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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. | |
b9d77223 | 8 | .TH MDADM 8 "" v3.0-devel3 |
52826846 | 9 | .SH NAME |
9a9dab36 | 10 | mdadm \- manage MD devices |
cd29a5c8 | 11 | .I aka |
93e790af | 12 | Linux Software RAID |
cd29a5c8 | 13 | |
52826846 NB |
14 | .SH SYNOPSIS |
15 | ||
e0d19036 | 16 | .BI mdadm " [mode] <raiddevice> [options] <component-devices>" |
52826846 | 17 | |
2ae555c3 | 18 | .SH DESCRIPTION |
52826846 | 19 | RAID devices are virtual devices created from two or more |
cd29a5c8 | 20 | real block devices. This allows multiple devices (typically disk |
35cc5be4 | 21 | drives or partitions thereof) to be combined into a single device to |
cd29a5c8 | 22 | hold (for example) a single filesystem. |
2d465520 | 23 | Some RAID levels include redundancy and so can survive some degree of |
cd29a5c8 NB |
24 | device failure. |
25 | ||
2d465520 NB |
26 | Linux Software RAID devices are implemented through the md (Multiple |
27 | Devices) device driver. | |
cd29a5c8 NB |
28 | |
29 | Currently, Linux supports | |
30 | .B LINEAR | |
31 | md devices, | |
32 | .B RAID0 | |
33 | (striping), | |
34 | .B RAID1 | |
35 | (mirroring), | |
d013a55e NB |
36 | .BR RAID4 , |
37 | .BR RAID5 , | |
98c6faba | 38 | .BR RAID6 , |
1a7dfc35 | 39 | .BR RAID10 , |
b5e64645 | 40 | .BR MULTIPATH , |
90c8d668 | 41 | .BR FAULTY , |
cd29a5c8 | 42 | and |
90c8d668 | 43 | .BR CONTAINER . |
d013a55e | 44 | |
a9d69660 NB |
45 | .B MULTIPATH |
46 | is not a Software RAID mechanism, but does involve | |
93e790af | 47 | multiple devices: |
d013a55e | 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 |
52826846 | 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 | |
a9d69660 NB |
93 | Build an array that doesn't have per-device superblocks. For these |
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 | |
105 | Create a new array with per-device superblocks. | |
e43d0cda NB |
106 | .\"It can progress |
107 | .\"in several step create-add-add-run or it can all happen with one command. | |
cd29a5c8 | 108 | |
cd29a5c8 NB |
109 | .TP |
110 | .B "Follow or Monitor" | |
5787fa49 | 111 | Monitor one or more md devices and act on any state changes. This is |
93e790af | 112 | only meaningful for raid1, 4, 5, 6, 10 or multipath arrays, as |
98c6faba NB |
113 | only these have interesting state. raid0 or linear never have |
114 | missing, spare, or failed drives, so there is nothing to monitor. | |
5787fa49 | 115 | |
dd0781e5 NB |
116 | .TP |
117 | .B "Grow" | |
118 | Grow (or shrink) an array, or otherwise reshape it in some way. | |
119 | Currently supported growth options including changing the active size | |
93e790af SW |
120 | of component devices and changing the number of active devices in RAID |
121 | levels 1/4/5/6, as well as adding or removing a write-intent bitmap. | |
cd29a5c8 | 122 | |
8382f19b NB |
123 | .TP |
124 | .B "Incremental Assembly" | |
125 | Add a single device to an appropriate array. If the addition of the | |
126 | device makes the array runnable, the array will be started. | |
127 | This provides a convenient interface to a | |
128 | .I hot-plug | |
129 | system. As each device is detected, | |
130 | .I mdadm | |
131 | has a chance to include it in some array as appropriate. | |
9652457e | 132 | |
8fd8d9c4 N |
133 | If a |
134 | .B CONTAINER | |
135 | is passed to | |
136 | .I mdadm | |
137 | in this mode, then any arrays within that container will be assembled | |
138 | and started. | |
8382f19b | 139 | |
2ae555c3 NB |
140 | .TP |
141 | .B Manage | |
142 | This is for doing things to specific components of an array such as | |
143 | adding new spares and removing faulty devices. | |
144 | ||
145 | .TP | |
146 | .B Misc | |
147 | This is an 'everything else' mode that supports operations on active | |
148 | arrays, operations on component devices such as erasing old superblocks, and | |
149 | information gathering operations. | |
e43d0cda NB |
150 | .\"This mode allows operations on independent devices such as examine MD |
151 | .\"superblocks, erasing old superblocks and stopping active arrays. | |
2ae555c3 | 152 | |
1f48664b NB |
153 | .TP |
154 | .B Auto-detect | |
155 | This mode does not act on a specific device or array, but rather it | |
156 | requests the Linux Kernel to activate any auto-detected arrays. | |
52826846 NB |
157 | .SH OPTIONS |
158 | ||
2ae555c3 | 159 | .SH Options for selecting a mode are: |
52826846 | 160 | |
cd29a5c8 | 161 | .TP |
7e23fc43 | 162 | .BR \-A ", " \-\-assemble |
2d465520 | 163 | Assemble a pre-existing array. |
52826846 | 164 | |
cd29a5c8 | 165 | .TP |
7e23fc43 | 166 | .BR \-B ", " \-\-build |
cd29a5c8 | 167 | Build a legacy array without superblocks. |
52826846 | 168 | |
cd29a5c8 | 169 | .TP |
7e23fc43 | 170 | .BR \-C ", " \-\-create |
cd29a5c8 | 171 | Create a new array. |
52826846 | 172 | |
cd29a5c8 | 173 | .TP |
7e23fc43 | 174 | .BR \-F ", " \-\-follow ", " \-\-monitor |
cd29a5c8 NB |
175 | Select |
176 | .B Monitor | |
177 | mode. | |
52826846 | 178 | |
dd0781e5 | 179 | .TP |
7e23fc43 | 180 | .BR \-G ", " \-\-grow |
dd0781e5 | 181 | Change the size or shape of an active array. |
8382f19b NB |
182 | |
183 | .TP | |
1f48664b | 184 | .BR \-I ", " \-\-incremental |
8382f19b NB |
185 | Add a single device into an appropriate array, and possibly start the array. |
186 | ||
1f48664b NB |
187 | .TP |
188 | .B \-\-auto-detect | |
189 | Request that the kernel starts any auto-detected arrays. This can only | |
190 | work if | |
191 | .I md | |
192 | is compiled into the kernel \(em not if it is a module. | |
193 | Arrays can be auto-detected by the kernel if all the components are in | |
194 | primary MS-DOS partitions with partition type | |
195 | .BR FD . | |
196 | In-kernel autodetect is not recommended for new installations. Using | |
197 | .I mdadm | |
198 | to detect and assemble arrays \(em possibly in an | |
199 | .I initrd | |
200 | \(em is substantially more flexible and should be preferred. | |
201 | ||
2ae555c3 NB |
202 | .P |
203 | If a device is given before any options, or if the first option is | |
7e23fc43 PS |
204 | .BR \-\-add , |
205 | .BR \-\-fail , | |
2ae555c3 | 206 | or |
7e23fc43 | 207 | .BR \-\-remove , |
2ae555c3 NB |
208 | then the MANAGE mode is assume. |
209 | Anything other than these will cause the | |
210 | .B Misc | |
211 | mode to be assumed. | |
dd0781e5 | 212 | |
2ae555c3 | 213 | .SH Options that are not mode-specific are: |
e793c2e5 | 214 | |
cd29a5c8 | 215 | .TP |
7e23fc43 | 216 | .BR \-h ", " \-\-help |
a9d69660 | 217 | Display general help message or, after one of the above options, a |
93e790af | 218 | mode-specific help message. |
56eedc1a NB |
219 | |
220 | .TP | |
7e23fc43 | 221 | .B \-\-help\-options |
56eedc1a NB |
222 | Display more detailed help about command line parsing and some commonly |
223 | used options. | |
52826846 | 224 | |
cd29a5c8 | 225 | .TP |
7e23fc43 | 226 | .BR \-V ", " \-\-version |
9a9dab36 | 227 | Print version information for mdadm. |
52826846 | 228 | |
cd29a5c8 | 229 | .TP |
7e23fc43 | 230 | .BR \-v ", " \-\-verbose |
22892d56 NB |
231 | Be more verbose about what is happening. This can be used twice to be |
232 | extra-verbose. | |
a9d69660 | 233 | The extra verbosity currently only affects |
7e23fc43 | 234 | .B \-\-detail \-\-scan |
22892d56 | 235 | and |
7e23fc43 | 236 | .BR "\-\-examine \-\-scan" . |
52826846 | 237 | |
dab6685f | 238 | .TP |
7e23fc43 | 239 | .BR \-q ", " \-\-quiet |
dab6685f | 240 | Avoid printing purely informative messages. With this, |
51ac42e3 | 241 | .I mdadm |
dab6685f NB |
242 | will be silent unless there is something really important to report. |
243 | ||
cd29a5c8 | 244 | .TP |
7e23fc43 | 245 | .BR \-b ", " \-\-brief |
cd29a5c8 | 246 | Be less verbose. This is used with |
7e23fc43 | 247 | .B \-\-detail |
cd29a5c8 | 248 | and |
7e23fc43 | 249 | .BR \-\-examine . |
22892d56 | 250 | Using |
7e23fc43 | 251 | .B \-\-brief |
22892d56 | 252 | with |
7e23fc43 | 253 | .B \-\-verbose |
22892d56 | 254 | gives an intermediate level of verbosity. |
52826846 | 255 | |
e0d19036 | 256 | .TP |
7e23fc43 | 257 | .BR \-f ", " \-\-force |
93e790af | 258 | Be more forceful about certain operations. See the various modes for |
e0d19036 NB |
259 | the exact meaning of this option in different contexts. |
260 | ||
261 | .TP | |
7e23fc43 | 262 | .BR \-c ", " \-\-config= |
2ae555c3 NB |
263 | Specify the config file. Default is to use |
264 | .BR /etc/mdadm.conf , | |
93e790af | 265 | or if that is missing then |
2ae555c3 | 266 | .BR /etc/mdadm/mdadm.conf . |
5787fa49 | 267 | If the config file given is |
93e790af | 268 | .B "partitions" |
5787fa49 NB |
269 | then nothing will be read, but |
270 | .I mdadm | |
271 | will act as though the config file contained exactly | |
8fd8d9c4 | 272 | .B "DEVICE partitions containers" |
5787fa49 NB |
273 | and will read |
274 | .B /proc/partitions | |
8fd8d9c4 N |
275 | to find a list of devices to scan, and |
276 | .B /proc/mdstat | |
277 | to find a list of containers to examine. | |
d013a55e | 278 | If the word |
93e790af | 279 | .B "none" |
d013a55e NB |
280 | is given for the config file, then |
281 | .I mdadm | |
282 | will act as though the config file were empty. | |
e0d19036 NB |
283 | |
284 | .TP | |
7e23fc43 | 285 | .BR \-s ", " \-\-scan |
93e790af | 286 | Scan config file or |
e0d19036 NB |
287 | .B /proc/mdstat |
288 | for missing information. | |
289 | In general, this option gives | |
51ac42e3 | 290 | .I mdadm |
93e790af SW |
291 | permission to get any missing information (like component devices, |
292 | array devices, array identities, and alert destination) from the | |
293 | configuration file (see previous option); | |
294 | one exception is MISC mode when using | |
7e23fc43 | 295 | .B \-\-detail |
e0d19036 | 296 | or |
93e790af | 297 | .B \-\-stop, |
e0d19036 | 298 | in which case |
7e23fc43 | 299 | .B \-\-scan |
e0d19036 NB |
300 | says to get a list of array devices from |
301 | .BR /proc/mdstat . | |
302 | ||
570c0542 | 303 | .TP |
7e23fc43 | 304 | .B \-e ", " \-\-metadata= |
570c0542 | 305 | Declare the style of superblock (raid metadata) to be used. The |
53e8b987 | 306 | default is 0.90 for |
7e23fc43 | 307 | .BR \-\-create , |
53e8b987 | 308 | and to guess for other operations. |
2790ffe3 GB |
309 | The default can be overridden by setting the |
310 | .B metadata | |
311 | value for the | |
312 | .B CREATE | |
313 | keyword in | |
314 | .BR mdadm.conf . | |
570c0542 NB |
315 | |
316 | Options are: | |
317 | .RS | |
318 | .IP "0, 0.90, default" | |
319 | Use the original 0.90 format superblock. This format limits arrays to | |
93e790af | 320 | 28 component devices and limits component devices of levels 1 and |
570c0542 NB |
321 | greater to 2 terabytes. |
322 | .IP "1, 1.0, 1.1, 1.2" | |
323 | Use the new version-1 format superblock. This has few restrictions. | |
93e790af | 324 | The different sub-versions store the superblock at different locations |
570c0542 NB |
325 | on the device, either at the end (for 1.0), at the start (for 1.1) or |
326 | 4K from the start (for 1.2). | |
8fd8d9c4 N |
327 | .IP ddf |
328 | Use the "Industry Standard" DDF (Disk Data Format) format. When | |
329 | creating a DDF array a | |
330 | .B CONTAINER | |
331 | will be created, and normal arrays can be created in that container. | |
332 | .IP imsm | |
4cce4069 | 333 | Use the Intel(R) Matrix Storage Manager metadata format. This creates a |
8fd8d9c4 | 334 | .B CONTAINER |
4cce4069 DW |
335 | which is managed in a similar manner to DDF, and is supported by an |
336 | option-rom on some platforms: | |
337 | .IP | |
338 | .B http://www.intel.com/design/chipsets/matrixstorage_sb.htm | |
339 | .PP | |
570c0542 NB |
340 | .RE |
341 | ||
41a3b72a | 342 | .TP |
7e23fc43 | 343 | .B \-\-homehost= |
35cc5be4 | 344 | This will override any |
41a3b72a | 345 | .B HOMEHOST |
93e790af | 346 | setting in the config file and provides the identity of the host which |
41a3b72a NB |
347 | should be considered the home for any arrays. |
348 | ||
349 | When creating an array, the | |
350 | .B homehost | |
