |
1129 | ||
773135f5 | 1130 | .TP |
7e23fc43 | 1131 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1132 | Cause all events to be reported through 'syslog'. The messages have |
1133 | facility of 'daemon' and varying priorities. | |
1134 | ||
e0d19036 | 1135 | .TP |
7e23fc43 | 1136 | .BR \-d ", " \-\-delay |
e0d19036 | 1137 | Give a delay in seconds. |
51ac42e3 | 1138 | .I mdadm |
e0d19036 NB |
1139 | polls the md arrays and then waits this many seconds before polling |
1140 | again. The default is 60 seconds. | |
1141 | ||
d013a55e | 1142 | .TP |
7e23fc43 | 1143 | .BR \-f ", " \-\-daemonise |
d013a55e | 1144 | Tell |
51ac42e3 | 1145 | .I mdadm |
d013a55e NB |
1146 | to run as a background daemon if it decides to monitor anything. This |
1147 | causes it to fork and run in the child, and to disconnect form the | |
1148 | terminal. The process id of the child is written to stdout. | |
1149 | This is useful with | |
7e23fc43 | 1150 | .B \-\-scan |
d013a55e NB |
1151 | which will only continue monitoring if a mail address or alert program |
1152 | is found in the config file. | |
1153 | ||
b5e64645 | 1154 | .TP |
7e23fc43 | 1155 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1156 | When |
51ac42e3 | 1157 | .I mdadm |
b5e64645 NB |
1158 | is running in daemon mode, write the pid of the daemon process to |
1159 | the specified file, instead of printing it on standard output. | |
1160 | ||
aa88f531 | 1161 | .TP |
7e23fc43 | 1162 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1163 | Check arrays only once. This will generate |
1164 | .B NewArray | |
1165 | events and more significantly | |
1166 | .B DegradedArray | |
a9d69660 NB |
1167 | and |
1168 | .B SparesMissing | |
aa88f531 NB |
1169 | events. Running |
1170 | .in +5 | |
7e23fc43 | 1171 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1172 | .in -5 |
1173 | from a cron script will ensure regular notification of any degraded arrays. | |
1174 | ||
98c6faba | 1175 | .TP |
7e23fc43 | 1176 | .BR \-t ", " \-\-test |
98c6faba NB |
1177 | Generate a |
1178 | .B TestMessage | |
1179 | alert for every array found at startup. This alert gets mailed and | |
1180 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1181 | message do get through successfully. |
98c6faba | 1182 | |
e0d19036 | 1183 | .SH ASSEMBLE MODE |
52826846 | 1184 | |
cd29a5c8 NB |
1185 | .HP 12 |
1186 | Usage: | |
7e23fc43 | 1187 | .B mdadm \-\-assemble |
5787fa49 NB |
1188 | .I md-device options-and-component-devices... |
1189 | .HP 12 | |
1190 | Usage: | |
7e23fc43 | 1191 | .B mdadm \-\-assemble \-\-scan |
5787fa49 | 1192 | .I md-devices-and-options... |
cd29a5c8 NB |
1193 | .HP 12 |
1194 | Usage: | |
7e23fc43 | 1195 | .B mdadm \-\-assemble \-\-scan |
cd29a5c8 | 1196 | .I options... |
52826846 | 1197 | |
cd29a5c8 | 1198 | .PP |
52826846 | 1199 | This usage assembles one or more raid arrays from pre-existing components. |
9a9dab36 | 1200 | For each array, mdadm needs to know the md device, the identity of the |
e0d19036 | 1201 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1202 | |
5787fa49 | 1203 | In the first usage example (without the |
7e23fc43 | 1204 | .BR \-\-scan ) |
5787fa49 NB |
1205 | the first device given is the md device. |
1206 | In the second usage example, all devices listed are treated as md | |
1207 | devices and assembly is attempted. | |
1208 | In the third (where no devices are listed) all md devices that are | |
8fd8d9c4 N |
1209 | listed in the configuration file are assembled. Then any arrays that |
1210 | can be found on unused devices will also be assembled. | |
52826846 | 1211 | |
d013a55e | 1212 | If precisely one device is listed, but |
7e23fc43 | 1213 | .B \-\-scan |
dd0781e5 | 1214 | is not given, then |
d013a55e NB |
1215 | .I mdadm |
1216 | acts as though | |
7e23fc43 | 1217 | .B \-\-scan |
93e790af | 1218 | was given and identity information is extracted from the configuration file. |
d013a55e | 1219 | |
2ae555c3 | 1220 | The identity can be given with the |
7e23fc43 | 1221 | .B \-\-uuid |
cd29a5c8 | 1222 | option, with the |
7e23fc43 | 1223 | .B \-\-super\-minor |
93e790af SW |
1224 | option, will be taken from the md-device record in the config file, or |
1225 | will be taken from the super block of the first component-device | |
1226 | listed on the command line. | |
52826846 | 1227 | |
2ae555c3 | 1228 | Devices can be given on the |
7e23fc43 | 1229 | .B \-\-assemble |
5787fa49 NB |
1230 | command line or in the config file. Only devices which have an md |
1231 | superblock which contains the right identity will be considered for | |
1232 | any array. | |
52826846 | 1233 | |
2ae555c3 | 1234 | The config file is only used if explicitly named with |
7e23fc43 | 1235 | .B \-\-config |
d013a55e | 1236 | or requested with (a possibly implicit) |
7e23fc43 | 1237 | .BR \-\-scan . |
52826846 | 1238 | In the later case, |
9a9dab36 | 1239 | .B /etc/mdadm.conf |
8fd8d9c4 N |
1240 | or |
1241 | .B /etc/mdadm/mdadm.conf | |
52826846 NB |
1242 | is used. |
1243 | ||
2ae555c3 | 1244 | If |
7e23fc43 | 1245 | .B \-\-scan |
cd29a5c8 NB |
1246 | is not given, then the config file will only be used to find the |
1247 | identity of md arrays. | |
52826846 | 1248 | |
2d465520 | 1249 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 1250 | .B \-\-scan |
2d465520 | 1251 | is not given and insufficient drives were listed to start a complete |
cd29a5c8 NB |
1252 | (non-degraded) array, then the array is not started (to guard against |
1253 | usage errors). To insist that the array be started in this case (as | |
1a7dfc35 | 1254 | may work for RAID1, 4, 5, 6, or 10), give the |
7e23fc43 | 1255 | .B \-\-run |
cd29a5c8 | 1256 | flag. |
52826846 | 1257 | |
75723446 NB |
1258 | If the md device does not exist, then it will be created providing the |
1259 | intent is clear. i.e. the name must be in a standard form, or the | |
7e23fc43 | 1260 | .B \-\-auto |
75723446 NB |
1261 | option must be given to clarify how and whether the device should be |
1262 | created. | |
dd0781e5 | 1263 | This can be useful for handling partitioned devices (which don't have |
b3f1c093 | 1264 | a stable device number \(em it can change after a reboot) and when using |
dd0781e5 NB |
