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52826846 | 1 | .\" -*- nroff -*- |
5e7519fa | 2 | .TH MDADM 8 "" v2.0-devel-3 |
52826846 | 3 | .SH NAME |
9a9dab36 | 4 | mdadm \- manage MD devices |
cd29a5c8 NB |
5 | .I aka |
6 | Linux Software Raid. | |
7 | ||
52826846 NB |
8 | .SH SYNOPSIS |
9 | ||
e0d19036 | 10 | .BI mdadm " [mode] <raiddevice> [options] <component-devices>" |
52826846 NB |
11 | |
12 | .SH DESCRIPTION | |
13 | RAID devices are virtual devices created from two or more | |
cd29a5c8 NB |
14 | real block devices. This allows multiple devices (typically disk |
15 | drives or partitions there-of) to be combined into a single device to | |
16 | hold (for example) a single filesystem. | |
2d465520 | 17 | Some RAID levels include redundancy and so can survive some degree of |
cd29a5c8 NB |
18 | device failure. |
19 | ||
2d465520 NB |
20 | Linux Software RAID devices are implemented through the md (Multiple |
21 | Devices) device driver. | |
cd29a5c8 NB |
22 | |
23 | Currently, Linux supports | |
24 | .B LINEAR | |
25 | md devices, | |
26 | .B RAID0 | |
27 | (striping), | |
28 | .B RAID1 | |
29 | (mirroring), | |
d013a55e NB |
30 | .BR RAID4 , |
31 | .BR RAID5 , | |
98c6faba | 32 | .BR RAID6 , |
b5e64645 | 33 | .BR MULTIPATH , |
cd29a5c8 | 34 | and |
b5e64645 | 35 | .BR FAULTY . |
d013a55e | 36 | |
a9d69660 NB |
37 | .B MULTIPATH |
38 | is not a Software RAID mechanism, but does involve | |
d013a55e NB |
39 | multiple devices. For |
40 | .B MULTIPATH | |
41 | each device is a path to one common physical storage device. | |
42 | ||
a9d69660 NB |
43 | .B FAULTY |
44 | is also not true RAID, and it only involves one device. It | |
b5e64645 | 45 | provides a layer over a true device that can be used to inject faults. |
52826846 | 46 | |
a9d69660 NB |
47 | '''.B mdadm |
48 | '''is a program that can be used to create, manage, and monitor | |
49 | '''MD devices. As | |
50 | '''such it provides a similar set of functionality to the | |
51 | '''.B raidtools | |
52 | '''packages. | |
53 | '''The key differences between | |
54 | '''.B mdadm | |
55 | '''and | |
56 | '''.B raidtools | |
57 | '''are: | |
58 | '''.IP \(bu 4 | |
59 | '''.B mdadm | |
60 | '''is a single program and not a collection of programs. | |
61 | '''.IP \(bu 4 | |
62 | '''.B mdadm | |
63 | '''can perform (almost) all of its functions without having a | |
64 | '''configuration file and does not use one by default. Also | |
65 | '''.B mdadm | |
66 | '''helps with management of the configuration | |
67 | '''file. | |
68 | '''.IP \(bu 4 | |
69 | '''.B mdadm | |
70 | '''can provide information about your arrays (through Query, Detail, and Examine) | |
71 | '''that | |
72 | '''.B raidtools | |
73 | '''cannot. | |
74 | '''.P | |
75 | '''.I mdadm | |
76 | '''does not use | |
77 | '''.IR /etc/raidtab , | |
78 | '''the | |
79 | '''.B raidtools | |
80 | '''configuration file, at all. It has a different configuration file | |
81 | '''with a different format and an different purpose. | |
52826846 NB |
82 | |
83 | .SH MODES | |
dd0781e5 | 84 | mdadm has 7 major modes of operation: |
cd29a5c8 NB |
85 | .TP |
86 | .B Assemble | |
87 | Assemble the parts of a previously created | |
52826846 NB |
88 | array into an active array. Components can be explicitly given |
89 | or can be searched for. | |
9a9dab36 | 90 | .B mdadm |
cd29a5c8 NB |
91 | checks that the components |
92 | do form a bona fide array, and can, on request, fiddle superblock | |
93 | information so as to assemble a faulty array. | |
94 | ||
95 | .TP | |
96 | .B Build | |
a9d69660 NB |
97 | Build an array that doesn't have per-device superblocks. For these |
98 | sorts of arrays, | |
99 | .I mdadm | |
100 | cannot differentiate between initial creation and subsequent assembly | |
101 | of an array. It also cannot perform any checks that appropriate | |
102 | devices have been requested. Because of this, the | |
103 | .B Build | |
104 | mode should only be used together with a complete understanding of | |
105 | what you are doing. | |
cd29a5c8 NB |
106 | |
107 | .TP | |
108 | .B Create | |
109 | Create a new array with per-device superblocks. | |
110 | '''It can progress | |
111 | '''in several step create-add-add-run or it can all happen with one command. | |
112 | ||
113 | .TP | |
e0d19036 NB |
114 | .B Manage |
115 | This is for doing things to specific components of an array such as | |
116 | adding new spares and removing faulty devices. | |
cd29a5c8 NB |
117 | |
118 | .TP | |
e0d19036 NB |
119 | .B Misc |
120 | This mode allows operations on independent devices such as examine MD | |
121 | superblocks, erasing old superblocks and stopping active arrays. | |
cd29a5c8 NB |
122 | |
123 | .TP | |
124 | .B "Follow or Monitor" | |
5787fa49 | 125 | Monitor one or more md devices and act on any state changes. This is |
98c6faba NB |
126 | only meaningful for raid1, 4, 5, 6 or multipath arrays as |
127 | only these have interesting state. raid0 or linear never have | |
128 | missing, spare, or failed drives, so there is nothing to monitor. | |
5787fa49 | 129 | |
dd0781e5 NB |
130 | .TP |
131 | .B "Grow" | |
132 | Grow (or shrink) an array, or otherwise reshape it in some way. | |
133 | Currently supported growth options including changing the active size | |
134 | of componenet devices in RAID level 1/4/5/6 and changing the number of | |
135 | active devices in RAID1. | |
cd29a5c8 | 136 | |
52826846 NB |
137 | .SH OPTIONS |
138 | ||
139 | Available options are: | |
140 | ||
cd29a5c8 NB |
141 | .TP |
142 | .BR -A ", " --assemble | |
2d465520 | 143 | Assemble a pre-existing array. |
52826846 | 144 | |
cd29a5c8 NB |
145 | .TP |
146 | .BR -B ", " --build | |
147 | Build a legacy array without superblocks. | |
52826846 | 148 | |
cd29a5c8 NB |
149 | .TP |
150 | .BR -C ", " --create | |
151 | Create a new array. | |
52826846 | 152 | |
e0d19036 NB |
153 | .TP |
154 | .BR -Q ", " --query | |
155 | Examine a device to see | |
156 | (1) if it is an md device and (2) if it is a component of an md | |
157 | array. | |
158 | Information about what is discovered is presented. | |
159 | ||
cd29a5c8 NB |
160 | .TP |
161 | .BR -D ", " --detail | |
162 | Print detail of one or more md devices. | |
52826846 | 163 | |
cd29a5c8 NB |
164 | .TP |
165 | .BR -E ", " --examine | |
166 | Print content of md superblock on device(s). | |
52826846 | 167 | |
cd29a5c8 NB |
168 | .TP |
169 | .BR -F ", " --follow ", " --monitor | |
170 | Select | |
171 | .B Monitor | |
172 | mode. | |
52826846 | 173 | |
dd0781e5 NB |
174 | .TP |
175 | .BR -G ", " --grow | |
176 | Change the size or shape of an active array. | |
177 | ||
e793c2e5 NB |
178 | .TP |
179 | .BR -X ", " --examine-bitmap | |
180 | Report information about a bitmap file. | |
181 | ||
cd29a5c8 NB |
182 | .TP |
183 | .BR -h ", " --help | |
a9d69660 NB |
184 | Display general help message or, after one of the above options, a |
185 | mode specific help message. | |
56eedc1a NB |
186 | |
187 | .TP | |
188 | .B --help-options | |
189 | Display more detailed help about command line parsing and some commonly | |
190 | used options. | |
52826846 | 191 | |
cd29a5c8 NB |
192 | .TP |
193 | .BR -V ", " --version | |
9a9dab36 | 194 | Print version information for mdadm. |
52826846 | 195 | |
cd29a5c8 NB |
196 | .TP |
197 | .BR -v ", " --verbose | |
22892d56 NB |
198 | Be more verbose about what is happening. This can be used twice to be |
199 | extra-verbose. | |
a9d69660 | 200 | The extra verbosity currently only affects |
