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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. | |
6e92d480 | 8 | .TH MDADM 8 "" v3.0 |
52826846 | 9 | .SH NAME |
9a9dab36 | 10 | mdadm \- manage MD devices |
cd29a5c8 | 11 | .I aka |
93e790af | 12 | Linux Software RAID |
cd29a5c8 | 13 | |
52826846 NB |
14 | .SH SYNOPSIS |
15 | ||
e0d19036 | 16 | .BI mdadm " [mode] <raiddevice> [options] <component-devices>" |
52826846 | 17 | |
2ae555c3 | 18 | .SH DESCRIPTION |
52826846 | 19 | RAID devices are virtual devices created from two or more |
e0fe762a | 20 | real block devices. This allows multiple devices (typically disk |
35cc5be4 | 21 | drives or partitions thereof) to be combined into a single device to |
cd29a5c8 | 22 | hold (for example) a single filesystem. |
2d465520 | 23 | Some RAID levels include redundancy and so can survive some degree of |
cd29a5c8 NB |
24 | device failure. |
25 | ||
2d465520 NB |
26 | Linux Software RAID devices are implemented through the md (Multiple |
27 | Devices) device driver. | |
cd29a5c8 NB |
28 | |
29 | Currently, Linux supports | |
30 | .B LINEAR | |
31 | md devices, | |
32 | .B RAID0 | |
33 | (striping), | |
34 | .B RAID1 | |
35 | (mirroring), | |
d013a55e NB |
36 | .BR RAID4 , |
37 | .BR RAID5 , | |
98c6faba | 38 | .BR RAID6 , |
1a7dfc35 | 39 | .BR RAID10 , |
b5e64645 | 40 | .BR MULTIPATH , |
90c8d668 | 41 | .BR FAULTY , |
cd29a5c8 | 42 | and |
90c8d668 | 43 | .BR CONTAINER . |
d013a55e | 44 | |
a9d69660 NB |
45 | .B MULTIPATH |
46 | is not a Software RAID mechanism, but does involve | |
93e790af | 47 | multiple devices: |
d013a55e | 48 | each device is a path to one common physical storage device. |
9652457e N |
49 | New installations should not use md/multipath as it is not well |
50 | supported and has no ongoing development. Use the Device Mapper based | |
51 | multipath-tools instead. | |
d013a55e | 52 | |
a9d69660 NB |
53 | .B FAULTY |
54 | is also not true RAID, and it only involves one device. It | |
b5e64645 | 55 | provides a layer over a true device that can be used to inject faults. |
52826846 | 56 | |
4cce4069 | 57 | .B CONTAINER |
8fd8d9c4 N |
58 | is different again. A |
59 | .B CONTAINER | |
60 | is a collection of devices that are | |
90c8d668 N |
61 | managed as a set. This is similar to the set of devices connected to |
62 | a hardware RAID controller. The set of devices may contain a number | |
9652457e | 63 | of different RAID arrays each utilising some (or all) of the blocks from a |
90c8d668 | 64 | number of the devices in the set. For example, two devices in a 5-device set |
9652457e | 65 | might form a RAID1 using the whole devices. The remaining three might |
90c8d668 N |
66 | have a RAID5 over the first half of each device, and a RAID0 over the |
67 | second half. | |
68 | ||
8fd8d9c4 N |
69 | With a |
70 | .BR CONTAINER , | |
71 | there is one set of metadata that describes all of | |
72 | the arrays in the container. So when | |
73 | .I mdadm | |
74 | creates a | |
75 | .B CONTAINER | |
9652457e N |
76 | device, the device just represents the metadata. Other normal arrays (RAID1 |
77 | etc) can be created inside the container. | |
52826846 NB |
78 | |
79 | .SH MODES | |
8382f19b | 80 | mdadm has several major modes of operation: |
cd29a5c8 NB |
81 | .TP |
82 | .B Assemble | |
93e790af | 83 | Assemble the components of a previously created |
e0fe762a | 84 | array into an active array. Components can be explicitly given |
2ae555c3 | 85 | or can be searched for. |
51ac42e3 | 86 | .I mdadm |
cd29a5c8 NB |
87 | checks that the components |
88 | do form a bona fide array, and can, on request, fiddle superblock | |
89 | information so as to assemble a faulty array. | |
90 | ||
91 | .TP | |
92 | .B Build | |
e0fe762a | 93 | Build an array that doesn't have per-device metadata (superblocks). For these |
a9d69660 NB |
94 | sorts of arrays, |
95 | .I mdadm | |
96 | cannot differentiate between initial creation and subsequent assembly | |
97 | of an array. It also cannot perform any checks that appropriate | |
93e790af | 98 | components have been requested. Because of this, the |
a9d69660 NB |
99 | .B Build |
100 | mode should only be used together with a complete understanding of | |
101 | what you are doing. | |
cd29a5c8 NB |
102 | |
103 | .TP | |
104 | .B Create | |
e0fe762a N |
105 | Create a new array with per-device metadata (superblocks). |
106 | Appropriate metadata is written to each device, and then the array | |
107 | comprising those devices is activated. A 'resync' process is started | |
108 | to make sure that the array is consistent (e.g. both sides of a mirror | |
109 | contain the same data) but the content of the device is left otherwise | |
110 | untouched. | |
111 | The array can be used as soon as it has been created. There is no | |
112 | need to wait for the initial resync to finish. | |
cd29a5c8 | 113 | |
cd29a5c8 NB |
114 | .TP |
115 | .B "Follow or Monitor" | |
5787fa49 | 116 | Monitor one or more md devices and act on any state changes. This is |
e0fe762a N |
117 | only meaningful for RAID1, 4, 5, 6, 10 or multipath arrays, as |
118 | only these have interesting state. RAID0 or Linear never have | |
98c6faba | 119 | missing, spare, or failed drives, so there is nothing to monitor. |
5787fa49 | 120 | |
dd0781e5 NB |
121 | .TP |
122 | .B "Grow" | |
123 | Grow (or shrink) an array, or otherwise reshape it in some way. | |
124 | Currently supported growth options including changing the active size | |
93e790af SW |
125 | of component devices and changing the number of active devices in RAID |
126 | levels 1/4/5/6, as well as adding or removing a write-intent bitmap. | |
cd29a5c8 | 127 | |
8382f19b NB |
128 | .TP |
129 | .B "Incremental Assembly" | |
130 | Add a single device to an appropriate array. If the addition of the | |
131 | device makes the array runnable, the array will be started. | |
132 | This provides a convenient interface to a | |
133 | .I hot-plug | |
134 | system. As each device is detected, | |
135 | .I mdadm | |
136 | has a chance to include it in some array as appropriate. | |
9652457e | 137 | |
8fd8d9c4 N |
138 | If a |
139 | .B CONTAINER | |
140 | is passed to | |
141 | .I mdadm | |
142 | in this mode, then any arrays within that container will be assembled | |
143 | and started. | |
8382f19b | 144 | |
2ae555c3 NB |
145 | .TP |
146 | .B Manage | |
147 | This is for doing things to specific components of an array such as | |
148 | adding new spares and removing faulty devices. | |
149 | ||
150 | .TP | |
151 | .B Misc | |
152 | This is an 'everything else' mode that supports operations on active | |
153 | arrays, operations on component devices such as erasing old superblocks, and | |
154 | information gathering operations. | |
e43d0cda NB |
155 | .\"This mode allows operations on independent devices such as examine MD |
156 | .\"superblocks, erasing old superblocks and stopping active arrays. | |
2ae555c3 | 157 | |
1f48664b NB |
158 | .TP |
159 | .B Auto-detect | |
160 | This mode does not act on a specific device or array, but rather it | |
161 | requests the Linux Kernel to activate any auto-detected arrays. | |
52826846 NB |
162 | .SH OPTIONS |
163 | ||
2ae555c3 | 164 | .SH Options for selecting a mode are: |
52826846 | 165 | |
cd29a5c8 | 166 | .TP |
7e23fc43 | 167 | .BR \-A ", " \-\-assemble |
2d465520 | 168 | Assemble a pre-existing array. |
52826846 | 169 | |
cd29a5c8 | 170 | .TP |
7e23fc43 | 171 | .BR \-B ", " \-\-build |
cd29a5c8 | 172 | Build a legacy array without superblocks. |
52826846 | 173 | |
cd29a5c8 | 174 | .TP |
7e23fc43 | 175 | .BR \-C ", " \-\-create |
cd29a5c8 | 176 | Create a new array. |
52826846 | 177 | |
cd29a5c8 | 178 | .TP |
7e23fc43 | 179 | .BR \-F ", " \-\-follow ", " \-\-monitor |
cd29a5c8 NB |
180 | Select |
181 | .B Monitor | |
182 | mode. | |
52826846 | 183 | |
dd0781e5 | 184 | .TP |
7e23fc43 | 185 | .BR \-G ", " \-\-grow |
dd0781e5 | 186 | Change the size or shape of an active array. |
8382f19b NB |
187 | |
188 | .TP | |
1f48664b | 189 | .BR \-I ", " \-\-incremental |
8382f19b NB |
190 | Add a single device into an appropriate array, and possibly start the array. |
191 | ||
1f48664b NB |
192 | .TP |
193 | .B \-\-auto-detect | |
194 | Request that the kernel starts any auto-detected arrays. This can only | |
195 | work if | |
196 | .I md | |
197 | is compiled into the kernel \(em not if it is a module. | |
198 | Arrays can be auto-detected by the kernel if all the components are in | |
199 | primary MS-DOS partitions with partition type | |
e0fe762a N |
200 | .BR FD , |
201 | and all use v0.90 metadata. | |
1f48664b NB |
202 | In-kernel autodetect is not recommended for new installations. Using |
203 | .I mdadm | |
204 | to detect and assemble arrays \(em possibly in an | |
205 | .I initrd | |
206 | \(em is substantially more flexible and should be preferred. | |
207 | ||
2ae555c3 NB |
208 | .P |
209 | If a device is given before any options, or if the first option is | |
7e23fc43 PS |
210 | .BR \-\-add , |
211 | .BR \-\-fail , | |
2ae555c3 | 212 | or |
7e23fc43 | 213 | .BR \-\-remove , |
e0fe762a | 214 | then the MANAGE mode is assumed. |
2ae555c3 NB |
215 | Anything other than these will cause the |
216 | .B Misc | |
217 | mode to be assumed. | |
dd0781e5 | 218 | |
2ae555c3 | 219 | .SH Options that are not mode-specific are: |
e793c2e5 | 220 | |
cd29a5c8 | 221 | .TP |
7e23fc43 | 222 | .BR \-h ", " \-\-help |
a9d69660 | 223 | Display general help message or, after one of the above options, a |
93e790af | 224 | mode-specific help message. |
56eedc1a NB |
225 | |
226 | .TP | |
7e23fc43 | 227 | .B \-\-help\-options |
56eedc1a NB |
228 | Display more detailed help about command line parsing and some commonly |
229 | used options. | |
52826846 | 230 | |
cd29a5c8 | 231 | .TP |
7e23fc43 | 232 | .BR \-V ", " \-\-version |
9a9dab36 | 233 | Print version information for mdadm. |
52826846 | 234 | |
cd29a5c8 | 235 | .TP |
7e23fc43 | 236 | .BR \-v ", " \-\-verbose |
22892d56 NB |
237 | Be more verbose about what is happening. This can be used twice to be |
238 | extra-verbose. | |
a9d69660 | 239 | The extra verbosity currently only affects |
7e23fc43 | 240 | .B \-\-detail \-\-scan |
22892d56 | 241 | and |
7e23fc43 | 242 | .BR "\-\-examine \-\-scan" . |
52826846 | 243 | |
dab6685f | 244 | .TP |
7e23fc43 | 245 | .BR \-q ", " \-\-quiet |
dab6685f | 246 | Avoid printing purely informative messages. With this, |
51ac42e3 | 247 | .I mdadm |
dab6685f NB |
248 | will be silent unless there is something really important to report. |
249 | ||
cd29a5c8 | 250 | .TP |
7e23fc43 | 251 | .BR \-b ", " \-\-brief |
cd29a5c8 | 252 | Be less verbose. This is used with |
7e23fc43 | 253 | .B \-\-detail |
cd29a5c8 | 254 | and |
7e23fc43 | 255 | .BR \-\-examine . |
22892d56 | 256 | Using |
7e23fc43 | 257 | .B \-\-brief |
22892d56 | 258 | with |
7e23fc43 | 259 | .B \-\-verbose |
22892d56 | 260 | gives an intermediate level of verbosity. |
52826846 | 261 | |
e0d19036 | 262 | .TP |
7e23fc43 | 263 | .BR \-f ", " \-\-force |
93e790af | 264 | Be more forceful about certain operations. See the various modes for |
e0d19036 NB |
265 | the exact meaning of this option in different contexts. |
266 | ||
267 | .TP | |
7e23fc43 | 268 | .BR \-c ", " \-\-config= |
2ae555c3 NB |
269 | Specify the config file. Default is to use |
270 | .BR /etc/mdadm.conf , | |
93e790af | 271 | or if that is missing then |
2ae555c3 | 272 | .BR /etc/mdadm/mdadm.conf . |
5787fa49 | 273 | If the config file given is |
93e790af | 274 | .B "partitions" |
5787fa49 NB |
275 | then nothing will be read, but |
276 | .I mdadm | |
277 | will act as though the config file contained exactly | |
8fd8d9c4 | 278 | .B "DEVICE partitions containers" |
5787fa49 NB |
279 | and will read |
280 | .B /proc/partitions | |
8fd8d9c4 N |
281 | to find a list of devices to scan, and |
282 | .B /proc/mdstat | |
283 | to find a list of containers to examine. | |
d013a55e | 284 | If the word |
93e790af | 285 | .B "none" |
d013a55e NB |
286 | is given for the config file, then |
287 | .I mdadm | |
288 | will act as though the config file were empty. | |
e0d19036 NB |
289 | |
290 | .TP | |
7e23fc43 | 291 | .BR \-s ", " \-\-scan |
93e790af | 292 | Scan config file or |
e0d19036 NB |
293 | .B /proc/mdstat |
294 | for missing information. | |
295 | In general, this option gives | |
51ac42e3 | 296 | .I mdadm |
93e790af SW |
297 | permission to get any missing information (like component devices, |
298 | array devices, array identities, and alert destination) from the | |
299 | configuration file (see previous option); | |
300 | one exception is MISC mode when using | |
7e23fc43 | 301 | .B \-\-detail |
e0d19036 | 302 | or |
93e790af | 303 | .B \-\-stop, |
e0d19036 | 304 | in which case |
7e23fc43 | 305 | .B \-\-scan |
e0d19036 NB |
306 | says to get a list of array devices from |
307 | .BR /proc/mdstat . | |
308 | ||
570c0542 | 309 | .TP |
7e23fc43 | 310 | .B \-e ", " \-\-metadata= |
e0fe762a | 311 | Declare the style of RAID metadata (superblock) to be used. The |
53e8b987 | 312 | default is 0.90 for |
7e23fc43 | 313 | .BR \-\-create , |
53e8b987 | 314 | and to guess for other operations. |
