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52826846 | 1 | .\" -*- nroff -*- |
e478dc86 | 2 | .TH MDADM 8 "" v2.1 |
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 , |
1a7dfc35 | 33 | .BR RAID10 , |
b5e64645 | 34 | .BR MULTIPATH , |
cd29a5c8 | 35 | and |
b5e64645 | 36 | .BR FAULTY . |
d013a55e | 37 | |
a9d69660 NB |
38 | .B MULTIPATH |
39 | is not a Software RAID mechanism, but does involve | |
d013a55e NB |
40 | multiple devices. For |
41 | .B MULTIPATH | |
42 | each device is a path to one common physical storage device. | |
43 | ||
a9d69660 NB |
44 | .B FAULTY |
45 | is also not true RAID, and it only involves one device. It | |
b5e64645 | 46 | provides a layer over a true device that can be used to inject faults. |
52826846 | 47 | |
a9d69660 NB |
48 | '''.B mdadm |
49 | '''is a program that can be used to create, manage, and monitor | |
50 | '''MD devices. As | |
51 | '''such it provides a similar set of functionality to the | |
52 | '''.B raidtools | |
53 | '''packages. | |
54 | '''The key differences between | |
55 | '''.B mdadm | |
56 | '''and | |
57 | '''.B raidtools | |
58 | '''are: | |
59 | '''.IP \(bu 4 | |
60 | '''.B mdadm | |
61 | '''is a single program and not a collection of programs. | |
62 | '''.IP \(bu 4 | |
63 | '''.B mdadm | |
64 | '''can perform (almost) all of its functions without having a | |
65 | '''configuration file and does not use one by default. Also | |
66 | '''.B mdadm | |
67 | '''helps with management of the configuration | |
68 | '''file. | |
69 | '''.IP \(bu 4 | |
70 | '''.B mdadm | |
71 | '''can provide information about your arrays (through Query, Detail, and Examine) | |
72 | '''that | |
73 | '''.B raidtools | |
74 | '''cannot. | |
75 | '''.P | |
76 | '''.I mdadm | |
77 | '''does not use | |
78 | '''.IR /etc/raidtab , | |
79 | '''the | |
80 | '''.B raidtools | |
81 | '''configuration file, at all. It has a different configuration file | |
82 | '''with a different format and an different purpose. | |
52826846 NB |
83 | |
84 | .SH MODES | |
dd0781e5 | 85 | mdadm has 7 major modes of operation: |
cd29a5c8 NB |
86 | .TP |
87 | .B Assemble | |
88 | Assemble the parts of a previously created | |
52826846 NB |
89 | array into an active array. Components can be explicitly given |
90 | or can be searched for. | |
9a9dab36 | 91 | .B mdadm |
cd29a5c8 NB |
92 | checks that the components |
93 | do form a bona fide array, and can, on request, fiddle superblock | |
94 | information so as to assemble a faulty array. | |
95 | ||
96 | .TP | |
97 | .B Build | |
a9d69660 NB |
98 | Build an array that doesn't have per-device superblocks. For these |
99 | sorts of arrays, | |
100 | .I mdadm | |
101 | cannot differentiate between initial creation and subsequent assembly | |
102 | of an array. It also cannot perform any checks that appropriate | |
103 | devices have been requested. Because of this, the | |
104 | .B Build | |
105 | mode should only be used together with a complete understanding of | |
106 | what you are doing. | |
cd29a5c8 NB |
107 | |
108 | .TP | |
109 | .B Create | |
110 | Create a new array with per-device superblocks. | |
111 | '''It can progress | |
112 | '''in several step create-add-add-run or it can all happen with one command. | |
113 | ||
114 | .TP | |
e0d19036 NB |
115 | .B Manage |
116 | This is for doing things to specific components of an array such as | |
117 | adding new spares and removing faulty devices. | |
cd29a5c8 NB |
118 | |
119 | .TP | |
e0d19036 NB |
120 | .B Misc |
121 | This mode allows operations on independent devices such as examine MD | |
122 | superblocks, erasing old superblocks and stopping active arrays. | |
cd29a5c8 NB |
123 | |
124 | .TP | |
125 | .B "Follow or Monitor" | |
5787fa49 | 126 | Monitor one or more md devices and act on any state changes. This is |
1a7dfc35 | 127 | only meaningful for raid1, 4, 5, 6, 10 or multipath arrays as |
98c6faba NB |
128 | only these have interesting state. raid0 or linear never have |
129 | missing, spare, or failed drives, so there is nothing to monitor. | |
5787fa49 | 130 | |
dd0781e5 NB |
131 | .TP |
132 | .B "Grow" | |
133 | Grow (or shrink) an array, or otherwise reshape it in some way. | |
134 | Currently supported growth options including changing the active size | |
135 | of componenet devices in RAID level 1/4/5/6 and changing the number of | |
136 | active devices in RAID1. | |
cd29a5c8 | 137 | |
52826846 NB |
138 | .SH OPTIONS |
139 | ||
140 | Available options are: | |
141 | ||
cd29a5c8 NB |
142 | .TP |
143 | .BR -A ", " --assemble | |
2d465520 | 144 | Assemble a pre-existing array. |
52826846 | 145 | |
cd29a5c8 NB |
146 | .TP |
147 | .BR -B ", " --build | |
148 | Build a legacy array without superblocks. | |
52826846 | 149 | |
cd29a5c8 NB |
150 | .TP |
151 | .BR -C ", " --create | |
152 | Create a new array. | |
52826846 | 153 | |
e0d19036 NB |
154 | .TP |
155 | .BR -Q ", " --query | |
156 | Examine a device to see | |
157 | (1) if it is an md device and (2) if it is a component of an md | |
158 | array. | |
159 | Information about what is discovered is presented. | |
160 | ||
cd29a5c8 NB |
161 | .TP |
162 | .BR -D ", " --detail | |
163 | Print detail of one or more md devices. | |
52826846 | 164 | |
cd29a5c8 NB |
165 | .TP |
166 | .BR -E ", " --examine | |
167 | Print content of md superblock on device(s). | |
52826846 | 168 | |
cd29a5c8 NB |
169 | .TP |
170 | .BR -F ", " --follow ", " --monitor | |
171 | Select | |
172 | .B Monitor | |
173 | mode. | |
52826846 | 174 | |
dd0781e5 NB |
175 | .TP |
176 | .BR -G ", " --grow | |
177 | Change the size or shape of an active array. | |
178 | ||
e793c2e5 NB |
179 | .TP |
180 | .BR -X ", " --examine-bitmap | |
181 | Report information about a bitmap file. | |
182 | ||
cd29a5c8 NB |
183 | .TP |
184 | .BR -h ", " --help | |
a9d69660 NB |
185 | Display general help message or, after one of the above options, a |
186 | mode specific help message. | |
56eedc1a NB |
187 | |
188 | .TP | |
189 | .B --help-options | |
190 | Display more detailed help about command line parsing and some commonly | |
191 | used options. | |
52826846 | 192 | |
cd29a5c8 NB |
193 | .TP |
194 | .BR -V ", " --version | |
9a9dab36 | 195 | Print version information for mdadm. |
52826846 | 196 | |
cd29a5c8 NB |
197 | .TP |
198 | .BR -v ", " --verbose | |
22892d56 NB |
199 | Be more verbose about what is happening. This can be used twice to be |
200 | extra-verbose. | |
a9d69660 | 201 | The extra verbosity currently only affects |
22892d56 NB |
202 | .B --detail --scan |
203 | and | |
204 | .BR "--examine --scan" . | |
52826846 | 205 | |
dab6685f NB |
206 | .TP |
207 | .BR -q ", " --quiet | |
208 | Avoid printing purely informative messages. With this, | |
209 | .B mdadm | |
210 | will be silent unless there is something really important to report. | |
211 | ||
cd29a5c8 NB |
212 | .TP |
213 | .BR -b ", " --brief | |
214 | Be less verbose. This is used with | |
215 | .B --detail | |
216 | and | |
217 | .BR --examine . | |
22892d56 NB |
218 | Using |
219 | .B --brief | |
220 | with | |
221 | .B --verbose | |
222 | gives an intermediate level of verbosity. | |
52826846 | 223 | |
dfd4d8ee NB |
224 | .TP |
225 | .BR -W ", " --write-mostly | |
226 | subsequent devices lists in a | |
227 | .BR --build , | |
228 | .BR --create , | |
229 | or | |
230 | .B --add | |
231 | command will be flagged as 'write-mostly'. This is valid for RAID1 | |
232 | only and means that the 'md' driver will avoid reading from these | |
233 | devices if at all possible. This can be useful if mirroring over a | |
234 | slow link. | |
235 | ||
