2 .\" Copyright Neil Brown and others.
3 .\" This program is free software; you can redistribute it and/or modify
4 .\" it under the terms of the GNU General Public License as published by
5 .\" the Free Software Foundation; either version 2 of the License, or
6 .\" (at your option) any later version.
7 .\" See file COPYING in distribution for details.
8 .TH MDADM 8 "" v3.0-devel2
10 mdadm \- manage MD devices
16 .BI mdadm " [mode] <raiddevice> [options] <component-devices>"
19 RAID devices are virtual devices created from two or more
20 real block devices. This allows multiple devices (typically disk
21 drives or partitions thereof) to be combined into a single device to
22 hold (for example) a single filesystem.
23 Some RAID levels include redundancy and so can survive some degree of
26 Linux Software RAID devices are implemented through the md (Multiple
27 Devices) device driver.
29 Currently, Linux supports
46 is not a Software RAID mechanism, but does involve
48 each device is a path to one common physical storage device.
51 is also not true RAID, and it only involves one device. It
52 provides a layer over a true device that can be used to inject faults.
57 is a collection of devices that are
58 managed as a set. This is similar to the set of devices connected to
59 a hardware RAID controller. The set of devices may contain a number
60 of different RAID arrays each utilising some (or all) blocks from a
61 number of the devices in the set. For example, two devices in a 5-device set
62 might form a RAID1 used the whole devices. The remaining three might
63 have a RAID5 over the first half of each device, and a RAID0 over the
68 there is one set of metadata that describes all of
69 the arrays in the container. So when
73 device, it just represents the metadata. Other normal arrays (RAID1
74 etc) can be created inside that container.
78 .\"is a program that can be used to create, manage, and monitor
80 .\"such it provides a similar set of functionality to the
83 .\"The key differences between
90 .\"is a single program and not a collection of programs.
93 .\"can perform (almost) all of its functions without having a
94 .\"configuration file and does not use one by default. Also
96 .\"helps with management of the configuration
100 .\"can provide information about your arrays (through Query, Detail, and Examine)
107 .\".IR /etc/raidtab ,
110 .\"configuration file, at all. It has a different configuration file
111 .\"with a different format and a different purpose.
114 mdadm has several major modes of operation:
117 Assemble the components of a previously created
118 array into an active array. Components can be explicitly given
119 or can be searched for.
121 checks that the components
122 do form a bona fide array, and can, on request, fiddle superblock
123 information so as to assemble a faulty array.
127 Build an array that doesn't have per-device superblocks. For these
130 cannot differentiate between initial creation and subsequent assembly
131 of an array. It also cannot perform any checks that appropriate
132 components have been requested. Because of this, the
134 mode should only be used together with a complete understanding of
139 Create a new array with per-device superblocks.
141 .\"in several step create-add-add-run or it can all happen with one command.
144 .B "Follow or Monitor"
145 Monitor one or more md devices and act on any state changes. This is
146 only meaningful for raid1, 4, 5, 6, 10 or multipath arrays, as
147 only these have interesting state. raid0 or linear never have
148 missing, spare, or failed drives, so there is nothing to monitor.
152 Grow (or shrink) an array, or otherwise reshape it in some way.
153 Currently supported growth options including changing the active size
154 of component devices and changing the number of active devices in RAID
155 levels 1/4/5/6, as well as adding or removing a write-intent bitmap.
158 .B "Incremental Assembly"
159 Add a single device to an appropriate array. If the addition of the
160 device makes the array runnable, the array will be started.
161 This provides a convenient interface to a
163 system. As each device is detected,
165 has a chance to include it in some array as appropriate.
171 in this mode, then any arrays within that container will be assembled
176 This is for doing things to specific components of an array such as
177 adding new spares and removing faulty devices.
181 This is an 'everything else' mode that supports operations on active
182 arrays, operations on component devices such as erasing old superblocks, and
183 information gathering operations.
184 .\"This mode allows operations on independent devices such as examine MD
185 .\"superblocks, erasing old superblocks and stopping active arrays.
189 This mode does not act on a specific device or array, but rather it
190 requests the Linux Kernel to activate any auto-detected arrays.
193 .SH Options for selecting a mode are:
196 .BR \-A ", " \-\-assemble
197 Assemble a pre-existing array.
200 .BR \-B ", " \-\-build
201 Build a legacy array without superblocks.
204 .BR \-C ", " \-\-create
208 .BR \-F ", " \-\-follow ", " \-\-monitor
214 .BR \-G ", " \-\-grow
215 Change the size or shape of an active array.
218 .BR \-I ", " \-\-incremental
219 Add a single device into an appropriate array, and possibly start the array.
223 Request that the kernel starts any auto-detected arrays. This can only
226 is compiled into the kernel \(em not if it is a module.
227 Arrays can be auto-detected by the kernel if all the components are in
228 primary MS-DOS partitions with partition type
230 In-kernel autodetect is not recommended for new installations. Using
232 to detect and assemble arrays \(em possibly in an
234 \(em is substantially more flexible and should be preferred.
237 If a device is given before any options, or if the first option is
242 then the MANAGE mode is assume.
243 Anything other than these will cause the
247 .SH Options that are not mode-specific are:
250 .BR \-h ", " \-\-help
251 Display general help message or, after one of the above options, a
252 mode-specific help message.
256 Display more detailed help about command line parsing and some commonly
260 .BR \-V ", " \-\-version
261 Print version information for mdadm.
264 .BR \-v ", " \-\-verbose
265 Be more verbose about what is happening. This can be used twice to be
267 The extra verbosity currently only affects
268 .B \-\-detail \-\-scan
270 .BR "\-\-examine \-\-scan" .
273 .BR \-q ", " \-\-quiet
274 Avoid printing purely informative messages. With this,
276 will be silent unless there is something really important to report.
279 .BR \-b ", " \-\-brief
280 Be less verbose. This is used with
288 gives an intermediate level of verbosity.
291 .BR \-f ", " \-\-force
292 Be more forceful about certain operations. See the various modes for
293 the exact meaning of this option in different contexts.