2790ffe3 GB |
315 | The default can be overridden by setting the |
316 | .B metadata | |
317 | value for the | |
318 | .B CREATE | |
319 | keyword in | |
320 | .BR mdadm.conf . | |
570c0542 NB |
321 | |
322 | Options are: | |
323 | .RS | |
324 | .IP "0, 0.90, default" | |
325 | Use the original 0.90 format superblock. This format limits arrays to | |
93e790af | 326 | 28 component devices and limits component devices of levels 1 and |
570c0542 NB |
327 | greater to 2 terabytes. |
328 | .IP "1, 1.0, 1.1, 1.2" | |
329 | Use the new version-1 format superblock. This has few restrictions. | |
93e790af | 330 | The different sub-versions store the superblock at different locations |
570c0542 NB |
331 | on the device, either at the end (for 1.0), at the start (for 1.1) or |
332 | 4K from the start (for 1.2). | |
8fd8d9c4 | 333 | .IP ddf |
e0fe762a N |
334 | Use the "Industry Standard" DDF (Disk Data Format) format defined by |
335 | SNIA. | |
336 | When creating a DDF array a | |
8fd8d9c4 N |
337 | .B CONTAINER |
338 | will be created, and normal arrays can be created in that container. | |
339 | .IP imsm | |
4cce4069 | 340 | Use the Intel(R) Matrix Storage Manager metadata format. This creates a |
8fd8d9c4 | 341 | .B CONTAINER |
4cce4069 DW |
342 | which is managed in a similar manner to DDF, and is supported by an |
343 | option-rom on some platforms: | |
344 | .IP | |
345 | .B http://www.intel.com/design/chipsets/matrixstorage_sb.htm | |
346 | .PP | |
570c0542 NB |
347 | .RE |
348 | ||
41a3b72a | 349 | .TP |
7e23fc43 | 350 | .B \-\-homehost= |
35cc5be4 | 351 | This will override any |
41a3b72a | 352 | .B HOMEHOST |
93e790af | 353 | setting in the config file and provides the identity of the host which |
41a3b72a NB |
354 | should be considered the home for any arrays. |
355 | ||
356 | When creating an array, the | |
357 | .B homehost | |
e0fe762a | 358 | will be recorded in the metadata. For version-1 superblocks, it will |
93e790af | 359 | be prefixed to the array name. For version-0.90 superblocks, part of |
41a3b72a NB |
360 | the SHA1 hash of the hostname will be stored in the later half of the |
361 | UUID. | |
362 | ||
363 | When reporting information about an array, any array which is tagged | |
364 | for the given homehost will be reported as such. | |
365 | ||
366 | When using Auto-Assemble, only arrays tagged for the given homehost | |
0ac91628 | 367 | will be allowed to use 'local' names (i.e. not ending in '_' followed |
e0fe762a N |
368 | by a digit string). See below under |
369 | .BR "Auto Assembly" . | |
41a3b72a | 370 | |
2ae555c3 NB |
371 | .SH For create, build, or grow: |
372 | ||
373 | .TP | |
7e23fc43 | 374 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
375 | Specify the number of active devices in the array. This, plus the |
376 | number of spare devices (see below) must equal the number of | |
377 | .I component-devices | |
378 | (including "\fBmissing\fP" devices) | |
379 | that are listed on the command line for | |
e0fe762a | 380 | .BR \-\-create . |
2ae555c3 NB |
381 | Setting a value of 1 is probably |
382 | a mistake and so requires that | |
7e23fc43 | 383 | .B \-\-force |
2ae555c3 | 384 | be specified first. A value of 1 will then be allowed for linear, |
e0fe762a | 385 | multipath, RAID0 and RAID1. It is never allowed for RAID4, RAID5 or RAID6. |
2ae555c3 NB |
386 | .br |
387 | This number can only be changed using | |
7e23fc43 | 388 | .B \-\-grow |
e0fe762a N |
389 | for RAID1, RAID4, RAID5 and RAID6 arrays, and only on kernels which provide |
390 | the necessary support. | |
2ae555c3 NB |
391 | |
392 | .TP | |
7e23fc43 | 393 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
394 | Specify the number of spare (eXtra) devices in the initial array. |
395 | Spares can also be added | |
396 | and removed later. The number of component devices listed | |
e0fe762a | 397 | on the command line must equal the number of RAID devices plus the |
2ae555c3 NB |
398 | number of spare devices. |
399 | ||
2ae555c3 | 400 | .TP |
7e23fc43 | 401 | .BR \-z ", " \-\-size= |
e0fe762a | 402 | Amount (in Kibibytes) of space to use from each drive in RAID levels 1/4/5/6. |
2ae555c3 NB |
403 | This must be a multiple of the chunk size, and must leave about 128Kb |
404 | of space at the end of the drive for the RAID superblock. | |
405 | If this is not specified | |
406 | (as it normally is not) the smallest drive (or partition) sets the | |
407 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
408 | issued. | |
409 | ||
410 | This value can be set with | |
7e23fc43 | 411 | .B \-\-grow |
e0fe762a | 412 | for RAID level 1/4/5/6. If the array was created with a size smaller |
2ae555c3 NB |
413 | than the currently active drives, the extra space can be accessed |
414 | using | |
7e23fc43 | 415 | .BR \-\-grow . |
2ae555c3 NB |
416 | The size can be given as |
417 | .B max | |
418 | which means to choose the largest size that fits on all current drives. | |
52826846 | 419 | |
8fd8d9c4 N |
420 | This value can not be used with |
421 | .B CONTAINER | |
422 | metadata such as DDF and IMSM. | |
423 | ||
cd29a5c8 | 424 | .TP |
7e23fc43 | 425 | .BR \-c ", " \-\-chunk= |
cd29a5c8 | 426 | Specify chunk size of kibibytes. The default is 64. |
e0fe762a | 427 | This is only meaningful for RAID0, RAID4, RAID5, RAID6, and RAID10. |
52826846 | 428 | |
cd29a5c8 | 429 | .TP |
7e23fc43 | 430 | .BR \-\-rounding= |
e0fe762a N |
431 | Specify rounding factor for a Linear array. The size of each |
432 | component will be rounded down to a multiple of this size. | |
433 | This is a synonym for | |
434 | .B \-\-chunk | |
435 | but highlights the different meaning for Linear as compared to other | |
436 | RAID levels. | |
52826846 | 437 | |
cd29a5c8 | 438 | .TP |
7e23fc43 | 439 | .BR \-l ", " \-\-level= |
e0fe762a | 440 | Set RAID level. When used with |
7e23fc43 | 441 | .BR \-\-create , |
98c6faba | 442 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
8fd8d9c4 N |
443 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container. |
444 | Obviously some of these are synonymous. | |
445 | ||
446 | When a | |
447 | .B CONTAINER | |
448 | metadata type is requested, only the | |
449 | .B container | |
450 | level is permitted, and it does not need to be explicitly given. | |
aa88f531 NB |
451 | |
452 | When used with | |
7e23fc43 | 453 | .BR \-\-build , |
a9d69660 | 454 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 455 | |
2ae555c3 | 456 | Not yet supported with |
7e23fc43 | 457 | .BR \-\-grow . |
2ae555c3 | 458 | |
cd29a5c8 | 459 | .TP |
7e23fc43 | 460 | .BR \-p ", " \-\-layout= |
e0fe762a N |
461 | This option configures the fine details of data layout for RAID5, RAID6, |
462 | and RAID10 arrays, and controls the failure modes for | |
1a7dfc35 NB |
463 | .IR faulty . |
464 | ||
e0fe762a | 465 | The layout of the RAID5 parity block can be one of |
7e23fc43 PS |
466 | .BR left\-asymmetric , |
467 | .BR left\-symmetric , | |
468 | .BR right\-asymmetric , | |
469 | .BR right\-symmetric , | |
53e8b987 PS |
470 | .BR la ", " ra ", " ls ", " rs . |
471 | The default is | |
7e23fc43 | 472 | .BR left\-symmetric . |
52826846 | 473 | |
e0fe762a N |
474 | It is also possibly to cause RAID5 to use a RAID4-like layout by |
475 | choosing | |
476 | .BR parity\-first , | |
477 | or | |
478 | .BR parity\-last . | |
479 | ||
480 | Finally for RAID5 there are DDF\-compatible layouts, | |
481 | .BR ddf\-zero\-restart , | |
482 | .BR ddf\-N\-restart , | |
483 | and | |
484 | .BR ddf\-N\-continue . | |
485 | ||
486 | These same layouts are available for RAID6. There are also 4 layouts | |
487 | that will provide an intermediate stage for converting between RAID5 | |
488 | and RAID6. These provide a layout which is identical to the | |
489 | corresponding RAID5 layout on the first N\-1 devices, and has the 'Q' | |
490 | syndrome (the second 'parity' block used by RAID6) on the last device. | |
491 | These layouts are: | |
492 | .BR left\-symmetric\-6 , | |
493 | .BR right\-symmetric\-6 , | |
494 | .BR left\-asymmetric\-6 , | |
495 | .BR right\-asymmetric\-6 , | |
496 | and | |
497 | .BR pairty\-first\-6 . | |
498 | ||
93e790af SW |
499 | When setting the failure mode for level |
500 | .I faulty, | |
1a7dfc35 | 501 | the options are: |
7e23fc43 PS |
502 | .BR write\-transient ", " wt , |
503 | .BR read\-transient ", " rt , | |
504 | .BR write\-persistent ", " wp , | |
505 | .BR read\-persistent ", " rp , | |
506 | .BR write\-all , | |
507 | .BR read\-fixable ", " rf , | |
53e8b987 | 508 | .BR clear ", " flush ", " none . |
b5e64645 | 509 | |
93e790af | 510 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
511 | between fault generation. Without a number, the fault is generated |
512 | once on the first relevant request. With a number, the fault will be | |
93e790af | 513 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
514 | every time the period elapses. |
515 | ||
516 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 517 | .B \-\-grow |
53e8b987 | 518 | option to set subsequent failure modes. |
b5e64645 NB |
519 | |
520 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 521 | and "flush" will clear any persistent faults. |
b5e64645 | 522 | |
53e8b987 | 523 | To set the parity with |
7e23fc43 | 524 | .BR \-\-grow , |
53e8b987 | 525 | the level of the array ("faulty") |
b5e64645 NB |
526 | must be specified before the fault mode is specified. |
527 | ||
6f9a21a7 | 528 | Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 529 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 530 | |
93e790af | 531 | .I 'n' |
e0fe762a | 532 | signals 'near' copies. Multiple copies of one data block are at |
b578481c NB |
533 | similar offsets in different devices. |
534 | ||
93e790af | 535 | .I 'o' |
b578481c NB |
536 | signals 'offset' copies. Rather than the chunks being duplicated |
537 | within a stripe, whole stripes are duplicated but are rotated by one | |
538 | device so duplicate blocks are on different devices. Thus subsequent | |
539 | copies of a block are in the next drive, and are one chunk further | |
540 | down. | |
541 | ||
93e790af | 542 | .I 'f' |
1a7dfc35 | 543 | signals 'far' copies |
93e790af | 544 | (multiple copies have very different offsets). |
e0fe762a | 545 | See md(4) for more detail about 'near', 'offset', and 'far'. |
1a7dfc35 NB |
546 | |
547 | The number is the number of copies of each datablock. 2 is normal, 3 | |
548 | can be useful. This number can be at most equal to the number of | |
549 | devices in the array. It does not need to divide evenly into that | |
550 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
551 | with an odd number of devices). | |
552 | ||
cd29a5c8 | 553 | .TP |
7e23fc43 | 554 | .BR \-\-parity= |
53e8b987 | 555 | same as |
7e23fc43 | 556 | .B \-\-layout |
53e8b987 | 557 | (thus explaining the p of |
7e23fc43 | 558 | .BR \-p ). |
52826846 | 559 | |
e793c2e5 | 560 | .TP |
7e23fc43 | 561 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 562 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 563 | exist unless |
7e23fc43 | 564 | .B \-\-force |
53e8b987 | 565 | is also given. The same file should be provided |
2ae555c3 | 566 | when assembling the array. If the word |
93e790af | 567 | .B "internal" |
2ae555c3 NB |
568 | is given, then the bitmap is stored with the metadata on the array, |
569 | and so is replicated on all devices. If the word | |
93e790af | 570 | .B "none" |
2ae555c3 | 571 | is given with |
7e23fc43 | 572 | .B \-\-grow |
2ae555c3 | 573 | mode, then any bitmap that is present is removed. |
e793c2e5 | 574 | |
2ae555c3 NB |
575 | To help catch typing errors, the filename must contain at least one |
576 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
577 | ||
578 | Note: external bitmaps are only known to work on ext2 and ext3. | |
579 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 580 | |
cd29a5c8 | 581 | .TP |
7e23fc43 | 582 | .BR \-\-bitmap\-chunk= |
e0fe762a | 583 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
584 | Kilobytes of storage. |
585 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 586 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
587 | When using an |
588 | .B internal | |
589 | bitmap, the chunksize is automatically determined to make best use of | |
590 | available space. | |
5787fa49 | 591 | |
cd29a5c8 | 592 | .TP |
7e23fc43 | 593 | .BR \-W ", " \-\-write\-mostly |
e0fe762a | 594 | subsequent devices listed in a |
7e23fc43 PS |
595 | .BR \-\-build , |
596 | .BR \-\-create , | |
2ae555c3 | 597 | or |
7e23fc43 | 598 | .B \-\-add |
2ae555c3 NB |
599 | command will be flagged as 'write-mostly'. This is valid for RAID1 |
600 | only and means that the 'md' driver will avoid reading from these | |
601 | devices if at all possible. This can be useful if mirroring over a | |
602 | slow link. | |
52826846 | 603 | |
2ae555c3 | 604 | .TP |
7e23fc43 | 605 | .BR \-\-write\-behind= |
2ae555c3 | 606 | Specify that write-behind mode should be enabled (valid for RAID1 |
e0fe762a N |
607 | only). If an argument is specified, it will set the maximum number |
608 | of outstanding writes allowed. The default value is 256. | |
2ae555c3 NB |