351 | will be recorded in the superblock. For version-1 superblocks, it will | |
93e790af | 352 | be prefixed to the array name. For version-0.90 superblocks, part of |
41a3b72a NB |
353 | the SHA1 hash of the hostname will be stored in the later half of the |
354 | UUID. | |
355 | ||
356 | When reporting information about an array, any array which is tagged | |
357 | for the given homehost will be reported as such. | |
358 | ||
359 | When using Auto-Assemble, only arrays tagged for the given homehost | |
360 | will be assembled. | |
361 | ||
2ae555c3 NB |
362 | .SH For create, build, or grow: |
363 | ||
364 | .TP | |
7e23fc43 | 365 | .BR \-n ", " \-\-raid\-devices= |
2ae555c3 NB |
366 | Specify the number of active devices in the array. This, plus the |
367 | number of spare devices (see below) must equal the number of | |
368 | .I component-devices | |
369 | (including "\fBmissing\fP" devices) | |
370 | that are listed on the command line for | |
7e23fc43 | 371 | .BR \-\-create . |
2ae555c3 NB |
372 | Setting a value of 1 is probably |
373 | a mistake and so requires that | |
7e23fc43 | 374 | .B \-\-force |
2ae555c3 NB |
375 | be specified first. A value of 1 will then be allowed for linear, |
376 | multipath, raid0 and raid1. It is never allowed for raid4 or raid5. | |
377 | .br | |
378 | This number can only be changed using | |
7e23fc43 | 379 | .B \-\-grow |
00be0b12 NB |
380 | for RAID1, RAID5 and RAID6 arrays, and only on kernels which provide |
381 | necessary support. | |
2ae555c3 NB |
382 | |
383 | .TP | |
7e23fc43 | 384 | .BR \-x ", " \-\-spare\-devices= |
2ae555c3 NB |
385 | Specify the number of spare (eXtra) devices in the initial array. |
386 | Spares can also be added | |
387 | and removed later. The number of component devices listed | |
388 | on the command line must equal the number of raid devices plus the | |
389 | number of spare devices. | |
390 | ||
391 | ||
392 | .TP | |
7e23fc43 | 393 | .BR \-z ", " \-\-size= |
93e790af | 394 | Amount (in Kibibytes) of space to use from each drive in RAID level 1/4/5/6. |
2ae555c3 NB |
395 | This must be a multiple of the chunk size, and must leave about 128Kb |
396 | of space at the end of the drive for the RAID superblock. | |
397 | If this is not specified | |
398 | (as it normally is not) the smallest drive (or partition) sets the | |
399 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
400 | issued. | |
401 | ||
402 | This value can be set with | |
7e23fc43 | 403 | .B \-\-grow |
2ae555c3 NB |
404 | for RAID level 1/4/5/6. If the array was created with a size smaller |
405 | than the currently active drives, the extra space can be accessed | |
406 | using | |
7e23fc43 | 407 | .BR \-\-grow . |
2ae555c3 NB |
408 | The size can be given as |
409 | .B max | |
410 | which means to choose the largest size that fits on all current drives. | |
52826846 | 411 | |
8fd8d9c4 N |
412 | This value can not be used with |
413 | .B CONTAINER | |
414 | metadata such as DDF and IMSM. | |
415 | ||
cd29a5c8 | 416 | .TP |
7e23fc43 | 417 | .BR \-c ", " \-\-chunk= |
cd29a5c8 | 418 | Specify chunk size of kibibytes. The default is 64. |
52826846 | 419 | |
cd29a5c8 | 420 | .TP |
7e23fc43 | 421 | .BR \-\-rounding= |
cd29a5c8 | 422 | Specify rounding factor for linear array (==chunk size) |
52826846 | 423 | |
cd29a5c8 | 424 | .TP |
7e23fc43 | 425 | .BR \-l ", " \-\-level= |
aa88f531 | 426 | Set raid level. When used with |
7e23fc43 | 427 | .BR \-\-create , |
98c6faba | 428 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
8fd8d9c4 N |
429 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container. |
430 | Obviously some of these are synonymous. | |
431 | ||
432 | When a | |
433 | .B CONTAINER | |
434 | metadata type is requested, only the | |
435 | .B container | |
436 | level is permitted, and it does not need to be explicitly given. | |
aa88f531 NB |
437 | |
438 | When used with | |
7e23fc43 | 439 | .BR \-\-build , |
a9d69660 | 440 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 441 | |
2ae555c3 | 442 | Not yet supported with |
7e23fc43 | 443 | .BR \-\-grow . |
2ae555c3 | 444 | |
cd29a5c8 | 445 | .TP |
7e23fc43 | 446 | .BR \-p ", " \-\-layout= |
1a7dfc35 NB |
447 | This option configures the fine details of data layout for raid5, |
448 | and raid10 arrays, and controls the failure modes for | |
449 | .IR faulty . | |
450 | ||
451 | The layout of the raid5 parity block can be one of | |
7e23fc43 PS |
452 | .BR left\-asymmetric , |
453 | .BR left\-symmetric , | |
454 | .BR right\-asymmetric , | |
455 | .BR right\-symmetric , | |
53e8b987 PS |
456 | .BR la ", " ra ", " ls ", " rs . |
457 | The default is | |
7e23fc43 | 458 | .BR left\-symmetric . |
52826846 | 459 | |
93e790af SW |
460 | When setting the failure mode for level |
461 | .I faulty, | |
1a7dfc35 | 462 | the options are: |
7e23fc43 PS |
463 | .BR write\-transient ", " wt , |
464 | .BR read\-transient ", " rt , | |
465 | .BR write\-persistent ", " wp , | |
466 | .BR read\-persistent ", " rp , | |
467 | .BR write\-all , | |
468 | .BR read\-fixable ", " rf , | |
53e8b987 | 469 | .BR clear ", " flush ", " none . |
b5e64645 | 470 | |
93e790af | 471 | Each failure mode can be followed by a number, which is used as a period |
b5e64645 NB |
472 | between fault generation. Without a number, the fault is generated |
473 | once on the first relevant request. With a number, the fault will be | |
93e790af | 474 | generated after that many requests, and will continue to be generated |
b5e64645 NB |
475 | every time the period elapses. |
476 | ||
477 | Multiple failure modes can be current simultaneously by using the | |
7e23fc43 | 478 | .B \-\-grow |
53e8b987 | 479 | option to set subsequent failure modes. |
b5e64645 NB |
480 | |
481 | "clear" or "none" will remove any pending or periodic failure modes, | |
2ae555c3 | 482 | and "flush" will clear any persistent faults. |
b5e64645 | 483 | |
53e8b987 | 484 | To set the parity with |
7e23fc43 | 485 | .BR \-\-grow , |
53e8b987 | 486 | the level of the array ("faulty") |
b5e64645 NB |
487 | must be specified before the fault mode is specified. |
488 | ||
6f9a21a7 | 489 | Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed |
93e790af | 490 | by a small number. The default is 'n2'. The supported options are: |
1a7dfc35 | 491 | |
93e790af | 492 | .I 'n' |
b578481c NB |
493 | signals 'near' copies. Multiple copies of one data block are at |
494 | similar offsets in different devices. | |
495 | ||
93e790af | 496 | .I 'o' |
b578481c NB |
497 | signals 'offset' copies. Rather than the chunks being duplicated |
498 | within a stripe, whole stripes are duplicated but are rotated by one | |
499 | device so duplicate blocks are on different devices. Thus subsequent | |
500 | copies of a block are in the next drive, and are one chunk further | |
501 | down. | |
502 | ||
93e790af | 503 | .I 'f' |
1a7dfc35 | 504 | signals 'far' copies |
93e790af SW |
505 | (multiple copies have very different offsets). |
506 | See md(4) for more detail about 'near' and 'far'. | |
1a7dfc35 NB |
507 | |
508 | The number is the number of copies of each datablock. 2 is normal, 3 | |
509 | can be useful. This number can be at most equal to the number of | |
510 | devices in the array. It does not need to divide evenly into that | |
511 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
512 | with an odd number of devices). | |
513 | ||
cd29a5c8 | 514 | .TP |
7e23fc43 | 515 | .BR \-\-parity= |
53e8b987 | 516 | same as |
7e23fc43 | 517 | .B \-\-layout |
53e8b987 | 518 | (thus explaining the p of |
7e23fc43 | 519 | .BR \-p ). |
52826846 | 520 | |
e793c2e5 | 521 | .TP |
7e23fc43 | 522 | .BR \-b ", " \-\-bitmap= |
e793c2e5 | 523 | Specify a file to store a write-intent bitmap in. The file should not |
53e8b987 | 524 | exist unless |
7e23fc43 | 525 | .B \-\-force |
53e8b987 | 526 | is also given. The same file should be provided |
2ae555c3 | 527 | when assembling the array. If the word |
93e790af | 528 | .B "internal" |
2ae555c3 NB |
529 | is given, then the bitmap is stored with the metadata on the array, |
530 | and so is replicated on all devices. If the word | |
93e790af | 531 | .B "none" |
2ae555c3 | 532 | is given with |
7e23fc43 | 533 | .B \-\-grow |
2ae555c3 | 534 | mode, then any bitmap that is present is removed. |
e793c2e5 | 535 | |
2ae555c3 NB |
536 | To help catch typing errors, the filename must contain at least one |
537 | slash ('/') if it is a real file (not 'internal' or 'none'). | |
538 | ||
539 | Note: external bitmaps are only known to work on ext2 and ext3. | |
540 | Storing bitmap files on other filesystems may result in serious problems. | |
e793c2e5 | 541 | |
cd29a5c8 | 542 | .TP |
7e23fc43 | 543 | .BR \-\-bitmap\-chunk= |
2ae555c3 | 544 | Set the chunksize of the bitmap. Each bit corresponds to that many |
1bfdbe01 NB |
545 | Kilobytes of storage. |
546 | When using a file based bitmap, the default is to use the smallest | |
93e790af | 547 | size that is at-least 4 and requires no more than 2^21 chunks. |
2ae555c3 NB |
548 | When using an |
549 | .B internal | |
550 | bitmap, the chunksize is automatically determined to make best use of | |
551 | available space. | |
5787fa49 | 552 | |
cd29a5c8 NB |
553 | |
554 | .TP | |
7e23fc43 | 555 | .BR \-W ", " \-\-write\-mostly |
2ae555c3 | 556 | subsequent devices lists in a |
7e23fc43 PS |
557 | .BR \-\-build , |
558 | .BR \-\-create , | |
2ae555c3 | 559 | or |
7e23fc43 | 560 | .B \-\-add |
2ae555c3 NB |
561 | command will be flagged as 'write-mostly'. This is valid for RAID1 |
562 | only and means that the 'md' driver will avoid reading from these | |
563 | devices if at all possible. This can be useful if mirroring over a | |
564 | slow link. | |
52826846 | 565 | |
2ae555c3 | 566 | .TP |
7e23fc43 | 567 | .BR \-\-write\-behind= |
2ae555c3 NB |
568 | Specify that write-behind mode should be enabled (valid for RAID1 |
569 | only). If an argument is specified, it will set the maximum number | |
570 | of outstanding writes allowed. The default value is 256. | |
571 | A write-intent bitmap is required in order to use write-behind | |
572 | mode, and write-behind is only attempted on drives marked as | |
573 | .IR write-mostly . | |
dd0781e5 NB |
574 | |
575 | .TP | |
7e23fc43 | 576 | .BR \-\-assume\-clean |
dd0781e5 NB |
577 | Tell |
578 | .I mdadm | |
47d79ef8 NB |
579 | that the array pre-existed and is known to be clean. It can be useful |
580 | when trying to recover from a major failure as you can be sure that no | |
581 | data will be affected unless you actually write to the array. It can | |
582 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
b3f1c093 | 583 | initial resync, however this practice \(em while normally safe \(em is not |
93e790af | 584 | recommended. Use this only if you really know what you are doing. |
dd0781e5 | 585 | |
2ae555c3 | 586 | .TP |
7e23fc43 | 587 | .BR \-\-backup\-file= |
53e8b987 | 588 | This is needed when |
7e23fc43 | 589 | .B \-\-grow |
53e8b987 | 590 | is used to increase the number of |
2ae555c3 NB |
591 | raid-devices in a RAID5 if there are no spare devices available. |
592 | See the section below on RAID_DEVICE CHANGES. The file should be | |
593 | stored on a separate device, not on the raid array being reshaped. | |
594 | ||
947fd4dd | 595 | .TP |
7e23fc43 | 596 | .BR \-N ", " \-\-name= |
947fd4dd NB |
597 | Set a |
598 | .B name | |
599 | for the array. This is currently only effective when creating an | |
600 | array with a version-1 superblock. The name is a simple textual | |
601 | string that can be used to identify array components when assembling. | |
602 | ||
dd0781e5 | 603 | .TP |
7e23fc43 | 604 | .BR \-R ", " \-\-run |
dd0781e5 NB |
605 | Insist that |
606 | .I mdadm | |
607 | run the array, even if some of the components | |
608 | appear to be active in another array or filesystem. Normally | |
609 | .I mdadm | |
610 | will ask for confirmation before including such components in an | |
611 | array. This option causes that question to be suppressed. | |
612 | ||
613 | .TP | |
7e23fc43 | 614 | .BR \-f ", " \-\-force |
dd0781e5 NB |
615 | Insist that |
616 | .I mdadm | |