22892d56 NB |
201 | .B --detail --scan |
202 | and | |
203 | .BR "--examine --scan" . | |
52826846 | 204 | |
dab6685f NB |
205 | .TP |
206 | .BR -q ", " --quiet | |
207 | Avoid printing purely informative messages. With this, | |
208 | .B mdadm | |
209 | will be silent unless there is something really important to report. | |
210 | ||
cd29a5c8 NB |
211 | .TP |
212 | .BR -b ", " --brief | |
213 | Be less verbose. This is used with | |
214 | .B --detail | |
215 | and | |
216 | .BR --examine . | |
22892d56 NB |
217 | Using |
218 | .B --brief | |
219 | with | |
220 | .B --verbose | |
221 | gives an intermediate level of verbosity. | |
52826846 | 222 | |
dfd4d8ee NB |
223 | .TP |
224 | .BR -W ", " --write-mostly | |
225 | subsequent devices lists in a | |
226 | .BR --build , | |
227 | .BR --create , | |
228 | or | |
229 | .B --add | |
230 | command will be flagged as 'write-mostly'. This is valid for RAID1 | |
231 | only and means that the 'md' driver will avoid reading from these | |
232 | devices if at all possible. This can be useful if mirroring over a | |
233 | slow link. | |
234 | ||
e793c2e5 NB |
235 | .TP |
236 | .BR -b ", " --bitmap= | |
237 | Give the name of a bitmap file to use with this array. Can be used | |
fe80f49b NB |
238 | with --create (file should not exist), --assemble (file should |
239 | exist), of --grow (file should not exist). | |
240 | ||
241 | The file | |
242 | .B internal | |
243 | can be used to indicate that the bitmap should be stored in the array, | |
244 | near the superblock. There is a limited amount of space for such | |
245 | bitmaps, but it is often sufficient. | |
246 | ||
247 | The file | |
248 | .B none | |
249 | can be given when used with --grow to remove a bitmap. | |
e793c2e5 NB |
250 | |
251 | .TP | |
252 | .BR --bitmap-chunk= | |
253 | Set the Chunksize of the bitmap. Each bit corresponds to that many | |
254 | Kilobytes of storage. Default is 4. | |
255 | ||
dfd4d8ee NB |
256 | .TP |
257 | .BR --write-behind= | |
258 | Specify that write-behind mode should be enabled (valid for RAID1 | |
259 | only). If an argument is specified, it will set the maximum number | |
260 | of outstanding writes allowed. The default value is 256. | |
261 | A write-intent bitmap is required in order to use write-behind | |
262 | mode, and write-behind is only attempted on drives marked as | |
263 | .IR write-mostly . | |
264 | ||
e793c2e5 | 265 | |
e0d19036 NB |
266 | .TP |
267 | .BR -f ", " --force | |
268 | Be more forceful about certain operations. See the various modes of | |
269 | the exact meaning of this option in different contexts. | |
270 | ||
271 | .TP | |
272 | .BR -c ", " --config= | |
273 | Specify the config file. Default is | |
274 | .BR /etc/mdadm.conf . | |
5787fa49 NB |
275 | If the config file given is |
276 | .B partitions | |
277 | then nothing will be read, but | |
278 | .I mdadm | |
279 | will act as though the config file contained exactly | |
280 | .B "DEVICE partitions" | |
281 | and will read | |
282 | .B /proc/partitions | |
283 | to find a list of devices to scan. | |
d013a55e NB |
284 | If the word |
285 | .B none | |
286 | is given for the config file, then | |
287 | .I mdadm | |
288 | will act as though the config file were empty. | |
e0d19036 NB |
289 | |
290 | .TP | |
291 | .BR -s ", " --scan | |
292 | scan config file or | |
293 | .B /proc/mdstat | |
294 | for missing information. | |
295 | In general, this option gives | |
296 | .B mdadm | |
297 | permission to get any missing information, like component devices, | |
298 | array devices, array identities, and alert destination from the | |
299 | configuration file: | |
300 | .BR /etc/mdadm.conf . | |
301 | One exception is MISC mode when using | |
302 | .B --detail | |
303 | or | |
304 | .B --stop | |
305 | in which case | |
306 | .B --scan | |
307 | says to get a list of array devices from | |
308 | .BR /proc/mdstat . | |
309 | ||
570c0542 NB |
310 | .TP |
311 | .B -e ", " --metadata= | |
312 | Declare the style of superblock (raid metadata) to be used. The | |
313 | default is 0.90 for --create, and to guess for other operations. | |
314 | ||
315 | Options are: | |
316 | .RS | |
317 | .IP "0, 0.90, default" | |
318 | Use the original 0.90 format superblock. This format limits arrays to | |
319 | 28 componenet devices and limits component devices of levels 1 and | |
320 | greater to 2 terabytes. | |
321 | .IP "1, 1.0, 1.1, 1.2" | |
322 | Use the new version-1 format superblock. This has few restrictions. | |
323 | The different subversion store the superblock at different locations | |
324 | on the device, either at the end (for 1.0), at the start (for 1.1) or | |
325 | 4K from the start (for 1.2). | |
326 | .RE | |
327 | ||
cd29a5c8 | 328 | .SH For create or build: |
52826846 | 329 | |
cd29a5c8 NB |
330 | .TP |
331 | .BR -c ", " --chunk= | |
332 | Specify chunk size of kibibytes. The default is 64. | |
52826846 | 333 | |
cd29a5c8 NB |
334 | .TP |
335 | .BR --rounding= | |
336 | Specify rounding factor for linear array (==chunk size) | |
52826846 | 337 | |
cd29a5c8 NB |
338 | .TP |
339 | .BR -l ", " --level= | |
aa88f531 NB |
340 | Set raid level. When used with |
341 | .IR --create , | |
98c6faba | 342 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
b5e64645 | 343 | raid5, 5, raid6, 6, multipath, mp, fautly. Obviously some of these are synonymous. |
aa88f531 NB |
344 | |
345 | When used with | |
346 | .IR --build , | |
a9d69660 | 347 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 348 | |
cd29a5c8 NB |
349 | .TP |
350 | .BR -p ", " --parity= | |
351 | Set raid5 parity algorithm. Options are: | |
2d465520 NB |
352 | left-asymmetric, |
353 | left-symmetric, | |
354 | right-asymmetric, | |
355 | right-symmetric, | |
356 | la, ra, ls, rs. The default is left-symmetric. | |
52826846 | 357 | |
b5e64645 NB |
358 | This option is also used to set the failure mode for |
359 | .IR faulty . | |
360 | The options are: | |
361 | write-transient, | |
362 | wt, | |
363 | read-transient, | |
364 | rt, | |
365 | write-presistent, | |
366 | wp, | |
367 | read-persistent, | |
368 | rp, | |
369 | write-all, | |
370 | read-fixable, | |
371 | rf, | |
372 | clear, | |
373 | flush, | |
374 | none. | |
375 | ||
376 | Each mode can be followed by a number which is used as a period | |
377 | between fault generation. Without a number, the fault is generated | |
378 | once on the first relevant request. With a number, the fault will be | |
379 | generated after that many request, and will continue to be generated | |
380 | every time the period elapses. | |
381 | ||
382 | Multiple failure modes can be current simultaneously by using the | |
383 | "--grow" option to set subsequent failure modes. | |
384 | ||
385 | "clear" or "none" will remove any pending or periodic failure modes, | |
386 | and "flush" will clear any persistant faults. | |
387 | ||
388 | To set the parity with "--grow", the level of the array ("faulty") | |
389 | must be specified before the fault mode is specified. | |
390 | ||
cd29a5c8 NB |
391 | .TP |
392 | .BR --layout= | |
393 | same as --parity | |
52826846 | 394 | |
e793c2e5 NB |
395 | .TP |
396 | .BR -b ", " --bitmap= | |
397 | Specify a file to store a write-intent bitmap in. The file should not | |
398 | exist unless --force is also given. The same file should be provided | |
399 | when assembling the array. | |
400 | ||
401 | .TP | |
402 | .BR --bitmap-chunk= | |
403 | Specifty the chunksize for the bitmap. | |
