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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. | |
7f0066ba | 8 | .TH MDADM 8 "" v3.1 |
52826846 | 9 | .SH NAME |
9a9dab36 | 10 | mdadm \- manage MD devices |
cd29a5c8 | 11 | .I aka |
93e790af | 12 | Linux Software RAID |
cd29a5c8 | 13 | |
52826846 NB |
14 | .SH SYNOPSIS |
15 | ||
e0d19036 | 16 | .BI mdadm " [mode] <raiddevice> [options] <component-devices>" |
52826846 | 17 | |
2ae555c3 | 18 | .SH DESCRIPTION |
52826846 | 19 | RAID devices are virtual devices created from two or more |
e0fe762a | 20 | real block devices. This allows multiple devices (typically disk |
35cc5be4 | 21 | drives or partitions thereof) to be combined into a single device to |
cd29a5c8 | 22 | hold (for example) a single filesystem. |
2d465520 | 23 | Some RAID levels include redundancy and so can survive some degree of |
cd29a5c8 NB |
24 | device failure. |
25 | ||
2d465520 NB |
26 | Linux Software RAID devices are implemented through the md (Multiple |
27 | Devices) device driver. | |
cd29a5c8 NB |
28 | |
29 | Currently, Linux supports | |
30 | .B LINEAR | |
31 | md devices, | |
32 | .B RAID0 | |
33 | (striping), | |
34 | .B RAID1 | |
35 | (mirroring), | |
d013a55e NB |
36 | .BR RAID4 , |
37 | .BR RAID5 , | |
98c6faba | 38 | .BR RAID6 , |
1a7dfc35 | 39 | .BR RAID10 , |
b5e64645 | 40 | .BR MULTIPATH , |
90c8d668 | 41 | .BR FAULTY , |
cd29a5c8 | 42 | and |
90c8d668 | 43 | .BR CONTAINER . |
d013a55e | 44 | |
a9d69660 NB |
45 | .B MULTIPATH |
46 | is not a Software RAID mechanism, but does involve | |
93e790af | 47 | multiple devices: |
d013a55e | 48 | each device is a path to one common physical storage device. |
9652457e N |
49 | New installations should not use md/multipath as it is not well |
50 | supported and has no ongoing development. Use the Device Mapper based | |
51 | multipath-tools instead. | |
d013a55e | 52 | |
a9d69660 NB |
53 | .B FAULTY |
54 | is also not true RAID, and it only involves one device. It | |
b5e64645 | 55 | provides a layer over a true device that can be used to inject faults. |
52826846 | 56 | |
4cce4069 | 57 | .B CONTAINER |
8fd8d9c4 N |
58 | is different again. A |
59 | .B CONTAINER | |
60 | is a collection of devices that are | |
90c8d668 N |
61 | managed as a set. This is similar to the set of devices connected to |
62 | a hardware RAID controller. The set of devices may contain a number | |
9652457e | 63 | of different RAID arrays each utilising some (or all) of the blocks from a |
90c8d668 | 64 | number of the devices in the set. For example, two devices in a 5-device set |
9652457e | 65 | might form a RAID1 using the whole devices. The remaining three might |
90c8d668 N |
66 | have a RAID5 over the first half of each device, and a RAID0 over the |
67 | second half. | |
68 | ||
8fd8d9c4 N |
69 | With a |
70 | .BR CONTAINER , | |
71 | there is one set of metadata that describes all of | |
72 | the arrays in the container. So when | |
73 | .I mdadm | |
74 | creates a | |
75 | .B CONTAINER | |
9652457e N |
76 | device, the device just represents the metadata. Other normal arrays (RAID1 |
77 | etc) can be created inside the container. | |
52826846 NB |
78 | |
79 | .SH MODES | |
8382f19b | 80 | mdadm has several major modes of operation: |
cd29a5c8 NB |
81 | .TP |
82 | .B Assemble | |
93e790af | 83 | Assemble the components of a previously created |
e0fe762a | 84 | array into an active array. Components can be explicitly given |
2ae555c3 | 85 | or can be searched for. |
51ac42e3 | 86 | .I mdadm |
cd29a5c8 NB |
87 | checks that the components |
88 | do form a bona fide array, and can, on request, fiddle superblock | |
89 | information so as to assemble a faulty array. | |
90 | ||
91 | .TP | |
92 | .B Build | |
e0fe762a | 93 | Build an array that doesn't have per-device metadata (superblocks). For these |
a9d69660 NB |
94 | sorts of arrays, |
95 | .I mdadm | |
96 | cannot differentiate between initial creation and subsequent assembly | |
97 | of an array. It also cannot perform any checks that appropriate | |
93e790af | 98 | components have been requested. Because of this, the |
a9d69660 NB |
99 | .B Build |
100 | mode should only be used together with a complete understanding of | |
101 | what you are doing. | |
cd29a5c8 NB |
102 | |
103 | .TP | |
104 | .B Create | |
e0fe762a N |
105 | Create a new array with per-device metadata (superblocks). |
106 | Appropriate metadata is written to each device, and then the array | |
107 | comprising those devices is activated. A 'resync' process is started | |
108 | to make sure that the array is consistent (e.g. both sides of a mirror | |
109 | contain the same data) but the content of the device is left otherwise | |
110 | untouched. | |
111 | The array can be used as soon as it has been created. There is no | |
112 | need to wait for the initial resync to finish. | |
cd29a5c8 | 113 | |
cd29a5c8 NB |
114 | .TP |
115 | .B "Follow or Monitor" | |
5787fa49 | 116 | Monitor one or more md devices and act on any state changes. This is |
e0fe762a N |
117 | only meaningful for RAID1, 4, 5, 6, 10 or multipath arrays, as |
118 | only these have interesting state. RAID0 or Linear never have | |
98c6faba | 119 | missing, spare, or failed drives, so there is nothing to monitor. |
5787fa49 | 120 | |
dd0781e5 NB |
121 | .TP |
122 | .B "Grow" | |
123 | Grow (or shrink) an array, or otherwise reshape it in some way. | |
124 | Currently supported growth options including changing the active size | |
93e790af | 125 | of component devices and changing the number of active devices in RAID |
f24e2d6c N |
126 | levels 1/4/5/6, changing the RAID level between 1, 5, and 6, changing |
127 | the chunk size and layout for RAID5 and RAID5, as well as adding or | |
128 | removing a write-intent bitmap. | |
cd29a5c8 | 129 | |
8382f19b NB |
130 | .TP |
131 | .B "Incremental Assembly" | |
132 | Add a single device to an appropriate array. If the addition of the | |
133 | device makes the array runnable, the array will be started. | |
134 | This provides a convenient interface to a | |
135 | .I hot-plug | |
136 | system. As each device is detected, | |
137 | .I mdadm | |
138 | has a chance to include it in some array as appropriate. | |
9652457e | 139 | |
8fd8d9c4 N |
140 | If a |
141 | .B CONTAINER | |
142 | is passed to | |
143 | .I mdadm | |
144 | in this mode, then any arrays within that container will be assembled | |
145 | and started. | |
8382f19b | 146 | |
2ae555c3 NB |
147 | .TP |
148 | .B Manage | |
149 | This is for doing things to specific components of an array such as | |
150 | adding new spares and removing faulty devices. | |
151 | ||
152 | .TP | |
153 | .B Misc | |
154 | This is an 'everything else' mode that supports operations on active | |
155 | arrays, operations on component devices such as erasing old superblocks, and | |
156 | information gathering operations. | |
e43d0cda NB |
157 | .\"This mode allows operations on independent devices such as examine MD |
158 | .\"superblocks, erasing old superblocks and stopping active arrays. | |
2ae555c3 | 159 | |
1f48664b NB |
160 | .TP |
161 | .B Auto-detect | |
162 | This mode does not act on a specific device or array, but rather it | |
163 | requests the Linux Kernel to activate any auto-detected arrays. | |
52826846 NB |
164 | .SH OPTIONS |
165 | ||
2ae555c3 | 166 | .SH Options for selecting a mode are: |
52826846 | 167 | |
cd29a5c8 | 168 | .TP |
7e23fc43 | 169 | .BR \-A ", " \-\-assemble |
2d465520 | 170 | Assemble a pre-existing array. |
52826846 | 171 | |
cd29a5c8 | 172 | .TP |
7e23fc43 | 173 | .BR \-B ", " \-\-build |
cd29a5c8 | 174 | Build a legacy array without superblocks. |
52826846 | 175 | |
cd29a5c8 | 176 | .TP |
7e23fc43 | 177 | .BR \-C ", " \-\-create |
cd29a5c8 | 178 | Create a new array. |
52826846 | 179 | |
cd29a5c8 | 180 | .TP |
7e23fc43 | 181 | .BR \-F ", " \-\-follow ", " \-\-monitor |
cd29a5c8 NB |
182 | Select |
183 | .B Monitor | |
184 | mode. | |
52826846 | 185 | |
dd0781e5 | 186 | .TP |
7e23fc43 | 187 | .BR \-G ", " \-\-grow |
dd0781e5 | 188 | Change the size or shape of an active array. |
8382f19b NB |
189 | |
190 | .TP | |
1f48664b | 191 | .BR \-I ", " \-\-incremental |
8382f19b NB |
192 | Add a single device into an appropriate array, and possibly start the array. |
193 | ||
1f48664b NB |
194 | .TP |
195 | .B \-\-auto-detect | |
196 | Request that the kernel starts any auto-detected arrays. This can only | |
197 | work if | |
198 | .I md | |
199 | is compiled into the kernel \(em not if it is a module. | |
200 | Arrays can be auto-detected by the kernel if all the components are in | |
201 | primary MS-DOS partitions with partition type | |
e0fe762a N |
202 | .BR FD , |
203 | and all use v0.90 metadata. | |
1f48664b NB |
204 | In-kernel autodetect is not recommended for new installations. Using |
205 | .I mdadm | |
206 | to detect and assemble arrays \(em possibly in an | |
207 | .I initrd | |
208 | \(em is substantially more flexible and should be preferred. | |
209 | ||
2ae555c3 NB |
210 | .P |
211 | If a device is given before any options, or if the first option is | |
7e23fc43 PS |
212 | .BR \-\-add , |
213 | .BR \-\-fail , | |
2ae555c3 | 214 | or |
7e23fc43 | 215 | .BR \-\-remove , |
e0fe762a | 216 | then the MANAGE mode is assumed. |
2ae555c3 NB |
217 | Anything other than these will cause the |
218 | .B Misc | |
219 | mode to be assumed. | |
dd0781e5 | 220 | |
2ae555c3 | 221 | .SH Options that are not mode-specific are: |
e793c2e5 | 222 | |
cd29a5c8 | 223 | .TP |
7e23fc43 | 224 | .BR \-h ", " \-\-help |
a9d69660 | 225 | Display general help message or, after one of the above options, a |
93e790af | 226 | mode-specific help message. |
56eedc1a NB |
227 | |
228 | .TP | |
7e23fc43 | 229 | .B \-\-help\-options |
56eedc1a NB |
230 | Display more detailed help about command line parsing and some commonly |
231 | used options. | |
52826846 | 232 | |
cd29a5c8 | 233 | .TP |
7e23fc43 | 234 | .BR \-V ", " \-\-version |
9a9dab36 | 235 | Print version information for mdadm. |
52826846 | 236 | |
cd29a5c8 | 237 | .TP |
7e23fc43 | 238 | .BR \-v ", " \-\-verbose |
22892d56 NB |
239 | Be more verbose about what is happening. This can be used twice to be |
240 | extra-verbose. | |
a9d69660 | 241 | The extra verbosity currently only affects |
7e23fc43 | 242 | .B \-\-detail \-\-scan |
22892d56 | 243 | and |
7e23fc43 | 244 | .BR "\-\-examine \-\-scan" . |
52826846 | 245 | |
dab6685f | 246 | .TP |
7e23fc43 | 247 | .BR \-q ", " \-\-quiet |
dab6685f | 248 | Avoid printing purely informative messages. With this, |
51ac42e3 | 249 | .I mdadm |
dab6685f NB |
250 | will be silent unless there is something really important to report. |
251 | ||
cd29a5c8 | 252 | .TP |
7e23fc43 | 253 | .BR \-b ", " \-\-brief |
cd29a5c8 | 254 | Be less verbose. This is used with |
7e23fc43 | 255 | .B \-\-detail |
cd29a5c8 | 256 | and |
7e23fc43 | 257 | .BR \-\-examine . |
22892d56 | 258 | Using |
7e23fc43 | 259 | .B \-\-brief |
22892d56 | 260 | with |
7e23fc43 | 261 | .B \-\-verbose |
22892d56 | 262 | gives an intermediate level of verbosity. |
52826846 | 263 | |
e0d19036 | 264 | .TP |
7e23fc43 | 265 | .BR \-f ", " \-\-force |
93e790af | 266 | Be more forceful about certain operations. See the various modes for |
e0d19036 NB |
267 | the exact meaning of this option in different contexts. |
268 | ||
269 | .TP | |
7e23fc43 | 270 | .BR \-c ", " \-\-config= |
2ae555c3 NB |
271 | Specify the config file. Default is to use |
272 | .BR /etc/mdadm.conf , | |
93e790af | 273 | or if that is missing then |
2ae555c3 | 274 | .BR /etc/mdadm/mdadm.conf . |
5787fa49 | 275 | If the config file given is |
93e790af | 276 | .B "partitions" |
5787fa49 NB |
277 | then nothing will be read, but |
278 | .I mdadm | |
279 | will act as though the config file contained exactly | |
8fd8d9c4 | 280 | .B "DEVICE partitions containers" |
5787fa49 NB |
281 | and will read |
282 | .B /proc/partitions | |
8fd8d9c4 N |
283 | to find a list of devices to scan, and |
284 | .B /proc/mdstat | |
285 | to find a list of containers to examine. | |
d013a55e | 286 | If the word |
93e790af | 287 | .B "none" |
d013a55e NB |
288 | is given for the config file, then |
289 | .I mdadm | |
290 | will act as though the config file were empty. | |
e0d19036 NB |
291 | |
292 | .TP | |
7e23fc43 | 293 | .BR \-s ", " \-\-scan |
93e790af | 294 | Scan config file or |
e0d19036 NB |
295 | .B /proc/mdstat |
296 | for missing information. | |
297 | In general, this option gives | |
51ac42e3 | 298 | .I mdadm |
93e790af SW |
299 | permission to get any missing information (like component devices, |
300 | array devices, array identities, and alert destination) from the | |
301 | configuration file (see previous option); | |
302 | one exception is MISC mode when using | |
7e23fc43 | 303 | .B \-\-detail |
e0d19036 | 304 | or |
93e790af | 305 | .B \-\-stop, |
e0d19036 | 306 | in which case |
7e23fc43 | 307 | .B \-\-scan |
e0d19036 NB |
308 | says to get a list of array devices from |
309 | .BR /proc/mdstat . | |
310 | ||
570c0542 | 311 | .TP |
d16c7af6 | 312 | .BR \-e ", " \-\-metadata= |
e0fe762a | 313 | Declare the style of RAID metadata (superblock) to be used. The |
7d5c3964 | 314 | default is 1.1 for |
7e23fc43 | 315 | .BR \-\-create , |
53e8b987 | 316 | and to guess for other operations. |
2790ffe3 GB |
317 | The default can be overridden by setting the |
318 | .B metadata | |
319 | value for the | |
320 | .B CREATE | |
321 | keyword in | |
322 | .BR mdadm.conf . | |
570c0542 NB |
323 | |
324 | Options are: | |
325 | .RS | |
7d5c3964 | 326 | .IP "0, 0.90" |
570c0542 | 327 | Use the original 0.90 format superblock. This format limits arrays to |
93e790af | 328 | 28 component devices and limits component devices of levels 1 and |
570c0542 | 329 | greater to 2 terabytes. |
7d5c3964 | 330 | .IP "1, 1.0, 1.1, 1.2 default" |