296 .BR \-c ", " \-\-config=
297 Specify the config file. Default is to use
298 .BR /etc/mdadm.conf ,
299 or if that is missing then
300 .BR /etc/mdadm/mdadm.conf .
301 If the config file given is
303 then nothing will be read, but
305 will act as though the config file contained exactly
306 .B "DEVICE partitions containers"
309 to find a list of devices to scan, and
311 to find a list of containers to examine.
314 is given for the config file, then
316 will act as though the config file were empty.
319 .BR \-s ", " \-\-scan
322 for missing information.
323 In general, this option gives
325 permission to get any missing information (like component devices,
326 array devices, array identities, and alert destination) from the
327 configuration file (see previous option);
328 one exception is MISC mode when using
334 says to get a list of array devices from
338 .B \-e ", " \-\-metadata=
339 Declare the style of superblock (raid metadata) to be used. The
342 and to guess for other operations.
343 The default can be overridden by setting the
352 .IP "0, 0.90, default"
353 Use the original 0.90 format superblock. This format limits arrays to
354 28 component devices and limits component devices of levels 1 and
355 greater to 2 terabytes.
356 .IP "1, 1.0, 1.1, 1.2"
357 Use the new version-1 format superblock. This has few restrictions.
358 The different sub-versions store the superblock at different locations
359 on the device, either at the end (for 1.0), at the start (for 1.1) or
360 4K from the start (for 1.2).
362 Use the "Industry Standard" DDF (Disk Data Format) format. When
363 creating a DDF array a
365 will be created, and normal arrays can be created in that container.
367 Use the Intel(R) Matrix Storage Manager metadata format. This creates a
369 which is managed in a similar manner to DDF, and is supported by an
370 option-rom on some platforms:
372 .B http://www.intel.com/design/chipsets/matrixstorage_sb.htm
378 This will override any
380 setting in the config file and provides the identity of the host which
381 should be considered the home for any arrays.
383 When creating an array, the
385 will be recorded in the superblock. For version-1 superblocks, it will
386 be prefixed to the array name. For version-0.90 superblocks, part of
387 the SHA1 hash of the hostname will be stored in the later half of the
390 When reporting information about an array, any array which is tagged
391 for the given homehost will be reported as such.
393 When using Auto-Assemble, only arrays tagged for the given homehost
396 .SH For create, build, or grow:
399 .BR \-n ", " \-\-raid\-devices=
400 Specify the number of active devices in the array. This, plus the
401 number of spare devices (see below) must equal the number of
403 (including "\fBmissing\fP" devices)
404 that are listed on the command line for
406 Setting a value of 1 is probably
407 a mistake and so requires that
409 be specified first. A value of 1 will then be allowed for linear,
410 multipath, raid0 and raid1. It is never allowed for raid4 or raid5.
412 This number can only be changed using
414 for RAID1, RAID5 and RAID6 arrays, and only on kernels which provide
418 .BR \-x ", " \-\-spare\-devices=
419 Specify the number of spare (eXtra) devices in the initial array.
420 Spares can also be added
421 and removed later. The number of component devices listed
422 on the command line must equal the number of raid devices plus the
423 number of spare devices.
427 .BR \-z ", " \-\-size=
428 Amount (in Kibibytes) of space to use from each drive in RAID level 1/4/5/6.
429 This must be a multiple of the chunk size, and must leave about 128Kb
430 of space at the end of the drive for the RAID superblock.
431 If this is not specified
432 (as it normally is not) the smallest drive (or partition) sets the
433 size, though if there is a variance among the drives of greater than 1%, a warning is
436 This value can be set with
438 for RAID level 1/4/5/6. If the array was created with a size smaller
439 than the currently active drives, the extra space can be accessed
442 The size can be given as
444 which means to choose the largest size that fits on all current drives.
446 This value can not be used with
448 metadata such as DDF and IMSM.
451 .BR \-c ", " \-\-chunk=
452 Specify chunk size of kibibytes. The default is 64.
456 Specify rounding factor for linear array (==chunk size)
459 .BR \-l ", " \-\-level=
460 Set raid level. When used with
462 options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4,
463 raid5, 5, raid6, 6, raid10, 10, multipath, mp, faulty, container.
464 Obviously some of these are synonymous.
468 metadata type is requested, only the
470 level is permitted, and it does not need to be explicitly given.
474 only linear, stripe, raid0, 0, raid1, multipath, mp, and faulty are valid.
476 Not yet supported with
480 .BR \-p ", " \-\-layout=
481 This option configures the fine details of data layout for raid5,
482 and raid10 arrays, and controls the failure modes for
485 The layout of the raid5 parity block can be one of
486 .BR left\-asymmetric ,
487 .BR left\-symmetric ,
488 .BR right\-asymmetric ,
489 .BR right\-symmetric ,
490 .BR la ", " ra ", " ls ", " rs .
492 .BR left\-symmetric .
494 When setting the failure mode for level
497 .BR write\-transient ", " wt ,
498 .BR read\-transient ", " rt ,
499 .BR write\-persistent ", " wp ,
500 .BR read\-persistent ", " rp ,
502 .BR read\-fixable ", " rf ,
503 .BR clear ", " flush ", " none .
505 Each failure mode can be followed by a number, which is used as a period
506 between fault generation. Without a number, the fault is generated
507 once on the first relevant request. With a number, the fault will be
508 generated after that many requests, and will continue to be generated
509 every time the period elapses.
511 Multiple failure modes can be current simultaneously by using the
513 option to set subsequent failure modes.
515 "clear" or "none" will remove any pending or periodic failure modes,
516 and "flush" will clear any persistent faults.
518 To set the parity with
520 the level of the array ("faulty")
521 must be specified before the fault mode is specified.
523 Finally, the layout options for RAID10 are one of 'n', 'o' or 'f' followed
524 by a small number. The default is 'n2'. The supported options are:
527 signals 'near' copies. Multiple copies of one data block are at
528 similar offsets in different devices.
531 signals 'offset' copies. Rather than the chunks being duplicated
532 within a stripe, whole stripes are duplicated but are rotated by one
533 device so duplicate blocks are on different devices. Thus subsequent
534 copies of a block are in the next drive, and are one chunk further
539 (multiple copies have very different offsets).