617 | accept the geometry and layout specified without question. Normally | |
618 | .I mdadm | |
619 | will not allow creation of an array with only one device, and will try | |
620 | to create a raid5 array with one missing drive (as this makes the | |
621 | initial resync work faster). With | |
7e23fc43 | 622 | .BR \-\-force , |
dd0781e5 NB |
623 | .I mdadm |
624 | will not try to be so clever. | |
625 | ||
626 | .TP | |
7e23fc43 | 627 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part,p}{NN}" |
48f7b27a NB |
628 | Instruct mdadm to create the device file if needed, possibly allocating |
629 | an unused minor number. "md" causes a non-partitionable array | |
dd0781e5 | 630 | to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and |
2ae555c3 | 631 | later) to be used. "yes" requires the named md device to have |
f9c25f1d | 632 | a 'standard' format, and the type and minor number will be determined |
48f7b27a NB |
633 | from this. See DEVICE NAMES below. |
634 | ||
a9d69660 | 635 | The argument can also come immediately after |
7e23fc43 | 636 | "\-a". e.g. "\-ap". |
dd0781e5 | 637 | |
53e8b987 | 638 | If |
7e23fc43 | 639 | .B \-\-auto |
53e8b987 | 640 | is not given on the command line or in the config file, then |
75723446 | 641 | the default will be |
7e23fc43 | 642 | .BR \-\-auto=yes . |
75723446 | 643 | |
1337546d | 644 | If |
7e23fc43 | 645 | .B \-\-scan |
1337546d NB |
646 | is also given, then any |
647 | .I auto= | |
35cc5be4 | 648 | entries in the config file will override the |
7e23fc43 | 649 | .B \-\-auto |
1337546d NB |
650 | instruction given on the command line. |
651 | ||
dd0781e5 NB |
652 | For partitionable arrays, |
653 | .I mdadm | |
654 | will create the device file for the whole array and for the first 4 | |
655 | partitions. A different number of partitions can be specified at the | |
656 | end of this option (e.g. | |
7e23fc43 | 657 | .BR \-\-auto=p7 ). |
2ae555c3 | 658 | If the device name ends with a digit, the partition names add a 'p', |
8fd8d9c4 | 659 | and a number, e.g. "/dev/md/home1p3". If there is no |
dd0781e5 | 660 | trailing digit, then the partition names just have a number added, |
8fd8d9c4 | 661 | e.g. "/dev/md/scratch3". |
dd0781e5 | 662 | |
48f7b27a NB |
663 | If the md device name is in a 'standard' format as described in DEVICE |
664 | NAMES, then it will be created, if necessary, with the appropriate | |
665 | number based on that name. If the device name is not in one of these | |
a9d69660 | 666 | formats, then a unused minor number will be allocated. The minor |
48f7b27a NB |
667 | number will be considered unused if there is no active array for that |
668 | number, and there is no entry in /dev for that number and with a | |
8fd8d9c4 N |
669 | non-standard name. Name that are not in 'standard' format are only |
670 | allowed in "/dev/md/". | |
671 | ||
672 | \".TP | |
673 | \".BR \-\-symlink = no | |
674 | \"Normally when | |
675 | \".B \-\-auto | |
676 | \"causes | |
677 | \".I mdadm | |
678 | \"to create devices in | |
679 | \".B /dev/md/ | |
680 | \"it will also create symlinks from | |
681 | \".B /dev/ | |
682 | \"with names starting with | |
683 | \".B md | |
684 | \"or | |
685 | \".BR md_ . | |
686 | \"Use | |
687 | \".B \-\-symlink=no | |
688 | \"to suppress this, or | |
689 | \".B \-\-symlink=yes | |
690 | \"to enforce this even if it is suppressing | |
691 | \".IR mdadm.conf . | |
692 | \" | |
38098016 | 693 | |
52826846 NB |
694 | .SH For assemble: |
695 | ||
cd29a5c8 | 696 | .TP |
7e23fc43 | 697 | .BR \-u ", " \-\-uuid= |
cd29a5c8 NB |
698 | uuid of array to assemble. Devices which don't have this uuid are |
699 | excluded | |
700 | ||
701 | .TP | |
7e23fc43 | 702 | .BR \-m ", " \-\-super\-minor= |
cd29a5c8 NB |
703 | Minor number of device that array was created for. Devices which |
704 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 705 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
706 | the array is later assembled as /dev/md2. |
707 | ||
d013a55e | 708 | Giving the literal word "dev" for |
7e23fc43 | 709 | .B \-\-super\-minor |
d013a55e NB |
710 | will cause |
711 | .I mdadm | |
712 | to use the minor number of the md device that is being assembled. | |
713 | e.g. when assembling | |
714 | .BR /dev/md0 , | |
51ac42e3 | 715 | .B \-\-super\-minor=dev |
d013a55e NB |
716 | will look for super blocks with a minor number of 0. |
717 | ||
947fd4dd | 718 | .TP |
7e23fc43 | 719 | .BR \-N ", " \-\-name= |
947fd4dd | 720 | Specify the name of the array to assemble. This must be the name |
624920bb | 721 | that was specified when creating the array. It must either match |
93e790af | 722 | the name stored in the superblock exactly, or it must match |
41a3b72a | 723 | with the current |
624920bb | 724 | .I homehost |
93e790af | 725 | prefixed to the start of the given name. |
947fd4dd | 726 | |
cd29a5c8 | 727 | .TP |
7e23fc43 | 728 | .BR \-f ", " \-\-force |
52826846 NB |
729 | Assemble the array even if some superblocks appear out-of-date |
730 | ||
cd29a5c8 | 731 | .TP |
7e23fc43 | 732 | .BR \-R ", " \-\-run |
b8a8ccf9 NB |
733 | Attempt to start the array even if fewer drives were given than were |
734 | present last time the array was active. Normally if not all the | |
735 | expected drives are found and | |
7e23fc43 | 736 | .B \-\-scan |
cd29a5c8 NB |
737 | is not used, then the array will be assembled but not started. |
738 | With | |
7e23fc43 | 739 | .B \-\-run |
cd29a5c8 | 740 | an attempt will be made to start it anyway. |
52826846 | 741 | |
b8a8ccf9 | 742 | .TP |
7e23fc43 | 743 | .B \-\-no\-degraded |
b8a8ccf9 | 744 | This is the reverse of |
7e23fc43 | 745 | .B \-\-run |
93e790af | 746 | in that it inhibits the startup of array unless all expected drives |
b8a8ccf9 | 747 | are present. This is only needed with |
93e790af SW |
748 | .B \-\-scan, |
749 | and can be used if the physical connections to devices are | |
b8a8ccf9 NB |
750 | not as reliable as you would like. |
751 | ||
dd0781e5 | 752 | .TP |
7e23fc43 | 753 | .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}" |
dd0781e5 NB |
754 | See this option under Create and Build options. |
755 | ||
e793c2e5 | 756 | .TP |
7e23fc43 | 757 | .BR \-b ", " \-\-bitmap= |
2ae555c3 NB |
758 | Specify the bitmap file that was given when the array was created. If |
759 | an array has an | |
760 | .B internal | |
761 | bitmap, there is no need to specify this when assembling the array. | |
762 | ||
763 | .TP | |
7e23fc43 | 764 | .BR \-\-backup\-file= |
2ae555c3 | 765 | If |
7e23fc43 | 766 | .B \-\-backup\-file |
2ae555c3 NB |
767 | was used to grow the number of raid-devices in a RAID5, and the system |
768 | crashed during the critical section, then the same | |
7e23fc43 | 769 | .B \-\-backup\-file |
53e8b987 | 770 | must be presented to |
7e23fc43 | 771 | .B \-\-assemble |
53e8b987 | 772 | to allow possibly corrupted data to be restored. |
e793c2e5 | 773 | |
5787fa49 | 774 | .TP |
7e23fc43 | 775 | .BR \-U ", " \-\-update= |
5787fa49 | 776 | Update the superblock on each device while assembling the array. The |
feb716e9 NB |
777 | argument given to this flag can be one of |
778 | .BR sparc2.2 , | |
779 | .BR summaries , | |
7d99579f | 780 | .BR uuid , |
c4f12c13 | 781 | .BR name , |
0237e0ca | 782 | .BR homehost , |
e5329c37 | 783 | .BR resync , |
586ed405 | 784 | .BR byteorder , |
bee8ec56 | 785 | .BR devicesize , |
5787fa49 | 786 | or |
7e23fc43 | 787 | .BR super\-minor . |
5787fa49 NB |
788 | |
789 | The | |
790 | .B sparc2.2 | |
7d99579f | 791 | option will adjust the superblock of an array what was created on a Sparc |
5787fa49 NB |
792 | machine running a patched 2.2 Linux kernel. This kernel got the |
793 | alignment of part of the superblock wrong. You can use the | |
7e23fc43 | 794 | .B "\-\-examine \-\-sparc2.2" |
5787fa49 NB |
795 | option to |
796 | .I mdadm | |
797 | to see what effect this would have. | |
798 | ||
799 | The | |
7e23fc43 | 800 | .B super\-minor |
5787fa49 | 801 | option will update the |
2ae555c3 | 802 | .B "preferred minor" |
5787fa49 | 803 | field on each superblock to match the minor number of the array being |
45c073c9 NB |
804 | assembled. |
805 | This can be useful if | |
7e23fc43 | 806 | .B \-\-examine |
45c073c9 | 807 | reports a different "Preferred Minor" to |
7e23fc43 | 808 | .BR \-\-detail . |
45c073c9 NB |
809 | In some cases this update will be performed automatically |
810 | by the kernel driver. In particular the update happens automatically | |
811 | at the first write to an array with redundancy (RAID level 1 or | |
812 | greater) on a 2.6 (or later) kernel. | |
5787fa49 | 813 | |
7d99579f NB |
814 | The |
815 | .B uuid | |
816 | option will change the uuid of the array. If a UUID is given with the | |
7e23fc43 | 817 | .B \-\-uuid |
53e8b987 | 818 | option that UUID will be used as a new UUID and will |
7d99579f NB |
819 | .B NOT |
820 | be used to help identify the devices in the array. | |
53e8b987 | 821 | If no |
7e23fc43 | 822 | .B \-\-uuid |
53e8b987 | 823 | is given, a random UUID is chosen. |
7d99579f | 824 | |
c4f12c13 NB |
825 | The |
826 | .B name | |
827 | option will change the | |
828 | .I name | |
829 | of the array as stored in the superblock. This is only supported for | |
830 | version-1 superblocks. | |
831 | ||
0237e0ca NB |
832 | The |
833 | .B homehost | |
834 | option will change the | |
835 | .I homehost | |
836 | as recorded in the superblock. For version-0 superblocks, this is the | |
837 | same as updating the UUID. | |
838 | For version-1 superblocks, this involves updating the name. | |
839 | ||
e5329c37 NB |
840 | The |
841 | .B resync | |
842 | option will cause the array to be marked | |
843 | .I dirty | |
844 | meaning that any redundancy in the array (e.g. parity for raid5, | |
845 | copies for raid1) may be incorrect. This will cause the raid system | |
846 | to perform a "resync" pass to make sure that all redundant information | |
847 | is correct. | |
848 | ||
586ed405 NB |
849 | The |
850 | .B byteorder | |
851 | option allows arrays to be moved between machines with different | |
852 | byte-order. | |
2ae555c3 | 853 | When assembling such an array for the first time after a move, giving |
7e23fc43 | 854 | .B "\-\-update=byteorder" |
586ed405 NB |
855 | will cause |
856 | .I mdadm | |
857 | to expect superblocks to have their byteorder reversed, and will | |
858 | correct that order before assembling the array. This is only valid | |
2ae555c3 | 859 | with original (Version 0.90) superblocks. |
586ed405 | 860 | |
feb716e9 NB |
861 | The |
862 | .B summaries | |
863 | option will correct the summaries in the superblock. That is the | |
864 | counts of total, working, active, failed, and spare devices. | |
5787fa49 | 865 | |
bee8ec56 NB |
866 | The |
867 | .B devicesize | |
868 | will rarely be of use. It applies to version 1.1 and 1.2 metadata | |
869 | only (where the metadata is at the start of the device) and is only | |
870 | useful when the component device has changed size (typically become | |
871 | larger). The version 1 metadata records the amount of the device that | |
872 | can be used to store data, so if a device in a version 1.1 or 1.2 | |
873 | array becomes larger, the metadata will still be visible, but the | |
874 | extra space will not. In this case it might be useful to assemble the | |
875 | array with | |
7e23fc43 | 876 | .BR \-\-update=devicesize . |
bee8ec56 NB |
877 | This will cause |
878 | .I mdadm | |
879 | to determine the maximum usable amount of space on each device and | |
880 | update the relevant field in the metadata. | |
881 | ||
41a3b72a | 882 | .TP |
7e23fc43 | 883 | .B \-\-auto\-update\-homehost |
93e790af | 884 | This flag is only meaningful with auto-assembly (see discussion below). |
41a3b72a NB |
885 | In that situation, if no suitable arrays are found for this homehost, |
886 | .I mdadm | |
93e790af | 887 | will rescan for any arrays at all and will assemble them and update the |
41a3b72a NB |
888 | homehost to match the current host. |
889 | ||
e0d19036 | 890 | .SH For Manage mode: |
52826846 | 891 | |
cd29a5c8 | 892 | .TP |
7e23fc43 | 893 | .BR \-a ", " \-\-add |