570c0542 | 331 | Use the new version-1 format superblock. This has few restrictions. |
93e790af | 332 | The different sub-versions store the superblock at different locations |
570c0542 | 333 | on the device, either at the end (for 1.0), at the start (for 1.1) or |
7d5c3964 N |
334 | 4K from the start (for 1.2). '1' is equivalent to '1.0', 'default' is |
335 | equivalent to '1.1'. | |
8fd8d9c4 | 336 | .IP ddf |
e0fe762a N |
337 | Use the "Industry Standard" DDF (Disk Data Format) format defined by |
338 | SNIA. | |
339 | When creating a DDF array a | |
8fd8d9c4 N |
340 | .B CONTAINER |
341 | will be created, and normal arrays can be created in that container. | |
342 | .IP imsm | |
4cce4069 | 343 | Use the Intel(R) Matrix Storage Manager metadata format. This creates a |
8fd8d9c4 | 344 | .B CONTAINER |
4cce4069 DW |
345 | which is managed in a similar manner to DDF, and is supported by an |
346 | option-rom on some platforms: | |
347 | .IP | |
348 | .B http://www.intel.com/design/chipsets/matrixstorage_sb.htm | |
349 | .PP | |
570c0542 NB |
350 | .RE |
351 | ||
41a3b72a | 352 | .TP |
7e23fc43 | 353 | .B \-\-homehost= |
35cc5be4 | 354 | This will override any |
41a3b72a | 355 | .B HOMEHOST |
93e790af | 356 | setting in the config file and provides the identity of the host which |
41a3b72a NB |
357 | should be considered the home for any arrays. |
358 | ||
359 | When creating an array, the | |
360 | .B homehost | |
e0fe762a | 361 | will be recorded in the metadata. For version-1 superblocks, it will |
93e790af | 362 | be prefixed to the array name. For version-0.90 superblocks, part of |
41a3b72a NB |
363 | the SHA1 hash of the hostname will be stored in the later half of the |
364 | UUID. | |
365 | ||
366 | When reporting information about an array, any array which is tagged | |
367 | for the given homehost will be reported as such. | |
368 | ||
369 | When using Auto-Assemble, only arrays tagged for the given homehost | |
0ac91628 | 370 | will be allowed to use 'local' names (i.e. not ending in '_' followed |
e0fe762a N |
371 | by a digit string). See below under |
372 | .BR "Auto Assembly" . | |
41a3b72a | 373 | |
2ae555c3 NB |
374 | .SH For create, build, or grow: |
375 | ||
376 | .TP | |
7e23fc43 | 377 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
378 | Specify the number of active devices in the array. This, plus the |
379 | number of spare devices (see below) must equal the number of | |
380 | .I component-devices | |
381 | (including "\fBmissing\fP" devices) | |
382 | that are listed on the command line for | |
e0fe762a | 383 | .BR \-\-create . |
2ae555c3 NB |
384 | Setting a value of 1 is probably |
385 | a mistake and so requires that | |
7e23fc43 | 386 | .B \-\-force |
2ae555c3 | 387 | be specified first. A value of 1 will then be allowed for linear, |
e0fe762a | 388 | multipath, RAID0 and RAID1. It is never allowed for RAID4, RAID5 or RAID6. |
2ae555c3 NB |
389 | .br |
390 | This number can only be changed using | |
7e23fc43 | 391 | .B \-\-grow |
e0fe762a N |
392 | for RAID1, RAID4, RAID5 and RAID6 arrays, and only on kernels which provide |
393 | the necessary support. | |
2ae555c3 NB |
394 | |
395 | .TP | |
7e23fc43 | 396 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
397 | Specify the number of spare (eXtra) devices in the initial array. |
398 | Spares can also be added | |
399 | and removed later. The number of component devices listed | |
e0fe762a | 400 | on the command line must equal the number of RAID devices plus the |
2ae555c3 NB |
401 | number of spare devices. |
402 | ||
2ae555c3 | 403 | .TP |
7e23fc43 | 404 | .BR \-z ", " \-\-size= |
e0fe762a | 405 | Amount (in Kibibytes) of space to use from each drive in RAID levels 1/4/5/6. |
2ae555c3 NB |
406 | This must be a multiple of the chunk size, and must leave about 128Kb |
407 | of space at the end of the drive for the RAID superblock. | |
408 | If this is not specified | |
409 | (as it normally is not) the smallest drive (or partition) sets the | |
410 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
411 | issued. | |
412 | ||
413 | This value can be set with | |
7e23fc43 | 414 | .B \-\-grow |
e0fe762a | 415 | for RAID level 1/4/5/6. If the array was created with a size smaller |
2ae555c3 NB |
416 | than the currently active drives, the extra space can be accessed |
417 | using | |
7e23fc43 | 418 | .BR \-\-grow . |
2ae555c3 NB |
419 | The size can be given as |
420 | .B max | |
421 | which means to choose the largest size that fits on all current drives. | |
52826846 | 422 | |
8fd8d9c4 N |
423 | This value can not be used with |
424 | .B CONTAINER | |
425 | metadata such as DDF and IMSM. | |
426 | ||
f24e2d6c N |
427 | .TP |
428 | .BR \-Z ", " \-\-array-size= | |
429 | This is only meaningful with | |
430 | .B \-\-grow | |
431 | and its effect is not persistent: when the array is stopped an | |
432 | restarted the default array size will be restored. | |
433 | ||
434 | Setting the array-size causes the array to appear smaller to programs | |
435 | that access the data. This is particularly needed before reshaping an | |
436 | array so that it will be smaller. As the reshape is not reversible, | |
437 | but setting the size with | |
438 | .B \-\-array-size | |
439 | is, it is required that the array size is reduced as appropriate | |
440 | before the number of devices in the array is reduced. | |
441 | ||
cd29a5c8 | 442 | .TP |
7e23fc43 | 443 | .BR \-c ", " \-\-chunk= |
5f175898 N |
444 | Specify chunk size of kibibytes. The default when creating an |
445 | array is 512KB. To ensure compatibility with earlier versions, the | |
446 | default when Building and array with no persistent metadata is 64KB. | |
e0fe762a | 447 | This is only meaningful for RAID0, RAID4, RAID5, RAID6, and RAID10. |
52826846 | 448 | |
cd29a5c8 | 449 | .TP |
7e23fc43 | 450 | .BR \-\-rounding= |
e0fe762a N |
451 | Specify rounding factor for a Linear array. The size of each |
452 | component will be rounded down to a multiple of this size. | |
453 | This is a synonym for | |
454 | .B \-\-chunk | |
455 | but highlights the different meaning for Linear as compared to other | |
5f175898 N |
456 | RAID levels. The default is 64K if a kernel earlier than 2.6.16 is in |
457 | use, and is 0K (i.e. no rounding) in later kernels. | |
52826846 | 458 | |
cd29a5c8 | 459 | .TP |
7e23fc43 | 460 | .BR \-l ", " \-\-level= |
e0fe762a | 461 | Set RAID level. When used with |
7e23fc43 | 462 | .BR \-\-create , |
98c6faba | 463 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
8fd8d9c4 N |
464 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container. |
465 | Obviously some of these are synonymous. | |
466 | ||
467 | When a | |
468 | .B CONTAINER | |
469 | metadata type is requested, only the | |
470 | .B container | |
471 | level is permitted, and it does not need to be explicitly given. | |
aa88f531 NB |
472 | |
473 | When used with | |
7e23fc43 | 474 | .BR \-\-build , |
a9d69660 | 475 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 476 | |
2ae555c3 | 477 | Not yet supported with |
7e23fc43 | 478 | .BR \-\-grow . |
2ae555c3 | 479 | |
cd29a5c8 | 480 | .TP |
7e23fc43 | 481 | .BR \-p ", " \-\-layout= |
f24e2d6c N |
482 | This option configures the fine details of data layout for RAID5, RAID6, |
483 | and RAID10 arrays, and controls the failure modes for | |
1a7dfc35 NB |
484 | .IR faulty . |
485 | ||
e0fe762a | 486 | The layout of the RAID5 parity block can be one of |
7e23fc43 PS |
487 | .BR left\-asymmetric , |
488 | .BR left\-symmetric , | |
489 | .BR right\-asymmetric , | |
490 | .BR right\-symmetric , | |
53e8b987 PS |
491 | .BR la ", " ra ", " ls ", " rs . |
492 | The default is | |
7e23fc43 | 493 | .BR left\-symmetric . |
52826846 | 494 | |
e0fe762a N |
495 | It is also possibly to cause RAID5 to use a RAID4-like layout by |
496 | choosing | |
497 | .BR parity\-first , | |
498 | or | |
499 | .BR parity\-last . | |
500 | ||
501 | Finally for RAID5 there are DDF\-compatible layouts, | |
502 | .BR ddf\-zero\-restart , | |
503 | .BR ddf\-N\-restart , | |
504 | and | |
505 | .BR ddf\-N\-continue . | |
506 | ||
507 | These same layouts are available for RAID6. There are also 4 layouts | |
508 | that will provide an intermediate stage for converting between RAID5 | |
509 | and RAID6. These provide a layout which is identical to the | |
510 | corresponding RAID5 layout on the first N\-1 devices, and has the 'Q' | |
511 | syndrome (the second 'parity' block used by RAID6) on the last device. | |
512 | These layouts are: | |
513 | .BR left\-symmetric\-6 , | |
514 | .BR right\-symmetric\-6 , | |
515 | .BR left\-asymmetric\-6 , | |
516 | .BR right\-asymmetric\-6 , | |
517 | and | |
518 | .BR pairty\-first\-6 . | |
519 | ||
93e790af SW |
520 | When setting the failure mode for level |
521 | .I faulty, | |
1a7dfc35 | 522 | the options are: |
7e23fc43 PS |
523 | .BR write\-transient ", " wt , |
524 | .BR read\-transient ", " rt , | |
525 | .BR write\-persistent ", " wp , | |
526 | .BR read\-persistent ", " rp , | |
527 | .BR write\-all , | |
528 | .BR read\-fixable ", " rf , | |
53e8b987 | 529 | .BR clear ", " flush ", " none . |
b5e64645 | 530 | |
93e790af | 531 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
532 | between fault generation. Without a number, the fault is generated |
533 | once on the first relevant request. With a number, the fault will be | |
93e790af | 534 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
535 | every time the period elapses. |
536 | ||
537 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 538 | .B \-\-grow |
53e8b987 | 539 | option to set subsequent failure modes. |
b5e64645 NB |
540 | |
541 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 542 | and "flush" will clear any persistent faults. |
b5e64645 | 543 | |
6f9a21a7 | 544 | Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 545 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 546 | |
93e790af | 547 | .I 'n' |
e0fe762a | 548 | signals 'near' copies. Multiple copies of one data block are at |
b578481c NB |
549 | similar offsets in different devices. |
550 | ||
93e790af | 551 | .I 'o' |
b578481c NB |
552 | signals 'offset' copies. Rather than the chunks being duplicated |
553 | within a stripe, whole stripes are duplicated but are rotated by one | |
554 | device so duplicate blocks are on different devices. Thus subsequent | |
555 | copies of a block are in the next drive, and are one chunk further | |
556 | down. | |
557 | ||
93e790af | 558 | .I 'f' |
1a7dfc35 | 559 | signals 'far' copies |
93e790af | 560 | (multiple copies have very different offsets). |
e0fe762a | 561 | See md(4) for more detail about 'near', 'offset', and 'far'. |
1a7dfc35 NB |
562 | |
563 | The number is the number of copies of each datablock. 2 is normal, 3 | |
564 | can be useful. This number can be at most equal to the number of | |
565 | devices in the array. It does not need to divide evenly into that | |
566 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
567 | with an odd number of devices). | |
568 | ||
f24e2d6c N |
569 | When an array is converted between RAID5 and RAID6 an intermediate |
570 | RAID6 layout is used in which the second parity block (Q) is always on | |
571 | the last device. To convert a RAID5 to RAID6 and leave it in this new | |
572 | layout (which does not require re-striping) use | |
573 | .BR \-\-layout=preserve . | |
574 | This will try to avoid any restriping. | |
575 | ||
576 | The converse of this is | |
577 | .B \-\-layout=normalise | |
578 | which will change a non-standard RAID6 layout into a more standard | |
579 | arrangement. | |
580 | ||
cd29a5c8 | 581 | .TP |
7e23fc43 | 582 | .BR \-\-parity= |
53e8b987 | 583 | same as |
7e23fc43 | 584 | .B \-\-layout |
53e8b987 | 585 | (thus explaining the p of |
7e23fc43 | 586 | .BR \-p ). |
52826846 | 587 | |
e793c2e5 | 588 | .TP |
7e23fc43 | 589 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 590 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 591 | exist unless |
7e23fc43 | 592 | .B \-\-force |
53e8b987 | 593 | is also given. The same file should be provided |
2ae555c3 | 594 | when assembling the array. If the word |
93e790af | 595 | .B "internal" |
2ae555c3 NB |
596 | is given, then the bitmap is stored with the metadata on the array, |
597 | and so is replicated on all devices. If the word | |
93e790af | 598 | .B "none" |
2ae555c3 | 599 | is given with |
7e23fc43 | 600 | .B \-\-grow |
2ae555c3 | 601 | mode, then any bitmap that is present is removed. |
e793c2e5 | 602 | |
2ae555c3 NB |
603 | To help catch typing errors, the filename must contain at least one |
604 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
605 | ||
606 | Note: external bitmaps are only known to work on ext2 and ext3. | |
607 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 608 | |
cd29a5c8 | 609 | .TP |
7e23fc43 | 610 | .BR \-\-bitmap\-chunk= |
e0fe762a | 611 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
612 | Kilobytes of storage. |
613 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 614 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
615 | When using an |
616 | .B internal | |
617 | bitmap, the chunksize is automatically determined to make best use of | |
618 | available space. | |
5787fa49 | 619 | |
cd29a5c8 | 620 | .TP |
7e23fc43 | 621 | .BR \-W ", " \-\-write\-mostly |
e0fe762a | 622 | subsequent devices listed in a |
7e23fc43 PS |
623 | .BR \-\-build , |
624 | .BR \-\-create , | |
2ae555c3 | 625 | or |
7e23fc43 | 626 | .B \-\-add |
2ae555c3 NB |
627 | command will be flagged as 'write-mostly'. This is valid for RAID1 |
628 | only and means that the 'md' driver will avoid reading from these | |
629 | devices if at all possible. This can be useful if mirroring over a | |
630 | slow link. | |
52826846 | 631 | |
2ae555c3 | 632 | .TP |
7e23fc43 | 633 | .BR \-\-write\-behind= |