e793c2e5 NB |
236 | .TP |
237 | .BR -b ", " --bitmap= | |
238 | Give the name of a bitmap file to use with this array. Can be used | |
fe80f49b NB |
239 | with --create (file should not exist), --assemble (file should |
240 | exist), of --grow (file should not exist). | |
241 | ||
242 | The file | |
243 | .B internal | |
244 | can be used to indicate that the bitmap should be stored in the array, | |
245 | near the superblock. There is a limited amount of space for such | |
246 | bitmaps, but it is often sufficient. | |
247 | ||
248 | The file | |
249 | .B none | |
250 | can be given when used with --grow to remove a bitmap. | |
e793c2e5 NB |
251 | |
252 | .TP | |
253 | .BR --bitmap-chunk= | |
254 | Set the Chunksize of the bitmap. Each bit corresponds to that many | |
255 | Kilobytes of storage. Default is 4. | |
256 | ||
dfd4d8ee NB |
257 | .TP |
258 | .BR --write-behind= | |
259 | Specify that write-behind mode should be enabled (valid for RAID1 | |
260 | only). If an argument is specified, it will set the maximum number | |
261 | of outstanding writes allowed. The default value is 256. | |
262 | A write-intent bitmap is required in order to use write-behind | |
263 | mode, and write-behind is only attempted on drives marked as | |
264 | .IR write-mostly . | |
265 | ||
e793c2e5 | 266 | |
e0d19036 NB |
267 | .TP |
268 | .BR -f ", " --force | |
269 | Be more forceful about certain operations. See the various modes of | |
270 | the exact meaning of this option in different contexts. | |
271 | ||
272 | .TP | |
273 | .BR -c ", " --config= | |
274 | Specify the config file. Default is | |
275 | .BR /etc/mdadm.conf . | |
5787fa49 NB |
276 | If the config file given is |
277 | .B partitions | |
278 | then nothing will be read, but | |
279 | .I mdadm | |
280 | will act as though the config file contained exactly | |
281 | .B "DEVICE partitions" | |
282 | and will read | |
283 | .B /proc/partitions | |
284 | to find a list of devices to scan. | |
d013a55e NB |
285 | If the word |
286 | .B none | |
287 | is given for the config file, then | |
288 | .I mdadm | |
289 | will act as though the config file were empty. | |
e0d19036 NB |
290 | |
291 | .TP | |
292 | .BR -s ", " --scan | |
293 | scan config file or | |
294 | .B /proc/mdstat | |
295 | for missing information. | |
296 | In general, this option gives | |
297 | .B mdadm | |
298 | permission to get any missing information, like component devices, | |
299 | array devices, array identities, and alert destination from the | |
300 | configuration file: | |
301 | .BR /etc/mdadm.conf . | |
302 | One exception is MISC mode when using | |
303 | .B --detail | |
304 | or | |
305 | .B --stop | |
306 | in which case | |
307 | .B --scan | |
308 | says to get a list of array devices from | |
309 | .BR /proc/mdstat . | |
310 | ||
570c0542 NB |
311 | .TP |
312 | .B -e ", " --metadata= | |
313 | Declare the style of superblock (raid metadata) to be used. The | |
314 | default is 0.90 for --create, and to guess for other operations. | |
315 | ||
316 | Options are: | |
317 | .RS | |
318 | .IP "0, 0.90, default" | |
319 | Use the original 0.90 format superblock. This format limits arrays to | |
320 | 28 componenet devices and limits component devices of levels 1 and | |
321 | greater to 2 terabytes. | |
322 | .IP "1, 1.0, 1.1, 1.2" | |
323 | Use the new version-1 format superblock. This has few restrictions. | |
324 | The different subversion store the superblock at different locations | |
325 | on the device, either at the end (for 1.0), at the start (for 1.1) or | |
326 | 4K from the start (for 1.2). | |
327 | .RE | |
328 | ||
cd29a5c8 | 329 | .SH For create or build: |
52826846 | 330 | |
cd29a5c8 NB |
331 | .TP |
332 | .BR -c ", " --chunk= | |
333 | Specify chunk size of kibibytes. The default is 64. | |
52826846 | 334 | |
cd29a5c8 NB |
335 | .TP |
336 | .BR --rounding= | |
337 | Specify rounding factor for linear array (==chunk size) | |
52826846 | 338 | |
cd29a5c8 NB |
339 | .TP |
340 | .BR -l ", " --level= | |
aa88f531 NB |
341 | Set raid level. When used with |
342 | .IR --create , | |
98c6faba | 343 | options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4, |
1a7dfc35 | 344 | raid5, 5, raid6, 6, raid10, 10, multipath, mp, fautly. Obviously some of these are synonymous. |
aa88f531 NB |
345 | |
346 | When used with | |
347 | .IR --build , | |
a9d69660 | 348 | only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid. |
52826846 | 349 | |
cd29a5c8 | 350 | .TP |
1a7dfc35 NB |
351 | .BR -p ", " --layout= |
352 | This option configures the fine details of data layout for raid5, | |
353 | and raid10 arrays, and controls the failure modes for | |
354 | .IR faulty . | |
355 | ||
356 | The layout of the raid5 parity block can be one of | |
2d465520 NB |
357 | left-asymmetric, |
358 | left-symmetric, | |
359 | right-asymmetric, | |
360 | right-symmetric, | |
361 | la, ra, ls, rs. The default is left-symmetric. | |
52826846 | 362 | |
1a7dfc35 NB |
363 | When setting the failure mode for |
364 | .I faulty | |
365 | the options are: | |
b5e64645 NB |
366 | write-transient, |
367 | wt, | |
368 | read-transient, | |
369 | rt, | |
370 | write-presistent, | |
371 | wp, | |
372 | read-persistent, | |
373 | rp, | |
374 | write-all, | |
375 | read-fixable, | |
376 | rf, | |
377 | clear, | |
378 | flush, | |
379 | none. | |
380 | ||
381 | Each mode can be followed by a number which is used as a period | |
382 | between fault generation. Without a number, the fault is generated | |
383 | once on the first relevant request. With a number, the fault will be | |
384 | generated after that many request, and will continue to be generated | |
385 | every time the period elapses. | |
386 | ||
387 | Multiple failure modes can be current simultaneously by using the | |
388 | "--grow" option to set subsequent failure modes. | |
389 | ||
390 | "clear" or "none" will remove any pending or periodic failure modes, | |
391 | and "flush" will clear any persistant faults. | |
392 | ||
393 | To set the parity with "--grow", the level of the array ("faulty") | |
394 | must be specified before the fault mode is specified. | |
395 | ||
1a7dfc35 NB |
396 | Finally, the layout options for RAID10 are either 'n' or 'p' followed |
397 | by a small number. The default is 'n2'. | |
398 | ||
399 | .I n | |
400 | signals 'near' copies (multiple copies of one data block are at | |
401 | similar offsets in different devices) while | |
402 | .I f | |
403 | signals 'far' copies | |
404 | (multiple copies have very different offsets). See md(4) for more | |
405 | detail about 'near' and 'far'. | |
406 | ||
407 | The number is the number of copies of each datablock. 2 is normal, 3 | |
408 | can be useful. This number can be at most equal to the number of | |
409 | devices in the array. It does not need to divide evenly into that | |
410 | number (e.g. it is perfectly legal to have an 'n2' layout for an array | |
411 | with an odd number of devices). | |
412 | ||
cd29a5c8 | 413 | .TP |
1a7dfc35 NB |
414 | .BR --parity= |
415 | same as --layout (thus explaining the p of | |
416 | .IR -p ). | |
52826846 | 417 | |
e793c2e5 NB |
418 | .TP |
419 | .BR -b ", " --bitmap= | |
420 | Specify a file to store a write-intent bitmap in. The file should not | |
421 | exist unless --force is also given. The same file should be provided | |
422 | when assembling the array. | |
423 | ||
424 | .TP | |
425 | .BR --bitmap-chunk= | |
426 | Specifty the chunksize for the bitmap. | |
427 | ||
cd29a5c8 | 428 | .TP |
b83d95f3 | 429 | .BR -n ", " --raid-devices= |
5787fa49 NB |