1265 | "udev" to manage your |
1266 | .B /dev | |
1267 | tree (udev cannot handle md devices because of the unusual device | |
1268 | initialisation conventions). | |
1269 | ||
1270 | If the option to "auto" is "mdp" or "part" or (on the command line | |
1271 | only) "p", then mdadm will create a partitionable array, using the | |
93e790af | 1272 | first free one that is not in use and does not already have an entry |
dd0781e5 NB |
1273 | in /dev (apart from numeric /dev/md* entries). |
1274 | ||
1275 | If the option to "auto" is "yes" or "md" or (on the command line) | |
1276 | nothing, then mdadm will create a traditional, non-partitionable md | |
1277 | array. | |
1278 | ||
1279 | It is expected that the "auto" functionality will be used to create | |
1280 | device entries with meaningful names such as "/dev/md/home" or | |
1281 | "/dev/md/root", rather than names based on the numerical array number. | |
1282 | ||
93e790af | 1283 | When using option "auto" to create a partitionable array, the device |
dd0781e5 NB |
1284 | files for the first 4 partitions are also created. If a different |
1285 | number is required it can be simply appended to the auto option. | |
1286 | e.g. "auto=part8". Partition names are created by appending a digit | |
a9d69660 | 1287 | string to the device name, with an intervening "p" if the device name |
dd0781e5 NB |
1288 | ends with a digit. |
1289 | ||
1290 | The | |
7e23fc43 | 1291 | .B \-\-auto |
dd0781e5 NB |
1292 | option is also available in Build and Create modes. As those modes do |
1293 | not use a config file, the "auto=" config option does not apply to | |
1294 | these modes. | |
52826846 | 1295 | |
41a3b72a NB |
1296 | .SS Auto Assembly |
1297 | When | |
7e23fc43 | 1298 | .B \-\-assemble |
41a3b72a | 1299 | is used with |
7e23fc43 | 1300 | .B \-\-scan |
41a3b72a NB |
1301 | and no devices are listed, |
1302 | .I mdadm | |
1303 | will first attempt to assemble all the arrays listed in the config | |
1304 | file. | |
1305 | ||
8fd8d9c4 N |
1306 | It will then look further for possible arrays and will try to assemble |
1307 | anything that it finds. Arrays which are tagged as belonging to the given | |
1308 | homehost will be assembled and started normally. Arrays which do not | |
1309 | obviously belong to this host are given names that are expected not to | |
1310 | conflict with anything local, and are started "read-auto" so that | |
1311 | nothing is written to any device until the array is written to. i.e. | |
1312 | automatic resync etc is delayed. | |
41a3b72a NB |
1313 | |
1314 | If | |
1315 | .I mdadm | |
1316 | finds a consistent set of devices that look like they should comprise | |
1317 | an array, and if the superblock is tagged as belonging to the given | |
1318 | home host, it will automatically choose a device name and try to | |
1319 | assemble the array. If the array uses version-0.90 metadata, then the | |
1320 | .B minor | |
1321 | number as recorded in the superblock is used to create a name in | |
1322 | .B /dev/md/ | |
1323 | so for example | |
1324 | .BR /dev/md/3 . | |
1325 | If the array uses version-1 metadata, then the | |
1326 | .B name | |
1327 | from the superblock is used to similarly create a name in | |
93e790af SW |
1328 | .BR /dev/md |
1329 | (the name will have any 'host' prefix stripped first). | |
41a3b72a NB |
1330 | |
1331 | If | |
1332 | .I mdadm | |
1333 | cannot find any array for the given host at all, and if | |
7e23fc43 | 1334 | .B \-\-auto\-update\-homehost |
41a3b72a NB |
1335 | is given, then |
1336 | .I mdadm | |
1337 | will search again for any array (not just an array created for this | |
1338 | host) and will assemble each assuming | |
7e23fc43 | 1339 | .BR \-\-update=homehost . |
41a3b72a NB |
1340 | This will change the host tag in the superblock so that on the next run, |
1341 | these arrays will be found without the second pass. The intention of | |
1342 | this feature is to support transitioning a set of md arrays to using | |
1343 | homehost tagging. | |
1344 | ||
1345 | The reason for requiring arrays to be tagged with the homehost for | |
1346 | auto assembly is to guard against problems that can arise when moving | |
1347 | devices from one host to another. | |
1348 | ||
cd29a5c8 | 1349 | .SH BUILD MODE |
52826846 | 1350 | |
cd29a5c8 NB |
1351 | .HP 12 |
1352 | Usage: | |
7e23fc43 | 1353 | .B mdadm \-\-build |
93e790af | 1354 | .I md-device |
7e23fc43 PS |
1355 | .BI \-\-chunk= X |
1356 | .BI \-\-level= Y | |
1357 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
1358 | .I devices |
1359 | ||
1360 | .PP | |
2ae555c3 | 1361 | This usage is similar to |
7e23fc43 | 1362 | .BR \-\-create . |
a9d69660 | 1363 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 1364 | these arrays there is no difference between initially creating the array and |
52826846 NB |
1365 | subsequently assembling the array, except that hopefully there is useful |
1366 | data there in the second case. | |
1367 | ||
a9d69660 NB |
1368 | The level may raid0, linear, multipath, or faulty, or one of their |
1369 | synonyms. All devices must be listed and the array will be started | |
1370 | once complete. | |
cd29a5c8 NB |
1371 | |
1372 | .SH CREATE MODE | |
1373 | ||
1374 | .HP 12 | |
1375 | Usage: | |
7e23fc43 | 1376 | .B mdadm \-\-create |
93e790af | 1377 | .I md-device |
7e23fc43 PS |
1378 | .BI \-\-chunk= X |
1379 | .BI \-\-level= Y | |
cd29a5c8 | 1380 | .br |
7e23fc43 | 1381 | .BI \-\-raid\-devices= Z |
cd29a5c8 NB |
1382 | .I devices |
1383 | ||
1384 | .PP | |
1385 | This usage will initialise a new md array, associate some devices with | |
1386 | it, and activate the array. | |
1387 | ||
a9d69660 | 1388 | If the |
7e23fc43 | 1389 | .B \-\-auto |
dd0781e5 NB |
1390 | option is given (as described in more detail in the section on |
1391 | Assemble mode), then the md device will be created with a suitable | |
1392 | device number if necessary. | |
1393 | ||
cd29a5c8 | 1394 | As devices are added, they are checked to see if they contain raid |
2d465520 | 1395 | superblocks or filesystems. They are also checked to see if the variance in |
cd29a5c8 NB |
1396 | device size exceeds 1%. |
1397 | ||
1398 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 1399 | the presence of a |