2ae555c3 | 634 | Specify that write-behind mode should be enabled (valid for RAID1 |
e0fe762a N |
635 | only). If an argument is specified, it will set the maximum number |
636 | of outstanding writes allowed. The default value is 256. | |
2ae555c3 NB |
637 | A write-intent bitmap is required in order to use write-behind |
638 | mode, and write-behind is only attempted on drives marked as | |
639 | .IR write-mostly . | |
dd0781e5 NB |
640 | |
641 | .TP | |
7e23fc43 | 642 | .BR \-\-assume\-clean |
dd0781e5 NB |
643 | Tell |
644 | .I mdadm | |
47d79ef8 NB |
645 | that the array pre-existed and is known to be clean. It can be useful |
646 | when trying to recover from a major failure as you can be sure that no | |
647 | data will be affected unless you actually write to the array. It can | |
648 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 649 | initial resync, however this practice \(em while normally safe \(em is not |
e0fe762a | 650 | recommended. Use this only if you really know what you are doing. |
dd0781e5 | 651 | |
2ae555c3 | 652 | .TP |
7e23fc43 | 653 | .BR \-\-backup\-file= |
53e8b987 | 654 | This is needed when |
7e23fc43 | 655 | .B \-\-grow |
53e8b987 | 656 | is used to increase the number of |
e0fe762a N |
657 | raid-devices in a RAID5 if there are no spare devices available. |
658 | See the GROW MODE section below on RAID\-DEVICES CHANGES. The file | |
659 | should be stored on a separate device, not on the RAID array being | |
660 | reshaped. | |
2ae555c3 | 661 | |
84e11361 N |
662 | .TP |
663 | .BR \-\-array-size= ", " \-Z | |
664 | Set the size of the array which is seen by users of the device such as | |
665 | filesystems. This can be less that the real size, but never greater. | |
666 | The size set this way does not persist across restarts of the array. | |
667 | ||
668 | This is most useful when reducing the number of devices in a RAID5 or | |
669 | RAID6. Such arrays require the array-size to be reduced before a | |
670 | reshape can be performed that reduces the real size. | |
671 | ||
672 | A value of | |
673 | .B max | |
674 | restores the apparent size of the array to be whatever the real | |
675 | amount of available space is. | |
676 | ||
947fd4dd | 677 | .TP |
7e23fc43 | 678 | .BR \-N ", " \-\-name= |
947fd4dd NB |
679 | Set a |
680 | .B name | |
681 | for the array. This is currently only effective when creating an | |
e0fe762a N |
682 | array with a version-1 superblock, or an array in a DDF container. |
683 | The name is a simple textual string that can be used to identify array | |
684 | components when assembling. If name is needed but not specified, it | |
685 | is taken from the basename of the device that is being created. | |
686 | e.g. when creating | |
687 | .I /dev/md/home | |
688 | the | |
689 | .B name | |
690 | will default to | |
691 | .IR home . | |
947fd4dd | 692 | |
dd0781e5 | 693 | .TP |
7e23fc43 | 694 | .BR \-R ", " \-\-run |
dd0781e5 NB |
695 | Insist that |
696 | .I mdadm | |
697 | run the array, even if some of the components | |
698 | appear to be active in another array or filesystem. Normally | |
699 | .I mdadm | |
700 | will ask for confirmation before including such components in an | |
701 | array. This option causes that question to be suppressed. | |
702 | ||
703 | .TP | |
7e23fc43 | 704 | .BR \-f ", " \-\-force |
dd0781e5 NB |
705 | Insist that |
706 | .I mdadm | |
707 | accept the geometry and layout specified without question. Normally | |
708 | .I mdadm | |
709 | will not allow creation of an array with only one device, and will try | |
e0fe762a | 710 | to create a RAID5 array with one missing drive (as this makes the |
dd0781e5 | 711 | initial resync work faster). With |
7e23fc43 | 712 | .BR \-\-force , |
dd0781e5 NB |
713 | .I mdadm |
714 | will not try to be so clever. | |
715 | ||
716 | .TP | |
257c1dc2 N |
717 | .BR \-a ", " "\-\-auto{=yes,md,mdp,part,p}{NN}" |
718 | Instruct mdadm how to create the device file if needed, possibly allocating | |
48f7b27a | 719 | an unused minor number. "md" causes a non-partitionable array |
257c1dc2 N |
720 | to be used (though since Linux 2.6.28, these array devices are in fact |
721 | partitionable). "mdp", "part" or "p" causes a partitionable array (2.6 and | |
2ae555c3 | 722 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 723 | a 'standard' format, and the type and minor number will be determined |
257c1dc2 N |
724 | from this. With mdadm 3.0, device creation is normally left up to |
725 | .I udev | |
726 | so this option is unlikely to be needed. | |
727 | See DEVICE NAMES below. | |
48f7b27a | 728 | |
a9d69660 | 729 | The argument can also come immediately after |
7e23fc43 | 730 | "\-a". e.g. "\-ap". |
dd0781e5 | 731 | |
53e8b987 | 732 | If |
7e23fc43 | 733 | .B \-\-auto |
53e8b987 | 734 | is not given on the command line or in the config file, then |
75723446 | 735 | the default will be |
7e23fc43 | 736 | .BR \-\-auto=yes . |
75723446 | 737 | |
1337546d | 738 | If |
7e23fc43 | 739 | .B \-\-scan |
1337546d NB |
740 | is also given, then any |
741 | .I auto= | |
35cc5be4 | 742 | entries in the config file will override the |
7e23fc43 | 743 | .B \-\-auto |
1337546d NB |
744 | instruction given on the command line. |
745 | ||
dd0781e5 NB |
746 | For partitionable arrays, |
747 | .I mdadm | |
748 | will create the device file for the whole array and for the first 4 | |
749 | partitions. A different number of partitions can be specified at the | |
750 | end of this option (e.g. | |
7e23fc43 | 751 | .BR \-\-auto=p7 ). |
2ae555c3 | 752 | If the device name ends with a digit, the partition names add a 'p', |
e0fe762a N |
753 | and a number, e.g. |
754 | .IR /dev/md/home1p3 . | |
755 | If there is no trailing digit, then the partition names just have a | |
756 | number added, e.g. | |
757 | .IR /dev/md/scratch3 . | |
dd0781e5 | 758 | |
48f7b27a NB |
759 | If the md device name is in a 'standard' format as described in DEVICE |
760 | NAMES, then it will be created, if necessary, with the appropriate | |
e0fe762a N |
761 | device number based on that name. If the device name is not in one of these |
762 | formats, then a unused device number will be allocated. The device | |
48f7b27a NB |
763 | number will be considered unused if there is no active array for that |
764 | number, and there is no entry in /dev for that number and with a | |
e0fe762a | 765 | non-standard name. Names that are not in 'standard' format are only |
8fd8d9c4 N |
766 | allowed in "/dev/md/". |
767 | ||
f24e2d6c | 768 | .ig XX |
e0fe762a N |
769 | .\".TP |
770 | .\".BR \-\-symlink = no | |
771 | .\"Normally when | |
772 | .\".B \-\-auto | |
773 | .\"causes | |
774 | .\".I mdadm | |
775 | .\"to create devices in | |
776 | .\".B /dev/md/ | |
777 | .\"it will also create symlinks from | |
778 | .\".B /dev/ | |
779 | .\"with names starting with | |
780 | .\".B md | |
781 | .\"or | |
782 | .\".BR md_ . | |
783 | .\"Use | |
784 | .\".B \-\-symlink=no | |
785 | .\"to suppress this, or | |
786 | .\".B \-\-symlink=yes | |
787 | .\"to enforce this even if it is suppressing | |
788 | .\".IR mdadm.conf . | |
789 | .\" | |
f24e2d6c | 790 | .XX |
38098016 | 791 | |
52826846 NB |
792 | .SH For assemble: |
793 | ||
cd29a5c8 | 794 | .TP |
7e23fc43 | 795 | .BR \-u ", " \-\-uuid= |
e0fe762a | 796 | uuid of array to assemble. Devices which don't have this uuid are |
cd29a5c8 NB |
797 | excluded |
798 | ||
799 | .TP | |
7e23fc43 | 800 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
801 | Minor number of device that array was created for. Devices which |
802 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 803 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
804 | the array is later assembled as /dev/md2. |
805 | ||
d013a55e | 806 | Giving the literal word "dev" for |
7e23fc43 | 807 | .B \-\-super\-minor |
d013a55e NB |
808 | will cause |
809 | .I mdadm | |
810 | to use the minor number of the md device that is being assembled. | |
811 | e.g. when assembling | |
812 | .BR /dev/md0 , | |
51ac42e3 | 813 | .B \-\-super\-minor=dev |
d013a55e NB |
814 | will look for super blocks with a minor number of 0. |
815 | ||
e0fe762a N |
816 | .B \-\-super\-minor |
817 | is only relevant for v0.90 metadata, and should not normally be used. | |
818 | Using | |
819 | .B \-\-uuid | |
820 | is much safer. | |
821 | ||
947fd4dd | 822 | .TP |
7e23fc43 | 823 | .BR \-N ", " \-\-name= |
947fd4dd | 824 | Specify the name of the array to assemble. This must be the name |
624920bb | 825 | that was specified when creating the array. It must either match |
93e790af | 826 | the name stored in the superblock exactly, or it must match |
41a3b72a | 827 | with the current |
624920bb | 828 | .I homehost |
93e790af | 829 | prefixed to the start of the given name. |
947fd4dd | 830 | |
cd29a5c8 | 831 | .TP |
7e23fc43 | 832 | .BR \-f ", " \-\-force |
e0fe762a N |
833 | Assemble the array even if the metadata on some devices appears to be |
834 | out-of-date. If | |
835 | .I mdadm | |
836 | cannot find enough working devices to start the array, but can find | |
837 | some devices that are recorded as having failed, then it will mark | |
838 | those devices as working so that the array can be started. | |
839 | An array which requires | |
840 | .B \-\-force | |
841 | to be started may contain data corruption. Use it carefully. | |
52826846 | 842 | |
cd29a5c8 | 843 | .TP |
7e23fc43 | 844 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
845 | Attempt to start the array even if fewer drives were given than were |
846 | present last time the array was active. Normally if not all the | |
847 | expected drives are found and | |
7e23fc43 | 848 | .B \-\-scan |
cd29a5c8 NB |
849 | is not used, then the array will be assembled but not started. |
850 | With | |
7e23fc43 | 851 | .B \-\-run |
cd29a5c8 | 852 | an attempt will be made to start it anyway. |
52826846 | 853 | |
b8a8ccf9 | 854 | .TP |
7e23fc43 | 855 | .B \-\-no\-degraded |
b8a8ccf9 | 856 | This is the reverse of |
7e23fc43 | 857 | .B \-\-run |
93e790af | 858 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 859 | are present. This is only needed with |
93e790af SW |
860 | .B \-\-scan, |
861 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
862 | not as reliable as you would like. |
863 | ||
dd0781e5 | 864 | .TP |
7e23fc43 | 865 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
866 | See this option under Create and Build options. |
867 | ||
e793c2e5 | 868 | .TP |
7e23fc43 | 869 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
870 | Specify the bitmap file that was given when the array was created. If |
871 | an array has an | |
872 | .B internal | |
873 | bitmap, there is no need to specify this when assembling the array. | |
874 | ||
875 | .TP | |
7e23fc43 | 876 | .BR \-\-backup\-file= |
2ae555c3 | 877 | If |
7e23fc43 | 878 | .B \-\-backup\-file |
2ae555c3 NB |
879 | was used to grow the number of raid-devices in a RAID5, and the system |
880 | crashed during the critical section, then the same | |
7e23fc43 | 881 | .B \-\-backup\-file |
53e8b987 | 882 | must be presented to |
7e23fc43 | 883 | .B \-\-assemble |
53e8b987 | 884 | to allow possibly corrupted data to be restored. |
e793c2e5 | 885 | |
5787fa49 | 886 | .TP |
7e23fc43 | 887 | .BR \-U ", " \-\-update= |
5787fa49 | 888 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
889 | argument given to this flag can be one of |
890 | .BR sparc2.2 , | |
891 | .BR summaries , | |
7d99579f | 892 | .BR uuid , |
c4f12c13 | 893 | .BR name , |
0237e0ca | 894 | .BR homehost , |
e5329c37 | 895 | .BR resync , |
586ed405 | 896 | .BR byteorder , |
bee8ec56 | 897 | .BR devicesize , |
5787fa49 | 898 | or |
7e23fc43 | 899 | .BR super\-minor . |
5787fa49 NB |
900 | |
901 | The | |
902 | .B sparc2.2 | |
7d99579f | 903 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
904 | machine running a patched 2.2 Linux kernel. This kernel got the |
905 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 906 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
907 | option to |
908 | .I mdadm | |
909 | to see what effect this would have. | |
910 | ||
911 | The | |
7e23fc43 | 912 | .B super\-minor |
5787fa49 | 913 | option will update the |
2ae555c3 | 914 | .B "preferred minor" |
5787fa49 | 915 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
916 | assembled. |
917 | This can be useful if | |
7e23fc43 | 918 | .B \-\-examine |
45c073c9 | 919 | reports a different "Preferred Minor" to |
7e23fc43 | 920 | .BR \-\-detail . |
45c073c9 | 921 | In some cases this update will be performed automatically |
e0fe762a | 922 | by the kernel driver. In particular the update happens automatically |
45c073c9 NB |
923 | at the first write to an array with redundancy (RAID level 1 or |
924 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 925 | |
7d99579f NB |
926 | The |
927 | .B uuid | |
928 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 929 | .B \-\-uuid |
53e8b987 | 930 | option that UUID will be used as a new UUID and will |
7d99579f NB |
931 | .B NOT |
932 | be used to help identify the devices in the array. | |
53e8b987 | 933 | If no |
7e23fc43 | 934 | .B \-\-uuid |
53e8b987 | 935 | is given, a random UUID is chosen. |
7d99579f | 936 | |
c4f12c13 NB |
937 | The |
938 | .B name | |
939 | option will change the | |
940 | .I name | |
941 | of the array as stored in the superblock. This is only supported for | |
942 | version-1 superblocks. | |
943 | ||
0237e0ca NB |
944 | The |
945 | .B homehost | |
946 | option will change the | |
947 | .I homehost | |
948 | as recorded in the superblock. For version-0 superblocks, this is the | |
949 | same as updating the UUID. | |
950 | For version-1 superblocks, this involves updating the name. | |
951 | ||
e5329c37 NB |
952 | The |
953 | .B resync | |
954 | option will cause the array to be marked | |