404 | ||
cd29a5c8 | 405 | .TP |
b83d95f3 | 406 | .BR -n ", " --raid-devices= |
5787fa49 NB |
407 | Specify the number of active devices in the array. This, plus the |
408 | number of spare devices (see below) must equal the number of | |
409 | .I component-devices | |
d013a55e | 410 | (including "\fBmissing\fP" devices) |
dd0781e5 NB |
411 | that are listed on the command line for |
412 | .BR --create . | |
413 | Setting a value of 1 is probably | |
aa88f531 NB |
414 | a mistake and so requires that |
415 | .B --force | |
416 | be specified first. A value of 1 will then be allowed for linear, | |
417 | multipath, raid0 and raid1. It is never allowed for raid4 or raid5. | |
418 | .br | |
dd0781e5 NB |
419 | This number can only be changed using |
420 | .B --grow | |
421 | for RAID1 arrays, and only on kernels which provide necessary support. | |
cd29a5c8 NB |
422 | |
423 | .TP | |
b83d95f3 | 424 | .BR -x ", " --spare-devices= |
5787fa49 NB |
425 | Specify the number of spare (eXtra) devices in the initial array. |
426 | Spares can also be added | |
427 | and removed later. The number of component devices listed | |
428 | on the command line must equal the number of raid devices plus the | |
429 | number of spare devices. | |
430 | ||
cd29a5c8 NB |
431 | |
432 | .TP | |
433 | .BR -z ", " --size= | |
98c6faba | 434 | Amount (in Kibibytes) of space to use from each drive in RAID1/4/5/6. |
cd29a5c8 NB |
435 | This must be a multiple of the chunk size, and must leave about 128Kb |
436 | of space at the end of the drive for the RAID superblock. | |
437 | If this is not specified | |
438 | (as it normally is not) the smallest drive (or partition) sets the | |
439 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
440 | issued. | |
52826846 | 441 | |
dd0781e5 NB |
442 | This value can be set with |
443 | .B --grow | |
444 | for RAID level 1/4/5/6. If the array was created with a size smaller | |
445 | than the currently active drives, the extra space can be accessed | |
446 | using | |
447 | .BR --grow . | |
779043ef NB |
448 | The size can be given as |
449 | .B max | |
a9d69660 | 450 | which means to choose the largest size that fits on all current drives. |
dd0781e5 NB |
451 | |
452 | .TP | |
453 | .BR --assume-clean | |
454 | Tell | |
455 | .I mdadm | |
456 | that the array pre-existed and is known to be clean. This is only | |
457 | really useful for Building RAID1 array. Only use this if you really | |
458 | know what you are doing. This is currently only supported for --build. | |
459 | ||
947fd4dd NB |
460 | .TP |
461 | .BR -N ", " --name= | |
462 | Set a | |
463 | .B name | |
464 | for the array. This is currently only effective when creating an | |
465 | array with a version-1 superblock. The name is a simple textual | |
466 | string that can be used to identify array components when assembling. | |
467 | ||
dd0781e5 NB |
468 | .TP |
469 | .BR -R ", " --run | |
470 | Insist that | |
471 | .I mdadm | |
472 | run the array, even if some of the components | |
473 | appear to be active in another array or filesystem. Normally | |
474 | .I mdadm | |
475 | will ask for confirmation before including such components in an | |
476 | array. This option causes that question to be suppressed. | |
477 | ||
478 | .TP | |
479 | .BR -f ", " --force | |
480 | Insist that | |
481 | .I mdadm | |
482 | accept the geometry and layout specified without question. Normally | |
483 | .I mdadm | |
484 | will not allow creation of an array with only one device, and will try | |
485 | to create a raid5 array with one missing drive (as this makes the | |
486 | initial resync work faster). With | |
487 | .BR --force , | |
488 | .I mdadm | |
489 | will not try to be so clever. | |
490 | ||
491 | .TP | |
492 | .BR -a ", " "--auto{=no,yes,md,mdp,part,p}{NN}" | |
48f7b27a NB |
493 | Instruct mdadm to create the device file if needed, possibly allocating |
494 | an unused minor number. "md" causes a non-partitionable array | |
dd0781e5 | 495 | to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and |
48f7b27a NB |
496 | later) to be used. "yes" requires the named md device to have a |
497 | 'standard' format, and the type and minor number will be determined | |
498 | from this. See DEVICE NAMES below. | |
499 | ||
a9d69660 | 500 | The argument can also come immediately after |
dd0781e5 NB |
501 | "-a". e.g. "-ap". |
502 | ||
1337546d NB |
503 | If |
504 | .I --scan | |
505 | is also given, then any | |
506 | .I auto= | |
507 | entries in the config file will over-ride the | |
508 | .I --auto | |
509 | instruction given on the command line. | |
510 | ||
dd0781e5 NB |
511 | For partitionable arrays, |
512 | .I mdadm | |
513 | will create the device file for the whole array and for the first 4 | |
514 | partitions. A different number of partitions can be specified at the | |
515 | end of this option (e.g. | |
516 | .BR --auto=p7 ). | |
48f7b27a NB |
517 | If the device name ends with a digit, the partition names add a'p', |
518 | and a number, e.g. "/dev/home1p3". If there is no | |
dd0781e5 NB |
519 | trailing digit, then the partition names just have a number added, |
520 | e.g. "/dev/scratch3". | |
521 | ||
48f7b27a NB |
522 | If the md device name is in a 'standard' format as described in DEVICE |
523 | NAMES, then it will be created, if necessary, with the appropriate | |
524 | number based on that name. If the device name is not in one of these | |
a9d69660 | 525 | formats, then a unused minor number will be allocated. The minor |
48f7b27a NB |
526 | number will be considered unused if there is no active array for that |
527 | number, and there is no entry in /dev for that number and with a | |
528 | non-standard name. | |
529 | ||
52826846 NB |
530 | .SH For assemble: |
531 | ||
cd29a5c8 NB |
532 | .TP |
533 | .BR -u ", " --uuid= | |
534 | uuid of array to assemble. Devices which don't have this uuid are | |
535 | excluded | |
536 | ||
537 | .TP | |
538 | .BR -m ", " --super-minor= | |
539 | Minor number of device that array was created for. Devices which | |
540 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 541 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
542 | the array is later assembled as /dev/md2. |
543 | ||
d013a55e NB |
544 | Giving the literal word "dev" for |
545 | .B --super-minor | |
546 | will cause | |
547 | .I mdadm | |
548 | to use the minor number of the md device that is being assembled. | |
549 | e.g. when assembling | |
550 | .BR /dev/md0 , | |
551 | .M --super-minor=dev | |
552 | will look for super blocks with a minor number of 0. | |
553 | ||
947fd4dd NB |
554 | .TP |
555 | .BR -N ", " --name= | |
556 | Specify the name of the array to assemble. This must be the name | |
557 | that was specified when creating the array. | |
558 | ||
cd29a5c8 NB |
559 | .TP |
560 | .BR -f ", " --force | |
52826846 NB |
561 | Assemble the array even if some superblocks appear out-of-date |
562 | ||
cd29a5c8 NB |
563 | .TP |
564 | .BR -R ", " --run | |
565 | Attempt to start the array even if fewer drives were given than are | |
566 | needed for a full array. Normally if not all drives are found and | |
567 | .B --scan | |
568 | is not used, then the array will be assembled but not started. | |
569 | With | |
570 | .B --run | |
571 | an attempt will be made to start it anyway. | |
52826846 | 572 | |
dd0781e5 NB |
573 | .TP |
574 | .BR -a ", " "--auto{=no,yes,md,mdp,part}" | |
575 | See this option under Create and Build options. | |