609 | A write-intent bitmap is required in order to use write-behind |
610 | mode, and write-behind is only attempted on drives marked as | |
611 | .IR write-mostly . | |
dd0781e5 NB |
612 | |
613 | .TP | |
7e23fc43 | 614 | .BR \-\-assume\-clean |
dd0781e5 NB |
615 | Tell |
616 | .I mdadm | |
47d79ef8 NB |
617 | that the array pre-existed and is known to be clean. It can be useful |
618 | when trying to recover from a major failure as you can be sure that no | |
619 | data will be affected unless you actually write to the array. It can | |
620 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 621 | initial resync, however this practice \(em while normally safe \(em is not |
e0fe762a | 622 | recommended. Use this only if you really know what you are doing. |
dd0781e5 | 623 | |
2ae555c3 | 624 | .TP |
7e23fc43 | 625 | .BR \-\-backup\-file= |
53e8b987 | 626 | This is needed when |
7e23fc43 | 627 | .B \-\-grow |
53e8b987 | 628 | is used to increase the number of |
e0fe762a N |
629 | raid-devices in a RAID5 if there are no spare devices available. |
630 | See the GROW MODE section below on RAID\-DEVICES CHANGES. The file | |
631 | should be stored on a separate device, not on the RAID array being | |
632 | reshaped. | |
2ae555c3 | 633 | |
947fd4dd | 634 | .TP |
7e23fc43 | 635 | .BR \-N ", " \-\-name= |
947fd4dd NB |
636 | Set a |
637 | .B name | |
638 | for the array. This is currently only effective when creating an | |
e0fe762a N |
639 | array with a version-1 superblock, or an array in a DDF container. |
640 | The name is a simple textual string that can be used to identify array | |
641 | components when assembling. If name is needed but not specified, it | |
642 | is taken from the basename of the device that is being created. | |
643 | e.g. when creating | |
644 | .I /dev/md/home | |
645 | the | |
646 | .B name | |
647 | will default to | |
648 | .IR home . | |
947fd4dd | 649 | |
dd0781e5 | 650 | .TP |
7e23fc43 | 651 | .BR \-R ", " \-\-run |
dd0781e5 NB |
652 | Insist that |
653 | .I mdadm | |
654 | run the array, even if some of the components | |
655 | appear to be active in another array or filesystem. Normally | |
656 | .I mdadm | |
657 | will ask for confirmation before including such components in an | |
658 | array. This option causes that question to be suppressed. | |
659 | ||
660 | .TP | |
7e23fc43 | 661 | .BR \-f ", " \-\-force |
dd0781e5 NB |
662 | Insist that |
663 | .I mdadm | |
664 | accept the geometry and layout specified without question. Normally | |
665 | .I mdadm | |
666 | will not allow creation of an array with only one device, and will try | |
e0fe762a | 667 | to create a RAID5 array with one missing drive (as this makes the |
dd0781e5 | 668 | initial resync work faster). With |
7e23fc43 | 669 | .BR \-\-force , |
dd0781e5 NB |
670 | .I mdadm |
671 | will not try to be so clever. | |
672 | ||
673 | .TP | |
257c1dc2 N |
674 | .BR \-a ", " "\-\-auto{=yes,md,mdp,part,p}{NN}" |
675 | Instruct mdadm how to create the device file if needed, possibly allocating | |
48f7b27a | 676 | an unused minor number. "md" causes a non-partitionable array |
257c1dc2 N |
677 | to be used (though since Linux 2.6.28, these array devices are in fact |
678 | partitionable). "mdp", "part" or "p" causes a partitionable array (2.6 and | |
2ae555c3 | 679 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 680 | a 'standard' format, and the type and minor number will be determined |
257c1dc2 N |
681 | from this. With mdadm 3.0, device creation is normally left up to |
682 | .I udev | |
683 | so this option is unlikely to be needed. | |
684 | See DEVICE NAMES below. | |
48f7b27a | 685 | |
a9d69660 | 686 | The argument can also come immediately after |
7e23fc43 | 687 | "\-a". e.g. "\-ap". |
dd0781e5 | 688 | |
53e8b987 | 689 | If |
7e23fc43 | 690 | .B \-\-auto |
53e8b987 | 691 | is not given on the command line or in the config file, then |
75723446 | 692 | the default will be |
7e23fc43 | 693 | .BR \-\-auto=yes . |
75723446 | 694 | |
1337546d | 695 | If |
7e23fc43 | 696 | .B \-\-scan |
1337546d NB |
697 | is also given, then any |
698 | .I auto= | |
35cc5be4 | 699 | entries in the config file will override the |
7e23fc43 | 700 | .B \-\-auto |
1337546d NB |
701 | instruction given on the command line. |
702 | ||
dd0781e5 NB |
703 | For partitionable arrays, |
704 | .I mdadm | |
705 | will create the device file for the whole array and for the first 4 | |
706 | partitions. A different number of partitions can be specified at the | |
707 | end of this option (e.g. | |
7e23fc43 | 708 | .BR \-\-auto=p7 ). |
2ae555c3 | 709 | If the device name ends with a digit, the partition names add a 'p', |
e0fe762a N |
710 | and a number, e.g. |
711 | .IR /dev/md/home1p3 . | |
712 | If there is no trailing digit, then the partition names just have a | |
713 | number added, e.g. | |
714 | .IR /dev/md/scratch3 . | |
dd0781e5 | 715 | |
48f7b27a NB |
716 | If the md device name is in a 'standard' format as described in DEVICE |
717 | NAMES, then it will be created, if necessary, with the appropriate | |
e0fe762a N |
718 | device number based on that name. If the device name is not in one of these |
719 | formats, then a unused device number will be allocated. The device | |
48f7b27a NB |
720 | number will be considered unused if there is no active array for that |
721 | number, and there is no entry in /dev for that number and with a | |
e0fe762a | 722 | non-standard name. Names that are not in 'standard' format are only |
8fd8d9c4 N |
723 | allowed in "/dev/md/". |
724 | ||
e0fe762a N |
725 | .\".TP |
726 | .\".BR \-\-symlink = no | |
727 | .\"Normally when | |
728 | .\".B \-\-auto | |
729 | .\"causes | |
730 | .\".I mdadm | |
731 | .\"to create devices in | |
732 | .\".B /dev/md/ | |
733 | .\"it will also create symlinks from | |
734 | .\".B /dev/ | |
735 | .\"with names starting with | |
736 | .\".B md | |
737 | .\"or | |
738 | .\".BR md_ . | |
739 | .\"Use | |
740 | .\".B \-\-symlink=no | |
741 | .\"to suppress this, or | |
742 | .\".B \-\-symlink=yes | |
743 | .\"to enforce this even if it is suppressing | |
744 | .\".IR mdadm.conf . | |
745 | .\" | |
38098016 | 746 | |
52826846 NB |
747 | .SH For assemble: |
748 | ||
cd29a5c8 | 749 | .TP |
7e23fc43 | 750 | .BR \-u ", " \-\-uuid= |
e0fe762a | 751 | uuid of array to assemble. Devices which don't have this uuid are |
cd29a5c8 NB |
752 | excluded |
753 | ||
754 | .TP | |
7e23fc43 | 755 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
756 | Minor number of device that array was created for. Devices which |
757 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 758 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
759 | the array is later assembled as /dev/md2. |
760 | ||
d013a55e | 761 | Giving the literal word "dev" for |
7e23fc43 | 762 | .B \-\-super\-minor |
d013a55e NB |
763 | will cause |
764 | .I mdadm | |
765 | to use the minor number of the md device that is being assembled. | |
766 | e.g. when assembling | |
767 | .BR /dev/md0 , | |
51ac42e3 | 768 | .B \-\-super\-minor=dev |
d013a55e NB |
769 | will look for super blocks with a minor number of 0. |
770 | ||
e0fe762a N |
771 | .B \-\-super\-minor |
772 | is only relevant for v0.90 metadata, and should not normally be used. | |
773 | Using | |
774 | .B \-\-uuid | |
775 | is much safer. | |
776 | ||
947fd4dd | 777 | .TP |
7e23fc43 | 778 | .BR \-N ", " \-\-name= |
947fd4dd | 779 | Specify the name of the array to assemble. This must be the name |
624920bb | 780 | that was specified when creating the array. It must either match |
93e790af | 781 | the name stored in the superblock exactly, or it must match |
41a3b72a | 782 | with the current |
624920bb | 783 | .I homehost |
93e790af | 784 | prefixed to the start of the given name. |
947fd4dd | 785 | |
cd29a5c8 | 786 | .TP |
7e23fc43 | 787 | .BR \-f ", " \-\-force |
e0fe762a N |
788 | Assemble the array even if the metadata on some devices appears to be |
789 | out-of-date. If | |
790 | .I mdadm | |
791 | cannot find enough working devices to start the array, but can find | |
792 | some devices that are recorded as having failed, then it will mark | |
793 | those devices as working so that the array can be started. | |
794 | An array which requires | |
795 | .B \-\-force | |
796 | to be started may contain data corruption. Use it carefully. | |
52826846 | 797 | |
cd29a5c8 | 798 | .TP |
7e23fc43 | 799 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
800 | Attempt to start the array even if fewer drives were given than were |
801 | present last time the array was active. Normally if not all the | |
802 | expected drives are found and | |
7e23fc43 | 803 | .B \-\-scan |
cd29a5c8 NB |
804 | is not used, then the array will be assembled but not started. |
805 | With | |
7e23fc43 | 806 | .B \-\-run |
cd29a5c8 | 807 | an attempt will be made to start it anyway. |
52826846 | 808 | |
b8a8ccf9 | 809 | .TP |
7e23fc43 | 810 | .B \-\-no\-degraded |
b8a8ccf9 | 811 | This is the reverse of |
7e23fc43 | 812 | .B \-\-run |
93e790af | 813 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 814 | are present. This is only needed with |
93e790af SW |
815 | .B \-\-scan, |
816 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
817 | not as reliable as you would like. |
818 | ||
dd0781e5 | 819 | .TP |
7e23fc43 | 820 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
821 | See this option under Create and Build options. |
822 | ||
e793c2e5 | 823 | .TP |
7e23fc43 | 824 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
825 | Specify the bitmap file that was given when the array was created. If |
826 | an array has an | |
827 | .B internal | |
828 | bitmap, there is no need to specify this when assembling the array. | |
829 | ||
830 | .TP | |
7e23fc43 | 831 | .BR \-\-backup\-file= |
2ae555c3 | 832 | If |
7e23fc43 | 833 | .B \-\-backup\-file |
2ae555c3 NB |
834 | was used to grow the number of raid-devices in a RAID5, and the system |
835 | crashed during the critical section, then the same | |
7e23fc43 | 836 | .B \-\-backup\-file |
53e8b987 | 837 | must be presented to |
7e23fc43 | 838 | .B \-\-assemble |
53e8b987 | 839 | to allow possibly corrupted data to be restored. |
e793c2e5 | 840 | |
5787fa49 | 841 | .TP |
7e23fc43 | 842 | .BR \-U ", " \-\-update= |
5787fa49 | 843 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
844 | argument given to this flag can be one of |
845 | .BR sparc2.2 , | |
846 | .BR summaries , | |
7d99579f | 847 | .BR uuid , |
c4f12c13 | 848 | .BR name , |
0237e0ca | 849 | .BR homehost , |
e5329c37 | 850 | .BR resync , |
586ed405 | 851 | .BR byteorder , |
bee8ec56 | 852 | .BR devicesize , |
5787fa49 | 853 | or |
7e23fc43 | 854 | .BR super\-minor . |
5787fa49 NB |
855 | |
856 | The | |
857 | .B sparc2.2 | |
7d99579f | 858 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
859 | machine running a patched 2.2 Linux kernel. This kernel got the |
860 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 861 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
862 | option to |
863 | .I mdadm | |
864 | to see what effect this would have. | |
865 | ||
866 | The | |
7e23fc43 | 867 | .B super\-minor |
5787fa49 | 868 | option will update the |
2ae555c3 | 869 | .B "preferred minor" |
5787fa49 | 870 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
871 | assembled. |
872 | This can be useful if | |
7e23fc43 | 873 | .B \-\-examine |
45c073c9 | 874 | reports a different "Preferred Minor" to |
7e23fc43 | 875 | .BR \-\-detail . |
45c073c9 | 876 | In some cases this update will be performed automatically |
e0fe762a | 877 | by the kernel driver. In particular the update happens automatically |
45c073c9 NB |
878 | at the first write to an array with redundancy (RAID level 1 or |
879 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 880 | |
7d99579f NB |
881 | The |
882 | .B uuid | |
883 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 884 | .B \-\-uuid |
53e8b987 | 885 | option that UUID will be used as a new UUID and will |
7d99579f NB |
886 | .B NOT |
887 | be used to help identify the devices in the array. | |
53e8b987 | 888 | If no |
7e23fc43 | 889 | .B \-\-uuid |
53e8b987 | 890 | is given, a random UUID is chosen. |
7d99579f | 891 | |
c4f12c13 NB |
892 | The |
893 | .B name | |
894 | option will change the | |
895 | .I name | |
896 | of the array as stored in the superblock. This is only supported for | |
897 | version-1 superblocks. | |
898 | ||
0237e0ca NB |
899 | The |
900 | .B homehost | |
901 | option will change the | |
902 | .I homehost | |
903 | as recorded in the superblock. For version-0 superblocks, this is the | |
904 | same as updating the UUID. | |
905 | For version-1 superblocks, this involves updating the name. | |
906 | ||
e5329c37 NB |
907 | The |
908 | .B resync | |
909 | option will cause the array to be marked | |
910 | .I dirty | |
e0fe762a N |
911 | meaning that any redundancy in the array (e.g. parity for RAID5, |
912 | copies for RAID1) may be incorrect. This will cause the RAID system | |
e5329c37 NB |
913 | to perform a "resync" pass to make sure that all redundant information |
914 | is correct. | |
915 | ||
586ed405 NB |
916 | The |