7e23fc43 | 1400 | .B \-\-run |
cd29a5c8 NB |
1401 | can override this caution. |
1402 | ||
2d465520 | 1403 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 1404 | give the word "\fBmissing\fP" |
2d465520 | 1405 | in place of a device name. This will cause |
51ac42e3 | 1406 | .I mdadm |
2d465520 NB |
1407 | to leave the corresponding slot in the array empty. |
1408 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 1409 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
1410 | For a RAID1 array, only one real device needs to be given. All of the |
1411 | others can be | |
d013a55e | 1412 | "\fBmissing\fP". |
2d465520 | 1413 | |
feb716e9 | 1414 | When creating a RAID5 array, |
51ac42e3 | 1415 | .I mdadm |
feb716e9 NB |
1416 | will automatically create a degraded array with an extra spare drive. |
1417 | This is because building the spare into a degraded array is in general faster than resyncing | |
1418 | the parity on a non-degraded, but not clean, array. This feature can | |
35cc5be4 | 1419 | be overridden with the |
7e23fc43 | 1420 | .B \-\-force |
feb716e9 NB |
1421 | option. |
1422 | ||
0ee4da98 | 1423 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
1424 | required. |
1425 | If this is not given with the | |
7e23fc43 | 1426 | .B \-\-name |
41a3b72a NB |
1427 | option, |
1428 | .I mdadm | |
0ee4da98 | 1429 | will choose a name based on the last component of the name of the |
41a3b72a NB |
1430 | device being created. So if |
1431 | .B /dev/md3 | |
1432 | is being created, then the name | |
1433 | .B 3 | |
1434 | will be chosen. | |
1435 | If | |
1436 | .B /dev/md/home | |
1437 | is being created, then the name | |
1438 | .B home | |
1439 | will be used. | |
1440 | ||
e0f31f50 PC |
1441 | When creating a partition based array, using |
1442 | .I mdadm | |
1443 | with version-1.x metadata, the partition type should be set to | |
1444 | .B 0xDA | |
1445 | (non fs-data). This type selection allows for greater precision since | |
1446 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], | |
1447 | might create problems in the event of array recovery through a live cdrom. | |
1448 | ||
3d3dd91e NB |
1449 | A new array will normally get a randomly assigned 128bit UUID which is |
1450 | very likely to be unique. If you have a specific need, you can choose | |
1451 | a UUID for the array by giving the | |
7e23fc43 | 1452 | .B \-\-uuid= |
3d3dd91e NB |
1453 | option. Be warned that creating two arrays with the same UUID is a |
1454 | recipe for disaster. Also, using | |
7e23fc43 | 1455 | .B \-\-uuid= |
3d3dd91e | 1456 | when creating a v0.90 array will silently override any |
7e23fc43 | 1457 | .B \-\-homehost= |
3d3dd91e | 1458 | setting. |
e43d0cda NB |
1459 | .\"If the |
1460 | .\".B \-\-size | |
1461 | .\"option is given, it is not necessary to list any component-devices in this command. | |
1462 | .\"They can be added later, before a | |
1463 | .\".B \-\-run. | |
1464 | .\"If no | |
1465 | .\".B \-\-size | |
1466 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 1467 | |
8fd8d9c4 N |
1468 | When creating an array within a |
1469 | .B CONTAINER | |
1470 | .I mdadm | |
1471 | can be given either the list of devices to use, or simply the name of | |
1472 | the container. The former case gives control over which devices in | |
1473 | the container will be used for the array. The latter case allows | |
1474 | .I mdadm | |
1475 | to automatically choose which devices to use based on how much spare | |
1476 | space is available. | |
1477 | ||
53e8b987 | 1478 | The General Management options that are valid with |
7e23fc43 | 1479 | .B \-\-create |
53e8b987 | 1480 | are: |
cd29a5c8 | 1481 | .TP |
7e23fc43 | 1482 | .B \-\-run |
dd0781e5 | 1483 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
1484 | be in use. |
1485 | ||
1486 | .TP | |
7e23fc43 | 1487 | .B \-\-readonly |
b3f1c093 | 1488 | start the array readonly \(em not supported yet. |
52826846 | 1489 | |
2ae555c3 | 1490 | |
e0d19036 | 1491 | .SH MANAGE MODE |
cd29a5c8 NB |
1492 | .HP 12 |
1493 | Usage: | |
e0d19036 NB |
1494 | .B mdadm |
1495 | .I device | |
1496 | .I options... devices... | |
cd29a5c8 NB |
1497 | .PP |
1498 | ||
e0d19036 NB |
1499 | This usage will allow individual devices in an array to be failed, |
1500 | removed or added. It is possible to perform multiple operations with | |
1501 | on command. For example: | |
1502 | .br | |
7e23fc43 | 1503 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
1504 | .br |
1505 | will firstly mark | |
1506 | .B /dev/hda1 | |
1507 | as faulty in | |
1508 | .B /dev/md0 | |
1509 | and will then remove it from the array and finally add it back | |
2d465520 | 1510 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 1511 | command. |
e0d19036 NB |
1512 | |
1513 | .SH MISC MODE | |
1514 | .HP 12 | |
1515 | Usage: | |
9a9dab36 | 1516 | .B mdadm |
e0d19036 NB |
1517 | .I options ... |
1518 | .I devices ... | |
1519 | .PP | |
cd29a5c8 | 1520 | |
b5e64645 | 1521 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1522 | operate on distinct devices. The operations are: |
1523 | .TP | |
962a108f | 1524 | .B \-\-query |
e0d19036 NB |
1525 | The device is examined to see if it is |
1526 | (1) an active md array, or | |
1527 | (2) a component of an md array. | |
1528 | The information discovered is reported. | |
1529 | ||
1530 | .TP | |
962a108f | 1531 | .B \-\-detail |
2d465520 NB |
1532 | The device should be an active md device. |
1533 | .B mdadm | |
1534 | will display a detailed description of the array. | |
7e23fc43 | 1535 | .B \-\-brief |
2d465520 | 1536 | or |
7e23fc43 | 1537 | .B \-\-scan |
2d465520 | 1538 | will cause the output to be less detailed and the format to be |
e0d19036 | 1539 | suitable for inclusion in |
9a9dab36 | 1540 | .BR /etc/mdadm.conf . |
feb716e9 NB |
1541 | The exit status of |
1542 | .I mdadm | |
1543 | will normally be 0 unless | |
1544 | .I mdadm | |
93e790af | 1545 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 1546 | .B \-\-test |
feb716e9 NB |
1547 | option is given, then the exit status will be: |
1548 | .RS | |
1549 | .TP | |
1550 | 0 | |
1551 | The array is functioning normally. | |
1552 | .TP | |
1553 | 1 | |