955 | .I dirty | |
e0fe762a N |
956 | meaning that any redundancy in the array (e.g. parity for RAID5, |
957 | copies for RAID1) may be incorrect. This will cause the RAID system | |
e5329c37 NB |
958 | to perform a "resync" pass to make sure that all redundant information |
959 | is correct. | |
960 | ||
586ed405 NB |
961 | The |
962 | .B byteorder | |
963 | option allows arrays to be moved between machines with different | |
964 | byte-order. | |
2ae555c3 | 965 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 966 | .B "\-\-update=byteorder" |
586ed405 NB |
967 | will cause |
968 | .I mdadm | |
969 | to expect superblocks to have their byteorder reversed, and will | |
970 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 971 | with original (Version 0.90) superblocks. |
586ed405 | 972 | |
feb716e9 NB |
973 | The |
974 | .B summaries | |
e0fe762a | 975 | option will correct the summaries in the superblock. That is the |
feb716e9 | 976 | counts of total, working, active, failed, and spare devices. |
5787fa49 | 977 | |
bee8ec56 NB |
978 | The |
979 | .B devicesize | |
980 | will rarely be of use. It applies to version 1.1 and 1.2 metadata | |
981 | only (where the metadata is at the start of the device) and is only | |
982 | useful when the component device has changed size (typically become | |
983 | larger). The version 1 metadata records the amount of the device that | |
984 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
985 | array becomes larger, the metadata will still be visible, but the | |
986 | extra space will not. In this case it might be useful to assemble the | |
987 | array with | |
7e23fc43 | 988 | .BR \-\-update=devicesize . |
bee8ec56 NB |
989 | This will cause |
990 | .I mdadm | |
991 | to determine the maximum usable amount of space on each device and | |
992 | update the relevant field in the metadata. | |
993 | ||
e0fe762a | 994 | .ig XX |
41a3b72a | 995 | .TP |
7e23fc43 | 996 | .B \-\-auto\-update\-homehost |
93e790af | 997 | This flag is only meaningful with auto-assembly (see discussion below). |
41a3b72a NB |
998 | In that situation, if no suitable arrays are found for this homehost, |
999 | .I mdadm | |
93e790af | 1000 | will rescan for any arrays at all and will assemble them and update the |
41a3b72a | 1001 | homehost to match the current host. |
e0fe762a | 1002 | .XX |
41a3b72a | 1003 | |
e0d19036 | 1004 | .SH For Manage mode: |
52826846 | 1005 | |
cd29a5c8 | 1006 | .TP |
7e23fc43 | 1007 | .BR \-a ", " \-\-add |
e0fe762a N |
1008 | hot-add listed devices. For arrays with redundancy, the listed |
1009 | devices become available as spares. If the array is degraded, it will | |
1010 | immediately start recovering data on to one of these spares. | |
52826846 | 1011 | |
fe80f49b | 1012 | .TP |
7e23fc43 | 1013 | .BR \-\-re\-add |
e0fe762a N |
1014 | re-add a device that was recently removed from an array. This is only |
1015 | needed for arrays that have be built (i.e. with | |
1016 | .BR --build ). | |
1017 | For created arrays, devices are always re-added if that is possible. | |
1018 | When re-adding a device, if nothing has changed on the array since the | |
1019 | device was removed, no recovery is performed. Also, if the array has | |
1020 | a write-intent bitmap, then the recovery performed after a re-add will | |
1021 | be limited to those blocks which, according to the bitmap, might have | |
1022 | changed since the device was removed. | |
fe80f49b | 1023 | |
cd29a5c8 | 1024 | .TP |
7e23fc43 | 1025 | .BR \-r ", " \-\-remove |
2d465520 | 1026 | remove listed devices. They must not be active. i.e. they should |
b80da661 NB |
1027 | be failed or spare devices. As well as the name of a device file |
1028 | (e.g. | |
1029 | .BR /dev/sda1 ) | |
1030 | the words | |
1031 | .B failed | |
1032 | and | |
1033 | .B detached | |
1034 | can be given to | |
1035 | .BR \-\-remove . | |
1036 | The first causes all failed device to be removed. The second causes | |
93e790af | 1037 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
1038 | returns |
1039 | .BR ENXIO ) | |
1040 | to be removed. This will only succeed for devices that are spares or | |
1041 | have already been marked as failed. | |
52826846 | 1042 | |
cd29a5c8 | 1043 | .TP |
7e23fc43 | 1044 | .BR \-f ", " \-\-fail |
cd29a5c8 | 1045 | mark listed devices as faulty. |
b80da661 NB |
1046 | As well as the name of a device file, the word |
1047 | .B detached | |
1048 | can be given. This will cause any device that has been detached from | |
1049 | the system to be marked as failed. It can then be removed. | |
52826846 | 1050 | |
cd29a5c8 | 1051 | .TP |
7e23fc43 | 1052 | .BR \-\-set\-faulty |
53e8b987 | 1053 | same as |
7e23fc43 | 1054 | .BR \-\-fail . |
52826846 | 1055 | |
b3d31955 N |
1056 | .TP |
1057 | .BR \-\-write\-mostly | |
1058 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
e0fe762a | 1059 | flag set. This is only valid for RAID1 and means that the 'md' driver |
b3d31955 N |
1060 | will avoid reading from these devices if possible. |
1061 | .TP | |
1062 | .BR \-\-readwrite | |
1063 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
1064 | flag cleared. | |
1065 | ||
2ae555c3 | 1066 | .P |
e0fe762a | 1067 | Each of these options requires that the first device listed is the array |
93e790af | 1068 | to be acted upon, and the remainder are component devices to be added, |
e0fe762a | 1069 | removed, marked as faulty, etc. Several different operations can be |
2ae555c3 NB |
1070 | specified for different devices, e.g. |
1071 | .in +5 | |
7e23fc43 | 1072 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
1073 | .in -5 |
1074 | Each operation applies to all devices listed until the next | |
93e790af | 1075 | operation. |
2ae555c3 NB |
1076 | |
1077 | If an array is using a write-intent bitmap, then devices which have | |
1078 | been removed can be re-added in a way that avoids a full | |
93e790af | 1079 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
1080 | since the device was removed. For arrays with persistent metadata |
1081 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 1082 | .B \-\-build |
2ae555c3 | 1083 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 1084 | .BR \-\-re\-add . |
2ae555c3 NB |
1085 | |
1086 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
1087 | use, i.e. that must be spares or failed devices. To remove an active |
1088 | device, it must first be marked as | |
1089 | .B faulty. | |
2ae555c3 NB |
1090 | |
1091 | .SH For Misc mode: | |
1092 | ||
1093 | .TP | |
7e23fc43 | 1094 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
1095 | Examine a device to see |
1096 | (1) if it is an md device and (2) if it is a component of an md | |
1097 | array. | |
1098 | Information about what is discovered is presented. | |
1099 | ||
1100 | .TP | |
7e23fc43 | 1101 | .BR \-D ", " \-\-detail |
e0fe762a | 1102 | Print details of one or more md devices. |
5787fa49 | 1103 | |
4cce4069 DW |
1104 | .TP |
1105 | .BR \-\-detail\-platform | |
e0fe762a | 1106 | Print details of the platform's RAID capabilities (firmware / hardware |
4cce4069 DW |
1107 | topology) for a given metadata format. |
1108 | ||
54bad364 KS |
1109 | .TP |
1110 | .BR \-Y ", " \-\-export | |
1111 | When used with | |
0d726f17 KS |
1112 | .B \-\-detail |
1113 | or | |
1114 | .BR \-\-examine , | |
54bad364 KS |
1115 | output will be formatted as |
1116 | .B key=value | |
1117 | pairs for easy import into the environment. | |
1118 | ||
2ae555c3 | 1119 | .TP |
7e23fc43 | 1120 | .BR \-E ", " \-\-examine |
e0fe762a N |
1121 | Print contents of the metadata stored on the named device(s). |
1122 | Note the contrast between | |
1123 | .B \-\-examine | |
1124 | and | |
1125 | .BR \-\-detail . | |
1126 | .B \-\-examine | |
1127 | applies to devices which are components of an array, while | |
1128 | .B \-\-detail | |
1129 | applies to a whole array which is currently active. | |
5787fa49 | 1130 | .TP |
7e23fc43 | 1131 | .B \-\-sparc2.2 |
e0fe762a N |
1132 | If an array was created on a SPARC machine with a 2.2 Linux kernel |
1133 | patched with RAID support, the superblock will have been created | |
1134 | incorrectly, or at least incompatibly with 2.4 and later kernels. | |
1135 | Using the | |
7e23fc43 | 1136 | .B \-\-sparc2.2 |
5787fa49 | 1137 | flag with |
7e23fc43 | 1138 | .B \-\-examine |
5787fa49 NB |
1139 | will fix the superblock before displaying it. If this appears to do |
1140 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 1141 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 1142 | |
2ae555c3 | 1143 | .TP |
7e23fc43 | 1144 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 1145 | Report information about a bitmap file. |
01d9299c | 1146 | The argument is either an external bitmap file or an array component |
e0fe762a N |
1147 | in case of an internal bitmap. Note that running this on an array |
1148 | device (e.g. | |
1149 | .BR /dev/md0 ) | |
1150 | does not report the bitmap for that array. | |
e0d19036 | 1151 | |
cd29a5c8 | 1152 | .TP |
7e23fc43 | 1153 | .BR \-R ", " \-\-run |
e0fe762a N |
1154 | start a partially assembled array. If |
1155 | .B \-\-assemble | |
1156 | did not find enough devices to fully start the array, it might leaving | |
1157 | it partially assembled. If you wish, you can then use | |
1158 | .B \-\-run | |
1159 | to start the array in degraded mode. | |
52826846 | 1160 | |
cd29a5c8 | 1161 | .TP |
7e23fc43 | 1162 | .BR \-S ", " \-\-stop |
cd29a5c8 | 1163 | deactivate array, releasing all resources. |
52826846 | 1164 | |
cd29a5c8 | 1165 | .TP |
7e23fc43 | 1166 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 1167 | mark array as readonly. |
52826846 | 1168 | |
cd29a5c8 | 1169 | .TP |
7e23fc43 | 1170 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 1171 | mark array as readwrite. |
52826846 | 1172 | |
e0d19036 | 1173 | .TP |
7e23fc43 | 1174 | .B \-\-zero\-superblock |
e0d19036 | 1175 | If the device contains a valid md superblock, the block is |
35cc5be4 | 1176 | overwritten with zeros. With |
7e23fc43 | 1177 | .B \-\-force |
35cc5be4 | 1178 | the block where the superblock would be is overwritten even if it |
e0d19036 | 1179 | doesn't appear to be valid. |
52826846 | 1180 | |
feb716e9 | 1181 | .TP |
7e23fc43 | 1182 | .BR \-t ", " \-\-test |
feb716e9 | 1183 | When used with |
7e23fc43 | 1184 | .BR \-\-detail , |
feb716e9 NB |
1185 | the exit status of |
1186 | .I mdadm | |
e0fe762a N |
1187 | is set to reflect the status of the device. See below in |
1188 | .B MISC MODE | |
1189 | for details. | |
feb716e9 | 1190 | |
b90c0e9a | 1191 | .TP |
7e23fc43 | 1192 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1193 | For each md device given, wait for any resync, recovery, or reshape |
1194 | activity to finish before returning. | |
1195 | .I mdadm | |
1196 | will return with success if it actually waited for every device | |
1197 | listed, otherwise it will return failure. | |
1198 | ||
1770662b DW |
1199 | .TP |
1200 | .BR \-\-wait\-clean | |
fabbfd48 DW |
1201 | For each md device given, or each device in /proc/mdstat if |
1202 | .B \-\-scan | |
1203 | is given, arrange for the array to be marked clean as soon as possible. | |
1204 | Also, quiesce resync so that the monitor for external metadata arrays | |
1205 | (mdmon) has an opportunity to checkpoint the resync position. | |
7146ec6a DW |
1206 | .I mdadm |
1207 | will return with success if the array uses external metadata and we | |
1208 | successfully waited. For native arrays this returns immediately as the | |
1209 | kernel handles both dirty-clean transitions and resync checkpointing in | |
1210 | the kernel at shutdown. No action is taken if safe-mode handling is | |
1211 | disabled. | |
1770662b | 1212 | |
8382f19b NB |
1213 | .SH For Incremental Assembly mode: |
1214 | .TP | |
7e23fc43 | 1215 | .BR \-\-rebuild\-map ", " \-r |
8382f19b NB |
1216 | Rebuild the map file |
1217 | .RB ( /var/run/mdadm/map ) | |
1218 | that | |
1219 | .I mdadm | |
1220 | uses to help track which arrays are currently being assembled. | |
1221 | ||
1222 | .TP | |
7e23fc43 | 1223 | .BR \-\-run ", " \-R |
8382f19b NB |
1224 | Run any array assembled as soon as a minimal number of devices are |
1225 | available, rather than waiting until all expected devices are present. | |
1226 | ||
fdb482f9 DW |
1227 | .TP |
1228 | .B \-\-no\-degraded | |
1229 | This allows the hot-plug system to prevent arrays from running when it knows | |
1230 | that more disks may arrive later in the discovery process. | |
1231 | ||
8382f19b | 1232 | .TP |
7e23fc43 | 1233 | .BR \-\-scan ", " \-s |
8382f19b | 1234 | Only meaningful with |
7e23fc43 | 1235 | .B \-R |
8382f19b NB |
1236 | this will scan the |
1237 | .B map | |
1238 | file for arrays that are being incrementally assembled and will try to | |
1239 | start any that are not already started. If any such array is listed | |
1240 | in | |
1241 | .B mdadm.conf | |
1242 | as requiring an external bitmap, that bitmap will be attached first. | |
1243 | ||
e0d19036 NB |
1244 | .SH For Monitor mode: |
1245 | .TP | |
7e23fc43 | 1246 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1247 | Give a mail address to send alerts to. |
1248 | ||
1249 | .TP | |
7e23fc43 | 1250 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1251 | Give a program to be run whenever an event is detected. |
1252 | ||
773135f5 | 1253 | .TP |
7e23fc43 | 1254 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1255 | Cause all events to be reported through 'syslog'. The messages have |
1256 | facility of 'daemon' and varying priorities. | |
1257 | ||
e0d19036 | 1258 | .TP |
7e23fc43 | 1259 | .BR \-d ", " \-\-delay |
e0d19036 | 1260 | Give a delay in seconds. |
51ac42e3 | 1261 | .I mdadm |
e0d19036 | 1262 | polls the md arrays and then waits this many seconds before polling |
e0fe762a N |