576 | ||
e793c2e5 NB |
577 | .TP |
578 | .BR -b ", " --bitmap= | |
579 | Specify the bitmap file that was given when the array was created. | |
580 | ||
5787fa49 NB |
581 | .TP |
582 | .BR -U ", " --update= | |
583 | Update the superblock on each device while assembling the array. The | |
feb716e9 NB |
584 | argument given to this flag can be one of |
585 | .BR sparc2.2 , | |
586 | .BR summaries , | |
e5329c37 | 587 | .BR resync , |
586ed405 | 588 | .BR byteorder , |
5787fa49 NB |
589 | or |
590 | .BR super-minor . | |
591 | ||
592 | The | |
593 | .B sparc2.2 | |
594 | option will adjust the superblock of an array what was created on a Sparc | |
595 | machine running a patched 2.2 Linux kernel. This kernel got the | |
596 | alignment of part of the superblock wrong. You can use the | |
597 | .B "--examine --sparc2.2" | |
598 | option to | |
599 | .I mdadm | |
600 | to see what effect this would have. | |
601 | ||
602 | The | |
603 | .B super-minor | |
604 | option will update the | |
605 | .B "prefered minor" | |
606 | field on each superblock to match the minor number of the array being | |
feb716e9 | 607 | assembled. This is not needed on 2.6 and later kernels as they make |
5787fa49 NB |
608 | this adjustment automatically. |
609 | ||
e5329c37 NB |
610 | The |
611 | .B resync | |
612 | option will cause the array to be marked | |
613 | .I dirty | |
614 | meaning that any redundancy in the array (e.g. parity for raid5, | |
615 | copies for raid1) may be incorrect. This will cause the raid system | |
616 | to perform a "resync" pass to make sure that all redundant information | |
617 | is correct. | |
618 | ||
586ed405 NB |
619 | The |
620 | .B byteorder | |
621 | option allows arrays to be moved between machines with different | |
622 | byte-order. | |
623 | When assembling such an array for the first time after a move, giving | |
624 | .B "--update=byteorder" | |
625 | will cause | |
626 | .I mdadm | |
627 | to expect superblocks to have their byteorder reversed, and will | |
628 | correct that order before assembling the array. This is only valid | |
629 | with original (Verion 0.90) superblocks. | |
630 | ||
feb716e9 NB |
631 | The |
632 | .B summaries | |
633 | option will correct the summaries in the superblock. That is the | |
634 | counts of total, working, active, failed, and spare devices. | |
5787fa49 | 635 | |
e0d19036 | 636 | .SH For Manage mode: |
52826846 | 637 | |
cd29a5c8 NB |
638 | .TP |
639 | .BR -a ", " --add | |
640 | '''add, or | |
641 | hotadd listed devices. | |
52826846 | 642 | |
fe80f49b NB |
643 | .TP |
644 | .BR --re-add | |
645 | Listed devices are assumed to have recently been part of the array, | |
646 | and they are re-added. This is only different from --add when a | |
647 | write-intent bitmap is present. It causes only those parts of the | |
648 | device that have changed since the device was removed from the array | |
649 | to be reconstructed. | |
650 | ||
651 | This flag is only needed with arrays that are built without a | |
652 | superblock (i.e. --build, not --create). For array with a superblock, | |
653 | .I mdadm | |
654 | checks if a superblock is present and automatically determines if a | |
655 | re-add is appropriate. | |
656 | ||
cd29a5c8 NB |
657 | .TP |
658 | .BR -r ", " --remove | |
2d465520 | 659 | remove listed devices. They must not be active. i.e. they should |
cd29a5c8 | 660 | be failed or spare devices. |
52826846 | 661 | |
cd29a5c8 NB |
662 | .TP |
663 | .BR -f ", " --fail | |
664 | mark listed devices as faulty. | |
52826846 | 665 | |
cd29a5c8 NB |
666 | .TP |
667 | .BR --set-faulty | |
668 | same as --fail. | |
52826846 | 669 | |
5787fa49 NB |
670 | .SH For Examine mode: |
671 | ||
672 | .TP | |
673 | .B --sparc2.2 | |
a9d69660 | 674 | If an array was created on a 2.2 Linux kernel patched with RAID |
5787fa49 NB |
675 | support, the superblock will have been created incorrectly, or at |
676 | least incompatibly with 2.4 and later kernels. Using the | |
677 | .B --sparc2.2 | |
678 | flag with | |
679 | .B --examine | |
680 | will fix the superblock before displaying it. If this appears to do | |
681 | the right thing, then the array can be successfully assembled using | |
682 | .BR "--assemble --update=sparc2.2" . | |
683 | ||
e0d19036 NB |
684 | .SH For Misc mode: |
685 | ||
cd29a5c8 NB |
686 | .TP |
687 | .BR -R ", " --run | |
688 | start a partially built array. | |
52826846 | 689 | |
cd29a5c8 NB |
690 | .TP |
691 | .BR -S ", " --stop | |
692 | deactivate array, releasing all resources. | |
52826846 | 693 | |
cd29a5c8 NB |
694 | .TP |
695 | .BR -o ", " --readonly | |
696 | mark array as readonly. | |
52826846 | 697 | |
cd29a5c8 NB |
698 | .TP |
699 | .BR -w ", " --readwrite | |
700 | mark array as readwrite. | |
52826846 | 701 | |
e0d19036 NB |
702 | .TP |
703 | .B --zero-superblock | |
704 | If the device contains a valid md superblock, the block is | |
705 | over-written with zeros. With | |
706 | --force | |
707 | the block where the superblock would be is over-written even if it | |
708 | doesn't appear to be valid. | |
52826846 | 709 | |
feb716e9 NB |
710 | .TP |
711 | .BR -t ", " --test | |
712 | When used with | |
713 | .BR --detail , | |
714 | the exit status of | |
715 | .I mdadm | |
716 | is set to reflect the status of the device. | |
717 | ||
e0d19036 NB |
718 | .SH For Monitor mode: |
719 | .TP | |
720 | .BR -m ", " --mail | |
721 | Give a mail address to send alerts to. | |
722 | ||
723 | .TP | |
724 | .BR -p ", " --program ", " --alert | |
725 | Give a program to be run whenever an event is detected. | |
726 | ||
727 | .TP | |
728 | .BR -d ", " --delay | |
729 | Give a delay in seconds. | |
730 | .B mdadm | |
731 | polls the md arrays and then waits this many seconds before polling | |
732 | again. The default is 60 seconds. | |
733 | ||
d013a55e NB |
734 | .TP |
735 | .BR -f ", " --daemonise | |
736 | Tell | |
737 | .B mdadm | |
738 | to run as a background daemon if it decides to monitor anything. This | |
739 | causes it to fork and run in the child, and to disconnect form the | |
740 | terminal. The process id of the child is written to stdout. | |
741 | This is useful with | |
742 | .B --scan | |
743 | which will only continue monitoring if a mail address or alert program | |
744 | is found in the config file. | |
745 | ||
b5e64645 NB |
746 | .TP |
747 | .BR -i ", " --pid-file | |
748 | When | |
749 | .B mdadm | |
750 | is running in daemon mode, write the pid of the daemon process to | |
751 | the specified file, instead of printing it on standard output. | |
752 | ||
aa88f531 NB |
753 | .TP |
754 | .BR -1 ", " --oneshot | |
755 | Check arrays only once. This will generate | |
756 | .B NewArray | |
757 | events and more significantly | |
758 | .B DegradedArray | |
a9d69660 NB |
759 | and |
760 | .B SparesMissing | |
aa88f531 NB |
761 | events. Running |
762 | .in +5 | |
763 | .B " mdadm --monitor --scan -1" | |
764 | .in -5 | |
765 | from a cron script will ensure regular notification of any degraded arrays. | |
766 | ||
98c6faba NB |
767 | .TP |
768 | .BR -t ", " --test | |
769 | Generate a | |
770 | .B TestMessage | |
771 | alert for every array found at startup. This alert gets mailed and | |
772 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 773 | message do get through successfully. |
98c6faba | 774 | |
e0d19036 | 775 | .SH ASSEMBLE MODE |
52826846 | 776 | |
cd29a5c8 NB |
777 | .HP 12 |
778 | Usage: | |
9a9dab36 | 779 | .B mdadm --assemble |