1554 | The array has at least one failed device. | |
1555 | .TP | |
1556 | 2 | |
a77be586 | 1557 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
1558 | .TP |
1559 | 4 | |
1560 | There was an error while trying to get information about the device. | |
1561 | .RE | |
cd29a5c8 | 1562 | |
e0d19036 | 1563 | .TP |
962a108f | 1564 | .B \-\-examine |
2d465520 | 1565 | The device should be a component of an md array. |
51ac42e3 | 1566 | .I mdadm |
2d465520 | 1567 | will read the md superblock of the device and display the contents. |
e0d19036 | 1568 | If |
7e23fc43 | 1569 | .B \-\-brief |
93e790af | 1570 | or |
7e23fc43 | 1571 | .B \-\-scan |
93e790af | 1572 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
1573 | are grouped together and reported in a single entry suitable |
1574 | for inclusion in | |
1575 | .BR /etc/mdadm.conf . | |
1576 | ||
2d465520 | 1577 | Having |
7e23fc43 | 1578 | .B \-\-scan |
e0d19036 NB |
1579 | without listing any devices will cause all devices listed in the |
1580 | config file to be examined. | |
1581 | ||
1582 | .TP | |
962a108f | 1583 | .B \-\-stop |
98c6faba NB |
1584 | The devices should be active md arrays which will be deactivated, as |
1585 | long as they are not currently in use. | |
e0d19036 NB |
1586 | |
1587 | .TP | |
962a108f | 1588 | .B \-\-run |
e0d19036 NB |
1589 | This will fully activate a partially assembled md array. |
1590 | ||
1591 | .TP | |
962a108f | 1592 | .B \-\-readonly |
e0d19036 NB |
1593 | This will mark an active array as read-only, providing that it is |
1594 | not currently being used. | |
1595 | ||
1596 | .TP | |
962a108f | 1597 | .B \-\-readwrite |
e0d19036 NB |
1598 | This will change a |
1599 | .B readonly | |
1600 | array back to being read/write. | |
1601 | ||
2d465520 | 1602 | .TP |
962a108f | 1603 | .B \-\-scan |
2d465520 | 1604 | For all operations except |
7e23fc43 PS |
1605 | .BR \-\-examine , |
1606 | .B \-\-scan | |
2d465520 NB |
1607 | will cause the operation to be applied to all arrays listed in |
1608 | .BR /proc/mdstat . | |
1609 | For | |
7e23fc43 PS |
1610 | .BR \-\-examine, |
1611 | .B \-\-scan | |
2d465520 NB |
1612 | causes all devices listed in the config file to be examined. |
1613 | ||
1614 | ||
e0d19036 NB |
1615 | .SH MONITOR MODE |
1616 | ||
cd29a5c8 NB |
1617 | .HP 12 |
1618 | Usage: | |
7e23fc43 | 1619 | .B mdadm \-\-monitor |
e0d19036 NB |
1620 | .I options... devices... |
1621 | ||
cd29a5c8 | 1622 | .PP |
e0d19036 | 1623 | This usage causes |
51ac42e3 | 1624 | .I mdadm |
e0d19036 NB |
1625 | to periodically poll a number of md arrays and to report on any events |
1626 | noticed. | |
51ac42e3 | 1627 | .I mdadm |
e0d19036 NB |
1628 | will never exit once it decides that there are arrays to be checked, |
1629 | so it should normally be run in the background. | |
1630 | ||
2d465520 | 1631 | As well as reporting events, |
51ac42e3 | 1632 | .I mdadm |
2d465520 NB |
1633 | may move a spare drive from one array to another if they are in the |
1634 | same | |
1635 | .B spare-group | |
a9d69660 | 1636 | and if the destination array has a failed drive but no spares. |
2d465520 | 1637 | |
e0d19036 | 1638 | If any devices are listed on the command line, |
51ac42e3 | 1639 | .I mdadm |
e0d19036 NB |
1640 | will only monitor those devices. Otherwise all arrays listed in the |
1641 | configuration file will be monitored. Further, if | |
7e23fc43 | 1642 | .B \-\-scan |
e0d19036 NB |
1643 | is given, then any other md devices that appear in |
1644 | .B /proc/mdstat | |
1645 | will also be monitored. | |
1646 | ||
1647 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 1648 | These events are passed to a separate program (if specified) and may |
2d465520 | 1649 | be mailed to a given E-mail address. |
e0d19036 | 1650 | |
93e790af SW |
1651 | When passing events to a program, the program is run once for each event, |
1652 | and is given 2 or 3 command-line arguments: the first is the | |
1653 | name of the event (see below), the second is the name of the | |
bd526cee | 1654 | md device which is affected, and the third is the name of a related |
93e790af | 1655 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
1656 | |
1657 | If | |
7e23fc43 | 1658 | .B \-\-scan |
e0d19036 NB |
1659 | is given, then a program or an E-mail address must be specified on the |
1660 | command line or in the config file. If neither are available, then | |
51ac42e3 | 1661 | .I mdadm |
e0d19036 NB |
1662 | will not monitor anything. |
1663 | Without | |
93e790af | 1664 | .B \-\-scan, |
51ac42e3 | 1665 | .I mdadm |
2d465520 | 1666 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
1667 | no program or email is given, then each event is reported to |
1668 | .BR stdout . | |
cd29a5c8 | 1669 | |
e0d19036 NB |
1670 | The different events are: |
1671 | ||
1672 | .RS 4 | |
1673 | .TP | |
1674 | .B DeviceDisappeared | |
2d465520 | 1675 | An md array which previously was configured appears to no longer be |
773135f5 | 1676 | configured. (syslog priority: Critical) |
e0d19036 | 1677 | |
b8f72a62 NB |
1678 | If |
1679 | .I mdadm | |
1680 | was told to monitor an array which is RAID0 or Linear, then it will | |
1681 | report | |
1682 | .B DeviceDisappeared | |
1683 | with the extra information | |
1684 | .BR Wrong-Level . | |
1685 | This is because RAID0 and Linear do not support the device-failed, | |
1686 | hot-spare and resync operations which are monitored. | |
1687 | ||
e0d19036 NB |
1688 | .TP |
1689 | .B RebuildStarted | |
773135f5 | 1690 | An md array started reconstruction. (syslog priority: Warning) |
e0d19036 NB |
1691 | |
1692 | .TP | |
1693 | .BI Rebuild NN | |
1694 | Where | |
1695 | .I NN | |
1696 | is 20, 40, 60, or 80, this indicates that rebuild has passed that many | |
773135f5 | 1697 | percentage of the total. (syslog priority: Warning) |
e0d19036 | 1698 | |
98c6faba NB |
1699 | .TP |
1700 | .B RebuildFinished | |
1701 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 1702 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 1703 | |
e0d19036 NB |
1704 | .TP |
1705 | .B Fail | |
773135f5 NB |
1706 | An active component device of an array has been marked as |
1707 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
1708 | |
1709 | .TP | |