917 | .B byteorder | |
918 | option allows arrays to be moved between machines with different | |
919 | byte-order. | |
2ae555c3 | 920 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 921 | .B "\-\-update=byteorder" |
586ed405 NB |
922 | will cause |
923 | .I mdadm | |
924 | to expect superblocks to have their byteorder reversed, and will | |
925 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 926 | with original (Version 0.90) superblocks. |
586ed405 | 927 | |
feb716e9 NB |
928 | The |
929 | .B summaries | |
e0fe762a | 930 | option will correct the summaries in the superblock. That is the |
feb716e9 | 931 | counts of total, working, active, failed, and spare devices. |
5787fa49 | 932 | |
bee8ec56 NB |
933 | The |
934 | .B devicesize | |
935 | will rarely be of use. It applies to version 1.1 and 1.2 metadata | |
936 | only (where the metadata is at the start of the device) and is only | |
937 | useful when the component device has changed size (typically become | |
938 | larger). The version 1 metadata records the amount of the device that | |
939 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
940 | array becomes larger, the metadata will still be visible, but the | |
941 | extra space will not. In this case it might be useful to assemble the | |
942 | array with | |
7e23fc43 | 943 | .BR \-\-update=devicesize . |
bee8ec56 NB |
944 | This will cause |
945 | .I mdadm | |
946 | to determine the maximum usable amount of space on each device and | |
947 | update the relevant field in the metadata. | |
948 | ||
e0fe762a | 949 | .ig XX |
41a3b72a | 950 | .TP |
7e23fc43 | 951 | .B \-\-auto\-update\-homehost |
93e790af | 952 | This flag is only meaningful with auto-assembly (see discussion below). |
41a3b72a NB |
953 | In that situation, if no suitable arrays are found for this homehost, |
954 | .I mdadm | |
93e790af | 955 | will rescan for any arrays at all and will assemble them and update the |
41a3b72a | 956 | homehost to match the current host. |
e0fe762a | 957 | .XX |
41a3b72a | 958 | |
e0d19036 | 959 | .SH For Manage mode: |
52826846 | 960 | |
cd29a5c8 | 961 | .TP |
7e23fc43 | 962 | .BR \-a ", " \-\-add |
e0fe762a N |
963 | hot-add listed devices. For arrays with redundancy, the listed |
964 | devices become available as spares. If the array is degraded, it will | |
965 | immediately start recovering data on to one of these spares. | |
52826846 | 966 | |
fe80f49b | 967 | .TP |
7e23fc43 | 968 | .BR \-\-re\-add |
e0fe762a N |
969 | re-add a device that was recently removed from an array. This is only |
970 | needed for arrays that have be built (i.e. with | |
971 | .BR --build ). | |
972 | For created arrays, devices are always re-added if that is possible. | |
973 | When re-adding a device, if nothing has changed on the array since the | |
974 | device was removed, no recovery is performed. Also, if the array has | |
975 | a write-intent bitmap, then the recovery performed after a re-add will | |
976 | be limited to those blocks which, according to the bitmap, might have | |
977 | changed since the device was removed. | |
fe80f49b | 978 | |
cd29a5c8 | 979 | .TP |
7e23fc43 | 980 | .BR \-r ", " \-\-remove |
2d465520 | 981 | remove listed devices. They must not be active. i.e. they should |
b80da661 NB |
982 | be failed or spare devices. As well as the name of a device file |
983 | (e.g. | |
984 | .BR /dev/sda1 ) | |
985 | the words | |
986 | .B failed | |
987 | and | |
988 | .B detached | |
989 | can be given to | |
990 | .BR \-\-remove . | |
991 | The first causes all failed device to be removed. The second causes | |
93e790af | 992 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
993 | returns |
994 | .BR ENXIO ) | |
995 | to be removed. This will only succeed for devices that are spares or | |
996 | have already been marked as failed. | |
52826846 | 997 | |
cd29a5c8 | 998 | .TP |
7e23fc43 | 999 | .BR \-f ", " \-\-fail |
cd29a5c8 | 1000 | mark listed devices as faulty. |
b80da661 NB |
1001 | As well as the name of a device file, the word |
1002 | .B detached | |
1003 | can be given. This will cause any device that has been detached from | |
1004 | the system to be marked as failed. It can then be removed. | |
52826846 | 1005 | |
cd29a5c8 | 1006 | .TP |
7e23fc43 | 1007 | .BR \-\-set\-faulty |
53e8b987 | 1008 | same as |
7e23fc43 | 1009 | .BR \-\-fail . |
52826846 | 1010 | |
b3d31955 N |
1011 | .TP |
1012 | .BR \-\-write\-mostly | |
1013 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
e0fe762a | 1014 | flag set. This is only valid for RAID1 and means that the 'md' driver |
b3d31955 N |
1015 | will avoid reading from these devices if possible. |
1016 | .TP | |
1017 | .BR \-\-readwrite | |
1018 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
1019 | flag cleared. | |
1020 | ||
2ae555c3 | 1021 | .P |
e0fe762a | 1022 | Each of these options requires that the first device listed is the array |
93e790af | 1023 | to be acted upon, and the remainder are component devices to be added, |
e0fe762a | 1024 | removed, marked as faulty, etc. Several different operations can be |
2ae555c3 NB |
1025 | specified for different devices, e.g. |
1026 | .in +5 | |
7e23fc43 | 1027 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
1028 | .in -5 |
1029 | Each operation applies to all devices listed until the next | |
93e790af | 1030 | operation. |
2ae555c3 NB |
1031 | |
1032 | If an array is using a write-intent bitmap, then devices which have | |
1033 | been removed can be re-added in a way that avoids a full | |
93e790af | 1034 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
1035 | since the device was removed. For arrays with persistent metadata |
1036 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 1037 | .B \-\-build |
2ae555c3 | 1038 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 1039 | .BR \-\-re\-add . |
2ae555c3 NB |
1040 | |
1041 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
1042 | use, i.e. that must be spares or failed devices. To remove an active |
1043 | device, it must first be marked as | |
1044 | .B faulty. | |
2ae555c3 NB |
1045 | |
1046 | .SH For Misc mode: | |
1047 | ||
1048 | .TP | |
7e23fc43 | 1049 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
1050 | Examine a device to see |
1051 | (1) if it is an md device and (2) if it is a component of an md | |
1052 | array. | |
1053 | Information about what is discovered is presented. | |
1054 | ||
1055 | .TP | |
7e23fc43 | 1056 | .BR \-D ", " \-\-detail |
e0fe762a | 1057 | Print details of one or more md devices. |
5787fa49 | 1058 | |
4cce4069 DW |
1059 | .TP |
1060 | .BR \-\-detail\-platform | |
e0fe762a | 1061 | Print details of the platform's RAID capabilities (firmware / hardware |
4cce4069 DW |
1062 | topology) for a given metadata format. |
1063 | ||
54bad364 KS |
1064 | .TP |
1065 | .BR \-Y ", " \-\-export | |
1066 | When used with | |
0d726f17 KS |
1067 | .B \-\-detail |
1068 | or | |
1069 | .BR \-\-examine , | |
54bad364 KS |
1070 | output will be formatted as |
1071 | .B key=value | |
1072 | pairs for easy import into the environment. | |
1073 | ||
2ae555c3 | 1074 | .TP |
7e23fc43 | 1075 | .BR \-E ", " \-\-examine |
e0fe762a N |
1076 | Print contents of the metadata stored on the named device(s). |
1077 | Note the contrast between | |
1078 | .B \-\-examine | |
1079 | and | |
1080 | .BR \-\-detail . | |
1081 | .B \-\-examine | |
1082 | applies to devices which are components of an array, while | |
1083 | .B \-\-detail | |
1084 | applies to a whole array which is currently active. | |
5787fa49 | 1085 | .TP |
7e23fc43 | 1086 | .B \-\-sparc2.2 |
e0fe762a N |
1087 | If an array was created on a SPARC machine with a 2.2 Linux kernel |
1088 | patched with RAID support, the superblock will have been created | |
1089 | incorrectly, or at least incompatibly with 2.4 and later kernels. | |
1090 | Using the | |
7e23fc43 | 1091 | .B \-\-sparc2.2 |
5787fa49 | 1092 | flag with |
7e23fc43 | 1093 | .B \-\-examine |
5787fa49 NB |
1094 | will fix the superblock before displaying it. If this appears to do |
1095 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 1096 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 1097 | |
2ae555c3 | 1098 | .TP |
7e23fc43 | 1099 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 1100 | Report information about a bitmap file. |
01d9299c | 1101 | The argument is either an external bitmap file or an array component |
e0fe762a N |
1102 | in case of an internal bitmap. Note that running this on an array |
1103 | device (e.g. | |
1104 | .BR /dev/md0 ) | |
1105 | does not report the bitmap for that array. | |
e0d19036 | 1106 | |
cd29a5c8 | 1107 | .TP |
7e23fc43 | 1108 | .BR \-R ", " \-\-run |
e0fe762a N |
1109 | start a partially assembled array. If |
1110 | .B \-\-assemble | |
1111 | did not find enough devices to fully start the array, it might leaving | |
1112 | it partially assembled. If you wish, you can then use | |
1113 | .B \-\-run | |
1114 | to start the array in degraded mode. | |
52826846 | 1115 | |
cd29a5c8 | 1116 | .TP |
7e23fc43 | 1117 | .BR \-S ", " \-\-stop |
cd29a5c8 | 1118 | deactivate array, releasing all resources. |
52826846 | 1119 | |
cd29a5c8 | 1120 | .TP |
7e23fc43 | 1121 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 1122 | mark array as readonly. |
52826846 | 1123 | |
cd29a5c8 | 1124 | .TP |
7e23fc43 | 1125 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 1126 | mark array as readwrite. |
52826846 | 1127 | |
e0d19036 | 1128 | .TP |
7e23fc43 | 1129 | .B \-\-zero\-superblock |
e0d19036 | 1130 | If the device contains a valid md superblock, the block is |
35cc5be4 | 1131 | overwritten with zeros. With |
7e23fc43 | 1132 | .B \-\-force |
35cc5be4 | 1133 | the block where the superblock would be is overwritten even if it |
e0d19036 | 1134 | doesn't appear to be valid. |
52826846 | 1135 | |
feb716e9 | 1136 | .TP |
7e23fc43 | 1137 | .BR \-t ", " \-\-test |
feb716e9 | 1138 | When used with |
7e23fc43 | 1139 | .BR \-\-detail , |
feb716e9 NB |
1140 | the exit status of |
1141 | .I mdadm | |
e0fe762a N |
1142 | is set to reflect the status of the device. See below in |
1143 | .B MISC MODE | |
1144 | for details. | |
feb716e9 | 1145 | |
b90c0e9a | 1146 | .TP |
7e23fc43 | 1147 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1148 | For each md device given, wait for any resync, recovery, or reshape |
1149 | activity to finish before returning. | |
1150 | .I mdadm | |
1151 | will return with success if it actually waited for every device | |
1152 | listed, otherwise it will return failure. | |
1153 | ||
1770662b DW |
1154 | .TP |
1155 | .BR \-\-wait\-clean | |
fabbfd48 DW |
1156 | For each md device given, or each device in /proc/mdstat if |
1157 | .B \-\-scan | |
1158 | is given, arrange for the array to be marked clean as soon as possible. | |
1159 | Also, quiesce resync so that the monitor for external metadata arrays | |
1160 | (mdmon) has an opportunity to checkpoint the resync position. | |
7146ec6a DW |
1161 | .I mdadm |
1162 | will return with success if the array uses external metadata and we | |
1163 | successfully waited. For native arrays this returns immediately as the | |
1164 | kernel handles both dirty-clean transitions and resync checkpointing in | |
1165 | the kernel at shutdown. No action is taken if safe-mode handling is | |
1166 | disabled. | |
1770662b | 1167 | |
8382f19b NB |
1168 | .SH For Incremental Assembly mode: |
1169 | .TP | |
7e23fc43 | 1170 | .BR \-\-rebuild\-map ", " \-r |
8382f19b NB |
1171 | Rebuild the map file |
1172 | .RB ( /var/run/mdadm/map ) | |
1173 | that | |
1174 | .I mdadm | |
1175 | uses to help track which arrays are currently being assembled. | |
1176 | ||
1177 | .TP | |
7e23fc43 | 1178 | .BR \-\-run ", " \-R |
8382f19b NB |
1179 | Run any array assembled as soon as a minimal number of devices are |
1180 | available, rather than waiting until all expected devices are present. | |
1181 | ||
fdb482f9 DW |
1182 | .TP |
1183 | .B \-\-no\-degraded | |
1184 | This allows the hot-plug system to prevent arrays from running when it knows | |
1185 | that more disks may arrive later in the discovery process. | |
1186 | ||
8382f19b | 1187 | .TP |
7e23fc43 | 1188 | .BR \-\-scan ", " \-s |
8382f19b | 1189 | Only meaningful with |
7e23fc43 | 1190 | .B \-R |
8382f19b NB |
1191 | this will scan the |
1192 | .B map | |
1193 | file for arrays that are being incrementally assembled and will try to | |
1194 | start any that are not already started. If any such array is listed | |
1195 | in | |
1196 | .B mdadm.conf | |
1197 | as requiring an external bitmap, that bitmap will be attached first. | |
1198 | ||
e0d19036 NB |
1199 | .SH For Monitor mode: |
1200 | .TP | |
7e23fc43 | 1201 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1202 | Give a mail address to send alerts to. |
1203 | ||
1204 | .TP | |
7e23fc43 | 1205 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1206 | Give a program to be run whenever an event is detected. |
1207 | ||
773135f5 | 1208 | .TP |
7e23fc43 | 1209 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1210 | Cause all events to be reported through 'syslog'. The messages have |
1211 | facility of 'daemon' and varying priorities. | |