2ae555c3 | 894 | hot-add listed devices. |
52826846 | 895 | |
fe80f49b | 896 | .TP |
7e23fc43 | 897 | .BR \-\-re\-add |
2ae555c3 | 898 | re-add a device that was recently removed from an array. |
fe80f49b | 899 | |
cd29a5c8 | 900 | .TP |
7e23fc43 | 901 | .BR \-r ", " \-\-remove |
2d465520 | 902 | remove listed devices. They must not be active. i.e. they should |
b80da661 NB |
903 | be failed or spare devices. As well as the name of a device file |
904 | (e.g. | |
905 | .BR /dev/sda1 ) | |
906 | the words | |
907 | .B failed | |
908 | and | |
909 | .B detached | |
910 | can be given to | |
911 | .BR \-\-remove . | |
912 | The first causes all failed device to be removed. The second causes | |
93e790af | 913 | any device which is no longer connected to the system (i.e an 'open' |
b80da661 NB |
914 | returns |
915 | .BR ENXIO ) | |
916 | to be removed. This will only succeed for devices that are spares or | |
917 | have already been marked as failed. | |
52826846 | 918 | |
cd29a5c8 | 919 | .TP |
7e23fc43 | 920 | .BR \-f ", " \-\-fail |
cd29a5c8 | 921 | mark listed devices as faulty. |
b80da661 NB |
922 | As well as the name of a device file, the word |
923 | .B detached | |
924 | can be given. This will cause any device that has been detached from | |
925 | the system to be marked as failed. It can then be removed. | |
52826846 | 926 | |
cd29a5c8 | 927 | .TP |
7e23fc43 | 928 | .BR \-\-set\-faulty |
53e8b987 | 929 | same as |
7e23fc43 | 930 | .BR \-\-fail . |
52826846 | 931 | |
b3d31955 N |
932 | .TP |
933 | .BR \-\-write\-mostly | |
934 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
935 | flag set. This is only valid for RAID! and means that the 'md' driver | |
936 | will avoid reading from these devices if possible. | |
937 | .TP | |
938 | .BR \-\-readwrite | |
939 | Subsequent devices that are added or re-added will have the 'write-mostly' | |
940 | flag cleared. | |
941 | ||
942 | ||
2ae555c3 | 943 | .P |
93e790af SW |
944 | Each of these options require that the first device listed is the array |
945 | to be acted upon, and the remainder are component devices to be added, | |
946 | removed, or marked as faulty. Several different operations can be | |
2ae555c3 NB |
947 | specified for different devices, e.g. |
948 | .in +5 | |
7e23fc43 | 949 | mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1 |
2ae555c3 NB |
950 | .in -5 |
951 | Each operation applies to all devices listed until the next | |
93e790af | 952 | operation. |
2ae555c3 NB |
953 | |
954 | If an array is using a write-intent bitmap, then devices which have | |
955 | been removed can be re-added in a way that avoids a full | |
93e790af | 956 | reconstruction but instead just updates the blocks that have changed |
2ae555c3 NB |
957 | since the device was removed. For arrays with persistent metadata |
958 | (superblocks) this is done automatically. For arrays created with | |
7e23fc43 | 959 | .B \-\-build |
2ae555c3 | 960 | mdadm needs to be told that this device we removed recently with |
7e23fc43 | 961 | .BR \-\-re\-add . |
2ae555c3 NB |
962 | |
963 | Devices can only be removed from an array if they are not in active | |
93e790af SW |
964 | use, i.e. that must be spares or failed devices. To remove an active |
965 | device, it must first be marked as | |
966 | .B faulty. | |
2ae555c3 NB |
967 | |
968 | .SH For Misc mode: | |
969 | ||
970 | .TP | |
7e23fc43 | 971 | .BR \-Q ", " \-\-query |
2ae555c3 NB |
972 | Examine a device to see |
973 | (1) if it is an md device and (2) if it is a component of an md | |
974 | array. | |
975 | Information about what is discovered is presented. | |
976 | ||
977 | .TP | |
7e23fc43 | 978 | .BR \-D ", " \-\-detail |
2ae555c3 | 979 | Print detail of one or more md devices. |
5787fa49 | 980 | |
4cce4069 DW |
981 | .TP |
982 | .BR \-\-detail\-platform | |
983 | Print detail of the platform's raid capabilities (firmware / hardware | |
984 | topology) for a given metadata format. | |
985 | ||
54bad364 KS |
986 | .TP |
987 | .BR \-Y ", " \-\-export | |
988 | When used with | |
0d726f17 KS |
989 | .B \-\-detail |
990 | or | |
991 | .BR \-\-examine , | |
54bad364 KS |
992 | output will be formatted as |
993 | .B key=value | |
994 | pairs for easy import into the environment. | |
995 | ||
2ae555c3 | 996 | .TP |
7e23fc43 | 997 | .BR \-E ", " \-\-examine |
2ae555c3 | 998 | Print content of md superblock on device(s). |
5787fa49 | 999 | .TP |
7e23fc43 | 1000 | .B \-\-sparc2.2 |
a9d69660 | 1001 | If an array was created on a 2.2 Linux kernel patched with RAID |
5787fa49 NB |
1002 | support, the superblock will have been created incorrectly, or at |
1003 | least incompatibly with 2.4 and later kernels. Using the | |
7e23fc43 | 1004 | .B \-\-sparc2.2 |
5787fa49 | 1005 | flag with |
7e23fc43 | 1006 | .B \-\-examine |
5787fa49 NB |
1007 | will fix the superblock before displaying it. If this appears to do |
1008 | the right thing, then the array can be successfully assembled using | |
7e23fc43 | 1009 | .BR "\-\-assemble \-\-update=sparc2.2" . |
5787fa49 | 1010 | |
2ae555c3 | 1011 | .TP |
7e23fc43 | 1012 | .BR \-X ", " \-\-examine\-bitmap |
2ae555c3 | 1013 | Report information about a bitmap file. |
01d9299c NB |
1014 | The argument is either an external bitmap file or an array component |
1015 | in case of an internal bitmap. | |
e0d19036 | 1016 | |
cd29a5c8 | 1017 | .TP |
7e23fc43 | 1018 | .BR \-R ", " \-\-run |
cd29a5c8 | 1019 | start a partially built array. |
52826846 | 1020 | |
cd29a5c8 | 1021 | .TP |
7e23fc43 | 1022 | .BR \-S ", " \-\-stop |
cd29a5c8 | 1023 | deactivate array, releasing all resources. |
52826846 | 1024 | |
cd29a5c8 | 1025 | .TP |
7e23fc43 | 1026 | .BR \-o ", " \-\-readonly |
cd29a5c8 | 1027 | mark array as readonly. |
52826846 | 1028 | |
cd29a5c8 | 1029 | .TP |
7e23fc43 | 1030 | .BR \-w ", " \-\-readwrite |
cd29a5c8 | 1031 | mark array as readwrite. |
52826846 | 1032 | |
e0d19036 | 1033 | .TP |
7e23fc43 | 1034 | .B \-\-zero\-superblock |
e0d19036 | 1035 | If the device contains a valid md superblock, the block is |
35cc5be4 | 1036 | overwritten with zeros. With |
7e23fc43 | 1037 | .B \-\-force |
35cc5be4 | 1038 | the block where the superblock would be is overwritten even if it |
e0d19036 | 1039 | doesn't appear to be valid. |
52826846 | 1040 | |
feb716e9 | 1041 | .TP |
7e23fc43 | 1042 | .BR \-t ", " \-\-test |
feb716e9 | 1043 | When used with |
7e23fc43 | 1044 | .BR \-\-detail , |
feb716e9 NB |
1045 | the exit status of |
1046 | .I mdadm | |
1047 | is set to reflect the status of the device. | |
1048 | ||
b90c0e9a | 1049 | .TP |
7e23fc43 | 1050 | .BR \-W ", " \-\-wait |
b90c0e9a NB |
1051 | For each md device given, wait for any resync, recovery, or reshape |
1052 | activity to finish before returning. | |
1053 | .I mdadm | |
1054 | will return with success if it actually waited for every device | |
1055 | listed, otherwise it will return failure. | |
1056 | ||
1770662b DW |
1057 | .TP |
1058 | .BR \-\-wait\-clean | |
fabbfd48 DW |
1059 | For each md device given, or each device in /proc/mdstat if |
1060 | .B \-\-scan | |
1061 | is given, arrange for the array to be marked clean as soon as possible. | |
1062 | Also, quiesce resync so that the monitor for external metadata arrays | |
1063 | (mdmon) has an opportunity to checkpoint the resync position. | |
7146ec6a DW |
1064 | .I mdadm |
1065 | will return with success if the array uses external metadata and we | |
1066 | successfully waited. For native arrays this returns immediately as the | |
1067 | kernel handles both dirty-clean transitions and resync checkpointing in | |
1068 | the kernel at shutdown. No action is taken if safe-mode handling is | |
1069 | disabled. | |
1770662b | 1070 | |
8382f19b NB |
1071 | .SH For Incremental Assembly mode: |
1072 | .TP | |
7e23fc43 | 1073 | .BR \-\-rebuild\-map ", " \-r |
8382f19b NB |
1074 | Rebuild the map file |
1075 | .RB ( /var/run/mdadm/map ) | |
1076 | that | |
1077 | .I mdadm | |
1078 | uses to help track which arrays are currently being assembled. | |
1079 | ||
1080 | .TP | |
7e23fc43 | 1081 | .BR \-\-run ", " \-R |
8382f19b NB |
1082 | Run any array assembled as soon as a minimal number of devices are |
1083 | available, rather than waiting until all expected devices are present. | |
1084 | ||
fdb482f9 DW |
1085 | .TP |
1086 | .B \-\-no\-degraded | |
1087 | This allows the hot-plug system to prevent arrays from running when it knows | |
1088 | that more disks may arrive later in the discovery process. | |
1089 | ||
8382f19b | 1090 | .TP |
7e23fc43 | 1091 | .BR \-\-scan ", " \-s |
8382f19b | 1092 | Only meaningful with |
7e23fc43 | 1093 | .B \-R |
8382f19b NB |
1094 | this will scan the |
1095 | .B map | |
1096 | file for arrays that are being incrementally assembled and will try to | |
1097 | start any that are not already started. If any such array is listed | |
1098 | in | |
1099 | .B mdadm.conf | |
1100 | as requiring an external bitmap, that bitmap will be attached first. | |
1101 | ||
e0d19036 NB |
1102 | .SH For Monitor mode: |
1103 | .TP | |
7e23fc43 | 1104 | .BR \-m ", " \-\-mail |
e0d19036 NB |
1105 | Give a mail address to send alerts to. |
1106 | ||
1107 | .TP | |
7e23fc43 | 1108 | .BR \-p ", " \-\-program ", " \-\-alert |
e0d19036 NB |
1109 | Give a program to be run whenever an event is detected. |
1110 | ||
773135f5 | 1111 | .TP |
7e23fc43 | 1112 | .BR \-y ", " \-\-syslog |
773135f5 NB |
1113 | Cause all events to be reported through 'syslog'. The messages have |
1114 | facility of 'daemon' and varying priorities. | |
1115 | ||
e0d19036 | 1116 | .TP |
7e23fc43 | 1117 | .BR \-d ", " \-\-delay |
e0d19036 | 1118 | Give a delay in seconds. |
51ac42e3 | 1119 | .I mdadm |
e0d19036 NB |
1120 | polls the md arrays and then waits this many seconds before polling |
1121 | again. The default is 60 seconds. | |
1122 | ||
d013a55e | 1123 | .TP |
7e23fc43 | 1124 | .BR \-f ", " \-\-daemonise |
d013a55e | 1125 | Tell |
51ac42e3 | 1126 | .I mdadm |
d013a55e NB |
1127 | to run as a background daemon if it decides to monitor anything. This |
1128 | causes it to fork and run in the child, and to disconnect form the | |
1129 | terminal. The process id of the child is written to stdout. | |
1130 | This is useful with | |
7e23fc43 | 1131 | .B \-\-scan |
d013a55e NB |
1132 | which will only continue monitoring if a mail address or alert program |
1133 | is found in the config file. | |
1134 | ||
b5e64645 | 1135 | .TP |
7e23fc43 | 1136 | .BR \-i ", " \-\-pid\-file |
b5e64645 | 1137 | When |
51ac42e3 | 1138 | .I mdadm |
b5e64645 NB |
1139 | is running in daemon mode, write the pid of the daemon process to |
1140 | the specified file, instead of printing it on standard output. | |
1141 | ||
aa88f531 | 1142 | .TP |
7e23fc43 | 1143 | .BR \-1 ", " \-\-oneshot |
aa88f531 NB |
1144 | Check arrays only once. This will generate |
1145 | .B NewArray | |
1146 | events and more significantly | |
1147 | .B DegradedArray | |
a9d69660 NB |
1148 | and |
1149 | .B SparesMissing | |
aa88f531 NB |
1150 | events. Running |
1151 | .in +5 | |
7e23fc43 | 1152 | .B " mdadm \-\-monitor \-\-scan \-1" |
aa88f531 NB |
1153 | .in -5 |
1154 | from a cron script will ensure regular notification of any degraded arrays. | |
1155 | ||
98c6faba | 1156 | .TP |
7e23fc43 | 1157 | .BR \-t ", " \-\-test |
98c6faba NB |
1158 | Generate a |
1159 | .B TestMessage | |
1160 | alert for every array found at startup. This alert gets mailed and | |
1161 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 1162 | message do get through successfully. |
98c6faba | 1163 | |
e0d19036 | 1164 | .SH ASSEMBLE MODE |
52826846 | 1165 | |
cd29a5c8 NB |
1166 | .HP 12 |
1167 | Usage: | |
7e23fc43 | 1168 | .B mdadm \-\-assemble |
5787fa49 NB |
1169 | .I md-device options-and-component-devices... |
1170 | .HP 12 | |
1171 | Usage: | |
7e23fc43 | 1172 | .B mdadm \-\-assemble \-\-scan |
5787fa49 | 1173 | .I md-devices-and-options... |
cd29a5c8 NB |
1174 | .HP 12 |
1175 | Usage: | |
7e23fc43 | 1176 | .B mdadm \-\-assemble \-\-scan |
cd29a5c8 | 1177 | .I options... |
52826846 | 1178 | |
cd29a5c8 | 1179 | .PP |
52826846 | 1180 | This usage assembles one or more raid arrays from pre-existing components. |
