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