1263 | again. The default is 60 seconds. Since 2.6.16, there is no need to |
1264 | reduce this as the kernel alerts | |
1265 | .I mdadm | |
1266 | immediately when there is any change. | |
e0d19036 | 1267 | |
9a36a9b7 ZB |
1268 | .TP |
1269 | .BR \-r ", " \-\-increment | |
1270 | Give a percentage increment. | |
1271 | .I mdadm | |
1272 | will generate RebuildNN events with the given percentage increment. | |
1273 | ||
d013a55e | 1274 | .TP |
7e23fc43 | 1275 | .BR \-f ", " \-\-daemonise |
d013a55e | 1276 | Tell |
51ac42e3 | 1277 | .I mdadm |
d013a55e | 1278 | to run as a background daemon if it decides to monitor anything. This |
e0fe762a | 1279 | causes it to fork and run in the child, and to disconnect from the |
d013a55e NB |
1280 | terminal. The process id of the child is written to stdout. |
1281 | This is useful with | |
7e23fc43 | 1282 | .B \-\-scan |
d013a55e NB |
1283 | which will only continue monitoring if a mail address or alert program |
1284 | is found in the config file. | |
1285 | ||
b5e64645 | 1286 | .TP |
7e23fc43 | 1287 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1288 | When |
51ac42e3 | 1289 | .I mdadm |
b5e64645 NB |
1290 | is running in daemon mode, write the pid of the daemon process to |
1291 | the specified file, instead of printing it on standard output. | |
1292 | ||
aa88f531 | 1293 | .TP |
7e23fc43 | 1294 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1295 | Check arrays only once. This will generate |
1296 | .B NewArray | |
1297 | events and more significantly | |
1298 | .B DegradedArray | |
a9d69660 NB |
1299 | and |
1300 | .B SparesMissing | |
aa88f531 NB |
1301 | events. Running |
1302 | .in +5 | |
7e23fc43 | 1303 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1304 | .in -5 |
1305 | from a cron script will ensure regular notification of any degraded arrays. | |
1306 | ||
98c6faba | 1307 | .TP |
7e23fc43 | 1308 | .BR \-t ", " \-\-test |
98c6faba NB |
1309 | Generate a |
1310 | .B TestMessage | |
1311 | alert for every array found at startup. This alert gets mailed and | |
1312 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1313 | message do get through successfully. |
98c6faba | 1314 | |
e0d19036 | 1315 | .SH ASSEMBLE MODE |
52826846 | 1316 | |
cd29a5c8 NB |
1317 | .HP 12 |
1318 | Usage: | |
7e23fc43 | 1319 | .B mdadm \-\-assemble |
5787fa49 NB |
1320 | .I md-device options-and-component-devices... |
1321 | .HP 12 | |
1322 | Usage: | |
7e23fc43 | 1323 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1324 | .I md-devices-and-options... |
cd29a5c8 NB |
1325 | .HP 12 |
1326 | Usage: | |
7e23fc43 | 1327 | .B mdadm \-\-assemble \-\-scan |
e0fe762a | 1328 | .I options... |
52826846 | 1329 | |
cd29a5c8 | 1330 | .PP |
e0fe762a | 1331 | This usage assembles one or more RAID arrays from pre-existing components. |
9a9dab36 | 1332 | For each array, mdadm needs to know the md device, the identity of the |
e0fe762a | 1333 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1334 | |
5787fa49 | 1335 | In the first usage example (without the |
7e23fc43 | 1336 | .BR \-\-scan ) |
5787fa49 NB |
1337 | the first device given is the md device. |
1338 | In the second usage example, all devices listed are treated as md | |
1339 | devices and assembly is attempted. | |
1340 | In the third (where no devices are listed) all md devices that are | |
e0fe762a N |
1341 | listed in the configuration file are assembled. If not arrays are |
1342 | described by the configuration file, then any arrays that | |
1343 | can be found on unused devices will be assembled. | |
52826846 | 1344 | |
d013a55e | 1345 | If precisely one device is listed, but |
7e23fc43 | 1346 | .B \-\-scan |
dd0781e5 | 1347 | is not given, then |
d013a55e NB |
1348 | .I mdadm |
1349 | acts as though | |
7e23fc43 | 1350 | .B \-\-scan |
93e790af | 1351 | was given and identity information is extracted from the configuration file. |
d013a55e | 1352 | |
2ae555c3 | 1353 | The identity can be given with the |
7e23fc43 | 1354 | .B \-\-uuid |
e0fe762a N |
1355 | option, the |
1356 | .B \-\-name | |
1357 | option, or the | |
7e23fc43 | 1358 | .B \-\-super\-minor |
93e790af SW |
1359 | option, will be taken from the md-device record in the config file, or |
1360 | will be taken from the super block of the first component-device | |
1361 | listed on the command line. | |
52826846 | 1362 | |
2ae555c3 | 1363 | Devices can be given on the |
7e23fc43 | 1364 | .B \-\-assemble |
e0fe762a | 1365 | command line or in the config file. Only devices which have an md |
5787fa49 NB |
1366 | superblock which contains the right identity will be considered for |
1367 | any array. | |
52826846 | 1368 | |
2ae555c3 | 1369 | The config file is only used if explicitly named with |
7e23fc43 | 1370 | .B \-\-config |
d013a55e | 1371 | or requested with (a possibly implicit) |
7e23fc43 | 1372 | .BR \-\-scan . |
52826846 | 1373 | In the later case, |
9a9dab36 | 1374 | .B /etc/mdadm.conf |
8fd8d9c4 N |
1375 | or |
1376 | .B /etc/mdadm/mdadm.conf | |
52826846 NB |
1377 | is used. |
1378 | ||
2ae555c3 | 1379 | If |
7e23fc43 | 1380 | .B \-\-scan |
cd29a5c8 NB |
1381 | is not given, then the config file will only be used to find the |
1382 | identity of md arrays. | |
52826846 | 1383 | |
2d465520 | 1384 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 1385 | .B \-\-scan |
e0fe762a N |
1386 | is not given and not all expected drives were listed, then the array |
1387 | is not started (to guard against usage errors). To insist that the | |
1388 | array be started in this case (as may work for RAID1, 4, 5, 6, or 10), | |
1389 | give the | |
7e23fc43 | 1390 | .B \-\-run |
cd29a5c8 | 1391 | flag. |
52826846 | 1392 | |
e0fe762a N |
1393 | If |
1394 | .I udev | |
1395 | is active, | |
1396 | .I mdadm | |
1397 | does not create any entries in | |
dd0781e5 | 1398 | .B /dev |
e0fe762a N |
1399 | but leaves that to |
1400 | .IR udev . | |
1401 | It does record information in | |
1402 | .B /var/run/mdadm/map | |
1403 | which will allow | |
1404 | .I udev | |
1405 | to choose the correct name. | |
dd0781e5 | 1406 | |
e0fe762a N |
1407 | If |
1408 | .I mdadm | |
1409 | detects that udev is not configured, it will create the devices in | |
1410 | .B /dev | |
1411 | itself. | |
dd0781e5 | 1412 | |
e0fe762a N |
1413 | In Linux kernels prior to version 2.6.28 there were two distinctly |
1414 | different types of md devices that could be created: one that could be | |
1415 | partitioned using standard partitioning tools and one that could not. | |
1416 | Since 2.6.28 that distinction is no longer relevant as both type of | |
1417 | devices can be partitioned. | |
1418 | .I mdadm | |
1419 | will normally create the type that originally could not be partitioned | |
1420 | as it has a well defined major number (9). | |
dd0781e5 | 1421 | |
e0fe762a N |
1422 | Prior to 2.6.28, it is important that mdadm chooses the correct type |
1423 | of array device to use. This can be controlled with the | |
1424 | .B \-\-auto | |
1425 | option. In particular, a value of "mdp" or "part" or "p" tells mdadm | |
1426 | to use a partitionable device rather than the default. | |
dd0781e5 | 1427 | |
e0fe762a N |
1428 | In the no-udev case, the value given to |
1429 | .B \-\-auto | |
1430 | can be suffixed by a number. This tells | |
1431 | .I mdadm | |
1432 | to create that number of partition devices rather than the default of 4. | |
dd0781e5 | 1433 | |
e0fe762a | 1434 | The value given to |
7e23fc43 | 1435 | .B \-\-auto |
e0fe762a N |
1436 | can also be given in the configuration file as a word starting |
1437 | .B auto= | |
1438 | on the ARRAY line for the relevant array. | |
52826846 | 1439 | |
41a3b72a NB |
1440 | .SS Auto Assembly |
1441 | When | |
7e23fc43 | 1442 | .B \-\-assemble |
41a3b72a | 1443 | is used with |
7e23fc43 | 1444 | .B \-\-scan |
41a3b72a NB |
1445 | and no devices are listed, |
1446 | .I mdadm | |
1447 | will first attempt to assemble all the arrays listed in the config | |
1448 | file. | |
1449 | ||
e0fe762a N |
1450 | In no array at listed in the config (other than those marked |
1451 | .BR <ignore> ) | |
1452 | it will look through the available devices for possible arrays and | |
1453 | will try to assemble anything that it finds. Arrays which are tagged | |
1454 | as belonging to the given homehost will be assembled and started | |
1455 | normally. Arrays which do not obviously belong to this host are given | |
1456 | names that are expected not to conflict with anything local, and are | |
1457 | started "read-auto" so that nothing is written to any device until the | |
1458 | array is written to. i.e. automatic resync etc is delayed. | |
41a3b72a NB |
1459 | |
1460 | If | |
1461 | .I mdadm | |
1462 | finds a consistent set of devices that look like they should comprise | |
1463 | an array, and if the superblock is tagged as belonging to the given | |
1464 | home host, it will automatically choose a device name and try to | |
1465 | assemble the array. If the array uses version-0.90 metadata, then the | |
1466 | .B minor | |
1467 | number as recorded in the superblock is used to create a name in | |
1468 | .B /dev/md/ | |
1469 | so for example | |
1470 | .BR /dev/md/3 . | |
1471 | If the array uses version-1 metadata, then the | |
1472 | .B name | |
1473 | from the superblock is used to similarly create a name in | |
e0fe762a | 1474 | .B /dev/md/ |
93e790af | 1475 | (the name will have any 'host' prefix stripped first). |
41a3b72a | 1476 | |
e0fe762a | 1477 | .ig XX |
41a3b72a NB |
1478 | If |
1479 | .I mdadm | |
1480 | cannot find any array for the given host at all, and if | |
7e23fc43 | 1481 | .B \-\-auto\-update\-homehost |
41a3b72a NB |
1482 | is given, then |
1483 | .I mdadm | |
1484 | will search again for any array (not just an array created for this | |
1485 | host) and will assemble each assuming | |
7e23fc43 | 1486 | .BR \-\-update=homehost . |
41a3b72a NB |
1487 | This will change the host tag in the superblock so that on the next run, |
1488 | these arrays will be found without the second pass. The intention of | |
1489 | this feature is to support transitioning a set of md arrays to using | |
1490 | homehost tagging. | |
1491 | ||
1492 | The reason for requiring arrays to be tagged with the homehost for | |
1493 | auto assembly is to guard against problems that can arise when moving | |
1494 | devices from one host to another. | |
e0fe762a | 1495 | .XX |
41a3b72a | 1496 | |
cd29a5c8 | 1497 | .SH BUILD MODE |
52826846 | 1498 | |
cd29a5c8 NB |
1499 | .HP 12 |
1500 | Usage: | |
7e23fc43 | 1501 | .B mdadm \-\-build |
93e790af | 1502 | .I md-device |
7e23fc43 PS |
1503 | .BI \-\-chunk= X |
1504 | .BI \-\-level= Y | |
1505 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
1506 | .I devices |
1507 | ||
1508 | .PP | |
2ae555c3 | 1509 | This usage is similar to |
7e23fc43 | 1510 | .BR \-\-create . |
e0fe762a | 1511 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 1512 | these arrays there is no difference between initially creating the array and |
52826846 NB |
1513 | subsequently assembling the array, except that hopefully there is useful |
1514 | data there in the second case. | |
1515 | ||
e0fe762a N |
1516 | The level may raid0, linear, raid1, raid10, multipath, or faulty, or |
1517 | one of their synonyms. All devices must be listed and the array will | |
1518 | be started once complete. It will often be appropriate to use | |
1519 | .B \-\-assume\-clean | |
1520 | with levels raid1 or raid10. | |
cd29a5c8 NB |
1521 | |
1522 | .SH CREATE MODE | |
1523 | ||
1524 | .HP 12 | |
1525 | Usage: | |
7e23fc43 | 1526 | .B mdadm \-\-create |
93e790af | 1527 | .I md-device |
7e23fc43 PS |
1528 | .BI \-\-chunk= X |
1529 | .BI \-\-level= Y | |
cd29a5c8 | 1530 | .br |
7e23fc43 | 1531 | .BI \-\-raid\-devices= Z |
e0fe762a | 1532 | .I devices |
cd29a5c8 NB |
1533 | |
1534 | .PP | |
1535 | This usage will initialise a new md array, associate some devices with | |
1536 | it, and activate the array. | |
1537 | ||
e0fe762a N |
1538 | The named device will normally not exist when |
1539 | .I "mdadm \-\-create" | |
1540 | is run, but will be created by | |
1541 | .I udev | |
1542 | once the array becomes active. | |
dd0781e5 | 1543 | |
e0fe762a N |
1544 | As devices are added, they are checked to see if they contain RAID |
1545 | superblocks or filesystems. They are also checked to see if the variance in | |
cd29a5c8 NB |
1546 | device size exceeds 1%. |
1547 | ||
1548 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 1549 | the presence of a |
7e23fc43 | 1550 | .B \-\-run |
cd29a5c8 NB |
1551 | can override this caution. |
1552 | ||
2d465520 | 1553 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 1554 | give the word "\fBmissing\fP" |
2d465520 | 1555 | in place of a device name. This will cause |
51ac42e3 | 1556 | .I mdadm |
2d465520 NB |
1557 | to leave the corresponding slot in the array empty. |
1558 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 1559 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
1560 | For a RAID1 array, only one real device needs to be given. All of the |
1561 | others can be | |
d013a55e | 1562 | "\fBmissing\fP". |
2d465520 | 1563 | |
feb716e9 | 1564 | When creating a RAID5 array, |
51ac42e3 | 1565 | .I mdadm |
feb716e9 | 1566 | will automatically create a degraded array with an extra spare drive. |
e0fe762a N |
1567 | This is because building the spare into a degraded array is in general |
1568 | faster than resyncing the parity on a non-degraded, but not clean, | |
1569 | array. This feature can be overridden with the | |
7e23fc43 | 1570 | .B \-\-force |
feb716e9 NB |
1571 | option. |
1572 | ||
0ee4da98 | 1573 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
1574 | required. |
1575 | If this is not given with the | |
7e23fc43 | 1576 | .B \-\-name |
41a3b72a NB |
1577 | option, |
1578 | .I mdadm | |