9a9dab36 | 1181 | For each array, mdadm needs to know the md device, the identity of the |
e0d19036 | 1182 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 1183 | |
5787fa49 | 1184 | In the first usage example (without the |
7e23fc43 | 1185 | .BR \-\-scan ) |
5787fa49 NB |
1186 | the first device given is the md device. |
1187 | In the second usage example, all devices listed are treated as md | |
1188 | devices and assembly is attempted. | |
1189 | In the third (where no devices are listed) all md devices that are | |
8fd8d9c4 N |
1190 | listed in the configuration file are assembled. Then any arrays that |
1191 | can be found on unused devices will also be assembled. | |
52826846 | 1192 | |
d013a55e | 1193 | If precisely one device is listed, but |
7e23fc43 | 1194 | .B \-\-scan |
dd0781e5 | 1195 | is not given, then |
d013a55e NB |
1196 | .I mdadm |
1197 | acts as though | |
7e23fc43 | 1198 | .B \-\-scan |
93e790af | 1199 | was given and identity information is extracted from the configuration file. |
d013a55e | 1200 | |
2ae555c3 | 1201 | The identity can be given with the |
7e23fc43 | 1202 | .B \-\-uuid |
cd29a5c8 | 1203 | option, with the |
7e23fc43 | 1204 | .B \-\-super\-minor |
93e790af SW |
1205 | option, will be taken from the md-device record in the config file, or |
1206 | will be taken from the super block of the first component-device | |
1207 | listed on the command line. | |
52826846 | 1208 | |
2ae555c3 | 1209 | Devices can be given on the |
7e23fc43 | 1210 | .B \-\-assemble |
5787fa49 NB |
1211 | command line or in the config file. Only devices which have an md |
1212 | superblock which contains the right identity will be considered for | |
1213 | any array. | |
52826846 | 1214 | |
2ae555c3 | 1215 | The config file is only used if explicitly named with |
7e23fc43 | 1216 | .B \-\-config |
d013a55e | 1217 | or requested with (a possibly implicit) |
7e23fc43 | 1218 | .BR \-\-scan . |
52826846 | 1219 | In the later case, |
9a9dab36 | 1220 | .B /etc/mdadm.conf |
8fd8d9c4 N |
1221 | or |
1222 | .B /etc/mdadm/mdadm.conf | |
52826846 NB |
1223 | is used. |
1224 | ||
2ae555c3 | 1225 | If |
7e23fc43 | 1226 | .B \-\-scan |
cd29a5c8 NB |
1227 | is not given, then the config file will only be used to find the |
1228 | identity of md arrays. | |
52826846 | 1229 | |
2d465520 | 1230 | Normally the array will be started after it is assembled. However if |
7e23fc43 | 1231 | .B \-\-scan |
2d465520 | 1232 | is not given and insufficient drives were listed to start a complete |
cd29a5c8 NB |
1233 | (non-degraded) array, then the array is not started (to guard against |
1234 | usage errors). To insist that the array be started in this case (as | |
1a7dfc35 | 1235 | may work for RAID1, 4, 5, 6, or 10), give the |
7e23fc43 | 1236 | .B \-\-run |
cd29a5c8 | 1237 | flag. |
52826846 | 1238 | |
75723446 NB |
1239 | If the md device does not exist, then it will be created providing the |
1240 | intent is clear. i.e. the name must be in a standard form, or the | |
7e23fc43 | 1241 | .B \-\-auto |
75723446 NB |
1242 | option must be given to clarify how and whether the device should be |
1243 | created. | |
dd0781e5 | 1244 | This can be useful for handling partitioned devices (which don't have |
b3f1c093 | 1245 | a stable device number \(em it can change after a reboot) and when using |
dd0781e5 NB |
1246 | "udev" to manage your |
1247 | .B /dev | |
1248 | tree (udev cannot handle md devices because of the unusual device | |
1249 | initialisation conventions). | |
1250 | ||
1251 | If the option to "auto" is "mdp" or "part" or (on the command line | |
1252 | only) "p", then mdadm will create a partitionable array, using the | |
93e790af | 1253 | first free one that is not in use and does not already have an entry |
dd0781e5 NB |
1254 | in /dev (apart from numeric /dev/md* entries). |
1255 | ||
1256 | If the option to "auto" is "yes" or "md" or (on the command line) | |
1257 | nothing, then mdadm will create a traditional, non-partitionable md | |
1258 | array. | |
1259 | ||
1260 | It is expected that the "auto" functionality will be used to create | |
1261 | device entries with meaningful names such as "/dev/md/home" or | |
1262 | "/dev/md/root", rather than names based on the numerical array number. | |
1263 | ||
93e790af | 1264 | When using option "auto" to create a partitionable array, the device |
dd0781e5 NB |
1265 | files for the first 4 partitions are also created. If a different |
1266 | number is required it can be simply appended to the auto option. | |
1267 | e.g. "auto=part8". Partition names are created by appending a digit | |
a9d69660 | 1268 | string to the device name, with an intervening "p" if the device name |
dd0781e5 NB |
1269 | ends with a digit. |
1270 | ||
1271 | The | |
7e23fc43 | 1272 | .B \-\-auto |
dd0781e5 NB |
1273 | option is also available in Build and Create modes. As those modes do |
1274 | not use a config file, the "auto=" config option does not apply to | |
1275 | these modes. | |
52826846 | 1276 | |
41a3b72a NB |
1277 | .SS Auto Assembly |
1278 | When | |
7e23fc43 | 1279 | .B \-\-assemble |
41a3b72a | 1280 | is used with |
7e23fc43 | 1281 | .B \-\-scan |
41a3b72a NB |
1282 | and no devices are listed, |
1283 | .I mdadm | |
1284 | will first attempt to assemble all the arrays listed in the config | |
1285 | file. | |
1286 | ||
8fd8d9c4 N |
1287 | It will then look further for possible arrays and will try to assemble |
1288 | anything that it finds. Arrays which are tagged as belonging to the given | |
1289 | homehost will be assembled and started normally. Arrays which do not | |
1290 | obviously belong to this host are given names that are expected not to | |
1291 | conflict with anything local, and are started "read-auto" so that | |
1292 | nothing is written to any device until the array is written to. i.e. | |
1293 | automatic resync etc is delayed. | |
41a3b72a NB |
1294 | |
1295 | If | |
1296 | .I mdadm | |
1297 | finds a consistent set of devices that look like they should comprise | |
1298 | an array, and if the superblock is tagged as belonging to the given | |
1299 | home host, it will automatically choose a device name and try to | |
1300 | assemble the array. If the array uses version-0.90 metadata, then the | |
1301 | .B minor | |
1302 | number as recorded in the superblock is used to create a name in | |
1303 | .B /dev/md/ | |
1304 | so for example | |
1305 | .BR /dev/md/3 . | |
1306 | If the array uses version-1 metadata, then the | |
1307 | .B name | |
1308 | from the superblock is used to similarly create a name in | |
93e790af SW |
1309 | .BR /dev/md |
1310 | (the name will have any 'host' prefix stripped first). | |
41a3b72a NB |
1311 | |
1312 | If | |
1313 | .I mdadm | |
1314 | cannot find any array for the given host at all, and if | |
7e23fc43 | 1315 | .B \-\-auto\-update\-homehost |
41a3b72a NB |
1316 | is given, then |
1317 | .I mdadm | |
1318 | will search again for any array (not just an array created for this | |
1319 | host) and will assemble each assuming | |
7e23fc43 | 1320 | .BR \-\-update=homehost . |
41a3b72a NB |
1321 | This will change the host tag in the superblock so that on the next run, |
1322 | these arrays will be found without the second pass. The intention of | |
1323 | this feature is to support transitioning a set of md arrays to using | |
1324 | homehost tagging. | |
1325 | ||
1326 | The reason for requiring arrays to be tagged with the homehost for | |
1327 | auto assembly is to guard against problems that can arise when moving | |
1328 | devices from one host to another. | |
1329 | ||
cd29a5c8 | 1330 | .SH BUILD MODE |
52826846 | 1331 | |
cd29a5c8 NB |
1332 | .HP 12 |
1333 | Usage: | |
7e23fc43 | 1334 | .B mdadm \-\-build |
93e790af | 1335 | .I md-device |
7e23fc43 PS |
1336 | .BI \-\-chunk= X |
1337 | .BI \-\-level= Y | |
1338 | .BI \-\-raid\-devices= Z | |
cd29a5c8 NB |
1339 | .I devices |
1340 | ||
1341 | .PP | |
2ae555c3 | 1342 | This usage is similar to |
7e23fc43 | 1343 | .BR \-\-create . |
a9d69660 | 1344 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 1345 | these arrays there is no difference between initially creating the array and |
52826846 NB |
1346 | subsequently assembling the array, except that hopefully there is useful |
1347 | data there in the second case. | |
1348 | ||
a9d69660 NB |
1349 | The level may raid0, linear, multipath, or faulty, or one of their |
1350 | synonyms. All devices must be listed and the array will be started | |
1351 | once complete. | |
cd29a5c8 NB |
1352 | |
1353 | .SH CREATE MODE | |
1354 | ||
1355 | .HP 12 | |
1356 | Usage: | |
7e23fc43 | 1357 | .B mdadm \-\-create |
93e790af | 1358 | .I md-device |
7e23fc43 PS |
1359 | .BI \-\-chunk= X |
1360 | .BI \-\-level= Y | |
cd29a5c8 | 1361 | .br |
7e23fc43 | 1362 | .BI \-\-raid\-devices= Z |
cd29a5c8 NB |
1363 | .I devices |
1364 | ||
1365 | .PP | |
1366 | This usage will initialise a new md array, associate some devices with | |
1367 | it, and activate the array. | |
1368 | ||
a9d69660 | 1369 | If the |
7e23fc43 | 1370 | .B \-\-auto |
dd0781e5 NB |
1371 | option is given (as described in more detail in the section on |
1372 | Assemble mode), then the md device will be created with a suitable | |
1373 | device number if necessary. | |
1374 | ||
cd29a5c8 | 1375 | As devices are added, they are checked to see if they contain raid |
2d465520 | 1376 | superblocks or filesystems. They are also checked to see if the variance in |
cd29a5c8 NB |
1377 | device size exceeds 1%. |
1378 | ||
1379 | If any discrepancy is found, the array will not automatically be run, though | |
2ae555c3 | 1380 | the presence of a |
7e23fc43 | 1381 | .B \-\-run |
cd29a5c8 NB |
1382 | can override this caution. |
1383 | ||
2d465520 | 1384 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 1385 | give the word "\fBmissing\fP" |
2d465520 | 1386 | in place of a device name. This will cause |
51ac42e3 | 1387 | .I mdadm |
2d465520 NB |
1388 | to leave the corresponding slot in the array empty. |
1389 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 1390 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
1391 | For a RAID1 array, only one real device needs to be given. All of the |
1392 | others can be | |
d013a55e | 1393 | "\fBmissing\fP". |
2d465520 | 1394 | |
feb716e9 | 1395 | When creating a RAID5 array, |
51ac42e3 | 1396 | .I mdadm |
feb716e9 NB |
1397 | will automatically create a degraded array with an extra spare drive. |
1398 | This is because building the spare into a degraded array is in general faster than resyncing | |
1399 | the parity on a non-degraded, but not clean, array. This feature can | |
35cc5be4 | 1400 | be overridden with the |
7e23fc43 | 1401 | .B \-\-force |
feb716e9 NB |
1402 | option. |
1403 | ||
0ee4da98 | 1404 | When creating an array with version-1 metadata a name for the array is |
41a3b72a NB |
1405 | required. |
1406 | If this is not given with the | |
7e23fc43 | 1407 | .B \-\-name |
41a3b72a NB |
1408 | option, |
1409 | .I mdadm | |
0ee4da98 | 1410 | will choose a name based on the last component of the name of the |
41a3b72a NB |
1411 | device being created. So if |
1412 | .B /dev/md3 | |
1413 | is being created, then the name | |
1414 | .B 3 | |
1415 | will be chosen. | |
1416 | If | |
1417 | .B /dev/md/home | |
1418 | is being created, then the name | |
1419 | .B home | |
1420 | will be used. | |
1421 | ||
e0f31f50 PC |
1422 | When creating a partition based array, using |
1423 | .I mdadm | |
1424 | with version-1.x metadata, the partition type should be set to | |
1425 | .B 0xDA | |
1426 | (non fs-data). This type selection allows for greater precision since | |
1427 | using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)], | |
1428 | might create problems in the event of array recovery through a live cdrom. | |
1429 | ||
3d3dd91e NB |
1430 | A new array will normally get a randomly assigned 128bit UUID which is |
1431 | very likely to be unique. If you have a specific need, you can choose | |
1432 | a UUID for the array by giving the | |
7e23fc43 | 1433 | .B \-\-uuid= |
3d3dd91e NB |
