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