1212 | ||
e0d19036 | 1213 | .TP |
7e23fc43 | 1214 | .BR \-d ", " \-\-delay |
e0d19036 | 1215 | Give a delay in seconds. |
51ac42e3 | 1216 | .I mdadm |
e0d19036 | 1217 | polls the md arrays and then waits this many seconds before polling |
e0fe762a N |
1218 | again. The default is 60 seconds. Since 2.6.16, there is no need to |
1219 | reduce this as the kernel alerts | |
1220 | .I mdadm | |
1221 | immediately when there is any change. | |
e0d19036 | 1222 | |
d013a55e | 1223 | .TP |
7e23fc43 | 1224 | .BR \-f ", " \-\-daemonise |
d013a55e | 1225 | Tell |
51ac42e3 | 1226 | .I mdadm |
d013a55e | 1227 | to run as a background daemon if it decides to monitor anything. This |
e0fe762a | 1228 | causes it to fork and run in the child, and to disconnect from the |
d013a55e NB |
1229 | terminal. The process id of the child is written to stdout. |
1230 | This is useful with | |
7e23fc43 | 1231 | .B \-\-scan |
d013a55e NB |
1232 | which will only continue monitoring if a mail address or alert program |
1233 | is found in the config file. | |
1234 | ||
b5e64645 | 1235 | .TP |
7e23fc43 | 1236 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1237 | When |
51ac42e3 | 1238 | .I mdadm |
b5e64645 NB |
1239 | is running in daemon mode, write the pid of the daemon process to |
1240 | the specified file, instead of printing it on standard output. | |
1241 | ||
aa88f531 | 1242 | .TP |
7e23fc43 | 1243 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1244 | Check arrays only once. This will generate |
1245 | .B NewArray | |
1246 | events and more significantly | |
1247 | .B DegradedArray | |
a9d69660 NB |
1248 | and |
1249 | .B SparesMissing | |
aa88f531 NB |
1250 | events. Running |
1251 | .in +5 | |
7e23fc43 | 1252 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1253 | .in -5 |
1254 | from a cron script will ensure regular notification of any degraded arrays. | |
1255 | ||
98c6faba | 1256 | .TP |
7e23fc43 | 1257 | .BR \-t ", " \-\-test |
98c6faba NB |
1258 | Generate a |
1259 | .B TestMessage | |
1260 | alert for every array found at startup. This alert gets mailed and | |
1261 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1262 | message do get through successfully. |
98c6faba | 1263 | |
e0d19036 | 1264 | .SH ASSEMBLE MODE |
52826846 | 1265 | |
cd29a5c8 NB |
1266 | .HP 12 |
1267 | Usage: | |
7e23fc43 | 1268 | .B mdadm \-\-assemble |
5787fa49 NB |
1269 | .I md-device options-and-component-devices... |
1270 | .HP 12 | |
1271 | Usage: | |
7e23fc43 | 1272 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1273 | .I md-devices-and-options... |
cd29a5c8 NB |
1274 | .HP 12 |
1275 | Usage: | |
7e23fc43 | 1276 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1277 | .I options... |
52826846 | 1278 | |
cd29a5c8 | 1279 | .PP |
e0fe762a | 1280 | This usage assembles one or more RAID arrays from pre-existing components. |
9a9dab36 | 1281 | For each array, mdadm needs to know the md device, the identity of the |
e0fe762a | 1282 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1283 | |
5787fa49 | 1284 | In the first usage example (without the |
7e23fc43 | 1285 | .BR \-\-scan ) |
5787fa49 NB |
1286 | the first device given is the md device. |
1287 | In the second usage example, all devices listed are treated as md | |
1288 | devices and assembly is attempted. | |
1289 | In the third (where no devices are listed) all md devices that are | |
e0fe762a N |
1290 | listed in the configuration file are assembled. If not arrays are |
1291 | described by the configuration file, then any arrays that | |
1292 | can be found on unused devices will be assembled. | |
52826846 | 1293 | |
d013a55e | 1294 | If precisely one device is listed, but |
7e23fc43 | 1295 | .B \-\-scan |
dd0781e5 | 1296 | is not given, then |
d013a55e NB |
1297 | .I mdadm |
1298 | acts as though | |
7e23fc43 | 1299 | .B \-\-scan |
93e790af | 1300 | was given and identity information is extracted from the configuration file. |
d013a55e | 1301 | |
2ae555c3 | 1302 | The identity can be given with the |
7e23fc43 | 1303 | .B \-\-uuid |
e0fe762a N |
1304 | option, the |
1305 | .B \-\-name | |
1306 | option, or the | |
7e23fc43 | 1307 | .B \-\-super\-minor |
93e790af SW |
1308 | option, will be taken from the md-device record in the config file, or |
1309 | will be taken from the super block of the first component-device | |
1310 | listed on the command line. | |
52826846 | 1311 | |
2ae555c3 | 1312 | Devices can be given on the |
7e23fc43 | 1313 | .B \-\-assemble |
e0fe762a | 1314 | command line or in the config file. Only devices which have an md |
5787fa49 NB |
1315 | superblock which contains the right identity will be considered for |
1316 | any array. | |
52826846 | 1317 | |
2ae555c3 | 1318 | The config file is only used if explicitly named with |
7e23fc43 | 1319 | .B \-\-config |
d013a55e | 1320 | or requested with (a possibly implicit) |
7e23fc43 | 1321 | .BR \-\-scan . |
52826846 | 1322 | In the later case, |
9a9dab36 | 1323 | .B /etc/mdadm.conf |
8fd8d9c4 N |
1324 | or |
1325 | .B /etc/mdadm/mdadm.conf | |
52826846 NB |
1326 | is used. |
1327 | ||
2ae555c3 | 1328 | If |
7e23fc43 | 1329 | .B \-\-scan |
cd29a5c8 NB |
1330 | is not given, then the config file will only be used to find the |
1331 | identity of md arrays. | |
52826846 | 1332 | |
2d465520 | 1333 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 1334 | .B \-\-scan |
e0fe762a N |
1335 | is not given and not all expected drives were listed, then the array |
1336 | is not started (to guard against usage errors). To insist that the | |
1337 | array be started in this case (as may work for RAID1, 4, 5, 6, or 10), | |
1338 | give the | |
7e23fc43 | 1339 | .B \-\-run |
cd29a5c8 | 1340 | flag. |
52826846 | 1341 | |
e0fe762a N |
1342 | If |
1343 | .I udev | |
1344 | is active, | |
1345 | .I mdadm | |
1346 | does not create any entries in | |
dd0781e5 | 1347 | .B /dev |
e0fe762a N |
1348 | but leaves that to |
1349 | .IR udev . | |
1350 | It does record information in | |
1351 | .B /var/run/mdadm/map | |
1352 | which will allow | |
1353 | .I udev | |
1354 | to choose the correct name. | |
dd0781e5 | 1355 | |
e0fe762a N |
1356 | If |
1357 | .I mdadm | |
1358 | detects that udev is not configured, it will create the devices in | |
1359 | .B /dev | |
1360 | itself. | |
dd0781e5 | 1361 | |
e0fe762a N |
1362 | In Linux kernels prior to version 2.6.28 there were two distinctly |
1363 | different types of md devices that could be created: one that could be | |
1364 | partitioned using standard partitioning tools and one that could not. | |
1365 | Since 2.6.28 that distinction is no longer relevant as both type of | |
1366 | devices can be partitioned. | |
1367 | .I mdadm | |
1368 | will normally create the type that originally could not be partitioned | |
1369 | as it has a well defined major number (9). | |
dd0781e5 | 1370 | |
e0fe762a N |
1371 | Prior to 2.6.28, it is important that mdadm chooses the correct type |
1372 | of array device to use. This can be controlled with the | |
1373 | .B \-\-auto | |
1374 | option. In particular, a value of "mdp" or "part" or "p" tells mdadm | |
1375 | to use a partitionable device rather than the default. | |
dd0781e5 | 1376 | |
e0fe762a N |
1377 | In the no-udev case, the value given to |
1378 | .B \-\-auto | |
1379 | can be suffixed by a number. This tells | |
1380 | .I mdadm | |
1381 | to create that number of partition devices rather than the default of 4. | |
dd0781e5 | 1382 | |
e0fe762a | 1383 | The value given to |
7e23fc43 | 1384 | .B \-\-auto |
e0fe762a N |
1385 | can also be given in the configuration file as a word starting |
1386 | .B auto= | |
1387 | on the ARRAY line for the relevant array. | |
52826846 | 1388 | |
41a3b72a NB |
1389 | .SS Auto Assembly |
1390 | When | |
7e23fc43 | 1391 | .B \-\-assemble |
41a3b72a | 1392 | is used with |
7e23fc43 | 1393 | .B \-\-scan |
41a3b72a NB |
1394 | and no devices are listed, |
1395 | .I mdadm | |
1396 | will first attempt to assemble all the arrays listed in the config | |
1397 | file. | |
1398 | ||
e0fe762a N |
1399 | In no array at listed in the config (other than those marked |
1400 | .BR <ignore> ) | |
1401 | it will look through the available devices for possible arrays and | |
1402 | will try to assemble anything that it finds. Arrays which are tagged | |
1403 | as belonging to the given homehost will be assembled and started | |
1404 | normally. Arrays which do not obviously belong to this host are given | |
1405 | names that are expected not to conflict with anything local, and are | |
1406 | started "read-auto" so that nothing is written to any device until the | |
1407 | array is written to. i.e. automatic resync etc is delayed. | |
41a3b72a NB |
1408 | |
1409 | If | |
1410 | .I mdadm | |
1411 | finds a consistent set of devices that look like they should comprise | |
1412 | an array, and if the superblock is tagged as belonging to the given | |
1413 | home host, it will automatically choose a device name and try to | |
1414 | assemble the array. If the array uses version-0.90 metadata, then the | |
1415 | .B minor | |
1416 | number as recorded in the superblock is used to create a name in | |
1417 | .B /dev/md/ | |
1418 | so for example | |
1419 | .BR /dev/md/3 . | |
1420 | If the array uses version-1 metadata, then the | |
1421 | .B name | |
1422 | from the superblock is used to similarly create a name in | |
e0fe762a | 1423 | .B /dev/md/ |
93e790af | 1424 | (the name will have any 'host' prefix stripped first). |
41a3b72a | 1425 | |
e0fe762a | 1426 | .ig XX |
41a3b72a NB |
1427 | If |
1428 | .I mdadm | |
1429 | cannot find any array for the given host at all, and if | |
7e23fc43 | 1430 | .B \-\-auto\-update\-homehost |
41a3b72a NB |
1431 | is given, then |
1432 | .I mdadm | |
1433 | will search again for any array (not just an array created for this | |
1434 | host) and will assemble each assuming | |
7e23fc43 | 1435 | .BR \-\-update=homehost . |
41a3b72a NB |
1436 | This will change the host tag in the superblock so that on the next run, |
1437 | these arrays will be found without the second pass. The intention of | |
1438 | this feature is to support transitioning a set of md arrays to using | |
1439 | homehost tagging. | |
1440 | ||
1441 | The reason for requiring arrays to be tagged with the homehost for | |
1442 | auto assembly is to guard against problems that can arise when moving | |
1443 | devices from one host to another. | |
e0fe762a | 1444 | .XX |
41a3b72a | 1445 | |
cd29a5c8 | 1446 | .SH BUILD MODE |
52826846 | 1447 | |
cd29a5c8 NB |
1448 | .HP 12 |
1449 | Usage: | |
7e23fc43 | 1450 | .B mdadm \-\-build |
93e790af | 1451 | .I md-device |
7e23fc43 PS |
1452 | .BI \-\-chunk= X |
1453 | .BI \-\-level= Y | |
1454 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
1455 | .I devices |
1456 | ||
1457 | .PP | |
2ae555c3 | 1458 | This usage is similar to |
7e23fc43 | 1459 | .BR \-\-create . |
e0fe762a | 1460 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 1461 | these arrays there is no difference between initially creating the array and |
52826846 NB |
1462 | subsequently assembling the array, except that hopefully there is useful |
1463 | data there in the second case. | |
1464 | ||
e0fe762a N |
1465 | The level may raid0, linear, raid1, raid10, multipath, or faulty, or |
1466 | one of their synonyms. All devices must be listed and the array will | |
1467 | be started once complete. It will often be appropriate to use | |
1468 | .B \-\-assume\-clean | |
1469 | with levels raid1 or raid10. | |
cd29a5c8 NB |
1470 | |
1471 | .SH CREATE MODE | |
1472 | ||
1473 | .HP 12 | |
1474 | Usage: | |
7e23fc43 | 1475 | .B mdadm \-\-create |
93e790af | 1476 | .I md-device |
7e23fc43 PS |
1477 | .BI \-\-chunk= X |
1478 | .BI \-\-level= Y | |
cd29a5c8 | 1479 | .br |
7e23fc43 | 1480 | .BI \-\-raid\-devices= Z |
e0fe762a | 1481 | .I devices |
cd29a5c8 NB |
1482 | |
1483 | .PP | |
1484 | This usage will initialise a new md array, associate some devices with | |
1485 | it, and activate the array. | |
1486 | ||
e0fe762a N |
1487 | The named device will normally not exist when |
1488 | .I "mdadm \-\-create" | |
1489 | is run, but will be created by | |
1490 | .I udev | |
1491 | once the array becomes active. | |
dd0781e5 | 1492 | |
e0fe762a N |
1493 | As devices are added, they are checked to see if they contain RAID |
1494 | superblocks or filesystems. They are also checked to see if the variance in | |
cd29a5c8 NB |
1495 | device size exceeds 1%. |
1496 | ||
1497 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 1498 | the presence of a |
7e23fc43 | 1499 | .B \-\-run |
cd29a5c8 NB |
1500 | can override this caution. |
1501 | ||
2d465520 | 1502 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 1503 | give the word "\fBmissing\fP" |
2d465520 | 1504 | in place of a device name. This will cause |
51ac42e3 | 1505 | .I mdadm |
2d465520 NB |
1506 | to leave the corresponding slot in the array empty. |
1507 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 1508 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
1509 | For a RAID1 array, only one real device needs to be given. All of the |