1434 | option. Be warned that creating two arrays with the same UUID is a |
1435 | recipe for disaster. Also, using | |
7e23fc43 | 1436 | .B \-\-uuid= |
3d3dd91e | 1437 | when creating a v0.90 array will silently override any |
7e23fc43 | 1438 | .B \-\-homehost= |
3d3dd91e | 1439 | setting. |
e43d0cda NB |
1440 | .\"If the |
1441 | .\".B \-\-size | |
1442 | .\"option is given, it is not necessary to list any component-devices in this command. | |
1443 | .\"They can be added later, before a | |
1444 | .\".B \-\-run. | |
1445 | .\"If no | |
1446 | .\".B \-\-size | |
1447 | .\"is given, the apparent size of the smallest drive given is used. | |
cd29a5c8 | 1448 | |
8fd8d9c4 N |
1449 | When creating an array within a |
1450 | .B CONTAINER | |
1451 | .I mdadm | |
1452 | can be given either the list of devices to use, or simply the name of | |
1453 | the container. The former case gives control over which devices in | |
1454 | the container will be used for the array. The latter case allows | |
1455 | .I mdadm | |
1456 | to automatically choose which devices to use based on how much spare | |
1457 | space is available. | |
1458 | ||
53e8b987 | 1459 | The General Management options that are valid with |
7e23fc43 | 1460 | .B \-\-create |
53e8b987 | 1461 | are: |
cd29a5c8 | 1462 | .TP |
7e23fc43 | 1463 | .B \-\-run |
dd0781e5 | 1464 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
1465 | be in use. |
1466 | ||
1467 | .TP | |
7e23fc43 | 1468 | .B \-\-readonly |
b3f1c093 | 1469 | start the array readonly \(em not supported yet. |
52826846 | 1470 | |
2ae555c3 | 1471 | |
e0d19036 | 1472 | .SH MANAGE MODE |
cd29a5c8 NB |
1473 | .HP 12 |
1474 | Usage: | |
e0d19036 NB |
1475 | .B mdadm |
1476 | .I device | |
1477 | .I options... devices... | |
cd29a5c8 NB |
1478 | .PP |
1479 | ||
e0d19036 NB |
1480 | This usage will allow individual devices in an array to be failed, |
1481 | removed or added. It is possible to perform multiple operations with | |
1482 | on command. For example: | |
1483 | .br | |
7e23fc43 | 1484 | .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1" |
e0d19036 NB |
1485 | .br |
1486 | will firstly mark | |
1487 | .B /dev/hda1 | |
1488 | as faulty in | |
1489 | .B /dev/md0 | |
1490 | and will then remove it from the array and finally add it back | |
2d465520 | 1491 | in as a spare. However only one md array can be affected by a single |
2ae555c3 | 1492 | command. |
e0d19036 NB |
1493 | |
1494 | .SH MISC MODE | |
1495 | .HP 12 | |
1496 | Usage: | |
9a9dab36 | 1497 | .B mdadm |
e0d19036 NB |
1498 | .I options ... |
1499 | .I devices ... | |
1500 | .PP | |
cd29a5c8 | 1501 | |
b5e64645 | 1502 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1503 | operate on distinct devices. The operations are: |
1504 | .TP | |
962a108f | 1505 | .B \-\-query |
e0d19036 NB |
1506 | The device is examined to see if it is |
1507 | (1) an active md array, or | |
1508 | (2) a component of an md array. | |
1509 | The information discovered is reported. | |
1510 | ||
1511 | .TP | |
962a108f | 1512 | .B \-\-detail |
2d465520 NB |
1513 | The device should be an active md device. |
1514 | .B mdadm | |
1515 | will display a detailed description of the array. | |
7e23fc43 | 1516 | .B \-\-brief |
2d465520 | 1517 | or |
7e23fc43 | 1518 | .B \-\-scan |
2d465520 | 1519 | will cause the output to be less detailed and the format to be |
e0d19036 | 1520 | suitable for inclusion in |
9a9dab36 | 1521 | .BR /etc/mdadm.conf . |
feb716e9 NB |
1522 | The exit status of |
1523 | .I mdadm | |
1524 | will normally be 0 unless | |
1525 | .I mdadm | |
93e790af | 1526 | failed to get useful information about the device(s); however, if the |
7e23fc43 | 1527 | .B \-\-test |
feb716e9 NB |
1528 | option is given, then the exit status will be: |
1529 | .RS | |
1530 | .TP | |
1531 | 0 | |
1532 | The array is functioning normally. | |
1533 | .TP | |
1534 | 1 | |
1535 | The array has at least one failed device. | |
1536 | .TP | |
1537 | 2 | |
a77be586 | 1538 | The array has multiple failed devices such that it is unusable. |
feb716e9 NB |
1539 | .TP |
1540 | 4 | |
1541 | There was an error while trying to get information about the device. | |
1542 | .RE | |
cd29a5c8 | 1543 | |
4cce4069 DW |
1544 | .TP |
1545 | .B \-\-detail\-platform | |
1546 | Print detail of the platform's raid capabilities (firmware / hardware | |
1547 | topology). If the metadata is specified with | |
1548 | .B \-e | |
1549 | or | |
1550 | .B \-\-metadata= | |
1551 | then the return status will be: | |
1552 | .RS | |
1553 | .TP | |
1554 | 0 | |
1555 | metadata successfully enumerated its platform components on this system | |
1556 | .TP | |
1557 | 1 | |
1558 | metadata is platform independent | |
1559 | .TP | |
1560 | 2 | |
1561 | metadata failed to find its platform components on this system | |
1562 | .RE | |
1563 | ||
e0d19036 | 1564 | .TP |
962a108f | 1565 | .B \-\-examine |
2d465520 | 1566 | The device should be a component of an md array. |
51ac42e3 | 1567 | .I mdadm |
2d465520 | 1568 | will read the md superblock of the device and display the contents. |
e0d19036 | 1569 | If |
7e23fc43 | 1570 | .B \-\-brief |
93e790af | 1571 | or |
7e23fc43 | 1572 | .B \-\-scan |
93e790af | 1573 | is given, then multiple devices that are components of the one array |
e0d19036 NB |
1574 | are grouped together and reported in a single entry suitable |
1575 | for inclusion in | |
1576 | .BR /etc/mdadm.conf . | |
1577 | ||
2d465520 | 1578 | Having |
7e23fc43 | 1579 | .B \-\-scan |
e0d19036 NB |
1580 | without listing any devices will cause all devices listed in the |
1581 | config file to be examined. | |
1582 | ||
1583 | .TP | |
962a108f | 1584 | .B \-\-stop |
98c6faba NB |
1585 | The devices should be active md arrays which will be deactivated, as |
1586 | long as they are not currently in use. | |
e0d19036 NB |
1587 | |
1588 | .TP | |
962a108f | 1589 | .B \-\-run |
e0d19036 NB |
1590 | This will fully activate a partially assembled md array. |
1591 | ||
1592 | .TP | |
962a108f | 1593 | .B \-\-readonly |
e0d19036 NB |
1594 | This will mark an active array as read-only, providing that it is |
1595 | not currently being used. | |
1596 | ||
1597 | .TP | |
962a108f | 1598 | .B \-\-readwrite |
e0d19036 NB |
1599 | This will change a |
1600 | .B readonly | |
1601 | array back to being read/write. | |
1602 | ||
2d465520 | 1603 | .TP |
962a108f | 1604 | .B \-\-scan |
2d465520 | 1605 | For all operations except |
7e23fc43 PS |
1606 | .BR \-\-examine , |
1607 | .B \-\-scan | |
2d465520 NB |
1608 | will cause the operation to be applied to all arrays listed in |
1609 | .BR /proc/mdstat . | |
1610 | For | |
7e23fc43 PS |
1611 | .BR \-\-examine, |
1612 | .B \-\-scan | |
2d465520 NB |
1613 | causes all devices listed in the config file to be examined. |
1614 | ||
1615 | ||
e0d19036 NB |
1616 | .SH MONITOR MODE |
1617 | ||
cd29a5c8 NB |
1618 | .HP 12 |
1619 | Usage: | |
7e23fc43 | 1620 | .B mdadm \-\-monitor |
e0d19036 NB |
1621 | .I options... devices... |
1622 | ||
cd29a5c8 | 1623 | .PP |
e0d19036 | 1624 | This usage causes |
51ac42e3 | 1625 | .I mdadm |
e0d19036 NB |
1626 | to periodically poll a number of md arrays and to report on any events |
1627 | noticed. | |
51ac42e3 | 1628 | .I mdadm |
e0d19036 NB |
1629 | will never exit once it decides that there are arrays to be checked, |
1630 | so it should normally be run in the background. | |
1631 | ||
2d465520 | 1632 | As well as reporting events, |
51ac42e3 | 1633 | .I mdadm |
2d465520 NB |
1634 | may move a spare drive from one array to another if they are in the |
1635 | same | |
1636 | .B spare-group | |
a9d69660 | 1637 | and if the destination array has a failed drive but no spares. |
2d465520 | 1638 | |
e0d19036 | 1639 | If any devices are listed on the command line, |
51ac42e3 | 1640 | .I mdadm |
e0d19036 NB |
1641 | will only monitor those devices. Otherwise all arrays listed in the |
1642 | configuration file will be monitored. Further, if | |
7e23fc43 | 1643 | .B \-\-scan |
e0d19036 NB |
1644 | is given, then any other md devices that appear in |
1645 | .B /proc/mdstat | |
1646 | will also be monitored. | |
1647 | ||
1648 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 1649 | These events are passed to a separate program (if specified) and may |
2d465520 | 1650 | be mailed to a given E-mail address. |
e0d19036 | 1651 | |
93e790af SW |
1652 | When passing events to a program, the program is run once for each event, |
1653 | and is given 2 or 3 command-line arguments: the first is the | |
1654 | name of the event (see below), the second is the name of the | |
bd526cee | 1655 | md device which is affected, and the third is the name of a related |
93e790af | 1656 | device if relevant (such as a component device that has failed). |
cd29a5c8 NB |
1657 | |
1658 | If | |
7e23fc43 | 1659 | .B \-\-scan |
e0d19036 NB |
1660 | is given, then a program or an E-mail address must be specified on the |
1661 | command line or in the config file. If neither are available, then | |
51ac42e3 | 1662 | .I mdadm |
e0d19036 NB |
1663 | will not monitor anything. |
1664 | Without | |
93e790af | 1665 | .B \-\-scan, |
51ac42e3 | 1666 | .I mdadm |
2d465520 | 1667 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
1668 | no program or email is given, then each event is reported to |
1669 | .BR stdout . | |
cd29a5c8 | 1670 | |
e0d19036 NB |
1671 | The different events are: |
1672 | ||
1673 | .RS 4 | |
1674 | .TP | |
1675 | .B DeviceDisappeared | |
2d465520 | 1676 | An md array which previously was configured appears to no longer be |
773135f5 | 1677 | configured. (syslog priority: Critical) |
e0d19036 | 1678 | |
b8f72a62 NB |
1679 | If |
1680 | .I mdadm | |
1681 | was told to monitor an array which is RAID0 or Linear, then it will | |
1682 | report | |
1683 | .B DeviceDisappeared | |
1684 | with the extra information | |
1685 | .BR Wrong-Level . | |
1686 | This is because RAID0 and Linear do not support the device-failed, | |
1687 | hot-spare and resync operations which are monitored. | |
1688 | ||
e0d19036 NB |
1689 | .TP |
1690 | .B RebuildStarted | |
773135f5 | 1691 | An md array started reconstruction. (syslog priority: Warning) |
e0d19036 NB |
1692 | |
1693 | .TP | |
1694 | .BI Rebuild NN | |
1695 | Where | |
1696 | .I NN | |
1697 | is 20, 40, 60, or 80, this indicates that rebuild has passed that many | |
773135f5 | 1698 | percentage of the total. (syslog priority: Warning) |
e0d19036 | 1699 | |
98c6faba NB |
1700 | .TP |
1701 | .B RebuildFinished | |
1702 | An md array that was rebuilding, isn't any more, either because it | |
773135f5 | 1703 | finished normally or was aborted. (syslog priority: Warning) |
98c6faba | 1704 | |
e0d19036 NB |
1705 | .TP |
1706 | .B Fail | |
773135f5 NB |
1707 | An active component device of an array has been marked as |
1708 | faulty. (syslog priority: Critical) | |
e0d19036 NB |
1709 | |
1710 | .TP | |
1711 | .B FailSpare | |
1712 | A spare component device which was being rebuilt to replace a faulty | |
93e790af | 1713 | device has failed. (syslog priority: Critical) |
e0d19036 NB |
1714 | |
1715 | .TP | |
1716 | .B SpareActive | |
1717 | A spare component device which was being rebuilt to replace a faulty | |
98b24a2a | 1718 | device has been successfully rebuilt and has been made active. |
773135f5 | 1719 | (syslog priority: Info) |
e0d19036 NB |
1720 | |
1721 | .TP | |
1722 | .B NewArray | |
1723 | A new md array has been detected in the | |
1724 | .B /proc/mdstat | |
773135f5 | 1725 | file. (syslog priority: Info) |
e0d19036 | 1726 | |
aa88f531 NB |
1727 | .TP |
1728 | .B DegradedArray | |
1729 | A newly noticed array appears to be degraded. This message is not | |
1730 | generated when | |
1731 | .I mdadm | |
1732 | notices a drive failure which causes degradation, but only when | |
1733 | .I mdadm | |
1734 | notices that an array is degraded when it first sees the array. | |
93e790af | 1735 | (syslog priority: Critical) |
aa88f531 | 1736 | |
e0d19036 NB |
1737 | .TP |
1738 | .B MoveSpare | |
1739 | A spare drive has been moved from one array in a | |
1740 | .B spare-group | |
1741 | to another to allow a failed drive to be replaced. | |