5787fa49 NB |
780 | .I md-device options-and-component-devices... |
781 | .HP 12 | |
782 | Usage: | |
783 | .B mdadm --assemble --scan | |
784 | .I md-devices-and-options... | |
cd29a5c8 NB |
785 | .HP 12 |
786 | Usage: | |
9a9dab36 | 787 | .B mdadm --assemble --scan |
cd29a5c8 | 788 | .I options... |
52826846 | 789 | |
cd29a5c8 | 790 | .PP |
52826846 | 791 | This usage assembles one or more raid arrays from pre-existing components. |
9a9dab36 | 792 | For each array, mdadm needs to know the md device, the identity of the |
e0d19036 | 793 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 794 | |
5787fa49 NB |
795 | In the first usage example (without the |
796 | .BR --scan ) | |
797 | the first device given is the md device. | |
798 | In the second usage example, all devices listed are treated as md | |
799 | devices and assembly is attempted. | |
800 | In the third (where no devices are listed) all md devices that are | |
801 | listed in the configuration file are assembled. | |
52826846 | 802 | |
d013a55e NB |
803 | If precisely one device is listed, but |
804 | .B --scan | |
dd0781e5 | 805 | is not given, then |
d013a55e NB |
806 | .I mdadm |
807 | acts as though | |
808 | .B --scan | |
809 | was given and identify information is extracted from the configuration file. | |
810 | ||
cd29a5c8 | 811 | The identity can be given with the |
52826846 | 812 | .B --uuid |
cd29a5c8 NB |
813 | option, with the |
814 | .B --super-minor | |
5787fa49 | 815 | option, can be found in the config file, or will be taken from the |
e0d19036 | 816 | super block on the first component-device listed on the command line. |
52826846 NB |
817 | |
818 | Devices can be given on the | |
819 | .B --assemble | |
5787fa49 NB |
820 | command line or in the config file. Only devices which have an md |
821 | superblock which contains the right identity will be considered for | |
822 | any array. | |
52826846 NB |
823 | |
824 | The config file is only used if explicitly named with | |
825 | .B --config | |
d013a55e | 826 | or requested with (a possibly implicit) |
52826846 NB |
827 | .B --scan. |
828 | In the later case, | |
9a9dab36 | 829 | .B /etc/mdadm.conf |
52826846 NB |
830 | is used. |
831 | ||
832 | If | |
833 | .B --scan | |
cd29a5c8 NB |
834 | is not given, then the config file will only be used to find the |
835 | identity of md arrays. | |
52826846 | 836 | |
2d465520 | 837 | Normally the array will be started after it is assembled. However if |
cd29a5c8 | 838 | .B --scan |
2d465520 | 839 | is not given and insufficient drives were listed to start a complete |
cd29a5c8 NB |
840 | (non-degraded) array, then the array is not started (to guard against |
841 | usage errors). To insist that the array be started in this case (as | |
98c6faba | 842 | may work for RAID1, 4, 5 or 6), give the |
cd29a5c8 NB |
843 | .B --run |
844 | flag. | |
52826846 | 845 | |
dd0781e5 NB |
846 | If an |
847 | .B auto | |
848 | option is given, either on the command line (--auto) or in the | |
849 | configuration file (e.g. auto=part), then | |
850 | .I mdadm | |
851 | will create the md device if necessary or will re-create it if it | |
852 | doesn't look usable as it is. | |
853 | ||
854 | This can be useful for handling partitioned devices (which don't have | |
855 | a stable device number - it can change after a reboot) and when using | |
856 | "udev" to manage your | |
857 | .B /dev | |
858 | tree (udev cannot handle md devices because of the unusual device | |
859 | initialisation conventions). | |
860 | ||
861 | If the option to "auto" is "mdp" or "part" or (on the command line | |
862 | only) "p", then mdadm will create a partitionable array, using the | |
863 | first free one that is not inuse, and does not already have an entry | |
864 | in /dev (apart from numeric /dev/md* entries). | |
865 | ||
866 | If the option to "auto" is "yes" or "md" or (on the command line) | |
867 | nothing, then mdadm will create a traditional, non-partitionable md | |
868 | array. | |
869 | ||
870 | It is expected that the "auto" functionality will be used to create | |
871 | device entries with meaningful names such as "/dev/md/home" or | |
872 | "/dev/md/root", rather than names based on the numerical array number. | |
873 | ||
874 | When using this option to create a partitionable array, the device | |
875 | files for the first 4 partitions are also created. If a different | |
876 | number is required it can be simply appended to the auto option. | |
877 | e.g. "auto=part8". Partition names are created by appending a digit | |
a9d69660 | 878 | string to the device name, with an intervening "p" if the device name |
dd0781e5 NB |
879 | ends with a digit. |
880 | ||
881 | The | |
882 | .B --auto | |
883 | option is also available in Build and Create modes. As those modes do | |
884 | not use a config file, the "auto=" config option does not apply to | |
885 | these modes. | |
52826846 | 886 | |
cd29a5c8 | 887 | .SH BUILD MODE |
52826846 | 888 | |
cd29a5c8 NB |
889 | .HP 12 |
890 | Usage: | |
9a9dab36 | 891 | .B mdadm --build |
cd29a5c8 NB |
892 | .I device |
893 | .BI --chunk= X | |
894 | .BI --level= Y | |
b83d95f3 | 895 | .BI --raid-devices= Z |
cd29a5c8 NB |
896 | .I devices |
897 | ||
898 | .PP | |
52826846 | 899 | This usage is similar to |
cd29a5c8 | 900 | .BR --create . |
a9d69660 | 901 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 902 | these arrays there is no difference between initially creating the array and |
52826846 NB |
903 | subsequently assembling the array, except that hopefully there is useful |
904 | data there in the second case. | |
905 | ||
a9d69660 NB |
906 | The level may raid0, linear, multipath, or faulty, or one of their |
907 | synonyms. All devices must be listed and the array will be started | |
908 | once complete. | |
cd29a5c8 NB |
909 | |
910 | .SH CREATE MODE | |
911 | ||
912 | .HP 12 | |
913 | Usage: | |
9a9dab36 | 914 | .B mdadm --create |
cd29a5c8 NB |
915 | .I device |
916 | .BI --chunk= X | |
917 | .BI --level= Y | |
918 | .br | |
b83d95f3 | 919 | .BI --raid-devices= Z |
cd29a5c8 NB |
920 | .I devices |
921 | ||
922 | .PP | |
923 | This usage will initialise a new md array, associate some devices with | |
924 | it, and activate the array. | |
925 | ||
a9d69660 | 926 | If the |
dd0781e5 NB |
927 | .B --auto |
928 | option is given (as described in more detail in the section on | |
929 | Assemble mode), then the md device will be created with a suitable | |
930 | device number if necessary. | |
931 | ||
cd29a5c8 | 932 | As devices are added, they are checked to see if they contain raid |
2d465520 | 933 | superblocks or filesystems. They are also checked to see if the variance in |
cd29a5c8 NB |
934 | device size exceeds 1%. |
935 | ||
936 | If any discrepancy is found, the array will not automatically be run, though | |
937 | the presence of a | |
938 | .B --run | |
939 | can override this caution. | |
940 | ||
2d465520 | 941 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 942 | give the word "\fBmissing\fP" |
2d465520 NB |
943 | in place of a device name. This will cause |
944 | .B mdadm | |
945 | to leave the corresponding slot in the array empty. | |
946 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 947 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
948 | For a RAID1 array, only one real device needs to be given. All of the |
949 | others can be | |
d013a55e | 950 | "\fBmissing\fP". |
2d465520 | 951 | |