0ee4da98 | 1579 | will choose a name based on the last component of the name of the |
41a3b72a NB |
1580 | device being created. So if |
1581 | .B /dev/md3 | |
1582 | is being created, then the name | |
1583 | .B 3 | |
1584 | will be chosen. | |
1585 | If | |
1586 | .B /dev/md/home | |
1587 | is being created, then the name | |
1588 | .B home | |
1589 | will be used. | |
1590 | ||
e0fe762a N |
1591 | When creating a partition based array, using |
1592 | .I mdadm | |
1593 | with version-1.x metadata, the partition type should be set to | |
e0f31f50 | 1594 | .B 0xDA |
e0fe762a | 1595 | (non fs-data). This type selection allows for greater precision since |
e0f31f50 PC |
1596 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], |
1597 | might create problems in the event of array recovery through a live cdrom. | |
1598 | ||
3d3dd91e NB |
1599 | A new array will normally get a randomly assigned 128bit UUID which is |
1600 | very likely to be unique. If you have a specific need, you can choose | |
1601 | a UUID for the array by giving the | |
7e23fc43 | 1602 | .B \-\-uuid= |
3d3dd91e NB |
1603 | option. Be warned that creating two arrays with the same UUID is a |
1604 | recipe for disaster. Also, using | |
7e23fc43 | 1605 | .B \-\-uuid= |
3d3dd91e | 1606 | when creating a v0.90 array will silently override any |
7e23fc43 | 1607 | .B \-\-homehost= |
3d3dd91e | 1608 | setting. |
e43d0cda NB |
1609 | .\"If the |
1610 | .\".B \-\-size | |
1611 | .\"option is given, it is not necessary to list any component-devices in this command. | |
1612 | .\"They can be added later, before a | |
1613 | .\".B \-\-run. | |
1614 | .\"If no | |
1615 | .\".B \-\-size | |
1616 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 1617 | |
8fd8d9c4 N |
1618 | When creating an array within a |
1619 | .B CONTAINER | |
1620 | .I mdadm | |
1621 | can be given either the list of devices to use, or simply the name of | |
1622 | the container. The former case gives control over which devices in | |
1623 | the container will be used for the array. The latter case allows | |
1624 | .I mdadm | |
1625 | to automatically choose which devices to use based on how much spare | |
1626 | space is available. | |
1627 | ||
53e8b987 | 1628 | The General Management options that are valid with |
7e23fc43 | 1629 | .B \-\-create |
53e8b987 | 1630 | are: |
cd29a5c8 | 1631 | .TP |
7e23fc43 | 1632 | .B \-\-run |
dd0781e5 | 1633 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
1634 | be in use. |
1635 | ||
1636 | .TP | |
7e23fc43 | 1637 | .B \-\-readonly |
b3f1c093 | 1638 | start the array readonly \(em not supported yet. |
52826846 | 1639 | |
e0d19036 | 1640 | .SH MANAGE MODE |
cd29a5c8 NB |
1641 | .HP 12 |
1642 | Usage: | |
e0d19036 NB |
1643 | .B mdadm |
1644 | .I device | |
1645 | .I options... devices... | |
cd29a5c8 NB |
1646 | .PP |
1647 | ||
e0d19036 NB |
1648 | This usage will allow individual devices in an array to be failed, |
1649 | removed or added. It is possible to perform multiple operations with | |
e0fe762a | 1650 | on command. For example: |
e0d19036 | 1651 | .br |
7e23fc43 | 1652 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
1653 | .br |
1654 | will firstly mark | |
1655 | .B /dev/hda1 | |
1656 | as faulty in | |
1657 | .B /dev/md0 | |
1658 | and will then remove it from the array and finally add it back | |
2d465520 | 1659 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 1660 | command. |
e0d19036 | 1661 | |
e0fe762a N |
1662 | When a device is added to an active array, mdadm checks to see if it |
1663 | has metadata on it which suggests that it was recently a member of the | |
1664 | array. If it does, it tried to "re-add" the device. If there have | |
1665 | been no changes since the device was removed, or if the array has a | |
1666 | write-intent bitmap which has recorded whatever changes there were, | |
1667 | then the device will immediately become a full member of the array and | |
1668 | those differences recorded in the bitmap will be resolved. | |
1669 | ||
e0d19036 NB |
1670 | .SH MISC MODE |
1671 | .HP 12 | |
1672 | Usage: | |
9a9dab36 | 1673 | .B mdadm |
e0d19036 | 1674 | .I options ... |
e0fe762a | 1675 | .I devices ... |
e0d19036 | 1676 | .PP |
cd29a5c8 | 1677 | |
b5e64645 | 1678 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1679 | operate on distinct devices. The operations are: |
1680 | .TP | |
962a108f | 1681 | .B \-\-query |
e0d19036 NB |
1682 | The device is examined to see if it is |
1683 | (1) an active md array, or | |
1684 | (2) a component of an md array. | |
1685 | The information discovered is reported. | |
1686 | ||
1687 | .TP | |
962a108f | 1688 | .B \-\-detail |
2d465520 | 1689 | The device should be an active md device. |
e0fe762a | 1690 | .B mdadm |
2d465520 | 1691 | will display a detailed description of the array. |
7e23fc43 | 1692 | .B \-\-brief |
2d465520 | 1693 | or |
7e23fc43 | 1694 | .B \-\-scan |
2d465520 | 1695 | will cause the output to be less detailed and the format to be |
e0d19036 | 1696 | suitable for inclusion in |
9a9dab36 | 1697 | .BR /etc/mdadm.conf . |
feb716e9 NB |
1698 | The exit status of |
1699 | .I mdadm | |
1700 | will normally be 0 unless | |
1701 | .I mdadm | |
93e790af | 1702 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 1703 | .B \-\-test |
feb716e9 NB |
1704 | option is given, then the exit status will be: |
1705 | .RS | |
1706 | .TP | |
1707 | 0 | |
1708 | The array is functioning normally. | |
1709 | .TP | |
1710 | 1 | |
1711 | The array has at least one failed device. | |
1712 | .TP | |
1713 | 2 | |
a77be586 | 1714 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
1715 | .TP |
1716 | 4 | |
1717 | There was an error while trying to get information about the device. | |
1718 | .RE | |
cd29a5c8 | 1719 | |
4cce4069 DW |
1720 | .TP |
1721 | .B \-\-detail\-platform | |
e0fe762a | 1722 | Print detail of the platform's RAID capabilities (firmware / hardware |
4cce4069 DW |
1723 | topology). If the metadata is specified with |
1724 | .B \-e | |
1725 | or | |
1726 | .B \-\-metadata= | |
1727 | then the return status will be: | |
1728 | .RS | |
1729 | .TP | |
1730 | 0 | |
1731 | metadata successfully enumerated its platform components on this system | |
1732 | .TP | |
1733 | 1 | |
1734 | metadata is platform independent | |
1735 | .TP | |
1736 | 2 | |
1737 | metadata failed to find its platform components on this system | |
1738 | .RE | |
1739 | ||
e0d19036 | 1740 | .TP |
962a108f | 1741 | .B \-\-examine |
2d465520 | 1742 | The device should be a component of an md array. |
51ac42e3 | 1743 | .I mdadm |
2d465520 | 1744 | will read the md superblock of the device and display the contents. |
e0d19036 | 1745 | If |
7e23fc43 | 1746 | .B \-\-brief |
93e790af | 1747 | or |
7e23fc43 | 1748 | .B \-\-scan |
93e790af | 1749 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
1750 | are grouped together and reported in a single entry suitable |
1751 | for inclusion in | |
1752 | .BR /etc/mdadm.conf . | |
1753 | ||
2d465520 | 1754 | Having |
7e23fc43 | 1755 | .B \-\-scan |
e0d19036 NB |
1756 | without listing any devices will cause all devices listed in the |
1757 | config file to be examined. | |
1758 | ||
1759 | .TP | |
962a108f | 1760 | .B \-\-stop |
98c6faba NB |
1761 | The devices should be active md arrays which will be deactivated, as |
1762 | long as they are not currently in use. | |
e0d19036 NB |
1763 | |
1764 | .TP | |
962a108f | 1765 | .B \-\-run |
e0d19036 NB |
1766 | This will fully activate a partially assembled md array. |
1767 | ||
1768 | .TP | |
962a108f | 1769 | .B \-\-readonly |
e0d19036 NB |
1770 | This will mark an active array as read-only, providing that it is |
1771 | not currently being used. | |
1772 | ||
1773 | .TP | |
962a108f | 1774 | .B \-\-readwrite |
e0d19036 NB |
1775 | This will change a |
1776 | .B readonly | |
1777 | array back to being read/write. | |
1778 | ||
2d465520 | 1779 | .TP |
962a108f | 1780 | .B \-\-scan |
2d465520 | 1781 | For all operations except |
7e23fc43 PS |
1782 | .BR \-\-examine , |
1783 | .B \-\-scan | |
2d465520 NB |
1784 | will cause the operation to be applied to all arrays listed in |
1785 | .BR /proc/mdstat . | |
1786 | For | |
7e23fc43 PS |
1787 | .BR \-\-examine, |
1788 | .B \-\-scan | |
2d465520 NB |
1789 | causes all devices listed in the config file to be examined. |
1790 | ||
e0d19036 NB |
1791 | .SH MONITOR MODE |
1792 | ||
cd29a5c8 NB |
1793 | .HP 12 |
1794 | Usage: | |
7e23fc43 | 1795 | .B mdadm \-\-monitor |
e0d19036 NB |
1796 | .I options... devices... |
1797 | ||
cd29a5c8 | 1798 | .PP |
e0d19036 | 1799 | This usage causes |
51ac42e3 | 1800 | .I mdadm |
e0d19036 NB |
1801 | to periodically poll a number of md arrays and to report on any events |
1802 | noticed. | |
51ac42e3 | 1803 | .I mdadm |
e0d19036 NB |
1804 | will never exit once it decides that there are arrays to be checked, |
1805 | so it should normally be run in the background. | |
1806 | ||
2d465520 | 1807 | As well as reporting events, |
51ac42e3 | 1808 | .I mdadm |
2d465520 NB |
1809 | may move a spare drive from one array to another if they are in the |
1810 | same | |
1811 | .B spare-group | |
a9d69660 | 1812 | and if the destination array has a failed drive but no spares. |
2d465520 | 1813 | |
e0d19036 | 1814 | If any devices are listed on the command line, |
51ac42e3 | 1815 | .I mdadm |
e0fe762a | 1816 | will only monitor those devices. Otherwise all arrays listed in the |
e0d19036 | 1817 | configuration file will be monitored. Further, if |
7e23fc43 | 1818 | .B \-\-scan |
e0d19036 NB |
1819 | is given, then any other md devices that appear in |
1820 | .B /proc/mdstat | |
1821 | will also be monitored. | |
1822 | ||
1823 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 1824 | These events are passed to a separate program (if specified) and may |
2d465520 | 1825 | be mailed to a given E-mail address. |
e0d19036 | 1826 | |
93e790af SW |
1827 | When passing events to a program, the program is run once for each event, |
1828 | and is given 2 or 3 command-line arguments: the first is the | |
1829 | name of the event (see below), the second is the name of the | |
bd526cee | 1830 | md device which is affected, and the third is the name of a related |
93e790af | 1831 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
1832 | |
1833 | If | |
7e23fc43 | 1834 | .B \-\-scan |
e0d19036 NB |
1835 | is given, then a program or an E-mail address must be specified on the |
1836 | command line or in the config file. If neither are available, then | |
51ac42e3 | 1837 | .I mdadm |
e0d19036 NB |
1838 | will not monitor anything. |
1839 | Without | |
93e790af | 1840 | .B \-\-scan, |
51ac42e3 | 1841 | .I mdadm |
2d465520 | 1842 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
1843 | no program or email is given, then each event is reported to |
1844 | .BR stdout . | |
cd29a5c8 | 1845 | |
e0d19036 NB |
1846 | The different events are: |
1847 | ||
1848 | .RS 4 | |
1849 | .TP | |
1850 | .B DeviceDisappeared | |
2d465520 | 1851 | An md array which previously was configured appears to no longer be |
773135f5 | 1852 | configured. (syslog priority: Critical) |
e0d19036 | 1853 | |
b8f72a62 NB |
1854 | If |
1855 | .I mdadm | |
1856 | was told to monitor an array which is RAID0 or Linear, then it will | |
1857 | report | |
1858 | .B DeviceDisappeared | |
1859 | with the extra information | |
1860 | .BR Wrong-Level . | |
1861 | This is because RAID0 and Linear do not support the device-failed, | |
1862 | hot-spare and resync operations which are monitored. | |
1863 | ||
e0d19036 NB |
1864 | .TP |
1865 | .B RebuildStarted | |
773135f5 | 1866 | An md array started reconstruction. (syslog priority: Warning) |
e0d19036 NB |
1867 | |
1868 | .TP | |
1869 | .BI Rebuild NN | |
1870 | Where | |
1871 | .I NN | |
9a36a9b7 ZB |
1872 | is a two-digit number (ie. 05, 48). This indicates that rebuild |
1873 | has passed that many percent of the total. The events are generated | |
1874 | with fixed increment since 0. Increment size may be specified with | |
1875 | a commandline option (default is 20). (syslog priority: Warning) | |
e0d19036 | 1876 | |
98c6faba NB |
1877 | .TP |
1878 | .B RebuildFinished | |
1879 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 1880 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 1881 | |
e0d19036 NB |
1882 | .TP |
1883 | .B Fail | |
773135f5 NB |
1884 | An active component device of an array has been marked as |
1885 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
1886 | |
1887 | .TP | |
1888 | .B FailSpare | |
1889 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 1890 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
1891 | |
1892 | .TP | |
1893 | .B SpareActive | |
1894 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 1895 | device has been successfully rebuilt and has been made active. |
773135f5 | 1896 | (syslog priority: Info) |
e0d19036 NB |
1897 | |
1898 | .TP | |
1899 | .B NewArray | |
1900 | A new md array has been detected in the | |
1901 | .B /proc/mdstat | |
e0fe762a | 1902 | file. (syslog priority: Info) |
e0d19036 | 1903 | |
aa88f531 NB |
1904 | .TP |
1905 | .B DegradedArray | |
1906 | A newly noticed array appears to be degraded. This message is not | |
1907 | generated when | |
1908 | .I mdadm | |
1909 | notices a drive failure which causes degradation, but only when | |
1910 | .I mdadm | |
1911 | notices that an array is degraded when it first sees the array. | |
93e790af | 1912 | (syslog priority: Critical) |
aa88f531 | 1913 | |
e0d19036 NB |
1914 | .TP |
1915 | .B MoveSpare | |
1916 | A spare drive has been moved from one array in a | |
1917 | .B spare-group | |
1918 | to another to allow a failed drive to be replaced. | |
773135f5 | 1919 | (syslog priority: Info) |
e0d19036 | 1920 | |
b8f72a62 NB |
1921 | .TP |
1922 | .B SparesMissing | |
1923 | If | |
1924 | .I mdadm | |