1510 | others can be | |
d013a55e | 1511 | "\fBmissing\fP". |
2d465520 | 1512 | |
feb716e9 | 1513 | When creating a RAID5 array, |
51ac42e3 | 1514 | .I mdadm |
feb716e9 | 1515 | will automatically create a degraded array with an extra spare drive. |
e0fe762a N |
1516 | This is because building the spare into a degraded array is in general |
1517 | faster than resyncing the parity on a non-degraded, but not clean, | |
1518 | array. This feature can be overridden with the | |
7e23fc43 | 1519 | .B \-\-force |
feb716e9 NB |
1520 | option. |
1521 | ||
0ee4da98 | 1522 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
1523 | required. |
1524 | If this is not given with the | |
7e23fc43 | 1525 | .B \-\-name |
41a3b72a NB |
1526 | option, |
1527 | .I mdadm | |
0ee4da98 | 1528 | will choose a name based on the last component of the name of the |
41a3b72a NB |
1529 | device being created. So if |
1530 | .B /dev/md3 | |
1531 | is being created, then the name | |
1532 | .B 3 | |
1533 | will be chosen. | |
1534 | If | |
1535 | .B /dev/md/home | |
1536 | is being created, then the name | |
1537 | .B home | |
1538 | will be used. | |
1539 | ||
e0fe762a N |
1540 | When creating a partition based array, using |
1541 | .I mdadm | |
1542 | with version-1.x metadata, the partition type should be set to | |
e0f31f50 | 1543 | .B 0xDA |
e0fe762a | 1544 | (non fs-data). This type selection allows for greater precision since |
e0f31f50 PC |
1545 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], |
1546 | might create problems in the event of array recovery through a live cdrom. | |
1547 | ||
3d3dd91e NB |
1548 | A new array will normally get a randomly assigned 128bit UUID which is |
1549 | very likely to be unique. If you have a specific need, you can choose | |
1550 | a UUID for the array by giving the | |
7e23fc43 | 1551 | .B \-\-uuid= |
3d3dd91e NB |
1552 | option. Be warned that creating two arrays with the same UUID is a |
1553 | recipe for disaster. Also, using | |
7e23fc43 | 1554 | .B \-\-uuid= |
3d3dd91e | 1555 | when creating a v0.90 array will silently override any |
7e23fc43 | 1556 | .B \-\-homehost= |
3d3dd91e | 1557 | setting. |
e43d0cda NB |
1558 | .\"If the |
1559 | .\".B \-\-size | |
1560 | .\"option is given, it is not necessary to list any component-devices in this command. | |
1561 | .\"They can be added later, before a | |
1562 | .\".B \-\-run. | |
1563 | .\"If no | |
1564 | .\".B \-\-size | |
1565 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 1566 | |
8fd8d9c4 N |
1567 | When creating an array within a |
1568 | .B CONTAINER | |
1569 | .I mdadm | |
1570 | can be given either the list of devices to use, or simply the name of | |
1571 | the container. The former case gives control over which devices in | |
1572 | the container will be used for the array. The latter case allows | |
1573 | .I mdadm | |
1574 | to automatically choose which devices to use based on how much spare | |
1575 | space is available. | |
1576 | ||
53e8b987 | 1577 | The General Management options that are valid with |
7e23fc43 | 1578 | .B \-\-create |
53e8b987 | 1579 | are: |
cd29a5c8 | 1580 | .TP |
7e23fc43 | 1581 | .B \-\-run |
dd0781e5 | 1582 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
1583 | be in use. |
1584 | ||
1585 | .TP | |
7e23fc43 | 1586 | .B \-\-readonly |
b3f1c093 | 1587 | start the array readonly \(em not supported yet. |
52826846 | 1588 | |
e0d19036 | 1589 | .SH MANAGE MODE |
cd29a5c8 NB |
1590 | .HP 12 |
1591 | Usage: | |
e0d19036 NB |
1592 | .B mdadm |
1593 | .I device | |
1594 | .I options... devices... | |
cd29a5c8 NB |
1595 | .PP |
1596 | ||
e0d19036 NB |
1597 | This usage will allow individual devices in an array to be failed, |
1598 | removed or added. It is possible to perform multiple operations with | |
e0fe762a | 1599 | on command. For example: |
e0d19036 | 1600 | .br |
7e23fc43 | 1601 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
1602 | .br |
1603 | will firstly mark | |
1604 | .B /dev/hda1 | |
1605 | as faulty in | |
1606 | .B /dev/md0 | |
1607 | and will then remove it from the array and finally add it back | |
2d465520 | 1608 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 1609 | command. |
e0d19036 | 1610 | |
e0fe762a N |
1611 | When a device is added to an active array, mdadm checks to see if it |
1612 | has metadata on it which suggests that it was recently a member of the | |
1613 | array. If it does, it tried to "re-add" the device. If there have | |
1614 | been no changes since the device was removed, or if the array has a | |
1615 | write-intent bitmap which has recorded whatever changes there were, | |
1616 | then the device will immediately become a full member of the array and | |
1617 | those differences recorded in the bitmap will be resolved. | |
1618 | ||
e0d19036 NB |
1619 | .SH MISC MODE |
1620 | .HP 12 | |
1621 | Usage: | |
9a9dab36 | 1622 | .B mdadm |
e0d19036 | 1623 | .I options ... |
e0fe762a | 1624 | .I devices ... |
e0d19036 | 1625 | .PP |
cd29a5c8 | 1626 | |
b5e64645 | 1627 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1628 | operate on distinct devices. The operations are: |
1629 | .TP | |
962a108f | 1630 | .B \-\-query |
e0d19036 NB |
1631 | The device is examined to see if it is |
1632 | (1) an active md array, or | |
1633 | (2) a component of an md array. | |
1634 | The information discovered is reported. | |
1635 | ||
1636 | .TP | |
962a108f | 1637 | .B \-\-detail |
2d465520 | 1638 | The device should be an active md device. |
e0fe762a | 1639 | .B mdadm |
2d465520 | 1640 | will display a detailed description of the array. |
7e23fc43 | 1641 | .B \-\-brief |
2d465520 | 1642 | or |
7e23fc43 | 1643 | .B \-\-scan |
2d465520 | 1644 | will cause the output to be less detailed and the format to be |
e0d19036 | 1645 | suitable for inclusion in |
9a9dab36 | 1646 | .BR /etc/mdadm.conf . |
feb716e9 NB |
1647 | The exit status of |
1648 | .I mdadm | |
1649 | will normally be 0 unless | |
1650 | .I mdadm | |
93e790af | 1651 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 1652 | .B \-\-test |
feb716e9 NB |
1653 | option is given, then the exit status will be: |
1654 | .RS | |
1655 | .TP | |
1656 | 0 | |
1657 | The array is functioning normally. | |
1658 | .TP | |
1659 | 1 | |
1660 | The array has at least one failed device. | |
1661 | .TP | |
1662 | 2 | |
a77be586 | 1663 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
1664 | .TP |
1665 | 4 | |
1666 | There was an error while trying to get information about the device. | |
1667 | .RE | |
cd29a5c8 | 1668 | |
4cce4069 DW |
1669 | .TP |
1670 | .B \-\-detail\-platform | |
e0fe762a | 1671 | Print detail of the platform's RAID capabilities (firmware / hardware |
4cce4069 DW |
1672 | topology). If the metadata is specified with |
1673 | .B \-e | |
1674 | or | |
1675 | .B \-\-metadata= | |
1676 | then the return status will be: | |
1677 | .RS | |
1678 | .TP | |
1679 | 0 | |
1680 | metadata successfully enumerated its platform components on this system | |
1681 | .TP | |
1682 | 1 | |
1683 | metadata is platform independent | |
1684 | .TP | |
1685 | 2 | |
1686 | metadata failed to find its platform components on this system | |
1687 | .RE | |
1688 | ||
e0d19036 | 1689 | .TP |
962a108f | 1690 | .B \-\-examine |
2d465520 | 1691 | The device should be a component of an md array. |
51ac42e3 | 1692 | .I mdadm |
2d465520 | 1693 | will read the md superblock of the device and display the contents. |
e0d19036 | 1694 | If |
7e23fc43 | 1695 | .B \-\-brief |
93e790af | 1696 | or |
7e23fc43 | 1697 | .B \-\-scan |
93e790af | 1698 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
1699 | are grouped together and reported in a single entry suitable |
1700 | for inclusion in | |
1701 | .BR /etc/mdadm.conf . | |
1702 | ||
2d465520 | 1703 | Having |
7e23fc43 | 1704 | .B \-\-scan |
e0d19036 NB |
1705 | without listing any devices will cause all devices listed in the |
1706 | config file to be examined. | |
1707 | ||
1708 | .TP | |
962a108f | 1709 | .B \-\-stop |
98c6faba NB |
1710 | The devices should be active md arrays which will be deactivated, as |
1711 | long as they are not currently in use. | |
e0d19036 NB |
1712 | |
1713 | .TP | |
962a108f | 1714 | .B \-\-run |
e0d19036 NB |
1715 | This will fully activate a partially assembled md array. |
1716 | ||
1717 | .TP | |
962a108f | 1718 | .B \-\-readonly |
e0d19036 NB |
1719 | This will mark an active array as read-only, providing that it is |
1720 | not currently being used. | |
1721 | ||
1722 | .TP | |
962a108f | 1723 | .B \-\-readwrite |
e0d19036 NB |
1724 | This will change a |
1725 | .B readonly | |
1726 | array back to being read/write. | |
1727 | ||
2d465520 | 1728 | .TP |
962a108f | 1729 | .B \-\-scan |
2d465520 | 1730 | For all operations except |
7e23fc43 PS |
1731 | .BR \-\-examine , |
1732 | .B \-\-scan | |
2d465520 NB |
1733 | will cause the operation to be applied to all arrays listed in |
1734 | .BR /proc/mdstat . | |
1735 | For | |
7e23fc43 PS |
1736 | .BR \-\-examine, |
1737 | .B \-\-scan | |
2d465520 NB |
1738 | causes all devices listed in the config file to be examined. |
1739 | ||
e0d19036 NB |
1740 | .SH MONITOR MODE |
1741 | ||
cd29a5c8 NB |
1742 | .HP 12 |
1743 | Usage: | |
7e23fc43 | 1744 | .B mdadm \-\-monitor |
e0d19036 NB |
1745 | .I options... devices... |
1746 | ||
cd29a5c8 | 1747 | .PP |
e0d19036 | 1748 | This usage causes |
51ac42e3 | 1749 | .I mdadm |
e0d19036 NB |
1750 | to periodically poll a number of md arrays and to report on any events |
1751 | noticed. | |
51ac42e3 | 1752 | .I mdadm |
e0d19036 NB |
1753 | will never exit once it decides that there are arrays to be checked, |
1754 | so it should normally be run in the background. | |
1755 | ||
2d465520 | 1756 | As well as reporting events, |
51ac42e3 | 1757 | .I mdadm |
2d465520 NB |
1758 | may move a spare drive from one array to another if they are in the |
1759 | same | |
1760 | .B spare-group | |
a9d69660 | 1761 | and if the destination array has a failed drive but no spares. |
2d465520 | 1762 | |
e0d19036 | 1763 | If any devices are listed on the command line, |
51ac42e3 | 1764 | .I mdadm |
e0fe762a | 1765 | will only monitor those devices. Otherwise all arrays listed in the |
e0d19036 | 1766 | configuration file will be monitored. Further, if |
7e23fc43 | 1767 | .B \-\-scan |
e0d19036 NB |
1768 | is given, then any other md devices that appear in |
1769 | .B /proc/mdstat | |
1770 | will also be monitored. | |
1771 | ||
1772 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 1773 | These events are passed to a separate program (if specified) and may |
2d465520 | 1774 | be mailed to a given E-mail address. |
e0d19036 | 1775 | |
93e790af SW |
1776 | When passing events to a program, the program is run once for each event, |
1777 | and is given 2 or 3 command-line arguments: the first is the | |
1778 | name of the event (see below), the second is the name of the | |
bd526cee | 1779 | md device which is affected, and the third is the name of a related |
93e790af | 1780 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
1781 | |
1782 | If | |
7e23fc43 | 1783 | .B \-\-scan |
e0d19036 NB |
1784 | is given, then a program or an E-mail address must be specified on the |
1785 | command line or in the config file. If neither are available, then | |
51ac42e3 | 1786 | .I mdadm |
e0d19036 NB |
1787 | will not monitor anything. |
1788 | Without | |
93e790af | 1789 | .B \-\-scan, |
51ac42e3 | 1790 | .I mdadm |
2d465520 | 1791 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
1792 | no program or email is given, then each event is reported to |
1793 | .BR stdout . | |
cd29a5c8 | 1794 | |
e0d19036 NB |
1795 | The different events are: |
1796 | ||
1797 | .RS 4 | |
1798 | .TP | |
1799 | .B DeviceDisappeared | |
2d465520 | 1800 | An md array which previously was configured appears to no longer be |
773135f5 | 1801 | configured. (syslog priority: Critical) |
e0d19036 | 1802 | |
b8f72a62 NB |
1803 | If |
1804 | .I mdadm | |
1805 | was told to monitor an array which is RAID0 or Linear, then it will | |
1806 | report | |
1807 | .B DeviceDisappeared | |
1808 | with the extra information | |
1809 | .BR Wrong-Level . | |
1810 | This is because RAID0 and Linear do not support the device-failed, | |
1811 | hot-spare and resync operations which are monitored. | |
1812 | ||
e0d19036 NB |
1813 | .TP |
1814 | .B RebuildStarted | |
773135f5 | 1815 | An md array started reconstruction. (syslog priority: Warning) |
e0d19036 NB |
1816 | |
1817 | .TP | |
1818 | .BI Rebuild NN | |
1819 | Where | |
1820 | .I NN | |
1821 | is 20, 40, 60, or 80, this indicates that rebuild has passed that many | |
773135f5 | 1822 | percentage of the total. (syslog priority: Warning) |
e0d19036 | 1823 | |
98c6faba NB |
1824 | .TP |
1825 | .B RebuildFinished | |
1826 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 1827 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 1828 | |
e0d19036 NB |
1829 | .TP |
1830 | .B Fail | |
773135f5 NB |
1831 | An active component device of an array has been marked as |
1832 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
1833 | |
1834 | .TP | |
1835 | .B FailSpare | |