1710 | .B FailSpare | |
1711 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 1712 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
1713 | |
1714 | .TP | |
1715 | .B SpareActive | |
1716 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 1717 | device has been successfully rebuilt and has been made active. |
773135f5 | 1718 | (syslog priority: Info) |
e0d19036 NB |
1719 | |
1720 | .TP | |
1721 | .B NewArray | |
1722 | A new md array has been detected in the | |
1723 | .B /proc/mdstat | |
773135f5 | 1724 | file. (syslog priority: Info) |
e0d19036 | 1725 | |
aa88f531 NB |
1726 | .TP |
1727 | .B DegradedArray | |
1728 | A newly noticed array appears to be degraded. This message is not | |
1729 | generated when | |
1730 | .I mdadm | |
1731 | notices a drive failure which causes degradation, but only when | |
1732 | .I mdadm | |
1733 | notices that an array is degraded when it first sees the array. | |
93e790af | 1734 | (syslog priority: Critical) |
aa88f531 | 1735 | |
e0d19036 NB |
1736 | .TP |
1737 | .B MoveSpare | |
1738 | A spare drive has been moved from one array in a | |
1739 | .B spare-group | |
1740 | to another to allow a failed drive to be replaced. | |
773135f5 | 1741 | (syslog priority: Info) |
e0d19036 | 1742 | |
b8f72a62 NB |
1743 | .TP |
1744 | .B SparesMissing | |
1745 | If | |
1746 | .I mdadm | |
1747 | has been told, via the config file, that an array should have a certain | |
1748 | number of spare devices, and | |
1749 | .I mdadm | |
93e790af | 1750 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
1751 | array, it will report a |
1752 | .B SparesMissing | |
1753 | message. | |
d1732eeb | 1754 | (syslog priority: Warning) |
b8f72a62 | 1755 | |
98c6faba NB |
1756 | .TP |
1757 | .B TestMessage | |
1758 | An array was found at startup, and the | |
7e23fc43 | 1759 | .B \-\-test |
98c6faba | 1760 | flag was given. |
773135f5 | 1761 | (syslog priority: Info) |
e0d19036 NB |
1762 | .RE |
1763 | ||
1764 | Only | |
93e790af SW |
1765 | .B Fail, |
1766 | .B FailSpare, | |
1767 | .B DegradedArray, | |
1768 | .B SparesMissing | |
e0d19036 | 1769 | and |
98c6faba | 1770 | .B TestMessage |
e0d19036 | 1771 | cause Email to be sent. All events cause the program to be run. |
93e790af | 1772 | The program is run with two or three arguments: the event |
e0d19036 NB |
1773 | name, the array device and possibly a second device. |
1774 | ||
1775 | Each event has an associated array device (e.g. | |
1776 | .BR /dev/md1 ) | |
1777 | and possibly a second device. For | |
1778 | .BR Fail , | |
1779 | .BR FailSpare , | |
1780 | and | |
1781 | .B SpareActive | |
1782 | the second device is the relevant component device. | |
1783 | For | |
1784 | .B MoveSpare | |
1785 | the second device is the array that the spare was moved from. | |
1786 | ||
1787 | For | |
51ac42e3 | 1788 | .I mdadm |
e0d19036 | 1789 | to move spares from one array to another, the different arrays need to |
93e790af | 1790 | be labeled with the same |
e0d19036 NB |
1791 | .B spare-group |
1792 | in the configuration file. The | |
1793 | .B spare-group | |
93e790af | 1794 | name can be any string; it is only necessary that different spare |
2d465520 | 1795 | groups use different names. |
e0d19036 NB |
1796 | |
1797 | When | |
51ac42e3 | 1798 | .I mdadm |
93e790af | 1799 | detects that an array in a spare group has fewer active |
e0d19036 NB |
1800 | devices than necessary for the complete array, and has no spare |
1801 | devices, it will look for another array in the same spare group that | |
1802 | has a full complement of working drive and a spare. It will then | |
1803 | attempt to remove the spare from the second drive and add it to the | |
1804 | first. | |
1805 | If the removal succeeds but the adding fails, then it is added back to | |
1806 | the original array. | |
1807 | ||
dd0781e5 NB |
1808 | .SH GROW MODE |
1809 | The GROW mode is used for changing the size or shape of an active | |
1810 | array. | |
1811 | For this to work, the kernel must support the necessary change. | |
2ae555c3 | 1812 | Various types of growth are being added during 2.6 development, |
dd0781e5 NB |
1813 | including restructuring a raid5 array to have more active devices. |
1814 | ||
dfd4d8ee NB |
1815 | Currently the only support available is to |
1816 | .IP \(bu 4 | |
1817 | change the "size" attribute | |
1818 | for RAID1, RAID5 and RAID6. | |
1819 | .IP \(bu 4 | |
e5669f40 | 1820 | increase the "raid\-devices" attribute of RAID1, RAID5, and RAID6. |
dfd4d8ee | 1821 | .IP \(bu 4 |
93e790af | 1822 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 1823 | remove a write-intent bitmap from such an array. |
dfd4d8ee | 1824 | .PP |
dd0781e5 | 1825 | |
8fd8d9c4 N |
1826 | GROW mode is not currently supported for |
1827 | .B CONTAINERS | |
1828 | or arrays inside containers. | |
1829 | ||
2ae555c3 | 1830 | .SS SIZE CHANGES |
fe80f49b | 1831 | Normally when an array is built the "size" it taken from the smallest |
dd0781e5 NB |
1832 | of the drives. If all the small drives in an arrays are, one at a |
1833 | time, removed and replaced with larger drives, then you could have an | |
1834 | array of large drives with only a small amount used. In this | |
1835 | situation, changing the "size" with "GROW" mode will allow the extra | |
1836 | space to start being used. If the size is increased in this way, a | |
1837 | "resync" process will start to make sure the new parts of the array | |
1838 | are synchronised. | |
1839 | ||
1840 | Note that when an array changes size, any filesystem that may be | |
1841 | stored in the array will not automatically grow to use the space. The | |
1842 | filesystem will need to be explicitly told to use the extra space. | |
1843 | ||
2ae555c3 NB |
1844 | .SS RAID-DEVICES CHANGES |
1845 | ||
dd0781e5 NB |
1846 | A RAID1 array can work with any number of devices from 1 upwards |
1847 | (though 1 is not very useful). There may be times which you want to | |
1848 | increase or decrease the number of active devices. Note that this is | |
1849 | different to hot-add or hot-remove which changes the number of | |
1850 | inactive devices. | |
1851 | ||
1852 | When reducing the number of devices in a RAID1 array, the slots which | |