540 See md(4) for more detail about 'near' and 'far'.
542 The number is the number of copies of each datablock. 2 is normal, 3
543 can be useful. This number can be at most equal to the number of
544 devices in the array. It does not need to divide evenly into that
545 number (e.g. it is perfectly legal to have an 'n2' layout for an array
546 with an odd number of devices).
552 (thus explaining the p of
556 .BR \-b ", " \-\-bitmap=
557 Specify a file to store a write-intent bitmap in. The file should not
560 is also given. The same file should be provided
561 when assembling the array. If the word
563 is given, then the bitmap is stored with the metadata on the array,
564 and so is replicated on all devices. If the word
568 mode, then any bitmap that is present is removed.
570 To help catch typing errors, the filename must contain at least one
571 slash ('/') if it is a real file (not 'internal' or 'none').
573 Note: external bitmaps are only known to work on ext2 and ext3.
574 Storing bitmap files on other filesystems may result in serious problems.
577 .BR \-\-bitmap\-chunk=
578 Set the chunksize of the bitmap. Each bit corresponds to that many
579 Kilobytes of storage.
580 When using a file based bitmap, the default is to use the smallest
581 size that is at-least 4 and requires no more than 2^21 chunks.
584 bitmap, the chunksize is automatically determined to make best use of
589 .BR \-W ", " \-\-write\-mostly
590 subsequent devices lists in a
595 command will be flagged as 'write-mostly'. This is valid for RAID1
596 only and means that the 'md' driver will avoid reading from these
597 devices if at all possible. This can be useful if mirroring over a
601 .BR \-\-write\-behind=
602 Specify that write-behind mode should be enabled (valid for RAID1
603 only). If an argument is specified, it will set the maximum number
604 of outstanding writes allowed. The default value is 256.
605 A write-intent bitmap is required in order to use write-behind
606 mode, and write-behind is only attempted on drives marked as
610 .BR \-\-assume\-clean
613 that the array pre-existed and is known to be clean. It can be useful
614 when trying to recover from a major failure as you can be sure that no
615 data will be affected unless you actually write to the array. It can
616 also be used when creating a RAID1 or RAID10 if you want to avoid the
617 initial resync, however this practice \(em while normally safe \(em is not
618 recommended. Use this only if you really know what you are doing.
621 .BR \-\-backup\-file=
624 is used to increase the number of
625 raid-devices in a RAID5 if there are no spare devices available.
626 See the section below on RAID_DEVICE CHANGES. The file should be
627 stored on a separate device, not on the raid array being reshaped.
630 .BR \-N ", " \-\-name=
633 for the array. This is currently only effective when creating an
634 array with a version-1 superblock. The name is a simple textual
635 string that can be used to identify array components when assembling.
641 run the array, even if some of the components
642 appear to be active in another array or filesystem. Normally
644 will ask for confirmation before including such components in an
645 array. This option causes that question to be suppressed.
648 .BR \-f ", " \-\-force
651 accept the geometry and layout specified without question. Normally
653 will not allow creation of an array with only one device, and will try
654 to create a raid5 array with one missing drive (as this makes the
655 initial resync work faster). With
658 will not try to be so clever.
661 .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part,p}{NN}"
662 Instruct mdadm to create the device file if needed, possibly allocating
663 an unused minor number. "md" causes a non-partitionable array
664 to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and
665 later) to be used. "yes" requires the named md device to have
666 a 'standard' format, and the type and minor number will be determined
667 from this. See DEVICE NAMES below.
669 The argument can also come immediately after
674 is not given on the command line or in the config file, then
680 is also given, then any
682 entries in the config file will override the
684 instruction given on the command line.
686 For partitionable arrays,
688 will create the device file for the whole array and for the first 4
689 partitions. A different number of partitions can be specified at the
690 end of this option (e.g.
692 If the device name ends with a digit, the partition names add a 'p',
693 and a number, e.g. "/dev/md/home1p3". If there is no
694 trailing digit, then the partition names just have a number added,
695 e.g. "/dev/md/scratch3".
697 If the md device name is in a 'standard' format as described in DEVICE
698 NAMES, then it will be created, if necessary, with the appropriate
699 number based on that name. If the device name is not in one of these
700 formats, then a unused minor number will be allocated. The minor
701 number will be considered unused if there is no active array for that
702 number, and there is no entry in /dev for that number and with a
703 non-standard name. Name that are not in 'standard' format are only
704 allowed in "/dev/md/".
707 \".BR \-\-symlink = no
712 \"to create devices in
714 \"it will also create symlinks from
716 \"with names starting with
722 \"to suppress this, or
724 \"to enforce this even if it is suppressing
731 .BR \-u ", " \-\-uuid=
732 uuid of array to assemble. Devices which don't have this uuid are
736 .BR \-m ", " \-\-super\-minor=
737 Minor number of device that array was created for. Devices which
738 don't have this minor number are excluded. If you create an array as
739 /dev/md1, then all superblocks will contain the minor number 1, even if
740 the array is later assembled as /dev/md2.
742 Giving the literal word "dev" for
746 to use the minor number of the md device that is being assembled.
749 .B \-\-super\-minor=dev
750 will look for super blocks with a minor number of 0.
753 .BR \-N ", " \-\-name=
754 Specify the name of the array to assemble. This must be the name
755 that was specified when creating the array. It must either match
756 the name stored in the superblock exactly, or it must match
759 prefixed to the start of the given name.
762 .BR \-f ", " \-\-force
763 Assemble the array even if some superblocks appear out-of-date
767 Attempt to start the array even if fewer drives were given than were
768 present last time the array was active. Normally if not all the
769 expected drives are found and
771 is not used, then the array will be assembled but not started.
774 an attempt will be made to start it anyway.
778 This is the reverse of
780 in that it inhibits the startup of array unless all expected drives
781 are present. This is only needed with
783 and can be used if the physical connections to devices are
784 not as reliable as you would like.