1925 | has been told, via the config file, that an array should have a certain | |
1926 | number of spare devices, and | |
1927 | .I mdadm | |
93e790af | 1928 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
1929 | array, it will report a |
1930 | .B SparesMissing | |
1931 | message. | |
d1732eeb | 1932 | (syslog priority: Warning) |
b8f72a62 | 1933 | |
98c6faba NB |
1934 | .TP |
1935 | .B TestMessage | |
1936 | An array was found at startup, and the | |
7e23fc43 | 1937 | .B \-\-test |
98c6faba | 1938 | flag was given. |
773135f5 | 1939 | (syslog priority: Info) |
e0d19036 NB |
1940 | .RE |
1941 | ||
1942 | Only | |
93e790af SW |
1943 | .B Fail, |
1944 | .B FailSpare, | |
1945 | .B DegradedArray, | |
1946 | .B SparesMissing | |
e0d19036 | 1947 | and |
98c6faba | 1948 | .B TestMessage |
e0d19036 | 1949 | cause Email to be sent. All events cause the program to be run. |
93e790af | 1950 | The program is run with two or three arguments: the event |
e0d19036 NB |
1951 | name, the array device and possibly a second device. |
1952 | ||
1953 | Each event has an associated array device (e.g. | |
1954 | .BR /dev/md1 ) | |
1955 | and possibly a second device. For | |
1956 | .BR Fail , | |
1957 | .BR FailSpare , | |
1958 | and | |
1959 | .B SpareActive | |
1960 | the second device is the relevant component device. | |
1961 | For | |
1962 | .B MoveSpare | |
1963 | the second device is the array that the spare was moved from. | |
1964 | ||
1965 | For | |
51ac42e3 | 1966 | .I mdadm |
e0d19036 | 1967 | to move spares from one array to another, the different arrays need to |
93e790af | 1968 | be labeled with the same |
e0d19036 NB |
1969 | .B spare-group |
1970 | in the configuration file. The | |
1971 | .B spare-group | |
93e790af | 1972 | name can be any string; it is only necessary that different spare |
2d465520 | 1973 | groups use different names. |
e0d19036 NB |
1974 | |
1975 | When | |
51ac42e3 | 1976 | .I mdadm |
93e790af | 1977 | detects that an array in a spare group has fewer active |
e0d19036 NB |
1978 | devices than necessary for the complete array, and has no spare |
1979 | devices, it will look for another array in the same spare group that | |
1980 | has a full complement of working drive and a spare. It will then | |
1981 | attempt to remove the spare from the second drive and add it to the | |
1982 | first. | |
1983 | If the removal succeeds but the adding fails, then it is added back to | |
1984 | the original array. | |
1985 | ||
dd0781e5 NB |
1986 | .SH GROW MODE |
1987 | The GROW mode is used for changing the size or shape of an active | |
1988 | array. | |
1989 | For this to work, the kernel must support the necessary change. | |
2ae555c3 | 1990 | Various types of growth are being added during 2.6 development, |
e0fe762a | 1991 | including restructuring a RAID5 array to have more active devices. |
dd0781e5 | 1992 | |
dfd4d8ee NB |
1993 | Currently the only support available is to |
1994 | .IP \(bu 4 | |
1995 | change the "size" attribute | |
1996 | for RAID1, RAID5 and RAID6. | |
1997 | .IP \(bu 4 | |
f24e2d6c N |
1998 | increase or decrease the "raid\-devices" attribute of RAID1, RAID5, |
1999 | and RAID6. | |
2000 | .IP \bu 4 | |
2001 | change the chunk-size and layout of RAID5 and RAID6. | |
2002 | .IP \bu 4 | |
2003 | convert between RAID1 and RAID5, and between RAID5 and RAID6. | |
dfd4d8ee | 2004 | .IP \(bu 4 |
93e790af | 2005 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 2006 | remove a write-intent bitmap from such an array. |
dfd4d8ee | 2007 | .PP |
dd0781e5 | 2008 | |
8fd8d9c4 N |
2009 | GROW mode is not currently supported for |
2010 | .B CONTAINERS | |
2011 | or arrays inside containers. | |
2012 | ||
2ae555c3 | 2013 | .SS SIZE CHANGES |
fe80f49b | 2014 | Normally when an array is built the "size" it taken from the smallest |
dd0781e5 NB |
2015 | of the drives. If all the small drives in an arrays are, one at a |
2016 | time, removed and replaced with larger drives, then you could have an | |
2017 | array of large drives with only a small amount used. In this | |
2018 | situation, changing the "size" with "GROW" mode will allow the extra | |
2019 | space to start being used. If the size is increased in this way, a | |
2020 | "resync" process will start to make sure the new parts of the array | |
2021 | are synchronised. | |
2022 | ||
2023 | Note that when an array changes size, any filesystem that may be | |
2024 | stored in the array will not automatically grow to use the space. The | |
2025 | filesystem will need to be explicitly told to use the extra space. | |
2026 | ||
e0fe762a N |
2027 | Also the size of an array cannot be changed while it has an active |
2028 | bitmap. If an array has a bitmap, it must be removed before the size | |
2029 | can be changed. Once the change it complete a new bitmap can be created. | |
2030 | ||
2031 | .SS RAID\-DEVICES CHANGES | |
2ae555c3 | 2032 | |
dd0781e5 NB |
2033 | A RAID1 array can work with any number of devices from 1 upwards |
2034 | (though 1 is not very useful). There may be times which you want to | |
2035 | increase or decrease the number of active devices. Note that this is | |
2036 | different to hot-add or hot-remove which changes the number of | |
2037 | inactive devices. | |
2038 | ||
2039 | When reducing the number of devices in a RAID1 array, the slots which | |
2040 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 2041 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
2042 | |
2043 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 2044 | present will be activated immediately. |
dd0781e5 | 2045 | |
f24e2d6c | 2046 | Changing the number of active devices in a RAID5 or RAID6 is much more |
2ae555c3 | 2047 | effort. Every block in the array will need to be read and written |
f24e2d6c | 2048 | back to a new location. From 2.6.17, the Linux Kernel is able to |
ca4f89a3 N |
2049 | increase the number of devices in a RAID5 safely, including restarting |
2050 | an interrupted "reshape". From 2.6.31, the Linux Kernel is able to | |
f24e2d6c N |
2051 | increase or decrease the number of devices in a RAID5 or RAID6. |
2052 | ||
2053 | When decreasing the number of devices, the size of the array will also | |
2054 | decrease. If there was data in the array, it could get destroyed and | |
2055 | this is not reversible. To help prevent accidents, | |
2056 | .I mdadm | |
2057 | requires that the size of the array be decreased first with | |
2058 | .BR "mdadm --grow --array-size" . | |
2059 | This is a reversible change which simply makes the end of the array | |
2060 | inaccessible. The integrity of any data can then be checked before | |
2061 | the non-reversible reduction in the number of devices is request. | |
2ae555c3 | 2062 | |
e0fe762a | 2063 | When relocating the first few stripes on a RAID5, it is not possible |
2ae555c3 NB |
2064 | to keep the data on disk completely consistent and crash-proof. To |
2065 | provide the required safety, mdadm disables writes to the array while | |
2066 | this "critical section" is reshaped, and takes a backup of the data | |
2067 | that is in that section. This backup is normally stored in any spare | |
2068 | devices that the array has, however it can also be stored in a | |
2069 | separate file specified with the | |
7e23fc43 | 2070 | .B \-\-backup\-file |
2ae555c3 NB |
2071 | option. If this option is used, and the system does crash during the |
2072 | critical period, the same file must be passed to | |
7e23fc43 | 2073 | .B \-\-assemble |
2ae555c3 NB |
2074 | to restore the backup and reassemble the array. |
2075 | ||
f24e2d6c N |
2076 | .SS LEVEL CHANGES |
2077 | ||
2078 | Changing the RAID level of any array happens instantaneously. However | |
2079 | in the RAID to RAID6 case this requires a non-standard layout of the | |
2080 | RAID6 data, and in the RAID6 to RAID5 case that non-standard layout is | |
2081 | required before the change can be accomplish. So while the level | |
2082 | change is instant, the accompanying layout change can take quite a | |
2083 | long time. | |
2084 | ||
2085 | .SS CHUNK-SIZE AND LAYOUT CHANGES | |
2086 | ||
2087 | Changing the chunk-size of layout without also changing the number of | |
2088 | devices as the same time will involve re-writing all blocks in-place. | |
2089 | To ensure against data loss in the case of a crash, a | |
2090 | .B --backup-file | |
2091 | must be provided for these changes. Small sections of the array will | |
2092 | be copied to the backup file while they are being rearranged. | |
2093 | ||
2094 | If the reshape is interrupted for any reason, this backup file must be | |
2095 | make available to | |
2096 | .B "mdadm --assemble" | |
2097 | so the array can be reassembled. Consequently the file cannot be | |
2098 | stored on the device being reshaped. | |
2099 | ||
2100 | ||
2ae555c3 NB |
2101 | .SS BITMAP CHANGES |
2102 | ||
2103 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 2104 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b | 2105 | can be added. Note that if you add a bitmap stored in a file which is |
e0fe762a | 2106 | in a filesystem that is on the RAID array being affected, the system |
fe80f49b NB |
2107 | will deadlock. The bitmap must be on a separate filesystem. |
2108 | ||
8382f19b NB |
2109 | .SH INCREMENTAL MODE |
2110 | ||
2111 | .HP 12 | |
2112 | Usage: | |
7e23fc43 PS |
2113 | .B mdadm \-\-incremental |
2114 | .RB [ \-\-run ] | |
2115 | .RB [ \-\-quiet ] | |
8382f19b NB |
2116 | .I component-device |
2117 | .HP 12 | |
2118 | Usage: | |
7e23fc43 | 2119 | .B mdadm \-\-incremental \-\-rebuild |
8382f19b NB |
2120 | .HP 12 |
2121 | Usage: | |
7e23fc43 | 2122 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b | 2123 | |
8382f19b NB |
2124 | .PP |
2125 | This mode is designed to be used in conjunction with a device | |
2126 | discovery system. As devices are found in a system, they can be | |
2127 | passed to | |
7e23fc43 | 2128 | .B "mdadm \-\-incremental" |
8382f19b NB |
2129 | to be conditionally added to an appropriate array. |
2130 | ||
8fd8d9c4 N |
2131 | If the device passed is a |
2132 | .B CONTAINER | |
2133 | device created by a previous call to | |
2134 | .IR mdadm , | |
2135 | then rather than trying to add that device to an array, all the arrays | |
2136 | described by the metadata of the container will be started. | |
2137 | ||
8382f19b NB |
2138 | .I mdadm |
2139 | performs a number of tests to determine if the device is part of an | |
93e790af | 2140 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
2141 | is found, or can be created, |
2142 | .I mdadm | |
2143 | adds the device to the array and conditionally starts the array. | |
2144 | ||
2145 | Note that | |
2146 | .I mdadm | |
2147 | will only add devices to an array which were previously working | |
2148 | (active or spare) parts of that array. It does not currently support | |
2149 | automatic inclusion of a new drive as a spare in some array. | |
2150 | ||
8382f19b NB |
2151 | The tests that |
2152 | .I mdadm | |
2153 | makes are as follow: | |
2154 | .IP + | |
2155 | Is the device permitted by | |
2156 | .BR mdadm.conf ? | |
2157 | That is, is it listed in a | |
2158 | .B DEVICES | |
2159 | line in that file. If | |
2160 | .B DEVICES | |
2161 | is absent then the default it to allow any device. Similar if | |
2162 | .B DEVICES | |
2163 | contains the special word | |
2164 | .B partitions | |
2165 | then any device is allowed. Otherwise the device name given to | |
2166 | .I mdadm | |
2167 | must match one of the names or patterns in a | |
2168 | .B DEVICES | |
2169 | line. | |
2170 | ||
2171 | .IP + | |
2172 | Does the device have a valid md superblock. If a specific metadata | |
2173 | version is request with | |
7e23fc43 | 2174 | .B \-\-metadata |
8382f19b | 2175 | or |
7e23fc43 | 2176 | .B \-e |
8382f19b NB |
2177 | then only that style of metadata is accepted, otherwise |
2178 | .I mdadm | |
2179 | finds any known version of metadata. If no | |
2180 | .I md | |
2181 | metadata is found, the device is rejected. | |
2182 | ||
e0fe762a | 2183 | .ig XX |
8382f19b NB |
2184 | .IP + |
2185 | Does the metadata match an expected array? | |
2186 | The metadata can match in two ways. Either there is an array listed | |
2187 | in | |
2188 | .B mdadm.conf | |
2189 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 2190 | or by minor-number), or the array was created with a |
8382f19b | 2191 | .B homehost |
93e790af | 2192 | specified and that |
8382f19b | 2193 | .B homehost |
93e790af | 2194 | matches the one in |
8382f19b NB |
2195 | .B mdadm.conf |
2196 | or on the command line. | |
2197 | If | |
2198 | .I mdadm | |
2199 | is not able to positively identify the array as belonging to the | |
2200 | current host, the device will be rejected. | |
e0fe762a | 2201 | .XX |
8382f19b | 2202 | |
8382f19b | 2203 | .I mdadm |
93e790af | 2204 | keeps a list of arrays that it has partially assembled in |
8382f19b NB |
2205 | .B /var/run/mdadm/map |
2206 | (or | |
2207 | .B /var/run/mdadm.map | |
e0fe762a N |
2208 | if the directory doesn't exist. Or maybe even |
2209 | .BR /dev/.mdadm.map ). | |
2210 | If no array exists which matches | |
8382f19b NB |
2211 | the metadata on the new device, |
2212 | .I mdadm | |
2213 | must choose a device name and unit number. It does this based on any | |
2214 | name given in | |
2215 | .B mdadm.conf | |
2216 | or any name information stored in the metadata. If this name | |
2217 | suggests a unit number, that number will be used, otherwise a free | |
2218 | unit number will be chosen. Normally | |
2219 | .I mdadm | |
2220 | will prefer to create a partitionable array, however if the | |
2221 | .B CREATE | |
2222 | line in | |
2223 | .B mdadm.conf | |
2224 | suggests that a non-partitionable array is preferred, that will be | |
2225 | honoured. | |
2226 | ||