773135f5 | 1742 | (syslog priority: Info) |
e0d19036 | 1743 | |
b8f72a62 NB |
1744 | .TP |
1745 | .B SparesMissing | |
1746 | If | |
1747 | .I mdadm | |
1748 | has been told, via the config file, that an array should have a certain | |
1749 | number of spare devices, and | |
1750 | .I mdadm | |
93e790af | 1751 | detects that it has fewer than this number when it first sees the |
b8f72a62 NB |
1752 | array, it will report a |
1753 | .B SparesMissing | |
1754 | message. | |
d1732eeb | 1755 | (syslog priority: Warning) |
b8f72a62 | 1756 | |
98c6faba NB |
1757 | .TP |
1758 | .B TestMessage | |
1759 | An array was found at startup, and the | |
7e23fc43 | 1760 | .B \-\-test |
98c6faba | 1761 | flag was given. |
773135f5 | 1762 | (syslog priority: Info) |
e0d19036 NB |
1763 | .RE |
1764 | ||
1765 | Only | |
93e790af SW |
1766 | .B Fail, |
1767 | .B FailSpare, | |
1768 | .B DegradedArray, | |
1769 | .B SparesMissing | |
e0d19036 | 1770 | and |
98c6faba | 1771 | .B TestMessage |
e0d19036 | 1772 | cause Email to be sent. All events cause the program to be run. |
93e790af | 1773 | The program is run with two or three arguments: the event |
e0d19036 NB |
1774 | name, the array device and possibly a second device. |
1775 | ||
1776 | Each event has an associated array device (e.g. | |
1777 | .BR /dev/md1 ) | |
1778 | and possibly a second device. For | |
1779 | .BR Fail , | |
1780 | .BR FailSpare , | |
1781 | and | |
1782 | .B SpareActive | |
1783 | the second device is the relevant component device. | |
1784 | For | |
1785 | .B MoveSpare | |
1786 | the second device is the array that the spare was moved from. | |
1787 | ||
1788 | For | |
51ac42e3 | 1789 | .I mdadm |
e0d19036 | 1790 | to move spares from one array to another, the different arrays need to |
93e790af | 1791 | be labeled with the same |
e0d19036 NB |
1792 | .B spare-group |
1793 | in the configuration file. The | |
1794 | .B spare-group | |
93e790af | 1795 | name can be any string; it is only necessary that different spare |
2d465520 | 1796 | groups use different names. |
e0d19036 NB |
1797 | |
1798 | When | |
51ac42e3 | 1799 | .I mdadm |
93e790af | 1800 | detects that an array in a spare group has fewer active |
e0d19036 NB |
1801 | devices than necessary for the complete array, and has no spare |
1802 | devices, it will look for another array in the same spare group that | |
1803 | has a full complement of working drive and a spare. It will then | |
1804 | attempt to remove the spare from the second drive and add it to the | |
1805 | first. | |
1806 | If the removal succeeds but the adding fails, then it is added back to | |
1807 | the original array. | |
1808 | ||
dd0781e5 NB |
1809 | .SH GROW MODE |
1810 | The GROW mode is used for changing the size or shape of an active | |
1811 | array. | |
1812 | For this to work, the kernel must support the necessary change. | |
2ae555c3 | 1813 | Various types of growth are being added during 2.6 development, |
dd0781e5 NB |
1814 | including restructuring a raid5 array to have more active devices. |
1815 | ||
dfd4d8ee NB |
1816 | Currently the only support available is to |
1817 | .IP \(bu 4 | |
1818 | change the "size" attribute | |
1819 | for RAID1, RAID5 and RAID6. | |
1820 | .IP \(bu 4 | |
e5669f40 | 1821 | increase the "raid\-devices" attribute of RAID1, RAID5, and RAID6. |
dfd4d8ee | 1822 | .IP \(bu 4 |
93e790af | 1823 | add a write-intent bitmap to any array which supports these bitmaps, or |
2ae555c3 | 1824 | remove a write-intent bitmap from such an array. |
dfd4d8ee | 1825 | .PP |
dd0781e5 | 1826 | |
8fd8d9c4 N |
1827 | GROW mode is not currently supported for |
1828 | .B CONTAINERS | |
1829 | or arrays inside containers. | |
1830 | ||
2ae555c3 | 1831 | .SS SIZE CHANGES |
fe80f49b | 1832 | Normally when an array is built the "size" it taken from the smallest |
dd0781e5 NB |
1833 | of the drives. If all the small drives in an arrays are, one at a |
1834 | time, removed and replaced with larger drives, then you could have an | |
1835 | array of large drives with only a small amount used. In this | |
1836 | situation, changing the "size" with "GROW" mode will allow the extra | |
1837 | space to start being used. If the size is increased in this way, a | |
1838 | "resync" process will start to make sure the new parts of the array | |
1839 | are synchronised. | |
1840 | ||
1841 | Note that when an array changes size, any filesystem that may be | |
1842 | stored in the array will not automatically grow to use the space. The | |
1843 | filesystem will need to be explicitly told to use the extra space. | |
1844 | ||
2ae555c3 NB |
1845 | .SS RAID-DEVICES CHANGES |
1846 | ||
dd0781e5 NB |
1847 | A RAID1 array can work with any number of devices from 1 upwards |
1848 | (though 1 is not very useful). There may be times which you want to | |
1849 | increase or decrease the number of active devices. Note that this is | |
1850 | different to hot-add or hot-remove which changes the number of | |
1851 | inactive devices. | |
1852 | ||
1853 | When reducing the number of devices in a RAID1 array, the slots which | |
1854 | are to be removed from the array must already be vacant. That is, the | |
93e790af | 1855 | devices which were in those slots must be failed and removed. |
dd0781e5 NB |
1856 | |
1857 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 1858 | present will be activated immediately. |
dd0781e5 | 1859 | |
2ae555c3 NB |
1860 | Increasing the number of active devices in a RAID5 is much more |
1861 | effort. Every block in the array will need to be read and written | |
1862 | back to a new location. From 2.6.17, the Linux Kernel is able to do | |
1863 | this safely, including restart and interrupted "reshape". | |
1864 | ||
1865 | When relocating the first few stripes on a raid5, it is not possible | |
1866 | to keep the data on disk completely consistent and crash-proof. To | |
1867 | provide the required safety, mdadm disables writes to the array while | |
1868 | this "critical section" is reshaped, and takes a backup of the data | |
1869 | that is in that section. This backup is normally stored in any spare | |
1870 | devices that the array has, however it can also be stored in a | |
1871 | separate file specified with the | |
7e23fc43 | 1872 | .B \-\-backup\-file |
2ae555c3 NB |
1873 | option. If this option is used, and the system does crash during the |
1874 | critical period, the same file must be passed to | |
7e23fc43 | 1875 | .B \-\-assemble |
2ae555c3 NB |
1876 | to restore the backup and reassemble the array. |
1877 | ||
1878 | .SS BITMAP CHANGES | |
1879 | ||
1880 | A write-intent bitmap can be added to, or removed from, an active | |
93e790af | 1881 | array. Either internal bitmaps, or bitmaps stored in a separate file, |
fe80f49b NB |
1882 | can be added. Note that if you add a bitmap stored in a file which is |
1883 | in a filesystem that is on the raid array being affected, the system | |
1884 | will deadlock. The bitmap must be on a separate filesystem. | |
1885 | ||
8382f19b NB |
1886 | .SH INCREMENTAL MODE |
1887 | ||
1888 | .HP 12 | |
1889 | Usage: | |
7e23fc43 PS |
1890 | .B mdadm \-\-incremental |
1891 | .RB [ \-\-run ] | |
1892 | .RB [ \-\-quiet ] | |
8382f19b NB |
1893 | .I component-device |
1894 | .HP 12 | |
1895 | Usage: | |
7e23fc43 | 1896 | .B mdadm \-\-incremental \-\-rebuild |
8382f19b NB |
1897 | .HP 12 |
1898 | Usage: | |
7e23fc43 | 1899 | .B mdadm \-\-incremental \-\-run \-\-scan |
8382f19b NB |
1900 | |
1901 | ||
1902 | .PP | |
1903 | This mode is designed to be used in conjunction with a device | |
1904 | discovery system. As devices are found in a system, they can be | |
1905 | passed to | |
7e23fc43 | 1906 | .B "mdadm \-\-incremental" |
8382f19b NB |
1907 | to be conditionally added to an appropriate array. |
1908 | ||
8fd8d9c4 N |
1909 | If the device passed is a |
1910 | .B CONTAINER | |
1911 | device created by a previous call to | |
1912 | .IR mdadm , | |
1913 | then rather than trying to add that device to an array, all the arrays | |
1914 | described by the metadata of the container will be started. | |
1915 | ||
8382f19b NB |
1916 | .I mdadm |
1917 | performs a number of tests to determine if the device is part of an | |
93e790af | 1918 | array, and which array it should be part of. If an appropriate array |
8382f19b NB |
1919 | is found, or can be created, |
1920 | .I mdadm | |
1921 | adds the device to the array and conditionally starts the array. | |
1922 | ||
1923 | Note that | |
1924 | .I mdadm | |
1925 | will only add devices to an array which were previously working | |
1926 | (active or spare) parts of that array. It does not currently support | |
1927 | automatic inclusion of a new drive as a spare in some array. | |
1928 | ||
8382f19b NB |
1929 | The tests that |
1930 | .I mdadm | |
1931 | makes are as follow: | |
1932 | .IP + | |
1933 | Is the device permitted by | |
1934 | .BR mdadm.conf ? | |
1935 | That is, is it listed in a | |
1936 | .B DEVICES | |
1937 | line in that file. If | |
1938 | .B DEVICES | |
1939 | is absent then the default it to allow any device. Similar if | |
1940 | .B DEVICES | |
1941 | contains the special word | |
1942 | .B partitions | |
1943 | then any device is allowed. Otherwise the device name given to | |
1944 | .I mdadm | |
1945 | must match one of the names or patterns in a | |
1946 | .B DEVICES | |
1947 | line. | |
1948 | ||
1949 | .IP + | |
1950 | Does the device have a valid md superblock. If a specific metadata | |
1951 | version is request with | |
7e23fc43 | 1952 | .B \-\-metadata |
8382f19b | 1953 | or |
7e23fc43 | 1954 | .B \-e |
8382f19b NB |
1955 | then only that style of metadata is accepted, otherwise |
1956 | .I mdadm | |
1957 | finds any known version of metadata. If no | |
1958 | .I md | |
1959 | metadata is found, the device is rejected. | |
1960 | ||
1961 | .IP + | |
1962 | Does the metadata match an expected array? | |
1963 | The metadata can match in two ways. Either there is an array listed | |
1964 | in | |
1965 | .B mdadm.conf | |
1966 | which identifies the array (either by UUID, by name, by device list, | |
93e790af | 1967 | or by minor-number), or the array was created with a |
8382f19b | 1968 | .B homehost |
93e790af | 1969 | specified and that |
8382f19b | 1970 | .B homehost |
93e790af | 1971 | matches the one in |
8382f19b NB |
1972 | .B mdadm.conf |
1973 | or on the command line. | |
1974 | If | |
1975 | .I mdadm | |
1976 | is not able to positively identify the array as belonging to the | |
1977 | current host, the device will be rejected. | |
1978 | ||
1979 | .IP + | |
1980 | .I mdadm | |
93e790af | 1981 | keeps a list of arrays that it has partially assembled in |
8382f19b NB |
1982 | .B /var/run/mdadm/map |
1983 | (or | |
1984 | .B /var/run/mdadm.map | |
1985 | if the directory doesn't exist). If no array exists which matches | |
1986 | the metadata on the new device, | |
1987 | .I mdadm | |
1988 | must choose a device name and unit number. It does this based on any | |
1989 | name given in | |
1990 | .B mdadm.conf | |
1991 | or any name information stored in the metadata. If this name | |
1992 | suggests a unit number, that number will be used, otherwise a free | |
1993 | unit number will be chosen. Normally | |
1994 | .I mdadm | |
1995 | will prefer to create a partitionable array, however if the | |
1996 | .B CREATE | |
1997 | line in | |
1998 | .B mdadm.conf | |
1999 | suggests that a non-partitionable array is preferred, that will be | |
2000 | honoured. | |
2001 | ||
2002 | .IP + | |
2003 | Once an appropriate array is found or created and the device is added, | |
2004 | .I mdadm | |
2005 | must decide if the array is ready to be started. It will | |
2006 | normally compare the number of available (non-spare) devices to the | |
2007 | number of devices that the metadata suggests need to be active. If | |
2008 | there are at least that many, the array will be started. This means | |
2009 | that if any devices are missing the array will not be restarted. | |
2010 | ||
2011 | As an alternative, | |
7e23fc43 | 2012 | .B \-\-run |
8382f19b | 2013 | may be passed to |