787 .BR \-a ", " "\-\-auto{=no,yes,md,mdp,part}"
788 See this option under Create and Build options.
791 .BR \-b ", " \-\-bitmap=
792 Specify the bitmap file that was given when the array was created. If
795 bitmap, there is no need to specify this when assembling the array.
798 .BR \-\-backup\-file=
801 was used to grow the number of raid-devices in a RAID5, and the system
802 crashed during the critical section, then the same
806 to allow possibly corrupted data to be restored.
809 .BR \-U ", " \-\-update=
810 Update the superblock on each device while assembling the array. The
811 argument given to this flag can be one of
825 option will adjust the superblock of an array what was created on a Sparc
826 machine running a patched 2.2 Linux kernel. This kernel got the
827 alignment of part of the superblock wrong. You can use the
828 .B "\-\-examine \-\-sparc2.2"
831 to see what effect this would have.
835 option will update the
837 field on each superblock to match the minor number of the array being
839 This can be useful if
841 reports a different "Preferred Minor" to
843 In some cases this update will be performed automatically
844 by the kernel driver. In particular the update happens automatically
845 at the first write to an array with redundancy (RAID level 1 or
846 greater) on a 2.6 (or later) kernel.
850 option will change the uuid of the array. If a UUID is given with the
852 option that UUID will be used as a new UUID and will
854 be used to help identify the devices in the array.
857 is given, a random UUID is chosen.
861 option will change the
863 of the array as stored in the superblock. This is only supported for
864 version-1 superblocks.
868 option will change the
870 as recorded in the superblock. For version-0 superblocks, this is the
871 same as updating the UUID.
872 For version-1 superblocks, this involves updating the name.
876 option will cause the array to be marked
878 meaning that any redundancy in the array (e.g. parity for raid5,
879 copies for raid1) may be incorrect. This will cause the raid system
880 to perform a "resync" pass to make sure that all redundant information
885 option allows arrays to be moved between machines with different
887 When assembling such an array for the first time after a move, giving
888 .B "\-\-update=byteorder"
891 to expect superblocks to have their byteorder reversed, and will
892 correct that order before assembling the array. This is only valid
893 with original (Version 0.90) superblocks.
897 option will correct the summaries in the superblock. That is the
898 counts of total, working, active, failed, and spare devices.
902 will rarely be of use. It applies to version 1.1 and 1.2 metadata
903 only (where the metadata is at the start of the device) and is only
904 useful when the component device has changed size (typically become
905 larger). The version 1 metadata records the amount of the device that
906 can be used to store data, so if a device in a version 1.1 or 1.2
907 array becomes larger, the metadata will still be visible, but the
908 extra space will not. In this case it might be useful to assemble the
910 .BR \-\-update=devicesize .
913 to determine the maximum usable amount of space on each device and
914 update the relevant field in the metadata.
917 .B \-\-auto\-update\-homehost
918 This flag is only meaningful with auto-assembly (see discussion below).
919 In that situation, if no suitable arrays are found for this homehost,
921 will rescan for any arrays at all and will assemble them and update the
922 homehost to match the current host.
928 hot-add listed devices.
932 re-add a device that was recently removed from an array.
935 .BR \-r ", " \-\-remove
936 remove listed devices. They must not be active. i.e. they should
937 be failed or spare devices. As well as the name of a device file
946 The first causes all failed device to be removed. The second causes
947 any device which is no longer connected to the system (i.e an 'open'
950 to be removed. This will only succeed for devices that are spares or
951 have already been marked as failed.
954 .BR \-f ", " \-\-fail
955 mark listed devices as faulty.
956 As well as the name of a device file, the word
958 can be given. This will cause any device that has been detached from
959 the system to be marked as failed. It can then be removed.
967 .BR \-\-write\-mostly
968 Subsequent devices that are added or re-added will have the 'write-mostly'
969 flag set. This is only valid for RAID! and means that the 'md' driver
970 will avoid reading from these devices if possible.
973 Subsequent devices that are added or re-added will have the 'write-mostly'
978 Each of these options require that the first device listed is the array
979 to be acted upon, and the remainder are component devices to be added,
980 removed, or marked as faulty. Several different operations can be
981 specified for different devices, e.g.
983 mdadm /dev/md0 \-\-add /dev/sda1 \-\-fail /dev/sdb1 \-\-remove /dev/sdb1
985 Each operation applies to all devices listed until the next
988 If an array is using a write-intent bitmap, then devices which have
989 been removed can be re-added in a way that avoids a full
990 reconstruction but instead just updates the blocks that have changed
991 since the device was removed. For arrays with persistent metadata
992 (superblocks) this is done automatically. For arrays created with
994 mdadm needs to be told that this device we removed recently with
997 Devices can only be removed from an array if they are not in active
998 use, i.e. that must be spares or failed devices. To remove an active
999 device, it must first be marked as
1005 .BR \-Q ", " \-\-query
1006 Examine a device to see
1007 (1) if it is an md device and (2) if it is a component of an md
1009 Information about what is discovered is presented.
1012 .BR \-D ", " \-\-detail
1013 Print detail of one or more md devices.
1016 .BR \-\-detail\-platform
1017 Print detail of the platform's raid capabilities (firmware / hardware
1018 topology) for a given metadata format.
1021 .BR \-Y ", " \-\-export
1026 output will be formatted as
1028 pairs for easy import into the environment.
1031 .BR \-E ", " \-\-examine
1032 Print content of md superblock on device(s).
1035 If an array was created on a 2.2 Linux kernel patched with RAID
1036 support, the superblock will have been created incorrectly, or at
1037 least incompatibly with 2.4 and later kernels. Using the
1041 will fix the superblock before displaying it. If this appears to do
1042 the right thing, then the array can be successfully assembled using
1043 .BR "\-\-assemble \-\-update=sparc2.2" .
1046 .BR \-X ", " \-\-examine\-bitmap
1047 Report information about a bitmap file.
1048 The argument is either an external bitmap file or an array component
1049 in case of an internal bitmap.
1052 .BR \-R ", " \-\-run
1053 start a partially built array.