e0fe762a N |
2227 | If the array is not found in the config file and its metadata does not |
2228 | identify it as belonging to the "homehost", then | |
2229 | .I mdadm | |
2230 | will choose a name for the array which is certain not to conflict with | |
2231 | any array which does belong to this host. It does this be adding an | |
2232 | underscore and a small number to the name preferred by the metadata. | |
2233 | ||
8382f19b NB |
2234 | Once an appropriate array is found or created and the device is added, |
2235 | .I mdadm | |
2236 | must decide if the array is ready to be started. It will | |
2237 | normally compare the number of available (non-spare) devices to the | |
2238 | number of devices that the metadata suggests need to be active. If | |
2239 | there are at least that many, the array will be started. This means | |
2240 | that if any devices are missing the array will not be restarted. | |
2241 | ||
2242 | As an alternative, | |
7e23fc43 | 2243 | .B \-\-run |
8382f19b | 2244 | may be passed to |
51ac42e3 | 2245 | .I mdadm |
8382f19b | 2246 | in which case the array will be run as soon as there are enough |
e0fe762a N |
2247 | devices present for the data to be accessible. For a RAID1, that |
2248 | means one device will start the array. For a clean RAID5, the array | |
8382f19b NB |
2249 | will be started as soon as all but one drive is present. |
2250 | ||
93e790af | 2251 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
2252 | be known that all device discovery has completed, then |
2253 | .br | |
7e23fc43 | 2254 | .B " mdadm \-IRs" |
8382f19b NB |
2255 | .br |
2256 | can be run which will try to start all arrays that are being | |
2257 | incrementally assembled. They are started in "read-auto" mode in | |
2258 | which they are read-only until the first write request. This means | |
2259 | that no metadata updates are made and no attempt at resync or recovery | |
2260 | happens. Further devices that are found before the first write can | |
2261 | still be added safely. | |
2262 | ||
5545fa6d DW |
2263 | .SH ENVIRONMENT |
2264 | This section describes environment variables that affect how mdadm | |
2265 | operates. | |
2266 | ||
2267 | .TP | |
2268 | .B MDADM_NO_MDMON | |
2269 | Setting this value to 1 will prevent mdadm from automatically launching | |
2270 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
2271 | ||
8fd8d9c4 N |
2272 | .TP |
2273 | .B MDADM_NO_UDEV | |
2274 | Normally, | |
2275 | .I mdadm | |
2276 | does not create any device nodes in /dev, but leaves that task to | |
2277 | .IR udev . | |
2278 | If | |
2279 | .I udev | |
2280 | appears not to be configured, or if this environment variable is set | |
2281 | to '1', the | |
2282 | .I mdadm | |
2283 | will create and devices that are needed. | |
2284 | ||
2d465520 NB |
2285 | .SH EXAMPLES |
2286 | ||
7e23fc43 | 2287 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 2288 | .br |
e0fe762a | 2289 | This will find out if a given device is a RAID array, or is part of |
5787fa49 | 2290 | one, and will provide brief information about the device. |
2d465520 | 2291 | |
7e23fc43 | 2292 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 2293 | .br |
93e790af | 2294 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 2295 | file. This command will typically go in a system startup file. |
2d465520 | 2296 | |
7e23fc43 | 2297 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 2298 | .br |
93e790af | 2299 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 2300 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 2301 | |
7e23fc43 | 2302 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 2303 | .br |
5787fa49 NB |
2304 | If (and only if) there is an Email address or program given in the |
2305 | standard config file, then | |
2306 | monitor the status of all arrays listed in that file by | |
2307 | polling them ever 2 minutes. | |
2d465520 | 2308 | |
7e23fc43 | 2309 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 2310 | .br |
5787fa49 | 2311 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 2312 | |
2d465520 | 2313 | .br |
7e23fc43 | 2314 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 2315 | .br |
7e23fc43 | 2316 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 2317 | .br |
5787fa49 NB |
2318 | This will create a prototype config file that describes currently |
2319 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
2320 | This file should be reviewed before being used as it may |
2321 | contain unwanted detail. | |
2322 | ||
7e23fc43 | 2323 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 2324 | .br |
7e23fc43 | 2325 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
2326 | .br |
2327 | This will find arrays which could be assembled from existing IDE and | |
2328 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 2329 | format of a config file. |
2d465520 NB |
2330 | This file is very likely to contain unwanted detail, particularly |
2331 | the | |
2332 | .B devices= | |
5787fa49 NB |
2333 | entries. It should be reviewed and edited before being used as an |
2334 | actual config file. | |
2d465520 | 2335 | |
7e23fc43 | 2336 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 2337 | .br |
7e23fc43 | 2338 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
2339 | .br |
2340 | Create a list of devices by reading | |
2341 | .BR /proc/partitions , | |
2342 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 2343 | that were found. |
2d465520 | 2344 | |
7e23fc43 | 2345 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 2346 | .br |
5787fa49 NB |
2347 | Scan all partitions and devices listed in |
2348 | .BR /proc/partitions | |
2349 | and assemble | |
2350 | .B /dev/md0 | |
2351 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 2352 | |
7e23fc43 | 2353 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm" |
d013a55e NB |
2354 | .br |
2355 | If config file contains a mail address or alert program, run mdadm in | |
2356 | the background in monitor mode monitoring all md devices. Also write | |
2357 | pid of mdadm daemon to | |
2358 | .BR /var/run/mdadm . | |
2359 | ||
7e23fc43 | 2360 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
2361 | .br |
2362 | Try to incorporate newly discovered device into some array as | |
2363 | appropriate. | |
2364 | ||
7e23fc43 | 2365 | .B " mdadm \-\-incremental \-\-rebuild \-\-run \-\-scan" |
8382f19b NB |
2366 | .br |
2367 | Rebuild the array map from any current arrays, and then start any that | |
2368 | can be started. | |
2369 | ||
b80da661 NB |
2370 | .B " mdadm /dev/md4 --fail detached --remove detached" |
2371 | .br | |
2372 | Any devices which are components of /dev/md4 will be marked as faulty | |
2373 | and then remove from the array. | |
2374 | ||
f24e2d6c N |
2375 | .B " mdadm --grow /dev/md4 --level=6 --backup-file=/root/backup-md4 |
2376 | .br | |
2377 | The array | |
2378 | .B /dev/md4 | |
2379 | which is currently a RAID5 array will be converted to RAID6. There | |
2380 | should normally already be a spare drive attached to the array as a | |
2381 | RAID6 needs one more drive than a matching RAID5. | |
2382 | ||
8fd8d9c4 N |
2383 | .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]" |
2384 | .br | |
2385 | Create a DDF array over 6 devices. | |
2386 | ||
2387 | .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf" | |
2388 | .br | |
e0fe762a | 2389 | Create a RAID5 array over any 3 devices in the given DDF set. Use |
8fd8d9c4 N |
2390 | only 30 gigabytes of each device. |
2391 | ||
2392 | .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]" | |
2393 | .br | |
2394 | Assemble a pre-exist ddf array. | |
2395 | ||
2396 | .B " mdadm -I /dev/md/ddf1" | |
2397 | .br | |
2398 | Assemble all arrays contained in the ddf array, assigning names as | |
2399 | appropriate. | |
2400 | ||
7e23fc43 | 2401 | .B " mdadm \-\-create \-\-help" |
2d465520 | 2402 | .br |
2ae555c3 | 2403 | Provide help about the Create mode. |
2d465520 | 2404 | |
7e23fc43 | 2405 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
2406 | .br |
2407 | Provide help about the format of the config file. | |
2d465520 | 2408 | |
7e23fc43 | 2409 | .B " mdadm \-\-help" |
5787fa49 NB |
2410 | .br |
2411 | Provide general help. | |
cd29a5c8 | 2412 | |
cd29a5c8 NB |
2413 | .SH FILES |
2414 | ||
2415 | .SS /proc/mdstat | |
2416 | ||
2ae555c3 NB |
2417 | If you're using the |
2418 | .B /proc | |
cd29a5c8 NB |
2419 | filesystem, |
2420 | .B /proc/mdstat | |
2d465520 | 2421 | lists all active md devices with information about them. |
51ac42e3 | 2422 | .I mdadm |
2d465520 | 2423 | uses this to find arrays when |
7e23fc43 | 2424 | .B \-\-scan |
2d465520 NB |
2425 | is given in Misc mode, and to monitor array reconstruction |
2426 | on Monitor mode. | |
2427 | ||
9a9dab36 | 2428 | .SS /etc/mdadm.conf |
cd29a5c8 | 2429 | |
11a3e71d NB |
2430 | The config file lists which devices may be scanned to see if |
2431 | they contain MD super block, and gives identifying information | |
2432 | (e.g. UUID) about known MD arrays. See | |
2433 | .BR mdadm.conf (5) | |
2434 | for more details. | |
cd29a5c8 | 2435 | |
8382f19b NB |
2436 | .SS /var/run/mdadm/map |
2437 | When | |
7e23fc43 | 2438 | .B \-\-incremental |
93e790af | 2439 | mode is used, this file gets a list of arrays currently being created. |
8382f19b NB |
2440 | If |
2441 | .B /var/run/mdadm | |
2442 | does not exist as a directory, then | |
2443 | .B /var/run/mdadm.map | |
e0fe762a N |
2444 | is used instead. If |
2445 | .B /var/run | |
2446 | is not available (as may be the case during early boot), | |
2447 | .B /dev/.mdadm.map | |
2448 | is used on the basis that | |
2449 | .B /dev | |
2450 | is usually available very early in boot. | |
8382f19b | 2451 | |
48f7b27a NB |
2452 | .SH DEVICE NAMES |
2453 | ||
48f7b27a | 2454 | .I mdadm |
8fd8d9c4 N |
2455 | understand two sorts of names for array devices. |
2456 | ||
2457 | The first is the so-called 'standard' format name, which matches the | |
2458 | names used by the kernel and which appear in | |
2459 | .IR /proc/mdstat . | |
2460 | ||
2461 | The second sort can be freely chosen, but must reside in | |
2462 | .IR /dev/md/ . | |
2463 | When giving a device name to | |
2464 | .I mdadm | |
2465 | to create or assemble an array, either full path name such as | |
2466 | .I /dev/md0 | |
2467 | or | |
2468 | .I /dev/md/home | |
2469 | can be given, or just the suffix of the second sort of name, such as | |
2470 | .I home | |
2471 | can be given. | |
2472 | ||
2473 | When | |
2474 | .I mdadm | |
e0fe762a N |
2475 | chooses device names during auto-assembly or incremental assembly, it |
2476 | will sometimes add a small sequence number to the end of the name to | |
2477 | avoid conflicted between multiple arrays that have the same name. If | |
8fd8d9c4 N |
2478 | .I mdadm |
2479 | can reasonably determine that the array really is meant for this host, | |
2480 | either by a hostname in the metadata, or by the presence of the array | |
e0fe762a N |
2481 | in /etc/mdadm.conf, then it will leave off the suffix if possible. |
2482 | Also if the homehost is specified as | |
2483 | .B <ignore> | |
2484 | .I mdadm | |
2485 | will only use a suffix if a different array of the same name already | |
2486 | exists or is listed in the config file. | |
48f7b27a NB |
2487 | |
2488 | The standard names for non-partitioned arrays (the only sort of md | |
8fd8d9c4 | 2489 | array available in 2.4 and earlier) are of the form |
48f7b27a NB |
2490 | .IP |
2491 | /dev/mdNN | |
48f7b27a NB |
2492 | .PP |
2493 | where NN is a number. | |
2494 | The standard names for partitionable arrays (as available from 2.6 | |
8fd8d9c4 | 2495 | onwards) are of the form |
48f7b27a | 2496 | .IP |
48f7b27a NB |
2497 | /dev/md_dNN |
2498 | .PP | |
2499 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
8fd8d9c4 N |
2500 | .PP |
2501 | From kernel version, 2.6.28 the "non-partitioned array" can actually | |
2502 | be partitioned. So the "md_dNN" names are no longer needed, and | |
2503 | partitions such as "/dev/mdNNpXX" are possible. | |
52826846 | 2504 | |
2d465520 | 2505 | .SH NOTE |
51ac42e3 | 2506 | .I mdadm |
2d465520 | 2507 | was previously known as |
51ac42e3 | 2508 | .IR mdctl . |
a9d69660 | 2509 | .P |
51ac42e3 | 2510 | .I mdadm |
a9d69660 | 2511 | is completely separate from the |
51ac42e3 | 2512 | .I raidtools |
a9d69660 NB |
2513 | package, and does not use the |
2514 | .I /etc/raidtab | |
2515 | configuration file at all. | |
2516 | ||
52826846 | 2517 | .SH SEE ALSO |
75f74377 | 2518 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 2519 | RAID, see: |
3cdfb6a7 | 2520 | .IP |
11cd8b79 | 2521 | .B http://linux\-raid.osdl.org/ |
75f74377 DG |
2522 | .PP |
2523 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
e43d0cda NB |
2524 | .\".PP |
2525 | .\"for new releases of the RAID driver check out: | |
2526 | .\" | |
2527 | .\".IP | |
e0fe762a | 2528 | .\".UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches |
e43d0cda NB |
2529 | .\"ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches |
2530 | .\".UE | |
2531 | .\".PP | |
2532 | .\"or | |
2533 | .\".IP | |
2534 | .\".UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2535 | .\"http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2536 | .\".UE | |
cd29a5c8 | 2537 | .PP |
2ae555c3 | 2538 | The latest version of |
a9d69660 NB |
2539 | .I mdadm |
2540 | should always be available from | |
cd29a5c8 | 2541 | .IP |
11cd8b79 N |
2542 | .B http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
2543 | .PP | |
2544 | Related man pages: | |
cd29a5c8 | 2545 | .PP |
e0fe762a | 2546 | .IR mdmon (8), |
a9d69660 NB |
2547 | .IR mdadm.conf (5), |
2548 | .IR md (4). | |
56eb10c0 | 2549 | .PP |
52826846 NB |
2550 | .IR raidtab (5), |
2551 | .IR raid0run (8), | |
2552 | .IR raidstop (8), | |
a9d69660 | 2553 | .IR mkraid (8). |