1836 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 1837 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
1838 | |
1839 | .TP | |
1840 | .B SpareActive | |
1841 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 1842 | device has been successfully rebuilt and has been made active. |
773135f5 | 1843 | (syslog priority: Info) |
e0d19036 NB |
1844 | |
1845 | .TP | |
1846 | .B NewArray | |
1847 | A new md array has been detected in the | |
1848 | .B /proc/mdstat | |
e0fe762a | 1849 | file. (syslog priority: Info) |
e0d19036 | 1850 | |
aa88f531 NB |
1851 | .TP |
1852 | .B DegradedArray | |
1853 | A newly noticed array appears to be degraded. This message is not | |
1854 | generated when | |
1855 | .I mdadm | |
1856 | notices a drive failure which causes degradation, but only when | |
1857 | .I mdadm | |
1858 | notices that an array is degraded when it first sees the array. | |
93e790af | 1859 | (syslog priority: Critical) |
aa88f531 | 1860 | |
e0d19036 NB |
1861 | .TP |
1862 | .B MoveSpare | |
1863 | A spare drive has been moved from one array in a | |
1864 | .B spare-group | |
1865 | to another to allow a failed drive to be replaced. | |
773135f5 | 1866 | (syslog priority: Info) |
e0d19036 | 1867 | |
b8f72a62 NB |
1868 | .TP |
1869 | .B SparesMissing | |
1870 | If | |
1871 | .I mdadm | |
1872 | has been told, via the config file, that an array should have a certain | |
1873 | number of spare devices, and | |
1874 | .I mdadm | |
93e790af | 1875 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
1876 | array, it will report a |
1877 | .B SparesMissing | |
1878 | message. | |
d1732eeb | 1879 | (syslog priority: Warning) |
b8f72a62 | 1880 | |
98c6faba NB |
1881 | .TP |
1882 | .B TestMessage | |
1883 | An array was found at startup, and the | |
7e23fc43 | 1884 | .B \-\-test |
98c6faba | 1885 | flag was given. |
773135f5 | 1886 | (syslog priority: Info) |
e0d19036 NB |
1887 | .RE |
1888 | ||
1889 | Only | |
93e790af SW |
1890 | .B Fail, |
1891 | .B FailSpare, | |
1892 | .B DegradedArray, | |
1893 | .B SparesMissing | |
e0d19036 | 1894 | and |
98c6faba | 1895 | .B TestMessage |
e0d19036 | 1896 | cause Email to be sent. All events cause the program to be run. |
93e790af | 1897 | The program is run with two or three arguments: the event |
e0d19036 NB |
1898 | name, the array device and possibly a second device. |
1899 | ||
1900 | Each event has an associated array device (e.g. | |
1901 | .BR /dev/md1 ) | |
1902 | and possibly a second device. For | |
1903 | .BR Fail , | |
1904 | .BR FailSpare , | |
1905 | and | |
1906 | .B SpareActive | |
1907 | the second device is the relevant component device. | |
1908 | For | |
1909 | .B MoveSpare | |
1910 | the second device is the array that the spare was moved from. | |
1911 | ||
1912 | For | |
51ac42e3 | 1913 | .I mdadm |
e0d19036 | 1914 | to move spares from one array to another, the different arrays need to |
93e790af | 1915 | be labeled with the same |
e0d19036 NB |
1916 | .B spare-group |
1917 | in the configuration file. The | |
1918 | .B spare-group | |
93e790af | 1919 | name can be any string; it is only necessary that different spare |
2d465520 | 1920 | groups use different names. |
e0d19036 NB |
1921 | |
1922 | When | |
51ac42e3 | 1923 | .I mdadm |
93e790af | 1924 | detects that an array in a spare group has fewer active |
e0d19036 NB |
1925 | devices than necessary for the complete array, and has no spare |
1926 | devices, it will look for another array in the same spare group that | |
1927 | has a full complement of working drive and a spare. It will then | |
1928 | attempt to remove the spare from the second drive and add it to the | |
1929 | first. | |
1930 | If the removal succeeds but the adding fails, then it is added back to | |
1931 | the original array. | |
1932 | ||
dd0781e5 NB |
1933 | .SH GROW MODE |
1934 | The GROW mode is used for changing the size or shape of an active | |
1935 | array. | |
1936 | For this to work, the kernel must support the necessary change. | |
2ae555c3 | 1937 | Various types of growth are being added during 2.6 development, |
e0fe762a | 1938 | including restructuring a RAID5 array to have more active devices. |
dd0781e5 | 1939 | |
dfd4d8ee NB |
1940 | Currently the only support available is to |
1941 | .IP \(bu 4 | |
1942 | change the "size" attribute | |
1943 | for RAID1, RAID5 and RAID6. | |
1944 | .IP \(bu 4 | |
e5669f40 | 1945 | increase the "raid\-devices" attribute of RAID1, RAID5, and RAID6. |
dfd4d8ee | 1946 | .IP \(bu 4 |
93e790af | 1947 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 1948 | remove a write-intent bitmap from such an array. |
dfd4d8ee | 1949 | .PP |
dd0781e5 | 1950 | |
8fd8d9c4 N |
1951 | GROW mode is not currently supported for |
1952 | .B CONTAINERS | |
1953 | or arrays inside containers. | |
1954 | ||
2ae555c3 | 1955 | .SS SIZE CHANGES |
fe80f49b | 1956 | Normally when an array is built the "size" it taken from the smallest |
dd0781e5 NB |
1957 | of the drives. If all the small drives in an arrays are, one at a |
1958 | time, removed and replaced with larger drives, then you could have an | |
1959 | array of large drives with only a small amount used. In this | |
1960 | situation, changing the "size" with "GROW" mode will allow the extra | |
1961 | space to start being used. If the size is increased in this way, a | |
1962 | "resync" process will start to make sure the new parts of the array | |
1963 | are synchronised. | |
1964 | ||
1965 | Note that when an array changes size, any filesystem that may be | |
1966 | stored in the array will not automatically grow to use the space. The | |
1967 | filesystem will need to be explicitly told to use the extra space. | |
1968 | ||
e0fe762a N |
1969 | Also the size of an array cannot be changed while it has an active |
1970 | bitmap. If an array has a bitmap, it must be removed before the size | |
1971 | can be changed. Once the change it complete a new bitmap can be created. | |
1972 | ||
1973 | .SS RAID\-DEVICES CHANGES | |
2ae555c3 | 1974 | |
dd0781e5 NB |
1975 | A RAID1 array can work with any number of devices from 1 upwards |
1976 | (though 1 is not very useful). There may be times which you want to | |
1977 | increase or decrease the number of active devices. Note that this is | |
1978 | different to hot-add or hot-remove which changes the number of | |
1979 | inactive devices. | |
1980 | ||
1981 | When reducing the number of devices in a RAID1 array, the slots which | |
1982 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 1983 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
1984 | |
1985 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 1986 | present will be activated immediately. |
dd0781e5 | 1987 | |
2ae555c3 NB |
1988 | Increasing the number of active devices in a RAID5 is much more |
1989 | effort. Every block in the array will need to be read and written | |
1990 | back to a new location. From 2.6.17, the Linux Kernel is able to do | |
e0fe762a | 1991 | this safely, including restarting an interrupted "reshape". |
2ae555c3 | 1992 | |
e0fe762a | 1993 | When relocating the first few stripes on a RAID5, it is not possible |
2ae555c3 NB |
1994 | to keep the data on disk completely consistent and crash-proof. To |
1995 | provide the required safety, mdadm disables writes to the array while | |
1996 | this "critical section" is reshaped, and takes a backup of the data | |
1997 | that is in that section. This backup is normally stored in any spare | |
1998 | devices that the array has, however it can also be stored in a | |
1999 | separate file specified with the | |
7e23fc43 | 2000 | .B \-\-backup\-file |
2ae555c3 NB |
2001 | option. If this option is used, and the system does crash during the |
2002 | critical period, the same file must be passed to | |
7e23fc43 | 2003 | .B \-\-assemble |
2ae555c3 NB |
2004 | to restore the backup and reassemble the array. |
2005 | ||
2006 | .SS BITMAP CHANGES | |
2007 | ||
2008 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 2009 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b | 2010 | can be added. Note that if you add a bitmap stored in a file which is |
e0fe762a | 2011 | in a filesystem that is on the RAID array being affected, the system |
fe80f49b NB |
2012 | will deadlock. The bitmap must be on a separate filesystem. |
2013 | ||
8382f19b NB |
2014 | .SH INCREMENTAL MODE |
2015 | ||
2016 | .HP 12 | |
2017 | Usage: | |
7e23fc43 PS |
2018 | .B mdadm \-\-incremental |
2019 | .RB [ \-\-run ] | |
2020 | .RB [ \-\-quiet ] | |
8382f19b NB |
2021 | .I component-device |
2022 | .HP 12 | |
2023 | Usage: | |
7e23fc43 | 2024 | .B mdadm \-\-incremental \-\-rebuild |
8382f19b NB |
2025 | .HP 12 |
2026 | Usage: | |
7e23fc43 | 2027 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b | 2028 | |
8382f19b NB |
2029 | .PP |
2030 | This mode is designed to be used in conjunction with a device | |
2031 | discovery system. As devices are found in a system, they can be | |
2032 | passed to | |
7e23fc43 | 2033 | .B "mdadm \-\-incremental" |
8382f19b NB |
2034 | to be conditionally added to an appropriate array. |
2035 | ||
8fd8d9c4 N |
2036 | If the device passed is a |
2037 | .B CONTAINER | |
2038 | device created by a previous call to | |
2039 | .IR mdadm , | |
2040 | then rather than trying to add that device to an array, all the arrays | |
2041 | described by the metadata of the container will be started. | |
2042 | ||
8382f19b NB |
2043 | .I mdadm |
2044 | performs a number of tests to determine if the device is part of an | |
93e790af | 2045 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
2046 | is found, or can be created, |
2047 | .I mdadm | |
2048 | adds the device to the array and conditionally starts the array. | |
2049 | ||
2050 | Note that | |
2051 | .I mdadm | |
2052 | will only add devices to an array which were previously working | |
2053 | (active or spare) parts of that array. It does not currently support | |
2054 | automatic inclusion of a new drive as a spare in some array. | |
2055 | ||
8382f19b NB |
2056 | The tests that |
2057 | .I mdadm | |
2058 | makes are as follow: | |
2059 | .IP + | |
2060 | Is the device permitted by | |
2061 | .BR mdadm.conf ? | |
2062 | That is, is it listed in a | |
2063 | .B DEVICES | |
2064 | line in that file. If | |
2065 | .B DEVICES | |
2066 | is absent then the default it to allow any device. Similar if | |
2067 | .B DEVICES | |
2068 | contains the special word | |
2069 | .B partitions | |
2070 | then any device is allowed. Otherwise the device name given to | |
2071 | .I mdadm | |
2072 | must match one of the names or patterns in a | |
2073 | .B DEVICES | |
2074 | line. | |
2075 | ||
2076 | .IP + | |
2077 | Does the device have a valid md superblock. If a specific metadata | |
2078 | version is request with | |
7e23fc43 | 2079 | .B \-\-metadata |
8382f19b | 2080 | or |
7e23fc43 | 2081 | .B \-e |
8382f19b NB |
2082 | then only that style of metadata is accepted, otherwise |
2083 | .I mdadm | |
2084 | finds any known version of metadata. If no | |
2085 | .I md | |
2086 | metadata is found, the device is rejected. | |
2087 | ||
e0fe762a | 2088 | .ig XX |
8382f19b NB |
2089 | .IP + |
2090 | Does the metadata match an expected array? | |
2091 | The metadata can match in two ways. Either there is an array listed | |
2092 | in | |
2093 | .B mdadm.conf | |
2094 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 2095 | or by minor-number), or the array was created with a |
8382f19b | 2096 | .B homehost |
93e790af | 2097 | specified and that |
8382f19b | 2098 | .B homehost |
93e790af | 2099 | matches the one in |
8382f19b NB |
2100 | .B mdadm.conf |
2101 | or on the command line. | |
2102 | If | |
2103 | .I mdadm | |
2104 | is not able to positively identify the array as belonging to the | |
2105 | current host, the device will be rejected. | |
e0fe762a | 2106 | .XX |
8382f19b | 2107 | |
8382f19b | 2108 | .I mdadm |
93e790af | 2109 | keeps a list of arrays that it has partially assembled in |
8382f19b NB |
2110 | .B /var/run/mdadm/map |
2111 | (or | |
2112 | .B /var/run/mdadm.map | |
e0fe762a N |
2113 | if the directory doesn't exist. Or maybe even |
2114 | .BR /dev/.mdadm.map ). | |
2115 | If no array exists which matches | |
8382f19b NB |
2116 | the metadata on the new device, |
2117 | .I mdadm | |
2118 | must choose a device name and unit number. It does this based on any | |
2119 | name given in | |
2120 | .B mdadm.conf | |
2121 | or any name information stored in the metadata. If this name | |
2122 | suggests a unit number, that number will be used, otherwise a free | |
2123 | unit number will be chosen. Normally | |
2124 | .I mdadm | |
2125 | will prefer to create a partitionable array, however if the | |
2126 | .B CREATE | |
2127 | line in | |
2128 | .B mdadm.conf | |
2129 | suggests that a non-partitionable array is preferred, that will be | |
2130 | honoured. | |
2131 | ||
e0fe762a N |
2132 | If the array is not found in the config file and its metadata does not |
2133 | identify it as belonging to the "homehost", then | |
2134 | .I mdadm | |
2135 | will choose a name for the array which is certain not to conflict with | |
2136 | any array which does belong to this host. It does this be adding an | |