1056 .BR \-S ", " \-\-stop
1057 deactivate array, releasing all resources.
1060 .BR \-o ", " \-\-readonly
1061 mark array as readonly.
1064 .BR \-w ", " \-\-readwrite
1065 mark array as readwrite.
1068 .B \-\-zero\-superblock
1069 If the device contains a valid md superblock, the block is
1070 overwritten with zeros. With
1072 the block where the superblock would be is overwritten even if it
1073 doesn't appear to be valid.
1076 .BR \-t ", " \-\-test
1081 is set to reflect the status of the device.
1084 .BR \-W ", " \-\-wait
1085 For each md device given, wait for any resync, recovery, or reshape
1086 activity to finish before returning.
1088 will return with success if it actually waited for every device
1089 listed, otherwise it will return failure.
1093 For each md device given, or each device in /proc/mdstat if
1095 is given, arrange for the array to be marked clean as soon as possible.
1096 Also, quiesce resync so that the monitor for external metadata arrays
1097 (mdmon) has an opportunity to checkpoint the resync position.
1099 will return with success if the array uses external metadata and we
1100 successfully waited. For native arrays this returns immediately as the
1101 kernel handles both dirty-clean transitions and resync checkpointing in
1102 the kernel at shutdown. No action is taken if safe-mode handling is
1105 .SH For Incremental Assembly mode:
1107 .BR \-\-rebuild\-map ", " \-r
1108 Rebuild the map file
1109 .RB ( /var/run/mdadm/map )
1112 uses to help track which arrays are currently being assembled.
1115 .BR \-\-run ", " \-R
1116 Run any array assembled as soon as a minimal number of devices are
1117 available, rather than waiting until all expected devices are present.
1120 .BR \-\-scan ", " \-s
1121 Only meaningful with
1125 file for arrays that are being incrementally assembled and will try to
1126 start any that are not already started. If any such array is listed
1129 as requiring an external bitmap, that bitmap will be attached first.
1131 .SH For Monitor mode:
1133 .BR \-m ", " \-\-mail
1134 Give a mail address to send alerts to.
1137 .BR \-p ", " \-\-program ", " \-\-alert
1138 Give a program to be run whenever an event is detected.
1141 .BR \-y ", " \-\-syslog
1142 Cause all events to be reported through 'syslog'. The messages have
1143 facility of 'daemon' and varying priorities.
1146 .BR \-d ", " \-\-delay
1147 Give a delay in seconds.
1149 polls the md arrays and then waits this many seconds before polling
1150 again. The default is 60 seconds.
1153 .BR \-f ", " \-\-daemonise
1156 to run as a background daemon if it decides to monitor anything. This
1157 causes it to fork and run in the child, and to disconnect form the
1158 terminal. The process id of the child is written to stdout.
1161 which will only continue monitoring if a mail address or alert program
1162 is found in the config file.
1165 .BR \-i ", " \-\-pid\-file
1168 is running in daemon mode, write the pid of the daemon process to
1169 the specified file, instead of printing it on standard output.
1172 .BR \-1 ", " \-\-oneshot
1173 Check arrays only once. This will generate
1175 events and more significantly
1181 .B " mdadm \-\-monitor \-\-scan \-1"
1183 from a cron script will ensure regular notification of any degraded arrays.
1186 .BR \-t ", " \-\-test
1189 alert for every array found at startup. This alert gets mailed and
1190 passed to the alert program. This can be used for testing that alert
1191 message do get through successfully.
1197 .B mdadm \-\-assemble
1198 .I md-device options-and-component-devices...
1201 .B mdadm \-\-assemble \-\-scan
1202 .I md-devices-and-options...
1205 .B mdadm \-\-assemble \-\-scan
1209 This usage assembles one or more raid arrays from pre-existing components.
1210 For each array, mdadm needs to know the md device, the identity of the
1211 array, and a number of component-devices. These can be found in a number of ways.
1213 In the first usage example (without the
1215 the first device given is the md device.
1216 In the second usage example, all devices listed are treated as md
1217 devices and assembly is attempted.
1218 In the third (where no devices are listed) all md devices that are
1219 listed in the configuration file are assembled. Then any arrays that
1220 can be found on unused devices will also be assembled.
1222 If precisely one device is listed, but
1228 was given and identity information is extracted from the configuration file.
1230 The identity can be given with the
1234 option, will be taken from the md-device record in the config file, or
1235 will be taken from the super block of the first component-device
1236 listed on the command line.
1238 Devices can be given on the
1240 command line or in the config file. Only devices which have an md
1241 superblock which contains the right identity will be considered for
1244 The config file is only used if explicitly named with
1246 or requested with (a possibly implicit)
1251 .B /etc/mdadm/mdadm.conf
1256 is not given, then the config file will only be used to find the
1257 identity of md arrays.
1259 Normally the array will be started after it is assembled. However if
1261 is not given and insufficient drives were listed to start a complete
1262 (non-degraded) array, then the array is not started (to guard against
1263 usage errors). To insist that the array be started in this case (as
1264 may work for RAID1, 4, 5, 6, or 10), give the
1268 If the md device does not exist, then it will be created providing the
1269 intent is clear. i.e. the name must be in a standard form, or the
1271 option must be given to clarify how and whether the device should be
1273 This can be useful for handling partitioned devices (which don't have
1274 a stable device number \(em it can change after a reboot) and when using
1275 "udev" to manage your
1277 tree (udev cannot handle md devices because of the unusual device
1278 initialisation conventions).
1280 If the option to "auto" is "mdp" or "part" or (on the command line
1281 only) "p", then mdadm will create a partitionable array, using the
1282 first free one that is not in use and does not already have an entry
1283 in /dev (apart from numeric /dev/md* entries).
1285 If the option to "auto" is "yes" or "md" or (on the command line)
1286 nothing, then mdadm will create a traditional, non-partitionable md
1289 It is expected that the "auto" functionality will be used to create
1290 device entries with meaningful names such as "/dev/md/home" or
1291 "/dev/md/root", rather than names based on the numerical array number.