1853 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 1854 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
1855 | |
1856 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 1857 | present will be activated immediately. |
dd0781e5 | 1858 | |
2ae555c3 NB |
1859 | Increasing the number of active devices in a RAID5 is much more |
1860 | effort. Every block in the array will need to be read and written | |
1861 | back to a new location. From 2.6.17, the Linux Kernel is able to do | |
1862 | this safely, including restart and interrupted "reshape". | |
1863 | ||
1864 | When relocating the first few stripes on a raid5, it is not possible | |
1865 | to keep the data on disk completely consistent and crash-proof. To | |
1866 | provide the required safety, mdadm disables writes to the array while | |
1867 | this "critical section" is reshaped, and takes a backup of the data | |
1868 | that is in that section. This backup is normally stored in any spare | |
1869 | devices that the array has, however it can also be stored in a | |
1870 | separate file specified with the | |
7e23fc43 | 1871 | .B \-\-backup\-file |
2ae555c3 NB |
1872 | option. If this option is used, and the system does crash during the |
1873 | critical period, the same file must be passed to | |
7e23fc43 | 1874 | .B \-\-assemble |
2ae555c3 NB |
1875 | to restore the backup and reassemble the array. |
1876 | ||
1877 | .SS BITMAP CHANGES | |
1878 | ||
1879 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 1880 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b NB |
1881 | can be added. Note that if you add a bitmap stored in a file which is |
1882 | in a filesystem that is on the raid array being affected, the system | |
1883 | will deadlock. The bitmap must be on a separate filesystem. | |
1884 | ||
8382f19b NB |
1885 | .SH INCREMENTAL MODE |
1886 | ||
1887 | .HP 12 | |
1888 | Usage: | |
7e23fc43 PS |
1889 | .B mdadm \-\-incremental |
1890 | .RB [ \-\-run ] | |
1891 | .RB [ \-\-quiet ] | |
8382f19b NB |
1892 | .I component-device |
1893 | .HP 12 | |
1894 | Usage: | |
7e23fc43 | 1895 | .B mdadm \-\-incremental \-\-rebuild |
8382f19b NB |
1896 | .HP 12 |
1897 | Usage: | |
7e23fc43 | 1898 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b NB |
1899 | |
1900 | ||
1901 | .PP | |
1902 | This mode is designed to be used in conjunction with a device | |
1903 | discovery system. As devices are found in a system, they can be | |
1904 | passed to | |
7e23fc43 | 1905 | .B "mdadm \-\-incremental" |
8382f19b NB |
1906 | to be conditionally added to an appropriate array. |
1907 | ||
8fd8d9c4 N |
1908 | If the device passed is a |
1909 | .B CONTAINER | |
1910 | device created by a previous call to | |
1911 | .IR mdadm , | |
1912 | then rather than trying to add that device to an array, all the arrays | |
1913 | described by the metadata of the container will be started. | |
1914 | ||
8382f19b NB |
1915 | .I mdadm |
1916 | performs a number of tests to determine if the device is part of an | |
93e790af | 1917 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
1918 | is found, or can be created, |
1919 | .I mdadm | |
1920 | adds the device to the array and conditionally starts the array. | |
1921 | ||
1922 | Note that | |
1923 | .I mdadm | |
1924 | will only add devices to an array which were previously working | |
1925 | (active or spare) parts of that array. It does not currently support | |
1926 | automatic inclusion of a new drive as a spare in some array. | |
1927 | ||
8382f19b NB |
1928 | The tests that |
1929 | .I mdadm | |
1930 | makes are as follow: | |
1931 | .IP + | |
1932 | Is the device permitted by | |
1933 | .BR mdadm.conf ? | |
1934 | That is, is it listed in a | |
1935 | .B DEVICES | |
1936 | line in that file. If | |
1937 | .B DEVICES | |
1938 | is absent then the default it to allow any device. Similar if | |
1939 | .B DEVICES | |
1940 | contains the special word | |
1941 | .B partitions | |
1942 | then any device is allowed. Otherwise the device name given to | |
1943 | .I mdadm | |
1944 | must match one of the names or patterns in a | |
1945 | .B DEVICES | |
1946 | line. | |
1947 | ||
1948 | .IP + | |
1949 | Does the device have a valid md superblock. If a specific metadata | |
1950 | version is request with | |
7e23fc43 | 1951 | .B \-\-metadata |
8382f19b | 1952 | or |
7e23fc43 | 1953 | .B \-e |
8382f19b NB |
1954 | then only that style of metadata is accepted, otherwise |
1955 | .I mdadm | |
1956 | finds any known version of metadata. If no | |
1957 | .I md | |
1958 | metadata is found, the device is rejected. | |
1959 | ||
1960 | .IP + | |
1961 | Does the metadata match an expected array? | |
1962 | The metadata can match in two ways. Either there is an array listed | |
1963 | in | |
1964 | .B mdadm.conf | |
1965 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 1966 | or by minor-number), or the array was created with a |
8382f19b | 1967 | .B homehost |
93e790af | 1968 | specified and that |
8382f19b | 1969 | .B homehost |
93e790af | 1970 | matches the one in |
8382f19b NB |
1971 | .B mdadm.conf |
1972 | or on the command line. | |
1973 | If | |
1974 | .I mdadm | |
1975 | is not able to positively identify the array as belonging to the | |
1976 | current host, the device will be rejected. | |
1977 | ||
1978 | .IP + | |
1979 | .I mdadm | |
93e790af | 1980 | keeps a list of arrays that it has partially assembled in |
8382f19b NB |
1981 | .B /var/run/mdadm/map |
1982 | (or | |
1983 | .B /var/run/mdadm.map | |
1984 | if the directory doesn't exist). If no array exists which matches | |
1985 | the metadata on the new device, | |
1986 | .I mdadm | |
1987 | must choose a device name and unit number. It does this based on any | |
1988 | name given in | |
1989 | .B mdadm.conf | |
1990 | or any name information stored in the metadata. If this name | |
1991 | suggests a unit number, that number will be used, otherwise a free | |
1992 | unit number will be chosen. Normally | |
1993 | .I mdadm | |
1994 | will prefer to create a partitionable array, however if the | |
1995 | .B CREATE | |
1996 | line in | |
1997 | .B mdadm.conf | |
1998 | suggests that a non-partitionable array is preferred, that will be | |
1999 | honoured. | |
2000 | ||