430 | Specify the number of active devices in the array. This, plus the |
431 | number of spare devices (see below) must equal the number of | |
432 | .I component-devices | |
d013a55e | 433 | (including "\fBmissing\fP" devices) |
dd0781e5 NB |
434 | that are listed on the command line for |
435 | .BR --create . | |
436 | Setting a value of 1 is probably | |
aa88f531 NB |
437 | a mistake and so requires that |
438 | .B --force | |
439 | be specified first. A value of 1 will then be allowed for linear, | |
440 | multipath, raid0 and raid1. It is never allowed for raid4 or raid5. | |
441 | .br | |
dd0781e5 NB |
442 | This number can only be changed using |
443 | .B --grow | |
444 | for RAID1 arrays, and only on kernels which provide necessary support. | |
cd29a5c8 NB |
445 | |
446 | .TP | |
b83d95f3 | 447 | .BR -x ", " --spare-devices= |
5787fa49 NB |
448 | Specify the number of spare (eXtra) devices in the initial array. |
449 | Spares can also be added | |
450 | and removed later. The number of component devices listed | |
451 | on the command line must equal the number of raid devices plus the | |
452 | number of spare devices. | |
453 | ||
cd29a5c8 NB |
454 | |
455 | .TP | |
456 | .BR -z ", " --size= | |
98c6faba | 457 | Amount (in Kibibytes) of space to use from each drive in RAID1/4/5/6. |
cd29a5c8 NB |
458 | This must be a multiple of the chunk size, and must leave about 128Kb |
459 | of space at the end of the drive for the RAID superblock. | |
460 | If this is not specified | |
461 | (as it normally is not) the smallest drive (or partition) sets the | |
462 | size, though if there is a variance among the drives of greater than 1%, a warning is | |
463 | issued. | |
52826846 | 464 | |
dd0781e5 NB |
465 | This value can be set with |
466 | .B --grow | |
467 | for RAID level 1/4/5/6. If the array was created with a size smaller | |
468 | than the currently active drives, the extra space can be accessed | |
469 | using | |
470 | .BR --grow . | |
779043ef NB |
471 | The size can be given as |
472 | .B max | |
a9d69660 | 473 | which means to choose the largest size that fits on all current drives. |
dd0781e5 NB |
474 | |
475 | .TP | |
476 | .BR --assume-clean | |
477 | Tell | |
478 | .I mdadm | |
47d79ef8 NB |
479 | that the array pre-existed and is known to be clean. It can be useful |
480 | when trying to recover from a major failure as you can be sure that no | |
481 | data will be affected unless you actually write to the array. It can | |
482 | also be used when creating a RAID1 or RAID10 if you want to avoid the | |
483 | initial resync, however this practice - while normally safe - is not | |
484 | recommended. Use this ony if you really know what you are doing. | |
dd0781e5 | 485 | |
947fd4dd NB |
486 | .TP |
487 | .BR -N ", " --name= | |
488 | Set a | |
489 | .B name | |
490 | for the array. This is currently only effective when creating an | |
491 | array with a version-1 superblock. The name is a simple textual | |
492 | string that can be used to identify array components when assembling. | |
493 | ||
dd0781e5 NB |
494 | .TP |
495 | .BR -R ", " --run | |
496 | Insist that | |
497 | .I mdadm | |
498 | run the array, even if some of the components | |
499 | appear to be active in another array or filesystem. Normally | |
500 | .I mdadm | |
501 | will ask for confirmation before including such components in an | |
502 | array. This option causes that question to be suppressed. | |
503 | ||
504 | .TP | |
505 | .BR -f ", " --force | |
506 | Insist that | |
507 | .I mdadm | |
508 | accept the geometry and layout specified without question. Normally | |
509 | .I mdadm | |
510 | will not allow creation of an array with only one device, and will try | |
511 | to create a raid5 array with one missing drive (as this makes the | |
512 | initial resync work faster). With | |
513 | .BR --force , | |
514 | .I mdadm | |
515 | will not try to be so clever. | |
516 | ||
517 | .TP | |
518 | .BR -a ", " "--auto{=no,yes,md,mdp,part,p}{NN}" | |
48f7b27a NB |
519 | Instruct mdadm to create the device file if needed, possibly allocating |
520 | an unused minor number. "md" causes a non-partitionable array | |
dd0781e5 | 521 | to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and |
f9c25f1d NB |
522 | later) to be used. "yes" requires the named md device to haveo |
523 | a 'standard' format, and the type and minor number will be determined | |
48f7b27a NB |
524 | from this. See DEVICE NAMES below. |
525 | ||
a9d69660 | 526 | The argument can also come immediately after |
dd0781e5 NB |
527 | "-a". e.g. "-ap". |
528 | ||
1337546d NB |
529 | If |
530 | .I --scan | |
531 | is also given, then any | |
532 | .I auto= | |
533 | entries in the config file will over-ride the | |
534 | .I --auto | |
535 | instruction given on the command line. | |
536 | ||
dd0781e5 NB |
537 | For partitionable arrays, |
538 | .I mdadm | |
539 | will create the device file for the whole array and for the first 4 | |
540 | partitions. A different number of partitions can be specified at the | |
541 | end of this option (e.g. | |
542 | .BR --auto=p7 ). | |
48f7b27a NB |
543 | If the device name ends with a digit, the partition names add a'p', |
544 | and a number, e.g. "/dev/home1p3". If there is no | |
dd0781e5 NB |
545 | trailing digit, then the partition names just have a number added, |
546 | e.g. "/dev/scratch3". | |
547 | ||
48f7b27a NB |
548 | If the md device name is in a 'standard' format as described in DEVICE |
549 | NAMES, then it will be created, if necessary, with the appropriate | |
550 | number based on that name. If the device name is not in one of these | |
a9d69660 | 551 | formats, then a unused minor number will be allocated. The minor |
48f7b27a NB |
552 | number will be considered unused if there is no active array for that |
553 | number, and there is no entry in /dev for that number and with a | |
554 | non-standard name. | |
555 | ||
52826846 NB |
556 | .SH For assemble: |
557 | ||
cd29a5c8 NB |
558 | .TP |
559 | .BR -u ", " --uuid= | |
560 | uuid of array to assemble. Devices which don't have this uuid are | |
561 | excluded | |
562 | ||
563 | .TP | |
564 | .BR -m ", " --super-minor= | |
565 | Minor number of device that array was created for. Devices which | |
566 | don't have this minor number are excluded. If you create an array as | |
2d465520 | 567 | /dev/md1, then all superblocks will contain the minor number 1, even if |
cd29a5c8 NB |
568 | the array is later assembled as /dev/md2. |
569 | ||
d013a55e NB |
570 | Giving the literal word "dev" for |
571 | .B --super-minor | |
572 | will cause | |
573 | .I mdadm | |
574 | to use the minor number of the md device that is being assembled. | |
575 | e.g. when assembling | |
576 | .BR /dev/md0 , | |
577 | .M --super-minor=dev | |
578 | will look for super blocks with a minor number of 0. | |
579 | ||
947fd4dd NB |
580 | .TP |
581 | .BR -N ", " --name= | |
582 | Specify the name of the array to assemble. This must be the name | |
583 | that was specified when creating the array. | |
584 | ||
cd29a5c8 NB |
585 | .TP |
586 | .BR -f ", " --force | |
52826846 NB |
587 | Assemble the array even if some superblocks appear out-of-date |
588 | ||
cd29a5c8 NB |
589 | .TP |
590 | .BR -R ", " --run | |
591 | Attempt to start the array even if fewer drives were given than are | |
592 | needed for a full array. Normally if not all drives are found and | |
593 | .B --scan | |
594 | is not used, then the array will be assembled but not started. | |
595 | With | |
596 | .B --run | |
597 | an attempt will be made to start it anyway. | |
52826846 | 598 | |