1293 When using option "auto" to create a partitionable array, the device
1294 files for the first 4 partitions are also created. If a different
1295 number is required it can be simply appended to the auto option.
1296 e.g. "auto=part8". Partition names are created by appending a digit
1297 string to the device name, with an intervening "p" if the device name
1302 option is also available in Build and Create modes. As those modes do
1303 not use a config file, the "auto=" config option does not apply to
1311 and no devices are listed,
1313 will first attempt to assemble all the arrays listed in the config
1316 It will then look further for possible arrays and will try to assemble
1317 anything that it finds. Arrays which are tagged as belonging to the given
1318 homehost will be assembled and started normally. Arrays which do not
1319 obviously belong to this host are given names that are expected not to
1320 conflict with anything local, and are started "read-auto" so that
1321 nothing is written to any device until the array is written to. i.e.
1322 automatic resync etc is delayed.
1326 finds a consistent set of devices that look like they should comprise
1327 an array, and if the superblock is tagged as belonging to the given
1328 home host, it will automatically choose a device name and try to
1329 assemble the array. If the array uses version-0.90 metadata, then the
1331 number as recorded in the superblock is used to create a name in
1335 If the array uses version-1 metadata, then the
1337 from the superblock is used to similarly create a name in
1339 (the name will have any 'host' prefix stripped first).
1343 cannot find any array for the given host at all, and if
1344 .B \-\-auto\-update\-homehost
1347 will search again for any array (not just an array created for this
1348 host) and will assemble each assuming
1349 .BR \-\-update=homehost .
1350 This will change the host tag in the superblock so that on the next run,
1351 these arrays will be found without the second pass. The intention of
1352 this feature is to support transitioning a set of md arrays to using
1355 The reason for requiring arrays to be tagged with the homehost for
1356 auto assembly is to guard against problems that can arise when moving
1357 devices from one host to another.
1367 .BI \-\-raid\-devices= Z
1371 This usage is similar to
1373 The difference is that it creates an array without a superblock. With
1374 these arrays there is no difference between initially creating the array and
1375 subsequently assembling the array, except that hopefully there is useful
1376 data there in the second case.
1378 The level may raid0, linear, multipath, or faulty, or one of their
1379 synonyms. All devices must be listed and the array will be started
1391 .BI \-\-raid\-devices= Z
1395 This usage will initialise a new md array, associate some devices with
1396 it, and activate the array.
1400 option is given (as described in more detail in the section on
1401 Assemble mode), then the md device will be created with a suitable
1402 device number if necessary.
1404 As devices are added, they are checked to see if they contain raid
1405 superblocks or filesystems. They are also checked to see if the variance in
1406 device size exceeds 1%.
1408 If any discrepancy is found, the array will not automatically be run, though
1411 can override this caution.
1413 To create a "degraded" array in which some devices are missing, simply
1414 give the word "\fBmissing\fP"
1415 in place of a device name. This will cause
1417 to leave the corresponding slot in the array empty.
1418 For a RAID4 or RAID5 array at most one slot can be
1419 "\fBmissing\fP"; for a RAID6 array at most two slots.
1420 For a RAID1 array, only one real device needs to be given. All of the
1424 When creating a RAID5 array,
1426 will automatically create a degraded array with an extra spare drive.
1427 This is because building the spare into a degraded array is in general faster than resyncing
1428 the parity on a non-degraded, but not clean, array. This feature can
1429 be overridden with the
1433 When creating an array with version-1 metadata a name for the array is
1435 If this is not given with the
1439 will choose a name based on the last component of the name of the
1440 device being created. So if
1442 is being created, then the name
1447 is being created, then the name
1451 When creating a partition based array, using
1453 with version-1.x metadata, the partition type should be set to
1455 (non fs-data). This type selection allows for greater precision since
1456 using any other [RAID auto-detect (0xFD) or a GNU/Linux partition (0x83)],
1457 might create problems in the event of array recovery through a live cdrom.
1459 A new array will normally get a randomly assigned 128bit UUID which is
1460 very likely to be unique. If you have a specific need, you can choose
1461 a UUID for the array by giving the
1463 option. Be warned that creating two arrays with the same UUID is a
1464 recipe for disaster. Also, using
1466 when creating a v0.90 array will silently override any
1471 .\"option is given, it is not necessary to list any component-devices in this command.
1472 .\"They can be added later, before a
1476 .\"is given, the apparent size of the smallest drive given is used.
1478 When creating an array within a
1481 can be given either the list of devices to use, or simply the name of
1482 the container. The former case gives control over which devices in
1483 the container will be used for the array. The latter case allows
1485 to automatically choose which devices to use based on how much spare
1488 The General Management options that are valid with
1493 insist on running the array even if some devices look like they might
1498 start the array readonly \(em not supported yet.
1506 .I options... devices...
1509 This usage will allow individual devices in an array to be failed,
1510 removed or added. It is possible to perform multiple operations with
1511 on command. For example:
1513 .B " mdadm /dev/md0 \-f /dev/hda1 \-r /dev/hda1 \-a /dev/hda1"
1519 and will then remove it from the array and finally add it back
1520 in as a spare. However only one md array can be affected by a single
1531 MISC mode includes a number of distinct operations that
1532 operate on distinct devices. The operations are:
1535 The device is examined to see if it is
1536 (1) an active md array, or
1537 (2) a component of an md array.
1538 The information discovered is reported.
1542 The device should be an active md device.
1544 will display a detailed description of the array.
1548 will cause the output to be less detailed and the format to be
1549 suitable for inclusion in
1550 .BR /etc/mdadm.conf .
1553 will normally be 0 unless
1555 failed to get useful information about the device(s); however, if the
1557 option is given, then the exit status will be:
1561 The array is functioning normally.
1564 The array has at least one failed device.
1567 The array has multiple failed devices such that it is unusable.
1570 There was an error while trying to get information about the device.
1574 .B \-\-detail\-platform
1575 Print detail of the platform's raid capabilities (firmware / hardware
1576 topology). If the metadata is specified with
1580 then the return status will be:
1584 metadata successfully enumerated its platform components on this system
1587 metadata is platform independent
1590 metadata failed to find its platform components on this system
1595 The device should be a component of an md array.
1597 will read the md superblock of the device and display the contents.