feb716e9 NB |
952 | When creating a RAID5 array, |
953 | .B mdadm | |
954 | will automatically create a degraded array with an extra spare drive. | |
955 | This is because building the spare into a degraded array is in general faster than resyncing | |
956 | the parity on a non-degraded, but not clean, array. This feature can | |
957 | be over-ridden with the | |
b5e64645 | 958 | .I --force |
feb716e9 NB |
959 | option. |
960 | ||
cd29a5c8 NB |
961 | '''If the |
962 | '''.B --size | |
e0d19036 | 963 | '''option is given, it is not necessary to list any component-devices in this command. |
cd29a5c8 NB |
964 | '''They can be added later, before a |
965 | '''.B --run. | |
966 | '''If no | |
967 | '''.B --size | |
968 | '''is given, the apparent size of the smallest drive given is used. | |
969 | ||
970 | The General Management options that are valid with --create are: | |
971 | .TP | |
972 | .B --run | |
dd0781e5 | 973 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
974 | be in use. |
975 | ||
976 | .TP | |
977 | .B --readonly | |
978 | start the array readonly - not supported yet. | |
52826846 | 979 | |
e0d19036 | 980 | .SH MANAGE MODE |
cd29a5c8 NB |
981 | .HP 12 |
982 | Usage: | |
e0d19036 NB |
983 | .B mdadm |
984 | .I device | |
985 | .I options... devices... | |
cd29a5c8 NB |
986 | .PP |
987 | ||
e0d19036 NB |
988 | This usage will allow individual devices in an array to be failed, |
989 | removed or added. It is possible to perform multiple operations with | |
990 | on command. For example: | |
991 | .br | |
5787fa49 | 992 | .B " mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1" |
e0d19036 NB |
993 | .br |
994 | will firstly mark | |
995 | .B /dev/hda1 | |
996 | as faulty in | |
997 | .B /dev/md0 | |
998 | and will then remove it from the array and finally add it back | |
2d465520 | 999 | in as a spare. However only one md array can be affected by a single |
e0d19036 NB |
1000 | command. |
1001 | ||
1002 | .SH MISC MODE | |
1003 | .HP 12 | |
1004 | Usage: | |
9a9dab36 | 1005 | .B mdadm |
e0d19036 NB |
1006 | .I options ... |
1007 | .I devices ... | |
1008 | .PP | |
cd29a5c8 | 1009 | |
b5e64645 | 1010 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1011 | operate on distinct devices. The operations are: |
1012 | .TP | |
1013 | --query | |
1014 | The device is examined to see if it is | |
1015 | (1) an active md array, or | |
1016 | (2) a component of an md array. | |
1017 | The information discovered is reported. | |
1018 | ||
1019 | .TP | |
1020 | --detail | |
2d465520 NB |
1021 | The device should be an active md device. |
1022 | .B mdadm | |
1023 | will display a detailed description of the array. | |
cd29a5c8 | 1024 | .B --brief |
2d465520 NB |
1025 | or |
1026 | .B --scan | |
1027 | will cause the output to be less detailed and the format to be | |
e0d19036 | 1028 | suitable for inclusion in |
9a9dab36 | 1029 | .BR /etc/mdadm.conf . |
feb716e9 NB |
1030 | The exit status of |
1031 | .I mdadm | |
1032 | will normally be 0 unless | |
1033 | .I mdadm | |
1034 | failed to get useful information about the device(s). However if the | |
1035 | .B --test | |
1036 | option is given, then the exit status will be: | |
1037 | .RS | |
1038 | .TP | |
1039 | 0 | |
1040 | The array is functioning normally. | |
1041 | .TP | |
1042 | 1 | |
1043 | The array has at least one failed device. | |
1044 | .TP | |
1045 | 2 | |
1046 | The array has multiple failed devices and hence is unusable (raid4 or | |
1047 | raid5). | |
1048 | .TP | |
1049 | 4 | |
1050 | There was an error while trying to get information about the device. | |
1051 | .RE | |
cd29a5c8 | 1052 | |
e0d19036 NB |
1053 | .TP |
1054 | --examine | |
2d465520 NB |
1055 | The device should be a component of an md array. |
1056 | .B mdadm | |
1057 | will read the md superblock of the device and display the contents. | |
e0d19036 NB |
1058 | If |
1059 | .B --brief | |
1060 | is given, or | |
1061 | .B --scan | |
1062 | then multiple devices that are components of the one array | |
1063 | are grouped together and reported in a single entry suitable | |
1064 | for inclusion in | |
1065 | .BR /etc/mdadm.conf . | |
1066 | ||
2d465520 | 1067 | Having |
e0d19036 NB |
1068 | .B --scan |
1069 | without listing any devices will cause all devices listed in the | |
1070 | config file to be examined. | |
1071 | ||
1072 | .TP | |
1073 | --stop | |
98c6faba NB |
1074 | The devices should be active md arrays which will be deactivated, as |
1075 | long as they are not currently in use. | |
e0d19036 NB |
1076 | |
1077 | .TP | |
1078 | --run | |
1079 | This will fully activate a partially assembled md array. | |
1080 | ||
1081 | .TP | |
1082 | --readonly | |
1083 | This will mark an active array as read-only, providing that it is | |
1084 | not currently being used. | |
1085 | ||
1086 | .TP | |
1087 | --readwrite | |
1088 | This will change a | |
1089 | .B readonly | |
1090 | array back to being read/write. | |
1091 | ||
2d465520 NB |
1092 | .TP |
1093 | --scan | |
1094 | For all operations except | |
1095 | .BR --examine , | |
1096 | .B --scan | |
1097 | will cause the operation to be applied to all arrays listed in | |
1098 | .BR /proc/mdstat . | |
1099 | For | |
1100 | .BR --examine, | |
1101 | .B --scan | |
1102 | causes all devices listed in the config file to be examined. | |
1103 | ||
1104 | ||
e0d19036 NB |
1105 | .SH MONITOR MODE |
1106 | ||
cd29a5c8 NB |
1107 | .HP 12 |
1108 | Usage: | |
e0d19036 NB |
1109 | .B mdadm --monitor |
1110 | .I options... devices... | |
1111 | ||
cd29a5c8 | 1112 | .PP |
e0d19036 NB |
1113 | This usage causes |
1114 | .B mdadm | |
1115 | to periodically poll a number of md arrays and to report on any events | |
1116 | noticed. | |
1117 | .B mdadm | |
1118 | will never exit once it decides that there are arrays to be checked, | |
1119 | so it should normally be run in the background. | |
1120 | ||
2d465520 NB |
1121 | As well as reporting events, |
1122 | .B mdadm | |
1123 | may move a spare drive from one array to another if they are in the | |
1124 | same | |
1125 | .B spare-group | |
a9d69660 | 1126 | and if the destination array has a failed drive but no spares. |
2d465520 | 1127 | |
e0d19036 NB |
1128 | If any devices are listed on the command line, |
1129 | .B mdadm | |
1130 | will only monitor those devices. Otherwise all arrays listed in the | |
1131 | configuration file will be monitored. Further, if | |
1132 | .B --scan | |
1133 | is given, then any other md devices that appear in | |
1134 | .B /proc/mdstat | |
1135 | will also be monitored. | |
1136 | ||
1137 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 1138 | These events are passed to a separate program (if specified) and may |
2d465520 | 1139 | be mailed to a given E-mail address. |
e0d19036 | 1140 | |
bd526cee NB |
1141 | When passing event to program, the program is run once for each event |
1142 | and is given 2 or 3 command-line arguements. The first is the | |
1143 | name of the event (see below). The second is the name of the | |
1144 | md device which is affected, and the third is the name of a related | |
1145 | device if relevant, such as a component device that has failed. | |
cd29a5c8 NB |
1146 | |
1147 | If | |
1148 | .B --scan | |
e0d19036 NB |
1149 | is given, then a program or an E-mail address must be specified on the |
1150 | command line or in the config file. If neither are available, then | |
1151 | .B mdadm | |
1152 | will not monitor anything. | |
1153 | Without | |