dd0781e5 NB |
599 | .TP |
600 | .BR -a ", " "--auto{=no,yes,md,mdp,part}" | |
601 | See this option under Create and Build options. | |
602 | ||
e793c2e5 NB |
603 | .TP |
604 | .BR -b ", " --bitmap= | |
605 | Specify the bitmap file that was given when the array was created. | |
606 | ||
5787fa49 NB |
607 | .TP |
608 | .BR -U ", " --update= | |
609 | Update the superblock on each device while assembling the array. The | |
feb716e9 NB |
610 | argument given to this flag can be one of |
611 | .BR sparc2.2 , | |
612 | .BR summaries , | |
e5329c37 | 613 | .BR resync , |
586ed405 | 614 | .BR byteorder , |
5787fa49 NB |
615 | or |
616 | .BR super-minor . | |
617 | ||
618 | The | |
619 | .B sparc2.2 | |
620 | option will adjust the superblock of an array what was created on a Sparc | |
621 | machine running a patched 2.2 Linux kernel. This kernel got the | |
622 | alignment of part of the superblock wrong. You can use the | |
623 | .B "--examine --sparc2.2" | |
624 | option to | |
625 | .I mdadm | |
626 | to see what effect this would have. | |
627 | ||
628 | The | |
629 | .B super-minor | |
630 | option will update the | |
631 | .B "prefered minor" | |
632 | field on each superblock to match the minor number of the array being | |
feb716e9 | 633 | assembled. This is not needed on 2.6 and later kernels as they make |
5787fa49 NB |
634 | this adjustment automatically. |
635 | ||
e5329c37 NB |
636 | The |
637 | .B resync | |
638 | option will cause the array to be marked | |
639 | .I dirty | |
640 | meaning that any redundancy in the array (e.g. parity for raid5, | |
641 | copies for raid1) may be incorrect. This will cause the raid system | |
642 | to perform a "resync" pass to make sure that all redundant information | |
643 | is correct. | |
644 | ||
586ed405 NB |
645 | The |
646 | .B byteorder | |
647 | option allows arrays to be moved between machines with different | |
648 | byte-order. | |
649 | When assembling such an array for the first time after a move, giving | |
650 | .B "--update=byteorder" | |
651 | will cause | |
652 | .I mdadm | |
653 | to expect superblocks to have their byteorder reversed, and will | |
654 | correct that order before assembling the array. This is only valid | |
655 | with original (Verion 0.90) superblocks. | |
656 | ||
feb716e9 NB |
657 | The |
658 | .B summaries | |
659 | option will correct the summaries in the superblock. That is the | |
660 | counts of total, working, active, failed, and spare devices. | |
5787fa49 | 661 | |
e0d19036 | 662 | .SH For Manage mode: |
52826846 | 663 | |
cd29a5c8 NB |
664 | .TP |
665 | .BR -a ", " --add | |
666 | '''add, or | |
667 | hotadd listed devices. | |
52826846 | 668 | |
fe80f49b NB |
669 | .TP |
670 | .BR --re-add | |
671 | Listed devices are assumed to have recently been part of the array, | |
672 | and they are re-added. This is only different from --add when a | |
673 | write-intent bitmap is present. It causes only those parts of the | |
674 | device that have changed since the device was removed from the array | |
675 | to be reconstructed. | |
676 | ||
677 | This flag is only needed with arrays that are built without a | |
678 | superblock (i.e. --build, not --create). For array with a superblock, | |
679 | .I mdadm | |
680 | checks if a superblock is present and automatically determines if a | |
681 | re-add is appropriate. | |
682 | ||
cd29a5c8 NB |
683 | .TP |
684 | .BR -r ", " --remove | |
2d465520 | 685 | remove listed devices. They must not be active. i.e. they should |
cd29a5c8 | 686 | be failed or spare devices. |
52826846 | 687 | |
cd29a5c8 NB |
688 | .TP |
689 | .BR -f ", " --fail | |
690 | mark listed devices as faulty. | |
52826846 | 691 | |
cd29a5c8 NB |
692 | .TP |
693 | .BR --set-faulty | |
694 | same as --fail. | |
52826846 | 695 | |
5787fa49 NB |
696 | .SH For Examine mode: |
697 | ||
698 | .TP | |
699 | .B --sparc2.2 | |
a9d69660 | 700 | If an array was created on a 2.2 Linux kernel patched with RAID |
5787fa49 NB |
701 | support, the superblock will have been created incorrectly, or at |
702 | least incompatibly with 2.4 and later kernels. Using the | |
703 | .B --sparc2.2 | |
704 | flag with | |
705 | .B --examine | |
706 | will fix the superblock before displaying it. If this appears to do | |
707 | the right thing, then the array can be successfully assembled using | |
708 | .BR "--assemble --update=sparc2.2" . | |
709 | ||
e0d19036 NB |
710 | .SH For Misc mode: |
711 | ||
cd29a5c8 NB |
712 | .TP |
713 | .BR -R ", " --run | |
714 | start a partially built array. | |
52826846 | 715 | |
cd29a5c8 NB |
716 | .TP |
717 | .BR -S ", " --stop | |
718 | deactivate array, releasing all resources. | |
52826846 | 719 | |
cd29a5c8 NB |
720 | .TP |
721 | .BR -o ", " --readonly | |
722 | mark array as readonly. | |
52826846 | 723 | |
cd29a5c8 NB |
724 | .TP |
725 | .BR -w ", " --readwrite | |
726 | mark array as readwrite. | |
52826846 | 727 | |
e0d19036 NB |
728 | .TP |
729 | .B --zero-superblock | |
730 | If the device contains a valid md superblock, the block is | |
731 | over-written with zeros. With | |
732 | --force | |
733 | the block where the superblock would be is over-written even if it | |
734 | doesn't appear to be valid. | |
52826846 | 735 | |
feb716e9 NB |
736 | .TP |
737 | .BR -t ", " --test | |
738 | When used with | |
739 | .BR --detail , | |
740 | the exit status of | |
741 | .I mdadm | |
742 | is set to reflect the status of the device. | |
743 | ||
e0d19036 NB |
744 | .SH For Monitor mode: |
745 | .TP | |
746 | .BR -m ", " --mail | |
747 | Give a mail address to send alerts to. | |
748 | ||
749 | .TP | |
750 | .BR -p ", " --program ", " --alert | |
751 | Give a program to be run whenever an event is detected. | |
752 | ||
753 | .TP | |
754 | .BR -d ", " --delay | |
755 | Give a delay in seconds. | |
756 | .B mdadm | |
757 | polls the md arrays and then waits this many seconds before polling | |
758 | again. The default is 60 seconds. | |
759 | ||
d013a55e NB |
760 | .TP |
761 | .BR -f ", " --daemonise | |
762 | Tell | |
763 | .B mdadm | |
764 | to run as a background daemon if it decides to monitor anything. This | |
765 | causes it to fork and run in the child, and to disconnect form the | |
766 | terminal. The process id of the child is written to stdout. | |
767 | This is useful with | |
768 | .B --scan | |
769 | which will only continue monitoring if a mail address or alert program | |
770 | is found in the config file. | |
771 | ||
b5e64645 NB |
772 | .TP |
773 | .BR -i ", " --pid-file | |
774 | When | |
775 | .B mdadm | |
776 | is running in daemon mode, write the pid of the daemon process to | |
777 | the specified file, instead of printing it on standard output. | |
778 | ||
aa88f531 NB |
779 | .TP |
780 | .BR -1 ", " --oneshot | |
781 | Check arrays only once. This will generate | |
782 | .B NewArray | |
783 | events and more significantly | |
784 | .B DegradedArray | |
a9d69660 NB |
785 | and |
786 | .B SparesMissing | |
aa88f531 NB |
787 | events. Running |
788 | .in +5 | |
789 | .B " mdadm --monitor --scan -1" | |
790 | .in -5 | |
791 | from a cron script will ensure regular notification of any degraded arrays. | |
792 | ||
98c6faba NB |
793 | .TP |
794 | .BR -t ", " --test | |
795 | Generate a | |
796 | .B TestMessage | |
797 | alert for every array found at startup. This alert gets mailed and | |
798 | passed to the alert program. This can be used for testing that alert | |
a9d69660 | 799 | message do get through successfully. |
98c6faba | 800 | |
e0d19036 | 801 | .SH ASSEMBLE MODE |
52826846 | 802 | |
cd29a5c8 NB |
803 | .HP 12 |