1602 is given, then multiple devices that are components of the one array
1603 are grouped together and reported in a single entry suitable
1605 .BR /etc/mdadm.conf .
1609 without listing any devices will cause all devices listed in the
1610 config file to be examined.
1614 The devices should be active md arrays which will be deactivated, as
1615 long as they are not currently in use.
1619 This will fully activate a partially assembled md array.
1623 This will mark an active array as read-only, providing that it is
1624 not currently being used.
1630 array back to being read/write.
1634 For all operations except
1637 will cause the operation to be applied to all arrays listed in
1642 causes all devices listed in the config file to be examined.
1649 .B mdadm \-\-monitor
1650 .I options... devices...
1655 to periodically poll a number of md arrays and to report on any events
1658 will never exit once it decides that there are arrays to be checked,
1659 so it should normally be run in the background.
1661 As well as reporting events,
1663 may move a spare drive from one array to another if they are in the
1666 and if the destination array has a failed drive but no spares.
1668 If any devices are listed on the command line,
1670 will only monitor those devices. Otherwise all arrays listed in the
1671 configuration file will be monitored. Further, if
1673 is given, then any other md devices that appear in
1675 will also be monitored.
1677 The result of monitoring the arrays is the generation of events.
1678 These events are passed to a separate program (if specified) and may
1679 be mailed to a given E-mail address.
1681 When passing events to a program, the program is run once for each event,
1682 and is given 2 or 3 command-line arguments: the first is the
1683 name of the event (see below), the second is the name of the
1684 md device which is affected, and the third is the name of a related
1685 device if relevant (such as a component device that has failed).
1689 is given, then a program or an E-mail address must be specified on the
1690 command line or in the config file. If neither are available, then
1692 will not monitor anything.
1696 will continue monitoring as long as something was found to monitor. If
1697 no program or email is given, then each event is reported to
1700 The different events are:
1704 .B DeviceDisappeared
1705 An md array which previously was configured appears to no longer be
1706 configured. (syslog priority: Critical)
1710 was told to monitor an array which is RAID0 or Linear, then it will
1712 .B DeviceDisappeared
1713 with the extra information
1715 This is because RAID0 and Linear do not support the device-failed,
1716 hot-spare and resync operations which are monitored.
1720 An md array started reconstruction. (syslog priority: Warning)
1726 is 20, 40, 60, or 80, this indicates that rebuild has passed that many
1727 percentage of the total. (syslog priority: Warning)
1731 An md array that was rebuilding, isn't any more, either because it
1732 finished normally or was aborted. (syslog priority: Warning)
1736 An active component device of an array has been marked as
1737 faulty. (syslog priority: Critical)
1741 A spare component device which was being rebuilt to replace a faulty
1742 device has failed. (syslog priority: Critical)
1746 A spare component device which was being rebuilt to replace a faulty
1747 device has been successfully rebuilt and has been made active.
1748 (syslog priority: Info)
1752 A new md array has been detected in the
1754 file. (syslog priority: Info)
1758 A newly noticed array appears to be degraded. This message is not
1761 notices a drive failure which causes degradation, but only when
1763 notices that an array is degraded when it first sees the array.
1764 (syslog priority: Critical)
1768 A spare drive has been moved from one array in a
1770 to another to allow a failed drive to be replaced.
1771 (syslog priority: Info)
1777 has been told, via the config file, that an array should have a certain
1778 number of spare devices, and
1780 detects that it has fewer than this number when it first sees the
1781 array, it will report a
1784 (syslog priority: Warning)
1788 An array was found at startup, and the
1791 (syslog priority: Info)
1801 cause Email to be sent. All events cause the program to be run.
1802 The program is run with two or three arguments: the event
1803 name, the array device and possibly a second device.
1805 Each event has an associated array device (e.g.
1807 and possibly a second device. For
1812 the second device is the relevant component device.
1815 the second device is the array that the spare was moved from.
1819 to move spares from one array to another, the different arrays need to
1820 be labeled with the same
1822 in the configuration file. The
1824 name can be any string; it is only necessary that different spare
1825 groups use different names.
1829 detects that an array in a spare group has fewer active
1830 devices than necessary for the complete array, and has no spare
1831 devices, it will look for another array in the same spare group that
1832 has a full complement of working drive and a spare. It will then
1833 attempt to remove the spare from the second drive and add it to the
1835 If the removal succeeds but the adding fails, then it is added back to
1839 The GROW mode is used for changing the size or shape of an active
1841 For this to work, the kernel must support the necessary change.
1842 Various types of growth are being added during 2.6 development,
1843 including restructuring a raid5 array to have more active devices.
1845 Currently the only support available is to
1847 change the "size" attribute
1848 for RAID1, RAID5 and RAID6.
1850 increase the "raid\-devices" attribute of RAID1, RAID5, and RAID6.
1852 add a write-intent bitmap to any array which supports these bitmaps, or
1853 remove a write-intent bitmap from such an array.
1856 GROW mode is not currently supported for
1858 or arrays inside containers.
1861 Normally when an array is built the "size" it taken from the smallest
1862 of the drives. If all the small drives in an arrays are, one at a
1863 time, removed and replaced with larger drives, then you could have an
1864 array of large drives with only a small amount used. In this
1865 situation, changing the "size" with "GROW" mode will allow the extra
1866 space to start being used. If the size is increased in this way, a
1867 "resync" process will start to make sure the new parts of the array
1870 Note that when an array changes size, any filesystem that may be
1871 stored in the array will not automatically grow to use the space. The
1872 filesystem will need to be explicitly told to use the extra space.
1874 .SS RAID-DEVICES CHANGES
1876 A RAID1 array can work with any number of devices from 1 upwards
1877 (though 1 is not very useful). There may be times which you want to
1878 increase or decrease the number of active devices. Note that this is
1879 different to hot-add or hot-remove which changes the number of
1882 When reducing the number of devices in a RAID1 array, the slots which
1883 are to be removed from the array must already be vacant. That is, the
1884 devices which were in those slots must be failed and removed.