51ac42e3 | 2014 | .I mdadm |
8382f19b NB |
2015 | in which case the array will be run as soon as there are enough |
2016 | devices present for the data to be accessible. For a raid1, that | |
2017 | means one device will start the array. For a clean raid5, the array | |
2018 | will be started as soon as all but one drive is present. | |
2019 | ||
93e790af | 2020 | Note that neither of these approaches is really ideal. If it can |
8382f19b NB |
2021 | be known that all device discovery has completed, then |
2022 | .br | |
7e23fc43 | 2023 | .B " mdadm \-IRs" |
8382f19b NB |
2024 | .br |
2025 | can be run which will try to start all arrays that are being | |
2026 | incrementally assembled. They are started in "read-auto" mode in | |
2027 | which they are read-only until the first write request. This means | |
2028 | that no metadata updates are made and no attempt at resync or recovery | |
2029 | happens. Further devices that are found before the first write can | |
2030 | still be added safely. | |
2031 | ||
5545fa6d DW |
2032 | |
2033 | .SH ENVIRONMENT | |
2034 | This section describes environment variables that affect how mdadm | |
2035 | operates. | |
2036 | ||
2037 | .TP | |
2038 | .B MDADM_NO_MDMON | |
2039 | Setting this value to 1 will prevent mdadm from automatically launching | |
2040 | mdmon. This variable is intended primarily for debugging mdadm/mdmon. | |
2041 | ||
8fd8d9c4 N |
2042 | .TP |
2043 | .B MDADM_NO_UDEV | |
2044 | Normally, | |
2045 | .I mdadm | |
2046 | does not create any device nodes in /dev, but leaves that task to | |
2047 | .IR udev . | |
2048 | If | |
2049 | .I udev | |
2050 | appears not to be configured, or if this environment variable is set | |
2051 | to '1', the | |
2052 | .I mdadm | |
2053 | will create and devices that are needed. | |
2054 | ||
2d465520 NB |
2055 | .SH EXAMPLES |
2056 | ||
7e23fc43 | 2057 | .B " mdadm \-\-query /dev/name-of-device" |
2d465520 | 2058 | .br |
5787fa49 NB |
2059 | This will find out if a given device is a raid array, or is part of |
2060 | one, and will provide brief information about the device. | |
2d465520 | 2061 | |
7e23fc43 | 2062 | .B " mdadm \-\-assemble \-\-scan" |
2d465520 | 2063 | .br |
93e790af | 2064 | This will assemble and start all arrays listed in the standard config |
5787fa49 | 2065 | file. This command will typically go in a system startup file. |
2d465520 | 2066 | |
7e23fc43 | 2067 | .B " mdadm \-\-stop \-\-scan" |
5787fa49 | 2068 | .br |
93e790af | 2069 | This will shut down all arrays that can be shut down (i.e. are not |
19f8b8fc | 2070 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 2071 | |
7e23fc43 | 2072 | .B " mdadm \-\-follow \-\-scan \-\-delay=120" |
2d465520 | 2073 | .br |
5787fa49 NB |
2074 | If (and only if) there is an Email address or program given in the |
2075 | standard config file, then | |
2076 | monitor the status of all arrays listed in that file by | |
2077 | polling them ever 2 minutes. | |
2d465520 | 2078 | |
7e23fc43 | 2079 | .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1" |
2d465520 | 2080 | .br |
5787fa49 | 2081 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 2082 | |
2d465520 | 2083 | .br |
7e23fc43 | 2084 | .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf" |
2d465520 | 2085 | .br |
7e23fc43 | 2086 | .B " mdadm \-\-detail \-\-scan >> mdadm.conf" |
2d465520 | 2087 | .br |
5787fa49 NB |
2088 | This will create a prototype config file that describes currently |
2089 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
2090 | This file should be reviewed before being used as it may |
2091 | contain unwanted detail. | |
2092 | ||
7e23fc43 | 2093 | .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf" |
2d465520 | 2094 | .br |
7e23fc43 | 2095 | .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf" |
93e790af SW |
2096 | .br |
2097 | This will find arrays which could be assembled from existing IDE and | |
2098 | SCSI whole drives (not partitions), and store the information in the | |
5787fa49 | 2099 | format of a config file. |
2d465520 NB |
2100 | This file is very likely to contain unwanted detail, particularly |
2101 | the | |
2102 | .B devices= | |
5787fa49 NB |
2103 | entries. It should be reviewed and edited before being used as an |
2104 | actual config file. | |
2d465520 | 2105 | |
7e23fc43 | 2106 | .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions" |
2d465520 | 2107 | .br |
7e23fc43 | 2108 | .B " mdadm \-Ebsc partitions" |
5787fa49 NB |
2109 | .br |
2110 | Create a list of devices by reading | |
2111 | .BR /proc/partitions , | |
2112 | scan these for RAID superblocks, and printout a brief listing of all | |
93e790af | 2113 | that were found. |
2d465520 | 2114 | |
7e23fc43 | 2115 | .B " mdadm \-Ac partitions \-m 0 /dev/md0" |
2d465520 | 2116 | .br |
5787fa49 NB |
2117 | Scan all partitions and devices listed in |
2118 | .BR /proc/partitions | |
2119 | and assemble | |
2120 | .B /dev/md0 | |
2121 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 2122 | |
7e23fc43 | 2123 | .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm" |
d013a55e NB |
2124 | .br |
2125 | If config file contains a mail address or alert program, run mdadm in | |
2126 | the background in monitor mode monitoring all md devices. Also write | |
2127 | pid of mdadm daemon to | |
2128 | .BR /var/run/mdadm . | |
2129 | ||
7e23fc43 | 2130 | .B " mdadm \-Iq /dev/somedevice" |
8382f19b NB |
2131 | .br |
2132 | Try to incorporate newly discovered device into some array as | |
2133 | appropriate. | |
2134 | ||
7e23fc43 | 2135 | .B " mdadm \-\-incremental \-\-rebuild \-\-run \-\-scan" |
8382f19b NB |
2136 | .br |
2137 | Rebuild the array map from any current arrays, and then start any that | |
2138 | can be started. | |
2139 | ||
b80da661 NB |
2140 | .B " mdadm /dev/md4 --fail detached --remove detached" |
2141 | .br | |
2142 | Any devices which are components of /dev/md4 will be marked as faulty | |
2143 | and then remove from the array. | |
2144 | ||
8fd8d9c4 N |
2145 | .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]" |
2146 | .br | |
2147 | Create a DDF array over 6 devices. | |
2148 | ||
2149 | .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf" | |
2150 | .br | |
2151 | Create a raid5 array over any 3 devices in the given DDF set. Use | |
2152 | only 30 gigabytes of each device. | |
2153 | ||
2154 | .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]" | |
2155 | .br | |
2156 | Assemble a pre-exist ddf array. | |
2157 | ||
2158 | .B " mdadm -I /dev/md/ddf1" | |
2159 | .br | |
2160 | Assemble all arrays contained in the ddf array, assigning names as | |
2161 | appropriate. | |
2162 | ||
7e23fc43 | 2163 | .B " mdadm \-\-create \-\-help" |
2d465520 | 2164 | .br |
2ae555c3 | 2165 | Provide help about the Create mode. |
2d465520 | 2166 | |
7e23fc43 | 2167 | .B " mdadm \-\-config \-\-help" |
5787fa49 NB |
2168 | .br |
2169 | Provide help about the format of the config file. | |
2d465520 | 2170 | |
7e23fc43 | 2171 | .B " mdadm \-\-help" |
5787fa49 NB |
2172 | .br |
2173 | Provide general help. | |
cd29a5c8 | 2174 | |
cd29a5c8 NB |
2175 | |
2176 | .SH FILES | |
2177 | ||
2178 | .SS /proc/mdstat | |
2179 | ||
2ae555c3 NB |
2180 | If you're using the |
2181 | .B /proc | |
cd29a5c8 NB |
2182 | filesystem, |
2183 | .B /proc/mdstat | |
2d465520 | 2184 | lists all active md devices with information about them. |
51ac42e3 | 2185 | .I mdadm |
2d465520 | 2186 | uses this to find arrays when |
7e23fc43 | 2187 | .B \-\-scan |
2d465520 NB |
2188 | is given in Misc mode, and to monitor array reconstruction |
2189 | on Monitor mode. | |
2190 | ||
cd29a5c8 | 2191 | |
9a9dab36 | 2192 | .SS /etc/mdadm.conf |
cd29a5c8 | 2193 | |
11a3e71d NB |
2194 | The config file lists which devices may be scanned to see if |
2195 | they contain MD super block, and gives identifying information | |
2196 | (e.g. UUID) about known MD arrays. See | |
2197 | .BR mdadm.conf (5) | |
2198 | for more details. | |
cd29a5c8 | 2199 | |
8382f19b NB |
2200 | .SS /var/run/mdadm/map |
2201 | When | |
7e23fc43 | 2202 | .B \-\-incremental |
93e790af | 2203 | mode is used, this file gets a list of arrays currently being created. |
8382f19b NB |
2204 | If |
2205 | .B /var/run/mdadm | |
2206 | does not exist as a directory, then | |
2207 | .B /var/run/mdadm.map | |
2208 | is used instead. | |
2209 | ||
48f7b27a NB |
2210 | .SH DEVICE NAMES |
2211 | ||
48f7b27a | 2212 | .I mdadm |
8fd8d9c4 N |
2213 | understand two sorts of names for array devices. |
2214 | ||
2215 | The first is the so-called 'standard' format name, which matches the | |
2216 | names used by the kernel and which appear in | |
2217 | .IR /proc/mdstat . | |
2218 | ||
2219 | The second sort can be freely chosen, but must reside in | |
2220 | .IR /dev/md/ . | |
2221 | When giving a device name to | |
2222 | .I mdadm | |
2223 | to create or assemble an array, either full path name such as | |
2224 | .I /dev/md0 | |
2225 | or | |
2226 | .I /dev/md/home | |
2227 | can be given, or just the suffix of the second sort of name, such as | |
2228 | .I home | |
2229 | can be given. | |
2230 | ||
2231 | When | |
2232 | .I mdadm | |
2233 | chooses device names during auto-assembly, it will normally add a | |
2234 | small sequence number to the end of the name to avoid conflicted | |
2235 | between multiple arrays that have the same name. If | |
2236 | .I mdadm | |
2237 | can reasonably determine that the array really is meant for this host, | |
2238 | either by a hostname in the metadata, or by the presence of the array | |
2239 | in /etc/mdadm.conf, then it will leave of the suffix if possible. | |
48f7b27a NB |
2240 | |
2241 | The standard names for non-partitioned arrays (the only sort of md | |
8fd8d9c4 | 2242 | array available in 2.4 and earlier) are of the form |
48f7b27a NB |
2243 | .IP |
2244 | /dev/mdNN | |
48f7b27a NB |
2245 | .PP |
2246 | where NN is a number. | |
2247 | The standard names for partitionable arrays (as available from 2.6 | |
8fd8d9c4 | 2248 | onwards) are of the form |
48f7b27a | 2249 | .IP |
48f7b27a NB |
2250 | /dev/md_dNN |
2251 | .PP | |
2252 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
8fd8d9c4 N |
2253 | .PP |
2254 | From kernel version, 2.6.28 the "non-partitioned array" can actually | |
2255 | be partitioned. So the "md_dNN" names are no longer needed, and | |
2256 | partitions such as "/dev/mdNNpXX" are possible. | |
52826846 | 2257 | |
2d465520 | 2258 | .SH NOTE |
51ac42e3 | 2259 | .I mdadm |
2d465520 | 2260 | was previously known as |
51ac42e3 | 2261 | .IR mdctl . |
a9d69660 | 2262 | .P |
51ac42e3 | 2263 | .I mdadm |
a9d69660 | 2264 | is completely separate from the |
51ac42e3 | 2265 | .I raidtools |
a9d69660 NB |
2266 | package, and does not use the |
2267 | .I /etc/raidtab | |
2268 | configuration file at all. | |
2269 | ||
52826846 | 2270 | .SH SEE ALSO |
75f74377 | 2271 | For further information on mdadm usage, MD and the various levels of |
3cdfb6a7 | 2272 | RAID, see: |
3cdfb6a7 | 2273 | .IP |
11cd8b79 | 2274 | .B http://linux\-raid.osdl.org/ |
75f74377 DG |
2275 | .PP |
2276 | (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO) | |
e43d0cda NB |
2277 | .\".PP |
2278 | .\"for new releases of the RAID driver check out: | |
2279 | .\" | |
2280 | .\".IP | |
2281 | .\".UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
2282 | .\"ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
2283 | .\".UE | |
2284 | .\".PP | |
2285 | .\"or | |
2286 | .\".IP | |
2287 | .\".UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2288 | .\"http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
2289 | .\".UE | |
cd29a5c8 | 2290 | .PP |
2ae555c3 | 2291 | The latest version of |
a9d69660 NB |
2292 | .I mdadm |
2293 | should always be available from | |
cd29a5c8 | 2294 | .IP |
11cd8b79 N |
2295 | .B http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
2296 | .PP | |
2297 | Related man pages: | |
cd29a5c8 | 2298 | .PP |
a9d69660 NB |
2299 | .IR mdadm.conf (5), |
2300 | .IR md (4). | |
56eb10c0 | 2301 | .PP |
52826846 NB |
2302 | .IR raidtab (5), |
2303 | .IR raid0run (8), | |
2304 | .IR raidstop (8), | |
a9d69660 | 2305 | .IR mkraid (8). |