804 | Usage: | |
9a9dab36 | 805 | .B mdadm --assemble |
5787fa49 NB |
806 | .I md-device options-and-component-devices... |
807 | .HP 12 | |
808 | Usage: | |
809 | .B mdadm --assemble --scan | |
810 | .I md-devices-and-options... | |
cd29a5c8 NB |
811 | .HP 12 |
812 | Usage: | |
9a9dab36 | 813 | .B mdadm --assemble --scan |
cd29a5c8 | 814 | .I options... |
52826846 | 815 | |
cd29a5c8 | 816 | .PP |
52826846 | 817 | This usage assembles one or more raid arrays from pre-existing components. |
9a9dab36 | 818 | For each array, mdadm needs to know the md device, the identity of the |
e0d19036 | 819 | array, and a number of component-devices. These can be found in a number of ways. |
52826846 | 820 | |
5787fa49 NB |
821 | In the first usage example (without the |
822 | .BR --scan ) | |
823 | the first device given is the md device. | |
824 | In the second usage example, all devices listed are treated as md | |
825 | devices and assembly is attempted. | |
826 | In the third (where no devices are listed) all md devices that are | |
827 | listed in the configuration file are assembled. | |
52826846 | 828 | |
d013a55e NB |
829 | If precisely one device is listed, but |
830 | .B --scan | |
dd0781e5 | 831 | is not given, then |
d013a55e NB |
832 | .I mdadm |
833 | acts as though | |
834 | .B --scan | |
835 | was given and identify information is extracted from the configuration file. | |
836 | ||
cd29a5c8 | 837 | The identity can be given with the |
52826846 | 838 | .B --uuid |
cd29a5c8 NB |
839 | option, with the |
840 | .B --super-minor | |
5787fa49 | 841 | option, can be found in the config file, or will be taken from the |
e0d19036 | 842 | super block on the first component-device listed on the command line. |
52826846 NB |
843 | |
844 | Devices can be given on the | |
845 | .B --assemble | |
5787fa49 NB |
846 | command line or in the config file. Only devices which have an md |
847 | superblock which contains the right identity will be considered for | |
848 | any array. | |
52826846 NB |
849 | |
850 | The config file is only used if explicitly named with | |
851 | .B --config | |
d013a55e | 852 | or requested with (a possibly implicit) |
52826846 NB |
853 | .B --scan. |
854 | In the later case, | |
9a9dab36 | 855 | .B /etc/mdadm.conf |
52826846 NB |
856 | is used. |
857 | ||
858 | If | |
859 | .B --scan | |
cd29a5c8 NB |
860 | is not given, then the config file will only be used to find the |
861 | identity of md arrays. | |
52826846 | 862 | |
2d465520 | 863 | Normally the array will be started after it is assembled. However if |
cd29a5c8 | 864 | .B --scan |
2d465520 | 865 | is not given and insufficient drives were listed to start a complete |
cd29a5c8 NB |
866 | (non-degraded) array, then the array is not started (to guard against |
867 | usage errors). To insist that the array be started in this case (as | |
1a7dfc35 | 868 | may work for RAID1, 4, 5, 6, or 10), give the |
cd29a5c8 NB |
869 | .B --run |
870 | flag. | |
52826846 | 871 | |
dd0781e5 NB |
872 | If an |
873 | .B auto | |
874 | option is given, either on the command line (--auto) or in the | |
875 | configuration file (e.g. auto=part), then | |
876 | .I mdadm | |
877 | will create the md device if necessary or will re-create it if it | |
878 | doesn't look usable as it is. | |
879 | ||
880 | This can be useful for handling partitioned devices (which don't have | |
881 | a stable device number - it can change after a reboot) and when using | |
882 | "udev" to manage your | |
883 | .B /dev | |
884 | tree (udev cannot handle md devices because of the unusual device | |
885 | initialisation conventions). | |
886 | ||
887 | If the option to "auto" is "mdp" or "part" or (on the command line | |
888 | only) "p", then mdadm will create a partitionable array, using the | |
889 | first free one that is not inuse, and does not already have an entry | |
890 | in /dev (apart from numeric /dev/md* entries). | |
891 | ||
892 | If the option to "auto" is "yes" or "md" or (on the command line) | |
893 | nothing, then mdadm will create a traditional, non-partitionable md | |
894 | array. | |
895 | ||
896 | It is expected that the "auto" functionality will be used to create | |
897 | device entries with meaningful names such as "/dev/md/home" or | |
898 | "/dev/md/root", rather than names based on the numerical array number. | |
899 | ||
900 | When using this option to create a partitionable array, the device | |
901 | files for the first 4 partitions are also created. If a different | |
902 | number is required it can be simply appended to the auto option. | |
903 | e.g. "auto=part8". Partition names are created by appending a digit | |
a9d69660 | 904 | string to the device name, with an intervening "p" if the device name |
dd0781e5 NB |
905 | ends with a digit. |
906 | ||
907 | The | |
908 | .B --auto | |
909 | option is also available in Build and Create modes. As those modes do | |
910 | not use a config file, the "auto=" config option does not apply to | |
911 | these modes. | |
52826846 | 912 | |
cd29a5c8 | 913 | .SH BUILD MODE |
52826846 | 914 | |
cd29a5c8 NB |
915 | .HP 12 |
916 | Usage: | |
9a9dab36 | 917 | .B mdadm --build |
cd29a5c8 NB |
918 | .I device |
919 | .BI --chunk= X | |
920 | .BI --level= Y | |
b83d95f3 | 921 | .BI --raid-devices= Z |
cd29a5c8 NB |
922 | .I devices |
923 | ||
924 | .PP | |
52826846 | 925 | This usage is similar to |
cd29a5c8 | 926 | .BR --create . |
a9d69660 | 927 | The difference is that it creates an array without a superblock. With |
cd29a5c8 | 928 | these arrays there is no difference between initially creating the array and |
52826846 NB |
929 | subsequently assembling the array, except that hopefully there is useful |
930 | data there in the second case. | |
931 | ||
a9d69660 NB |
932 | The level may raid0, linear, multipath, or faulty, or one of their |
933 | synonyms. All devices must be listed and the array will be started | |
934 | once complete. | |
cd29a5c8 NB |
935 | |
936 | .SH CREATE MODE | |
937 | ||
938 | .HP 12 | |
939 | Usage: | |
9a9dab36 | 940 | .B mdadm --create |
cd29a5c8 NB |
941 | .I device |
942 | .BI --chunk= X | |
943 | .BI --level= Y | |
944 | .br | |
b83d95f3 | 945 | .BI --raid-devices= Z |
cd29a5c8 NB |
946 | .I devices |
947 | ||
948 | .PP | |
949 | This usage will initialise a new md array, associate some devices with | |
950 | it, and activate the array. | |
951 | ||
a9d69660 | 952 | If the |
dd0781e5 NB |
953 | .B --auto |
954 | option is given (as described in more detail in the section on | |
955 | Assemble mode), then the md device will be created with a suitable | |
956 | device number if necessary. | |
957 | ||
cd29a5c8 | 958 | As devices are added, they are checked to see if they contain raid |
2d465520 | 959 | superblocks or filesystems. They are also checked to see if the variance in |
cd29a5c8 NB |
960 | device size exceeds 1%. |
961 | ||
962 | If any discrepancy is found, the array will not automatically be run, though | |
963 | the presence of a | |
964 | .B --run | |
965 | can override this caution. | |
966 | ||
2d465520 | 967 | To create a "degraded" array in which some devices are missing, simply |
d013a55e | 968 | give the word "\fBmissing\fP" |
2d465520 NB |
969 | in place of a device name. This will cause |
970 | .B mdadm | |
971 | to leave the corresponding slot in the array empty. | |
972 | For a RAID4 or RAID5 array at most one slot can be | |
98c6faba | 973 | "\fBmissing\fP"; for a RAID6 array at most two slots. |
2d465520 NB |
974 | For a RAID1 array, only one real device needs to be given. All of the |
975 | others can be | |