2001 | .IP + | |
2002 | Once an appropriate array is found or created and the device is added, | |
2003 | .I mdadm | |
2004 | must decide if the array is ready to be started. It will | |
2005 | normally compare the number of available (non-spare) devices to the | |
2006 | number of devices that the metadata suggests need to be active. If | |
2007 | there are at least that many, the array will be started. This means | |
2008 | that if any devices are missing the array will not be restarted. | |
2009 | ||
2010 | As an alternative, | |
7e23fc43 | 2011 | .B \-\-run |
8382f19b | 2012 | may be passed to |
51ac42e3 | 2013 | .I mdadm |
8382f19b NB |
2014 | in which case the array will be run as soon as there are enough |
2015 | devices present for the data to be accessible. For a raid1, that | |
2016 | means one device will start the array. For a clean raid5, the array | |
2017 | will be started as soon as all but one drive is present. | |
2018 | ||
93e790af | 2019 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
2020 | be known that all device discovery has completed, then |
2021 | .br | |
7e23fc43 | 2022 | .B " mdadm \-IRs" |
8382f19b NB |
2023 | .br |
2024 | can be run which will try to start all arrays that are being | |
2025 | incrementally assembled. They are started in "read-auto" mode in | |
2026 | which they are read-only until the first write request. This means | |
2027 | that no metadata updates are made and no attempt at resync or recovery | |
2028 | happens. Further devices that are found before the first write can | |
2029 | still be added safely. | |
2030 | ||
5545fa6d DW |
2031 | |
2032 | .SH ENVIRONMENT | |
2033 | This section describes environment variables that affect how mdadm | |
2034 | operates. | |
2035 | ||
2036 | .TP | |
2037 | .B MDADM_NO_MDMON | |
2038 | Setting this value to 1 will prevent mdadm from automatically launching | |
2039 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
2040 | ||
8fd8d9c4 N |
2041 | .TP |
2042 | .B MDADM_NO_UDEV | |
2043 | Normally, | |
2044 | .I mdadm | |
2045 | does not create any device nodes in /dev, but leaves that task to | |
2046 | .IR udev . | |
2047 | If | |
2048 | .I udev | |
2049 | appears not to be configured, or if this environment variable is set | |
2050 | to '1', the | |
2051 | .I mdadm | |
2052 | will create and devices that are needed. | |
2053 | ||
2d465520 NB |
2054 | .SH EXAMPLES |
2055 | ||
7e23fc43 | 2056 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 2057 | .br |
5787fa49 NB |
2058 | This will find out if a given device is a raid array, or is part of |
2059 | one, and will provide brief information about the device. | |
2d465520 | 2060 | |
7e23fc43 | 2061 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 2062 | .br |
93e790af | 2063 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 2064 | file. This command will typically go in a system startup file. |
2d465520 | 2065 | |
7e23fc43 | 2066 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 2067 | .br |
93e790af | 2068 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 2069 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 2070 | |
7e23fc43 | 2071 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 2072 | .br |
5787fa49 NB |
2073 | If (and only if) there is an Email address or program given in the |
2074 | standard config file, then | |
2075 | monitor the status of all arrays listed in that file by | |
2076 | polling them ever 2 minutes. | |
2d465520 | 2077 | |
7e23fc43 | 2078 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 2079 | .br |
5787fa49 | 2080 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 2081 | |
2d465520 | 2082 | .br |
7e23fc43 | 2083 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 2084 | .br |
7e23fc43 | 2085 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 2086 | .br |
5787fa49 NB |
2087 | This will create a prototype config file that describes currently |
2088 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
2089 | This file should be reviewed before being used as it may |
2090 | contain unwanted detail. | |
2091 | ||
7e23fc43 | 2092 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 2093 | .br |
7e23fc43 | 2094 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
2095 | .br |
2096 | This will find arrays which could be assembled from existing IDE and | |
2097 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 2098 | format of a config file. |
2d465520 NB |
2099 | This file is very likely to contain unwanted detail, particularly |
2100 | the | |
2101 | .B devices= | |
5787fa49 NB |
2102 | entries. It should be reviewed and edited before being used as an |
2103 | actual config file. | |
2d465520 | 2104 | |
7e23fc43 | 2105 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 2106 | .br |
7e23fc43 | 2107 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
2108 | .br |
2109 | Create a list of devices by reading | |
2110 | .BR /proc/partitions , | |
2111 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 2112 | that were found. |
2d465520 | 2113 | |
7e23fc43 | 2114 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 2115 | .br |
5787fa49 NB |
2116 | Scan all partitions and devices listed in |
2117 | .BR /proc/partitions | |
2118 | and assemble | |
2119 | .B /dev/md0 | |
2120 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 2121 | |
7e23fc43 | 2122 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm" |
d013a55e NB |
2123 | .br |
2124 | If config file contains a mail address or alert program, run mdadm in | |
2125 | the background in monitor mode monitoring all md devices. Also write | |
2126 | pid of mdadm daemon to | |
2127 | .BR /var/run/mdadm . | |
2128 | ||
7e23fc43 | 2129 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
2130 | .br |
2131 | Try to incorporate newly discovered device into some array as | |
2132 | appropriate. | |
2133 | ||
7e23fc43 | 2134 | .B " mdadm \-\-incremental \-\-rebuild \-\-run \-\-scan" |
8382f19b NB |
2135 | .br |
2136 | Rebuild the array map from any current arrays, and then start any that | |
2137 | can be started. | |
2138 | ||
b80da661 NB |
2139 | .B " mdadm /dev/md4 --fail detached --remove detached" |
2140 | .br | |