2137 | underscore and a small number to the name preferred by the metadata. | |
2138 | ||
8382f19b NB |
2139 | Once an appropriate array is found or created and the device is added, |
2140 | .I mdadm | |
2141 | must decide if the array is ready to be started. It will | |
2142 | normally compare the number of available (non-spare) devices to the | |
2143 | number of devices that the metadata suggests need to be active. If | |
2144 | there are at least that many, the array will be started. This means | |
2145 | that if any devices are missing the array will not be restarted. | |
2146 | ||
2147 | As an alternative, | |
7e23fc43 | 2148 | .B \-\-run |
8382f19b | 2149 | may be passed to |
51ac42e3 | 2150 | .I mdadm |
8382f19b | 2151 | in which case the array will be run as soon as there are enough |
e0fe762a N |
2152 | devices present for the data to be accessible. For a RAID1, that |
2153 | means one device will start the array. For a clean RAID5, the array | |
8382f19b NB |
2154 | will be started as soon as all but one drive is present. |
2155 | ||
93e790af | 2156 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
2157 | be known that all device discovery has completed, then |
2158 | .br | |
7e23fc43 | 2159 | .B " mdadm \-IRs" |
8382f19b NB |
2160 | .br |
2161 | can be run which will try to start all arrays that are being | |
2162 | incrementally assembled. They are started in "read-auto" mode in | |
2163 | which they are read-only until the first write request. This means | |
2164 | that no metadata updates are made and no attempt at resync or recovery | |
2165 | happens. Further devices that are found before the first write can | |
2166 | still be added safely. | |
2167 | ||
5545fa6d DW |
2168 | .SH ENVIRONMENT |
2169 | This section describes environment variables that affect how mdadm | |
2170 | operates. | |
2171 | ||
2172 | .TP | |
2173 | .B MDADM_NO_MDMON | |
2174 | Setting this value to 1 will prevent mdadm from automatically launching | |
2175 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
2176 | ||
8fd8d9c4 N |
2177 | .TP |
2178 | .B MDADM_NO_UDEV | |
2179 | Normally, | |
2180 | .I mdadm | |
2181 | does not create any device nodes in /dev, but leaves that task to | |
2182 | .IR udev . | |
2183 | If | |
2184 | .I udev | |
2185 | appears not to be configured, or if this environment variable is set | |
2186 | to '1', the | |
2187 | .I mdadm | |
2188 | will create and devices that are needed. | |
2189 | ||
2d465520 NB |
2190 | .SH EXAMPLES |
2191 | ||
7e23fc43 | 2192 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 2193 | .br |
e0fe762a | 2194 | This will find out if a given device is a RAID array, or is part of |
5787fa49 | 2195 | one, and will provide brief information about the device. |
2d465520 | 2196 | |
7e23fc43 | 2197 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 2198 | .br |
93e790af | 2199 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 2200 | file. This command will typically go in a system startup file. |
2d465520 | 2201 | |
7e23fc43 | 2202 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 2203 | .br |
93e790af | 2204 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 2205 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 2206 | |
7e23fc43 | 2207 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 2208 | .br |
5787fa49 NB |
2209 | If (and only if) there is an Email address or program given in the |
2210 | standard config file, then | |
2211 | monitor the status of all arrays listed in that file by | |
2212 | polling them ever 2 minutes. | |
2d465520 | 2213 | |
7e23fc43 | 2214 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 2215 | .br |
5787fa49 | 2216 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 2217 | |
2d465520 | 2218 | .br |
7e23fc43 | 2219 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 2220 | .br |
7e23fc43 | 2221 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 2222 | .br |
5787fa49 NB |
2223 | This will create a prototype config file that describes currently |
2224 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
2225 | This file should be reviewed before being used as it may |
2226 | contain unwanted detail. | |
2227 | ||
7e23fc43 | 2228 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 2229 | .br |
7e23fc43 | 2230 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
2231 | .br |
2232 | This will find arrays which could be assembled from existing IDE and | |
2233 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 2234 | format of a config file. |
2d465520 NB |
2235 | This file is very likely to contain unwanted detail, particularly |
2236 | the | |
2237 | .B devices= | |
5787fa49 NB |
2238 | entries. It should be reviewed and edited before being used as an |
2239 | actual config file. | |
2d465520 | 2240 | |
7e23fc43 | 2241 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 2242 | .br |
7e23fc43 | 2243 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
2244 | .br |
2245 | Create a list of devices by reading | |
2246 | .BR /proc/partitions , | |
2247 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 2248 | that were found. |
2d465520 | 2249 | |
7e23fc43 | 2250 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 2251 | .br |
5787fa49 NB |
2252 | Scan all partitions and devices listed in |
2253 | .BR /proc/partitions | |
2254 | and assemble | |
2255 | .B /dev/md0 | |
2256 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 2257 | |
7e23fc43 | 2258 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm" |
d013a55e NB |
2259 | .br |
2260 | If config file contains a mail address or alert program, run mdadm in | |
2261 | the background in monitor mode monitoring all md devices. Also write | |
2262 | pid of mdadm daemon to | |
2263 | .BR /var/run/mdadm . | |
2264 | ||
7e23fc43 | 2265 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
2266 | .br |
2267 | Try to incorporate newly discovered device into some array as | |
2268 | appropriate. | |
2269 | ||
7e23fc43 | 2270 | .B " mdadm \-\-incremental \-\-rebuild \-\-run \-\-scan" |
8382f19b NB |
2271 | .br |
2272 | Rebuild the array map from any current arrays, and then start any that | |
2273 | can be started. | |
2274 | ||
b80da661 NB |
2275 | .B " mdadm /dev/md4 --fail detached --remove detached" |
2276 | .br | |
2277 | Any devices which are components of /dev/md4 will be marked as faulty | |
2278 | and then remove from the array. | |
2279 | ||
8fd8d9c4 N |
2280 | .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]" |
2281 | .br | |
2282 | Create a DDF array over 6 devices. | |
2283 | ||
2284 | .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf" | |
2285 | .br | |
e0fe762a | 2286 | Create a RAID5 array over any 3 devices in the given DDF set. Use |
8fd8d9c4 N |
2287 | only 30 gigabytes of each device. |
2288 | ||
2289 | .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]" | |
2290 | .br | |
2291 | Assemble a pre-exist ddf array. | |
2292 | ||
2293 | .B " mdadm -I /dev/md/ddf1" | |
2294 | .br | |
2295 | Assemble all arrays contained in the ddf array, assigning names as | |
2296 | appropriate. | |
2297 | ||
7e23fc43 | 2298 | .B " mdadm \-\-create \-\-help" |
2d465520 | 2299 | .br |
2ae555c3 | 2300 | Provide help about the Create mode. |
2d465520 | 2301 | |
7e23fc43 | 2302 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
2303 | .br |
2304 | Provide help about the format of the config file. | |
2d465520 | 2305 | |
7e23fc43 | 2306 | .B " mdadm \-\-help" |
5787fa49 NB |
2307 | .br |
2308 | Provide general help. | |
cd29a5c8 | 2309 | |
cd29a5c8 NB |
2310 | .SH FILES |
2311 | ||
2312 | .SS /proc/mdstat | |
2313 | ||
2ae555c3 NB |
2314 | If you're using the |
2315 | .B /proc | |
cd29a5c8 NB |
2316 | filesystem, |
2317 | .B /proc/mdstat | |
2d465520 | 2318 | lists all active md devices with information about them. |
51ac42e3 | 2319 | .I mdadm |
2d465520 | 2320 | uses this to find arrays when |
7e23fc43 | 2321 | .B \-\-scan |
2d465520 NB |
2322 | is given in Misc mode, and to monitor array reconstruction |
2323 | on Monitor mode. | |
2324 | ||
9a9dab36 | 2325 | .SS /etc/mdadm.conf |
cd29a5c8 | 2326 | |
11a3e71d NB |
2327 | The config file lists which devices may be scanned to see if |
2328 | they contain MD super block, and gives identifying information | |
2329 | (e.g. UUID) about known MD arrays. See | |
2330 | .BR mdadm.conf (5) | |
2331 | for more details. | |
cd29a5c8 | 2332 | |
8382f19b NB |
2333 | .SS /var/run/mdadm/map |
2334 | When | |
7e23fc43 | 2335 | .B \-\-incremental |
93e790af | 2336 | mode is used, this file gets a list of arrays currently being created. |
8382f19b NB |
2337 | If |
2338 | .B /var/run/mdadm | |
2339 | does not exist as a directory, then | |
2340 | .B /var/run/mdadm.map | |
e0fe762a N |
2341 | is used instead. If |
2342 | .B /var/run | |
2343 | is not available (as may be the case during early boot), | |
2344 | .B /dev/.mdadm.map | |
2345 | is used on the basis that | |
2346 | .B /dev | |
2347 | is usually available very early in boot. | |
8382f19b | 2348 | |
48f7b27a NB |
2349 | .SH DEVICE NAMES |
2350 | ||
48f7b27a | 2351 | .I mdadm |
8fd8d9c4 N |
2352 | understand two sorts of names for array devices. |
2353 | ||
2354 | The first is the so-called 'standard' format name, which matches the | |
2355 | names used by the kernel and which appear in | |
2356 | .IR /proc/mdstat . | |
2357 | ||
2358 | The second sort can be freely chosen, but must reside in | |
2359 | .IR /dev/md/ . | |
2360 | When giving a device name to | |
2361 | .I mdadm | |
2362 | to create or assemble an array, either full path name such as | |
2363 | .I /dev/md0 | |
2364 | or | |
2365 | .I /dev/md/home | |
2366 | can be given, or just the suffix of the second sort of name, such as | |
2367 | .I home | |
2368 | can be given. | |
2369 | ||
2370 | When | |
2371 | .I mdadm | |
e0fe762a N |
2372 | chooses device names during auto-assembly or incremental assembly, it |
2373 | will sometimes add a small sequence number to the end of the name to | |
2374 | avoid conflicted between multiple arrays that have the same name. If | |
8fd8d9c4 N |
2375 | .I mdadm |
2376 | can reasonably determine that the array really is meant for this host, | |
2377 | either by a hostname in the metadata, or by the presence of the array | |
e0fe762a N |
2378 | in /etc/mdadm.conf, then it will leave off the suffix if possible. |
2379 | Also if the homehost is specified as | |
2380 | .B <ignore> | |
2381 | .I mdadm | |
2382 | will only use a suffix if a different array of the same name already | |
2383 | exists or is listed in the config file. | |
48f7b27a NB |
2384 | |
2385 | The standard names for non-partitioned arrays (the only sort of md | |
8fd8d9c4 | 2386 | array available in 2.4 and earlier) are of the form |
48f7b27a NB |
2387 | .IP |
2388 | /dev/mdNN | |
48f7b27a NB |
2389 | .PP |
2390 | where NN is a number. | |
2391 | The standard names for partitionable arrays (as available from 2.6 | |
8fd8d9c4 | 2392 | onwards) are of the form |
48f7b27a | 2393 | .IP |
48f7b27a NB |
2394 | /dev/md_dNN |
2395 | .PP | |
2396 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
8fd8d9c4 N |
2397 | .PP |
2398 | From kernel version, 2.6.28 the "non-partitioned array" can actually | |
2399 | be partitioned. So the "md_dNN" names are no longer needed, and | |
2400 | partitions such as "/dev/mdNNpXX" are possible. | |
52826846 | 2401 | |
2d465520 | 2402 | .SH NOTE |
51ac42e3 | 2403 | .I mdadm |
2d465520 | 2404 | was previously known as |
51ac42e3 | 2405 | .IR mdctl . |
a9d69660 | 2406 | .P |
51ac42e3 | 2407 | .I mdadm |
a9d69660 | 2408 | is completely separate from the |
51ac42e3 | 2409 | .I raidtools |
a9d69660 NB |
2410 | package, and does not use the |
2411 | .I /etc/raidtab | |
2412 | configuration file at all. | |
2413 | ||
52826846 | 2414 | .SH SEE ALSO |
75f74377 | 2415 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 2416 | RAID, see: |
3cdfb6a7 | 2417 | .IP |
11cd8b79 | 2418 | .B http://linux\-raid.osdl.org/ |
75f74377 DG |
2419 | .PP |
2420 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
e43d0cda NB |
2421 | .\".PP |
2422 | .\"for new releases of the RAID driver check out: | |
2423 | .\" | |
2424 | .\".IP | |
e0fe762a | 2425 | .\".UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches |
e43d0cda NB |
2426 | .\"ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches |
2427 | .\".UE | |
2428 | .\".PP | |
2429 | .\"or | |
2430 | .\".IP | |
2431 | .\".UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2432 | .\"http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2433 | .\".UE | |
cd29a5c8 | 2434 | .PP |
2ae555c3 | 2435 | The latest version of |
a9d69660 NB |
2436 | .I mdadm |
2437 | should always be available from | |
cd29a5c8 | 2438 | .IP |
11cd8b79 N |
2439 | .B http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
2440 | .PP | |
2441 | Related man pages: | |
cd29a5c8 | 2442 | .PP |
e0fe762a | 2443 | .IR mdmon (8), |
a9d69660 NB |
2444 | .IR mdadm.conf (5), |
2445 | .IR md (4). | |
56eb10c0 | 2446 | .PP |
52826846 NB |
2447 | .IR raidtab (5), |
2448 | .IR raid0run (8), | |
2449 | .IR raidstop (8), | |
a9d69660 | 2450 | .IR mkraid (8). |