d013a55e | 976 | "\fBmissing\fP". |
2d465520 | 977 | |
feb716e9 NB |
978 | When creating a RAID5 array, |
979 | .B mdadm | |
980 | will automatically create a degraded array with an extra spare drive. | |
981 | This is because building the spare into a degraded array is in general faster than resyncing | |
982 | the parity on a non-degraded, but not clean, array. This feature can | |
983 | be over-ridden with the | |
b5e64645 | 984 | .I --force |
feb716e9 NB |
985 | option. |
986 | ||
cd29a5c8 NB |
987 | '''If the |
988 | '''.B --size | |
e0d19036 | 989 | '''option is given, it is not necessary to list any component-devices in this command. |
cd29a5c8 NB |
990 | '''They can be added later, before a |
991 | '''.B --run. | |
992 | '''If no | |
993 | '''.B --size | |
994 | '''is given, the apparent size of the smallest drive given is used. | |
995 | ||
996 | The General Management options that are valid with --create are: | |
997 | .TP | |
998 | .B --run | |
dd0781e5 | 999 | insist on running the array even if some devices look like they might |
cd29a5c8 NB |
1000 | be in use. |
1001 | ||
1002 | .TP | |
1003 | .B --readonly | |
1004 | start the array readonly - not supported yet. | |
52826846 | 1005 | |
e0d19036 | 1006 | .SH MANAGE MODE |
cd29a5c8 NB |
1007 | .HP 12 |
1008 | Usage: | |
e0d19036 NB |
1009 | .B mdadm |
1010 | .I device | |
1011 | .I options... devices... | |
cd29a5c8 NB |
1012 | .PP |
1013 | ||
e0d19036 NB |
1014 | This usage will allow individual devices in an array to be failed, |
1015 | removed or added. It is possible to perform multiple operations with | |
1016 | on command. For example: | |
1017 | .br | |
5787fa49 | 1018 | .B " mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1" |
e0d19036 NB |
1019 | .br |
1020 | will firstly mark | |
1021 | .B /dev/hda1 | |
1022 | as faulty in | |
1023 | .B /dev/md0 | |
1024 | and will then remove it from the array and finally add it back | |
2d465520 | 1025 | in as a spare. However only one md array can be affected by a single |
e0d19036 NB |
1026 | command. |
1027 | ||
1028 | .SH MISC MODE | |
1029 | .HP 12 | |
1030 | Usage: | |
9a9dab36 | 1031 | .B mdadm |
e0d19036 NB |
1032 | .I options ... |
1033 | .I devices ... | |
1034 | .PP | |
cd29a5c8 | 1035 | |
b5e64645 | 1036 | MISC mode includes a number of distinct operations that |
e0d19036 NB |
1037 | operate on distinct devices. The operations are: |
1038 | .TP | |
1039 | --query | |
1040 | The device is examined to see if it is | |
1041 | (1) an active md array, or | |
1042 | (2) a component of an md array. | |
1043 | The information discovered is reported. | |
1044 | ||
1045 | .TP | |
1046 | --detail | |
2d465520 NB |
1047 | The device should be an active md device. |
1048 | .B mdadm | |
1049 | will display a detailed description of the array. | |
cd29a5c8 | 1050 | .B --brief |
2d465520 NB |
1051 | or |
1052 | .B --scan | |
1053 | will cause the output to be less detailed and the format to be | |
e0d19036 | 1054 | suitable for inclusion in |
9a9dab36 | 1055 | .BR /etc/mdadm.conf . |
feb716e9 NB |
1056 | The exit status of |
1057 | .I mdadm | |
1058 | will normally be 0 unless | |
1059 | .I mdadm | |
1060 | failed to get useful information about the device(s). However if the | |
1061 | .B --test | |
1062 | option is given, then the exit status will be: | |
1063 | .RS | |
1064 | .TP | |
1065 | 0 | |
1066 | The array is functioning normally. | |
1067 | .TP | |
1068 | 1 | |
1069 | The array has at least one failed device. | |
1070 | .TP | |
1071 | 2 | |
1072 | The array has multiple failed devices and hence is unusable (raid4 or | |
1073 | raid5). | |
1074 | .TP | |
1075 | 4 | |
1076 | There was an error while trying to get information about the device. | |
1077 | .RE | |
cd29a5c8 | 1078 | |
e0d19036 NB |
1079 | .TP |
1080 | --examine | |
2d465520 NB |
1081 | The device should be a component of an md array. |
1082 | .B mdadm | |
1083 | will read the md superblock of the device and display the contents. | |
e0d19036 NB |
1084 | If |
1085 | .B --brief | |
1086 | is given, or | |
1087 | .B --scan | |
1088 | then multiple devices that are components of the one array | |
1089 | are grouped together and reported in a single entry suitable | |
1090 | for inclusion in | |
1091 | .BR /etc/mdadm.conf . | |
1092 | ||
2d465520 | 1093 | Having |
e0d19036 NB |
1094 | .B --scan |
1095 | without listing any devices will cause all devices listed in the | |
1096 | config file to be examined. | |
1097 | ||
1098 | .TP | |
1099 | --stop | |
98c6faba NB |
1100 | The devices should be active md arrays which will be deactivated, as |
1101 | long as they are not currently in use. | |
e0d19036 NB |
1102 | |
1103 | .TP | |
1104 | --run | |
1105 | This will fully activate a partially assembled md array. | |
1106 | ||
1107 | .TP | |
1108 | --readonly | |
1109 | This will mark an active array as read-only, providing that it is | |
1110 | not currently being used. | |
1111 | ||
1112 | .TP | |
1113 | --readwrite | |
1114 | This will change a | |
1115 | .B readonly | |
1116 | array back to being read/write. | |
1117 | ||
2d465520 NB |
1118 | .TP |
1119 | --scan | |
1120 | For all operations except | |
1121 | .BR --examine , | |
1122 | .B --scan | |
1123 | will cause the operation to be applied to all arrays listed in | |
1124 | .BR /proc/mdstat . | |
1125 | For | |
1126 | .BR --examine, | |
1127 | .B --scan | |
1128 | causes all devices listed in the config file to be examined. | |
1129 | ||
1130 | ||
e0d19036 NB |
1131 | .SH MONITOR MODE |
1132 | ||
cd29a5c8 NB |
1133 | .HP 12 |
1134 | Usage: | |
e0d19036 NB |
1135 | .B mdadm --monitor |
1136 | .I options... devices... | |
1137 | ||
cd29a5c8 | 1138 | .PP |
e0d19036 NB |
1139 | This usage causes |
1140 | .B mdadm | |
1141 | to periodically poll a number of md arrays and to report on any events | |
1142 | noticed. | |
1143 | .B mdadm | |
1144 | will never exit once it decides that there are arrays to be checked, | |
1145 | so it should normally be run in the background. | |
1146 | ||
2d465520 NB |
1147 | As well as reporting events, |
1148 | .B mdadm | |
1149 | may move a spare drive from one array to another if they are in the | |
1150 | same | |
1151 | .B spare-group | |
a9d69660 | 1152 | and if the destination array has a failed drive but no spares. |
2d465520 | 1153 | |
e0d19036 NB |
1154 | If any devices are listed on the command line, |
1155 | .B mdadm | |
1156 | will only monitor those devices. Otherwise all arrays listed in the | |
1157 | configuration file will be monitored. Further, if | |
1158 | .B --scan | |
1159 | is given, then any other md devices that appear in | |
1160 | .B /proc/mdstat | |
1161 | will also be monitored. | |
1162 | ||
1163 | The result of monitoring the arrays is the generation of events. | |
bd526cee | 1164 | These events are passed to a separate program (if specified) and may |
2d465520 | 1165 | be mailed to a given E-mail address. |
e0d19036 | 1166 | |
bd526cee NB |
1167 | When passing event to program, the program is run once for each event |
1168 | and is given 2 or 3 command-line arguements. The first is the | |
1169 | name of the event (see below). The second is the name of the | |
1170 | md device which is affected, and the third is the name of a related | |
1171 | device if relevant, such as a component device that has failed. | |
cd29a5c8 NB |
1172 | |
1173 | If | |
1174 | .B --scan | |
e0d19036 NB |
1175 | is given, then a program or an E-mail address must be specified on the |
1176 | command line or in the config file. If neither are available, then | |
1177 | .B mdadm | |