2141 | Any devices which are components of /dev/md4 will be marked as faulty | |
2142 | and then remove from the array. | |
2143 | ||
8fd8d9c4 N |
2144 | .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]" |
2145 | .br | |
2146 | Create a DDF array over 6 devices. | |
2147 | ||
2148 | .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf" | |
2149 | .br | |
2150 | Create a raid5 array over any 3 devices in the given DDF set. Use | |
2151 | only 30 gigabytes of each device. | |
2152 | ||
2153 | .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]" | |
2154 | .br | |
2155 | Assemble a pre-exist ddf array. | |
2156 | ||
2157 | .B " mdadm -I /dev/md/ddf1" | |
2158 | .br | |
2159 | Assemble all arrays contained in the ddf array, assigning names as | |
2160 | appropriate. | |
2161 | ||
7e23fc43 | 2162 | .B " mdadm \-\-create \-\-help" |
2d465520 | 2163 | .br |
2ae555c3 | 2164 | Provide help about the Create mode. |
2d465520 | 2165 | |
7e23fc43 | 2166 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
2167 | .br |
2168 | Provide help about the format of the config file. | |
2d465520 | 2169 | |
7e23fc43 | 2170 | .B " mdadm \-\-help" |
5787fa49 NB |
2171 | .br |
2172 | Provide general help. | |
cd29a5c8 | 2173 | |
cd29a5c8 NB |
2174 | |
2175 | .SH FILES | |
2176 | ||
2177 | .SS /proc/mdstat | |
2178 | ||
2ae555c3 NB |
2179 | If you're using the |
2180 | .B /proc | |
cd29a5c8 NB |
2181 | filesystem, |
2182 | .B /proc/mdstat | |
2d465520 | 2183 | lists all active md devices with information about them. |
51ac42e3 | 2184 | .I mdadm |
2d465520 | 2185 | uses this to find arrays when |
7e23fc43 | 2186 | .B \-\-scan |
2d465520 NB |
2187 | is given in Misc mode, and to monitor array reconstruction |
2188 | on Monitor mode. | |
2189 | ||
cd29a5c8 | 2190 | |
9a9dab36 | 2191 | .SS /etc/mdadm.conf |
cd29a5c8 | 2192 | |
11a3e71d NB |
2193 | The config file lists which devices may be scanned to see if |
2194 | they contain MD super block, and gives identifying information | |
2195 | (e.g. UUID) about known MD arrays. See | |
2196 | .BR mdadm.conf (5) | |
2197 | for more details. | |
cd29a5c8 | 2198 | |
8382f19b NB |
2199 | .SS /var/run/mdadm/map |
2200 | When | |
7e23fc43 | 2201 | .B \-\-incremental |
93e790af | 2202 | mode is used, this file gets a list of arrays currently being created. |
8382f19b NB |
2203 | If |
2204 | .B /var/run/mdadm | |
2205 | does not exist as a directory, then | |
2206 | .B /var/run/mdadm.map | |
2207 | is used instead. | |
2208 | ||
48f7b27a NB |
2209 | .SH DEVICE NAMES |
2210 | ||
48f7b27a | 2211 | .I mdadm |
8fd8d9c4 N |
2212 | understand two sorts of names for array devices. |
2213 | ||
2214 | The first is the so-called 'standard' format name, which matches the | |
2215 | names used by the kernel and which appear in | |
2216 | .IR /proc/mdstat . | |
2217 | ||
2218 | The second sort can be freely chosen, but must reside in | |
2219 | .IR /dev/md/ . | |
2220 | When giving a device name to | |
2221 | .I mdadm | |
2222 | to create or assemble an array, either full path name such as | |
2223 | .I /dev/md0 | |
2224 | or | |
2225 | .I /dev/md/home | |
2226 | can be given, or just the suffix of the second sort of name, such as | |
2227 | .I home | |
2228 | can be given. | |
2229 | ||
2230 | When | |
2231 | .I mdadm | |
2232 | chooses device names during auto-assembly, it will normally add a | |
2233 | small sequence number to the end of the name to avoid conflicted | |
2234 | between multiple arrays that have the same name. If | |
2235 | .I mdadm | |
2236 | can reasonably determine that the array really is meant for this host, | |
2237 | either by a hostname in the metadata, or by the presence of the array | |
2238 | in /etc/mdadm.conf, then it will leave of the suffix if possible. | |
48f7b27a NB |
2239 | |
2240 | The standard names for non-partitioned arrays (the only sort of md | |
8fd8d9c4 | 2241 | array available in 2.4 and earlier) are of the form |
48f7b27a NB |
2242 | .IP |
2243 | /dev/mdNN | |
48f7b27a NB |
2244 | .PP |
2245 | where NN is a number. | |
2246 | The standard names for partitionable arrays (as available from 2.6 | |
8fd8d9c4 | 2247 | onwards) are of the form |
48f7b27a | 2248 | .IP |
48f7b27a NB |
2249 | /dev/md_dNN |
2250 | .PP | |
2251 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
8fd8d9c4 N |
2252 | .PP |
2253 | From kernel version, 2.6.28 the "non-partitioned array" can actually | |
2254 | be partitioned. So the "md_dNN" names are no longer needed, and | |
2255 | partitions such as "/dev/mdNNpXX" are possible. | |
52826846 | 2256 | |
2d465520 | 2257 | .SH NOTE |
51ac42e3 | 2258 | .I mdadm |
2d465520 | 2259 | was previously known as |
51ac42e3 | 2260 | .IR mdctl . |
a9d69660 | 2261 | .P |
51ac42e3 | 2262 | .I mdadm |
a9d69660 | 2263 | is completely separate from the |
51ac42e3 | 2264 | .I raidtools |
a9d69660 NB |
2265 | package, and does not use the |
2266 | .I /etc/raidtab | |
2267 | configuration file at all. | |
2268 | ||
52826846 | 2269 | .SH SEE ALSO |
75f74377 | 2270 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 2271 | RAID, see: |
3cdfb6a7 | 2272 | .IP |
11cd8b79 | 2273 | .B http://linux\-raid.osdl.org/ |
75f74377 DG |
2274 | .PP |
2275 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
e43d0cda NB |
2276 | .\".PP |
2277 | .\"for new releases of the RAID driver check out: | |
2278 | .\" | |
2279 | .\".IP | |
2280 | .\".UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
2281 | .\"ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
2282 | .\".UE | |
2283 | .\".PP | |
2284 | .\"or | |
2285 | .\".IP | |
2286 | .\".UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2287 | .\"http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2288 | .\".UE | |
cd29a5c8 | 2289 | .PP |
2ae555c3 | 2290 | The latest version of |
a9d69660 NB |
2291 | .I mdadm |
2292 | should always be available from | |
cd29a5c8 | 2293 | .IP |
11cd8b79 N |
2294 | .B http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
2295 | .PP | |
2296 | Related man pages: | |
cd29a5c8 | 2297 | .PP |
a9d69660 NB |
2298 | .IR mdadm.conf (5), |
2299 | .IR md (4). | |
56eb10c0 | 2300 | .PP |
52826846 NB |
2301 | .IR raidtab (5), |
2302 | .IR raid0run (8), | |
2303 | .IR raidstop (8), | |
a9d69660 | 2304 | .IR mkraid (8). |