cd29a5c8 | 1154 | .B --scan |
e0d19036 | 1155 | .B mdadm |
2d465520 | 1156 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
1157 | no program or email is given, then each event is reported to |
1158 | .BR stdout . | |
cd29a5c8 | 1159 | |
e0d19036 NB |
1160 | The different events are: |
1161 | ||
1162 | .RS 4 | |
1163 | .TP | |
1164 | .B DeviceDisappeared | |
2d465520 | 1165 | An md array which previously was configured appears to no longer be |
e0d19036 NB |
1166 | configured. |
1167 | ||
b8f72a62 NB |
1168 | If |
1169 | .I mdadm | |
1170 | was told to monitor an array which is RAID0 or Linear, then it will | |
1171 | report | |
1172 | .B DeviceDisappeared | |
1173 | with the extra information | |
1174 | .BR Wrong-Level . | |
1175 | This is because RAID0 and Linear do not support the device-failed, | |
1176 | hot-spare and resync operations which are monitored. | |
1177 | ||
e0d19036 NB |
1178 | .TP |
1179 | .B RebuildStarted | |
1180 | An md array started reconstruction. | |
1181 | ||
1182 | .TP | |
1183 | .BI Rebuild NN | |
1184 | Where | |
1185 | .I NN | |
1186 | is 20, 40, 60, or 80, this indicates that rebuild has passed that many | |
1187 | percentage of the total. | |
1188 | ||
98c6faba NB |
1189 | .TP |
1190 | .B RebuildFinished | |
1191 | An md array that was rebuilding, isn't any more, either because it | |
1192 | finished normally or was aborted. | |
1193 | ||
e0d19036 NB |
1194 | .TP |
1195 | .B Fail | |
1196 | An active component device of an array has been marked as faulty. | |
1197 | ||
1198 | .TP | |
1199 | .B FailSpare | |
1200 | A spare component device which was being rebuilt to replace a faulty | |
1201 | device has failed. | |
1202 | ||
1203 | .TP | |
1204 | .B SpareActive | |
1205 | A spare component device which was being rebuilt to replace a faulty | |
1206 | device as been successfully rebuild and has been made active. | |
1207 | ||
1208 | .TP | |
1209 | .B NewArray | |
1210 | A new md array has been detected in the | |
1211 | .B /proc/mdstat | |
1212 | file. | |
1213 | ||
aa88f531 NB |
1214 | .TP |
1215 | .B DegradedArray | |
1216 | A newly noticed array appears to be degraded. This message is not | |
1217 | generated when | |
1218 | .I mdadm | |
1219 | notices a drive failure which causes degradation, but only when | |
1220 | .I mdadm | |
1221 | notices that an array is degraded when it first sees the array. | |
1222 | ||
e0d19036 NB |
1223 | .TP |
1224 | .B MoveSpare | |
1225 | A spare drive has been moved from one array in a | |
1226 | .B spare-group | |
1227 | to another to allow a failed drive to be replaced. | |
1228 | ||
b8f72a62 NB |
1229 | .TP |
1230 | .B SparesMissing | |
1231 | If | |
1232 | .I mdadm | |
1233 | has been told, via the config file, that an array should have a certain | |
1234 | number of spare devices, and | |
1235 | .I mdadm | |
1236 | detects that it has fewer that this number when it first sees the | |
1237 | array, it will report a | |
1238 | .B SparesMissing | |
1239 | message. | |
1240 | ||
98c6faba NB |
1241 | .TP |
1242 | .B TestMessage | |
1243 | An array was found at startup, and the | |
1244 | .B --test | |
1245 | flag was given. | |
e0d19036 NB |
1246 | .RE |
1247 | ||
1248 | Only | |
98c6faba NB |
1249 | .B Fail , |
1250 | .B FailSpare , | |
1251 | .B DegradedArray , | |
e0d19036 | 1252 | and |
98c6faba | 1253 | .B TestMessage |
e0d19036 NB |
1254 | cause Email to be sent. All events cause the program to be run. |
1255 | The program is run with two or three arguments, they being the event | |
1256 | name, the array device and possibly a second device. | |
1257 | ||
1258 | Each event has an associated array device (e.g. | |
1259 | .BR /dev/md1 ) | |
1260 | and possibly a second device. For | |
1261 | .BR Fail , | |
1262 | .BR FailSpare , | |
1263 | and | |
1264 | .B SpareActive | |
1265 | the second device is the relevant component device. | |
1266 | For | |
1267 | .B MoveSpare | |
1268 | the second device is the array that the spare was moved from. | |
1269 | ||
1270 | For | |
1271 | .B mdadm | |
1272 | to move spares from one array to another, the different arrays need to | |
1273 | be labelled with the same | |
1274 | .B spare-group | |
1275 | in the configuration file. The | |
1276 | .B spare-group | |
1277 | name can be any string. It is only necessary that different spare | |
2d465520 | 1278 | groups use different names. |
e0d19036 NB |
1279 | |
1280 | When | |
9a9dab36 | 1281 | .B mdadm |
e0d19036 NB |
1282 | detects that an array which is in a spare group has fewer active |
1283 | devices than necessary for the complete array, and has no spare | |
1284 | devices, it will look for another array in the same spare group that | |
1285 | has a full complement of working drive and a spare. It will then | |
1286 | attempt to remove the spare from the second drive and add it to the | |
1287 | first. | |
1288 | If the removal succeeds but the adding fails, then it is added back to | |
1289 | the original array. | |
1290 | ||
dd0781e5 NB |
1291 | .SH GROW MODE |
1292 | The GROW mode is used for changing the size or shape of an active | |
1293 | array. | |
1294 | For this to work, the kernel must support the necessary change. | |
1295 | Various types of growth may be added during 2.6 development, possibly | |
1296 | including restructuring a raid5 array to have more active devices. | |
1297 | ||
dfd4d8ee NB |
1298 | Currently the only support available is to |
1299 | .IP \(bu 4 | |
1300 | change the "size" attribute | |
1301 | for RAID1, RAID5 and RAID6. | |
1302 | .IP \(bu 4 | |
1303 | change the "raid-disks" attribute of RAID1. | |
1304 | .IP \(bu 4 | |
1305 | add a write-intent bitmap to a RAID1 array. | |
1306 | .PP | |
dd0781e5 | 1307 | |
fe80f49b | 1308 | Normally when an array is built the "size" it taken from the smallest |
dd0781e5 NB |
1309 | of the drives. If all the small drives in an arrays are, one at a |
1310 | time, removed and replaced with larger drives, then you could have an | |
1311 | array of large drives with only a small amount used. In this | |
1312 | situation, changing the "size" with "GROW" mode will allow the extra | |
1313 | space to start being used. If the size is increased in this way, a | |
1314 | "resync" process will start to make sure the new parts of the array | |
1315 | are synchronised. | |
1316 | ||
1317 | Note that when an array changes size, any filesystem that may be | |
1318 | stored in the array will not automatically grow to use the space. The | |
1319 | filesystem will need to be explicitly told to use the extra space. | |
1320 | ||
1321 | A RAID1 array can work with any number of devices from 1 upwards | |
1322 | (though 1 is not very useful). There may be times which you want to | |
1323 | increase or decrease the number of active devices. Note that this is | |
1324 | different to hot-add or hot-remove which changes the number of | |
1325 | inactive devices. | |
1326 | ||
1327 | When reducing the number of devices in a RAID1 array, the slots which | |
1328 | are to be removed from the array must already be vacant. That is, the | |
1329 | devices that which were in those slots must be failed and removed. | |
1330 | ||
1331 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 1332 | present will be activated immediately. |
dd0781e5 | 1333 | |
fe80f49b NB |
1334 | A write-intent bitmap can be added to, or remove from, an active RAID1 |
1335 | array. Either internal bitmap, of bitmaps stored in a separate file | |