1178 | will not monitor anything. | |
1179 | Without | |
cd29a5c8 | 1180 | .B --scan |
e0d19036 | 1181 | .B mdadm |
2d465520 | 1182 | will continue monitoring as long as something was found to monitor. If |
e0d19036 NB |
1183 | no program or email is given, then each event is reported to |
1184 | .BR stdout . | |
cd29a5c8 | 1185 | |
e0d19036 NB |
1186 | The different events are: |
1187 | ||
1188 | .RS 4 | |
1189 | .TP | |
1190 | .B DeviceDisappeared | |
2d465520 | 1191 | An md array which previously was configured appears to no longer be |
e0d19036 NB |
1192 | configured. |
1193 | ||
b8f72a62 NB |
1194 | If |
1195 | .I mdadm | |
1196 | was told to monitor an array which is RAID0 or Linear, then it will | |
1197 | report | |
1198 | .B DeviceDisappeared | |
1199 | with the extra information | |
1200 | .BR Wrong-Level . | |
1201 | This is because RAID0 and Linear do not support the device-failed, | |
1202 | hot-spare and resync operations which are monitored. | |
1203 | ||
e0d19036 NB |
1204 | .TP |
1205 | .B RebuildStarted | |
1206 | An md array started reconstruction. | |
1207 | ||
1208 | .TP | |
1209 | .BI Rebuild NN | |
1210 | Where | |
1211 | .I NN | |
1212 | is 20, 40, 60, or 80, this indicates that rebuild has passed that many | |
1213 | percentage of the total. | |
1214 | ||
98c6faba NB |
1215 | .TP |
1216 | .B RebuildFinished | |
1217 | An md array that was rebuilding, isn't any more, either because it | |
1218 | finished normally or was aborted. | |
1219 | ||
e0d19036 NB |
1220 | .TP |
1221 | .B Fail | |
1222 | An active component device of an array has been marked as faulty. | |
1223 | ||
1224 | .TP | |
1225 | .B FailSpare | |
1226 | A spare component device which was being rebuilt to replace a faulty | |
1227 | device has failed. | |
1228 | ||
1229 | .TP | |
1230 | .B SpareActive | |
1231 | A spare component device which was being rebuilt to replace a faulty | |
1232 | device as been successfully rebuild and has been made active. | |
1233 | ||
1234 | .TP | |
1235 | .B NewArray | |
1236 | A new md array has been detected in the | |
1237 | .B /proc/mdstat | |
1238 | file. | |
1239 | ||
aa88f531 NB |
1240 | .TP |
1241 | .B DegradedArray | |
1242 | A newly noticed array appears to be degraded. This message is not | |
1243 | generated when | |
1244 | .I mdadm | |
1245 | notices a drive failure which causes degradation, but only when | |
1246 | .I mdadm | |
1247 | notices that an array is degraded when it first sees the array. | |
1248 | ||
e0d19036 NB |
1249 | .TP |
1250 | .B MoveSpare | |
1251 | A spare drive has been moved from one array in a | |
1252 | .B spare-group | |
1253 | to another to allow a failed drive to be replaced. | |
1254 | ||
b8f72a62 NB |
1255 | .TP |
1256 | .B SparesMissing | |
1257 | If | |
1258 | .I mdadm | |
1259 | has been told, via the config file, that an array should have a certain | |
1260 | number of spare devices, and | |
1261 | .I mdadm | |
1262 | detects that it has fewer that this number when it first sees the | |
1263 | array, it will report a | |
1264 | .B SparesMissing | |
1265 | message. | |
1266 | ||
98c6faba NB |
1267 | .TP |
1268 | .B TestMessage | |
1269 | An array was found at startup, and the | |
1270 | .B --test | |
1271 | flag was given. | |
e0d19036 NB |
1272 | .RE |
1273 | ||
1274 | Only | |
98c6faba NB |
1275 | .B Fail , |
1276 | .B FailSpare , | |
1277 | .B DegradedArray , | |
e0d19036 | 1278 | and |
98c6faba | 1279 | .B TestMessage |
e0d19036 NB |
1280 | cause Email to be sent. All events cause the program to be run. |
1281 | The program is run with two or three arguments, they being the event | |
1282 | name, the array device and possibly a second device. | |
1283 | ||
1284 | Each event has an associated array device (e.g. | |
1285 | .BR /dev/md1 ) | |
1286 | and possibly a second device. For | |
1287 | .BR Fail , | |
1288 | .BR FailSpare , | |
1289 | and | |
1290 | .B SpareActive | |
1291 | the second device is the relevant component device. | |
1292 | For | |
1293 | .B MoveSpare | |
1294 | the second device is the array that the spare was moved from. | |
1295 | ||
1296 | For | |
1297 | .B mdadm | |
1298 | to move spares from one array to another, the different arrays need to | |
1299 | be labelled with the same | |
1300 | .B spare-group | |
1301 | in the configuration file. The | |
1302 | .B spare-group | |
1303 | name can be any string. It is only necessary that different spare | |
2d465520 | 1304 | groups use different names. |
e0d19036 NB |
1305 | |
1306 | When | |
9a9dab36 | 1307 | .B mdadm |
e0d19036 NB |
1308 | detects that an array which is in a spare group has fewer active |
1309 | devices than necessary for the complete array, and has no spare | |
1310 | devices, it will look for another array in the same spare group that | |
1311 | has a full complement of working drive and a spare. It will then | |
1312 | attempt to remove the spare from the second drive and add it to the | |
1313 | first. | |
1314 | If the removal succeeds but the adding fails, then it is added back to | |
1315 | the original array. | |
1316 | ||
dd0781e5 NB |
1317 | .SH GROW MODE |
1318 | The GROW mode is used for changing the size or shape of an active | |
1319 | array. | |
1320 | For this to work, the kernel must support the necessary change. | |
1321 | Various types of growth may be added during 2.6 development, possibly | |
1322 | including restructuring a raid5 array to have more active devices. | |
1323 | ||
dfd4d8ee NB |
1324 | Currently the only support available is to |
1325 | .IP \(bu 4 | |
1326 | change the "size" attribute | |
1327 | for RAID1, RAID5 and RAID6. | |
1328 | .IP \(bu 4 | |
1329 | change the "raid-disks" attribute of RAID1. | |
1330 | .IP \(bu 4 | |
1331 | add a write-intent bitmap to a RAID1 array. | |
1332 | .PP | |
dd0781e5 | 1333 | |
fe80f49b | 1334 | Normally when an array is built the "size" it taken from the smallest |
dd0781e5 NB |
1335 | of the drives. If all the small drives in an arrays are, one at a |
1336 | time, removed and replaced with larger drives, then you could have an | |
1337 | array of large drives with only a small amount used. In this | |
1338 | situation, changing the "size" with "GROW" mode will allow the extra | |
1339 | space to start being used. If the size is increased in this way, a | |
1340 | "resync" process will start to make sure the new parts of the array | |
1341 | are synchronised. | |
1342 | ||
1343 | Note that when an array changes size, any filesystem that may be | |
1344 | stored in the array will not automatically grow to use the space. The | |
1345 | filesystem will need to be explicitly told to use the extra space. | |
1346 | ||
1347 | A RAID1 array can work with any number of devices from 1 upwards | |
1348 | (though 1 is not very useful). There may be times which you want to | |
1349 | increase or decrease the number of active devices. Note that this is | |
1350 | different to hot-add or hot-remove which changes the number of | |
1351 | inactive devices. | |
1352 | ||
1353 | When reducing the number of devices in a RAID1 array, the slots which | |
1354 | are to be removed from the array must already be vacant. That is, the | |
1355 | devices that which were in those slots must be failed and removed. | |
1356 | ||
1357 | When the number of devices is increased, any hot spares that are | |
a9d69660 | 1358 | present will be activated immediately. |
dd0781e5 | 1359 | |
fe80f49b NB |
1360 | A write-intent bitmap can be added to, or remove from, an active RAID1 |
1361 | array. Either internal bitmap, of bitmaps stored in a separate file | |
1362 | can be added. Note that if you add a bitmap stored in a file which is | |
1363 | in a filesystem that is on the raid array being affected, the system | |
1364 | will deadlock. The bitmap must be on a separate filesystem. | |
1365 | ||
2d465520 NB |
1366 | .SH EXAMPLES |
1367 | ||
5787fa49 | 1368 | .B " mdadm --query /dev/name-of-device" |
2d465520 | 1369 | .br |
5787fa49 NB |
1370 | This will find out if a given device is a raid array, or is part of |
1371 | one, and will provide brief information about the device. | |
2d465520 | 1372 | |
5787fa49 | 1373 | .B " mdadm --assemble --scan" |
2d465520 | 1374 | .br |
5787fa49 NB |
1375 | This will assemble and start all arrays listed in the standard confile |
1376 | file. This command will typically go in a system startup file. | |
2d465520 | 1377 | |
2d465520 | 1378 | .B " mdadm --stop --scan" |
5787fa49 NB |
1379 | .br |
1380 | This will shut down all array that can be shut down (i.e. are not | |
19f8b8fc | 1381 | currently in use). This will typically go in a system shutdown script. |
2d465520 | 1382 | |
5787fa49 | 1383 | .B " mdadm --follow --scan --delay=120" |
2d465520 | 1384 | .br |
5787fa49 NB |
1385 | If (and only if) there is an Email address or program given in the |
1386 | standard config file, then | |
1387 | monitor the status of all arrays listed in that file by | |
1388 | polling them ever 2 minutes. | |
2d465520 | 1389 | |
5787fa49 | 1390 | .B " mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/hd[ac]1" |
2d465520 | 1391 | .br |
5787fa49 | 1392 | Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1. |
2d465520 | 1393 | |
2d465520 NB |
1394 | .br |
1395 | .B " echo 'DEVICE /dev/hd*[0-9] /dev/sd*[0-9]' > mdadm.conf" | |
1396 | .br | |
1397 | .B " mdadm --detail --scan >> mdadm.conf" | |
1398 | .br | |
5787fa49 NB |
1399 | This will create a prototype config file that describes currently |
1400 | active arrays that are known to be made from partitions of IDE or SCSI drives. | |
2d465520 NB |
1401 | This file should be reviewed before being used as it may |
1402 | contain unwanted detail. | |
1403 | ||
2d465520 NB |
1404 | .B " echo 'DEVICE /dev/hd[a-z] /dev/sd*[a-z]' > mdadm.conf" |
1405 | .br | |
5787fa49 NB |
1406 | .B " mdadm --examine --scan --config=mdadm.conf >> mdadm.conf" |
1407 | .ber | |
1408 | This will find what arrays could be assembled from existign IDE and | |
1409 | SCSI whole drives (not partitions) and store the information is the | |
1410 | format of a config file. | |
2d465520 NB |
1411 | This file is very likely to contain unwanted detail, particularly |
1412 | the | |
1413 | .B devices= | |
5787fa49 NB |
1414 | entries. It should be reviewed and edited before being used as an |
1415 | actual config file. | |
2d465520 | 1416 | |
5787fa49 | 1417 | .B " mdadm --examine --brief --scan --config=partitions" |
2d465520 | 1418 | .br |
5787fa49 NB |
1419 | .B " mdadm -Ebsc partitions" |
1420 | .br | |
1421 | Create a list of devices by reading | |
1422 | .BR /proc/partitions , | |
1423 | scan these for RAID superblocks, and printout a brief listing of all | |
1424 | that was found. | |
2d465520 | 1425 | |
5787fa49 | 1426 | .B " mdadm -Ac partitions -m 0 /dev/md0" |
2d465520 | 1427 | .br |
5787fa49 NB |
1428 | Scan all partitions and devices listed in |
1429 | .BR /proc/partitions | |
1430 | and assemble | |
1431 | .B /dev/md0 | |
1432 | out of all such devices with a RAID superblock with a minor number of 0. | |
2d465520 | 1433 | |
d013a55e NB |
1434 | .B " mdadm --monitor --scan --daemonise > /var/run/mdadm" |
1435 | .br | |
1436 | If config file contains a mail address or alert program, run mdadm in | |
1437 | the background in monitor mode monitoring all md devices. Also write | |
1438 | pid of mdadm daemon to | |
1439 | .BR /var/run/mdadm . | |
1440 | ||
5787fa49 | 1441 | .B " mdadm --create --help" |
2d465520 | 1442 | .br |
5787fa49 | 1443 | Providew help about the Create mode. |
2d465520 | 1444 | |
5787fa49 NB |
1445 | .B " mdadm --config --help" |
1446 | .br | |
1447 | Provide help about the format of the config file. | |
2d465520 | 1448 | |
5787fa49 NB |
1449 | .B " mdadm --help" |
1450 | .br | |
1451 | Provide general help. | |
cd29a5c8 | 1452 | |
cd29a5c8 NB |
1453 | |
1454 | .SH FILES | |
1455 | ||
1456 | .SS /proc/mdstat | |
1457 | ||
1458 | If you're using the | |
1459 | .B /proc | |
1460 | filesystem, | |
1461 | .B /proc/mdstat | |
2d465520 NB |
1462 | lists all active md devices with information about them. |
1463 | .B mdadm | |
1464 | uses this to find arrays when | |
1465 | .B --scan | |
1466 | is given in Misc mode, and to monitor array reconstruction | |
1467 | on Monitor mode. | |
1468 | ||
cd29a5c8 | 1469 | |
9a9dab36 | 1470 | .SS /etc/mdadm.conf |
cd29a5c8 | 1471 | |
11a3e71d NB |
1472 | The config file lists which devices may be scanned to see if |
1473 | they contain MD super block, and gives identifying information | |
1474 | (e.g. UUID) about known MD arrays. See | |
1475 | .BR mdadm.conf (5) | |
1476 | for more details. | |
cd29a5c8 | 1477 | |
48f7b27a NB |
1478 | .SH DEVICE NAMES |
1479 | ||
1480 | While entries in the /dev directory can have any format you like, | |
1481 | .I mdadm | |
1482 | has an understanding of 'standard' formats which it uses to guide its | |
1483 | behaviour when creating device files via the | |
1484 | .I --auto | |
1485 | option. | |
1486 | ||
1487 | The standard names for non-partitioned arrays (the only sort of md | |
1488 | array available in 2.4 and earlier) either of | |
1489 | .IP | |
1490 | /dev/mdNN | |
1491 | .br | |
1492 | /dev/md/NN | |
1493 | .PP | |
1494 | where NN is a number. | |
1495 | The standard names for partitionable arrays (as available from 2.6 | |
1496 | onwards) is one of | |
1497 | .IP | |
1498 | /dev/md/dNN | |
1499 | .br | |
1500 | /dev/md_dNN | |
1501 | .PP | |
1502 | Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2". | |
52826846 | 1503 | |
2d465520 NB |
1504 | .SH NOTE |
1505 | .B mdadm | |
1506 | was previously known as | |
1507 | .BR mdctl . | |
a9d69660 NB |
1508 | .P |
1509 | .B mdadm | |
1510 | is completely separate from the | |
1511 | .B raidtools | |
1512 | package, and does not use the | |
1513 | .I /etc/raidtab | |
1514 | configuration file at all. | |
1515 | ||
52826846 | 1516 | .SH SEE ALSO |
cd29a5c8 NB |
1517 | For information on the various levels of |
1518 | RAID, check out: | |
1519 | ||
1520 | .IP | |
1521 | .UR http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/ | |
1522 | http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/ | |
1523 | .UE | |
a9d69660 NB |
1524 | '''.PP |
1525 | '''for new releases of the RAID driver check out: | |
1526 | ''' | |
1527 | '''.IP | |
1528 | '''.UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
1529 | '''ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches | |
1530 | '''.UE | |
1531 | '''.PP | |
1532 | '''or | |
1533 | '''.IP | |
1534 | '''.UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
1535 | '''http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/ | |
1536 | '''.UE | |
cd29a5c8 | 1537 | .PP |
a9d69660 NB |
1538 | The lastest version of |
1539 | .I mdadm | |
1540 | should always be available from | |
cd29a5c8 | 1541 | .IP |
a9d69660 NB |
1542 | .UR http://www.kernel.org/pub/linux/utils/raid/mdadm/ |
1543 | http://www.kernel.org/pub/linux/utils/raid/mdadm/ | |
cd29a5c8 NB |
1544 | .UE |
1545 | .PP | |
a9d69660 NB |
1546 | .IR mdadm.conf (5), |
1547 | .IR md (4). | |
56eb10c0 | 1548 | .PP |
52826846 NB |
1549 | .IR raidtab (5), |
1550 | .IR raid0run (8), | |
1551 | .IR raidstop (8), | |
a9d69660 | 1552 | .IR mkraid (8). |