1336 | can be added. Note that if you add a bitmap stored in a file which is | |
1337 | in a filesystem that is on the raid array being affected, the system | |
1338 | will deadlock. The bitmap must be on a separate filesystem. | |
1339 | ||
2d465520 NB |
1340 | .SH EXAMPLES |
1341 | ||
5787fa49 | 1342 | .B " mdadm --query /dev/name-of-device" |
2d465520 | 1343 | .br |
5787fa49 NB |
1344 | This will find out if a given device is a raid array, or is part of |
1345 | one, and will provide brief information about the device. | |
2d465520 | 1346 | |
5787fa49 | 1347 | .B " mdadm --assemble --scan" |
2d465520 | 1348 | .br |
5787fa49 NB |
1349 | This will assemble and start all arrays listed in the standard confile |
1350 | file. This command will typically go in a system startup file. | |
2d465520 | 1351 | |
2d465520 | 1352 | .B " mdadm --stop --scan" |
5787fa49 NB |
1353 | .br |
1354 | This will shut down all array that can be shut down (i.e. are not | |
19f8b8fc | 1355 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 1356 | |
5787fa49 | 1357 | .B " mdadm --follow --scan --delay=120" |
2d465520 | 1358 | .br |
5787fa49 NB |
1359 | If (and only if) there is an Email address or program given in the |
1360 | standard config file, then | |
1361 | monitor the status of all arrays listed in that file by | |
1362 | polling them ever 2 minutes. | |
2d465520 | 1363 | |
5787fa49 | 1364 | .B " mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/hd[ac]1" |
2d465520 | 1365 | .br |
5787fa49 | 1366 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 1367 | |
2d465520 NB |
1368 | .br |
1369 | .B " echo 'DEVICE /dev/hd*[0-9] /dev/sd*[0-9]' > mdadm.conf" | |
1370 | .br | |
1371 | .B " mdadm --detail --scan >> mdadm.conf" | |
1372 | .br | |
5787fa49 NB |
1373 | This will create a prototype config file that describes currently |
1374 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
1375 | This file should be reviewed before being used as it may |
1376 | contain unwanted detail. | |
1377 | ||
2d465520 NB |
1378 | .B " echo 'DEVICE /dev/hd[a-z] /dev/sd*[a-z]' > mdadm.conf" |
1379 | .br | |
5787fa49 NB |
1380 | .B " mdadm --examine --scan --config=mdadm.conf >> mdadm.conf" |
1381 | .ber | |
1382 | This will find what arrays could be assembled from existign IDE and | |
1383 | SCSI whole drives (not partitions) and store the information is the | |
1384 | format of a config file. | |
2d465520 NB |
1385 | This file is very likely to contain unwanted detail, particularly |
1386 | the | |
1387 | .B devices= | |
5787fa49 NB |
1388 | entries. It should be reviewed and edited before being used as an |
1389 | actual config file. | |
2d465520 | 1390 | |
5787fa49 | 1391 | .B " mdadm --examine --brief --scan --config=partitions" |
2d465520 | 1392 | .br |
5787fa49 NB |
1393 | .B " mdadm -Ebsc partitions" |
1394 | .br | |
1395 | Create a list of devices by reading | |
1396 | .BR /proc/partitions , | |
1397 | scan these for RAID superblocks, and printout a brief listing of all | |
1398 | that was found. | |
2d465520 | 1399 | |
5787fa49 | 1400 | .B " mdadm -Ac partitions -m 0 /dev/md0" |
2d465520 | 1401 | .br |
5787fa49 NB |
1402 | Scan all partitions and devices listed in |
1403 | .BR /proc/partitions | |
1404 | and assemble | |
1405 | .B /dev/md0 | |
1406 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 1407 | |
d013a55e NB |
1408 | .B " mdadm --monitor --scan --daemonise > /var/run/mdadm" |
1409 | .br | |
1410 | If config file contains a mail address or alert program, run mdadm in | |
1411 | the background in monitor mode monitoring all md devices. Also write | |
1412 | pid of mdadm daemon to | |
1413 | .BR /var/run/mdadm . | |
1414 | ||
5787fa49 | 1415 | .B " mdadm --create --help" |
2d465520 | 1416 | .br |
5787fa49 | 1417 | Providew help about the Create mode. |
2d465520 | 1418 | |
5787fa49 NB |
1419 | .B " mdadm --config --help" |
1420 | .br | |
1421 | Provide help about the format of the config file. | |
2d465520 | 1422 | |
5787fa49 NB |
1423 | .B " mdadm --help" |
1424 | .br | |
1425 | Provide general help. | |
cd29a5c8 | 1426 | |
cd29a5c8 NB |
1427 | |
1428 | .SH FILES | |
1429 | ||
1430 | .SS /proc/mdstat | |
1431 | ||
1432 | If you're using the | |
1433 | .B /proc | |
1434 | filesystem, | |
1435 | .B /proc/mdstat | |
2d465520 NB |
1436 | lists all active md devices with information about them. |
1437 | .B mdadm | |
1438 | uses this to find arrays when | |
1439 | .B --scan | |
1440 | is given in Misc mode, and to monitor array reconstruction | |
1441 | on Monitor mode. | |
1442 | ||
cd29a5c8 | 1443 | |
9a9dab36 | 1444 | .SS /etc/mdadm.conf |
cd29a5c8 | 1445 | |
11a3e71d NB |
1446 | The config file lists which devices may be scanned to see if |
1447 | they contain MD super block, and gives identifying information | |
1448 | (e.g. UUID) about known MD arrays. See | |
1449 | .BR mdadm.conf (5) | |
1450 | for more details. | |
cd29a5c8 | 1451 | |
48f7b27a NB |
1452 | .SH DEVICE NAMES |
1453 | ||
1454 | While entries in the /dev directory can have any format you like, | |
1455 | .I mdadm | |
1456 | has an understanding of 'standard' formats which it uses to guide its | |
1457 | behaviour when creating device files via the | |
1458 | .I --auto | |
1459 | option. | |
1460 | ||
1461 | The standard names for non-partitioned arrays (the only sort of md | |
1462 | array available in 2.4 and earlier) either of | |
1463 | .IP | |
1464 | /dev/mdNN | |
1465 | .br | |
1466 | /dev/md/NN | |
1467 | .PP | |
1468 | where NN is a number. | |
1469 | The standard names for partitionable arrays (as available from 2.6 | |
1470 | onwards) is one of | |
1471 | .IP | |
1472 | /dev/md/dNN | |
1473 | .br | |
1474 | /dev/md_dNN | |
1475 | .PP | |
1476 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
52826846 | 1477 | |
2d465520 NB |
1478 | .SH NOTE |
1479 | .B mdadm | |
1480 | was previously known as | |
1481 | .BR mdctl . | |
a9d69660 NB |
1482 | .P |
1483 | .B mdadm | |
1484 | is completely separate from the | |
1485 | .B raidtools | |
1486 | package, and does not use the | |
1487 | .I /etc/raidtab | |
1488 | configuration file at all. | |
1489 | ||
52826846 | 1490 | .SH SEE ALSO |
cd29a5c8 NB |
1491 | For information on the various levels of |
1492 | RAID, check out: | |
1493 | ||
1494 | .IP | |
1495 | .UR http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/ | |
1496 | http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/ | |
1497 | .UE | |
a9d69660 NB |
1498 | '''.PP |
1499 | '''for new releases of the RAID driver check out: | |
1500 | ''' | |
1501 | '''.IP | |
1502 | '''.UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
1503 | '''ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
1504 | '''.UE | |
1505 | '''.PP | |
1506 | '''or | |
1507 | '''.IP | |
1508 | '''.UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
1509 | '''http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
1510 | '''.UE | |
cd29a5c8 | 1511 | .PP |
a9d69660 NB |
1512 | The lastest version of |
1513 | .I mdadm | |
1514 | should always be available from | |
cd29a5c8 | 1515 | .IP |
a9d69660 NB |
1516 | .UR http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
1517 | http://www.kernel.org/pub/linux/utils/raid/mdadm/ | |
cd29a5c8 NB |
1518 | .UE |
1519 | .PP | |
a9d69660 NB |
1520 | .IR mdadm.conf (5), |
1521 | .IR md (4). | |
56eb10c0 | 1522 | .PP |
52826846 NB |
1523 | .IR raidtab (5), |
1524 | .IR raid0run (8), | |
1525 | .IR raidstop (8), | |
a9d69660 | 1526 | .IR mkraid (8). |