1886 When the number of devices is increased, any hot spares that are
1887 present will be activated immediately.
1889 Increasing the number of active devices in a RAID5 is much more
1890 effort. Every block in the array will need to be read and written
1891 back to a new location. From 2.6.17, the Linux Kernel is able to do
1892 this safely, including restart and interrupted "reshape".
1894 When relocating the first few stripes on a raid5, it is not possible
1895 to keep the data on disk completely consistent and crash-proof. To
1896 provide the required safety, mdadm disables writes to the array while
1897 this "critical section" is reshaped, and takes a backup of the data
1898 that is in that section. This backup is normally stored in any spare
1899 devices that the array has, however it can also be stored in a
1900 separate file specified with the
1902 option. If this option is used, and the system does crash during the
1903 critical period, the same file must be passed to
1905 to restore the backup and reassemble the array.
1909 A write-intent bitmap can be added to, or removed from, an active
1910 array. Either internal bitmaps, or bitmaps stored in a separate file,
1911 can be added. Note that if you add a bitmap stored in a file which is
1912 in a filesystem that is on the raid array being affected, the system
1913 will deadlock. The bitmap must be on a separate filesystem.
1915 .SH INCREMENTAL MODE
1919 .B mdadm \-\-incremental
1925 .B mdadm \-\-incremental \-\-rebuild
1928 .B mdadm \-\-incremental \-\-run \-\-scan
1932 This mode is designed to be used in conjunction with a device
1933 discovery system. As devices are found in a system, they can be
1935 .B "mdadm \-\-incremental"
1936 to be conditionally added to an appropriate array.
1938 If the device passed is a
1940 device created by a previous call to
1942 then rather than trying to add that device to an array, all the arrays
1943 described by the metadata of the container will be started.
1946 performs a number of tests to determine if the device is part of an
1947 array, and which array it should be part of. If an appropriate array
1948 is found, or can be created,
1950 adds the device to the array and conditionally starts the array.
1954 will only add devices to an array which were previously working
1955 (active or spare) parts of that array. It does not currently support
1956 automatic inclusion of a new drive as a spare in some array.
1960 makes are as follow:
1962 Is the device permitted by
1964 That is, is it listed in a
1966 line in that file. If
1968 is absent then the default it to allow any device. Similar if
1970 contains the special word
1972 then any device is allowed. Otherwise the device name given to
1974 must match one of the names or patterns in a
1979 Does the device have a valid md superblock. If a specific metadata
1980 version is request with
1984 then only that style of metadata is accepted, otherwise
1986 finds any known version of metadata. If no
1988 metadata is found, the device is rejected.
1991 Does the metadata match an expected array?
1992 The metadata can match in two ways. Either there is an array listed
1995 which identifies the array (either by UUID, by name, by device list,
1996 or by minor-number), or the array was created with a
2002 or on the command line.
2005 is not able to positively identify the array as belonging to the
2006 current host, the device will be rejected.
2010 keeps a list of arrays that it has partially assembled in
2011 .B /var/run/mdadm/map
2013 .B /var/run/mdadm.map
2014 if the directory doesn't exist). If no array exists which matches
2015 the metadata on the new device,
2017 must choose a device name and unit number. It does this based on any
2020 or any name information stored in the metadata. If this name
2021 suggests a unit number, that number will be used, otherwise a free
2022 unit number will be chosen. Normally
2024 will prefer to create a partitionable array, however if the
2028 suggests that a non-partitionable array is preferred, that will be
2032 Once an appropriate array is found or created and the device is added,
2034 must decide if the array is ready to be started. It will
2035 normally compare the number of available (non-spare) devices to the
2036 number of devices that the metadata suggests need to be active. If
2037 there are at least that many, the array will be started. This means
2038 that if any devices are missing the array will not be restarted.
2044 in which case the array will be run as soon as there are enough
2045 devices present for the data to be accessible. For a raid1, that
2046 means one device will start the array. For a clean raid5, the array
2047 will be started as soon as all but one drive is present.
2049 Note that neither of these approaches is really ideal. If it can
2050 be known that all device discovery has completed, then
2054 can be run which will try to start all arrays that are being
2055 incrementally assembled. They are started in "read-auto" mode in
2056 which they are read-only until the first write request. This means
2057 that no metadata updates are made and no attempt at resync or recovery
2058 happens. Further devices that are found before the first write can
2059 still be added safely.
2063 This section describes environment variables that affect how mdadm
2068 Setting this value to 1 will prevent mdadm from automatically launching
2069 mdmon. This variable is intended primarily for debugging mdadm/mdmon.
2075 does not create any device nodes in /dev, but leaves that task to
2079 appears not to be configured, or if this environment variable is set
2082 will create and devices that are needed.
2086 .B " mdadm \-\-query /dev/name-of-device"
2088 This will find out if a given device is a raid array, or is part of
2089 one, and will provide brief information about the device.
2091 .B " mdadm \-\-assemble \-\-scan"
2093 This will assemble and start all arrays listed in the standard config
2094 file. This command will typically go in a system startup file.
2096 .B " mdadm \-\-stop \-\-scan"
2098 This will shut down all arrays that can be shut down (i.e. are not
2099 currently in use). This will typically go in a system shutdown script.
2101 .B " mdadm \-\-follow \-\-scan \-\-delay=120"
2103 If (and only if) there is an Email address or program given in the
2104 standard config file, then
2105 monitor the status of all arrays listed in that file by
2106 polling them ever 2 minutes.
2108 .B " mdadm \-\-create /dev/md0 \-\-level=1 \-\-raid\-devices=2 /dev/hd[ac]1"
2110 Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1.
2113 .B " echo 'DEVICE /dev/hd*[0\-9] /dev/sd*[0\-9]' > mdadm.conf"
2115 .B " mdadm \-\-detail \-\-scan >> mdadm.conf"
2117 This will create a prototype config file that describes currently
2118 active arrays that are known to be made from partitions of IDE or SCSI drives.
2119 This file should be reviewed before being used as it may
2120 contain unwanted detail.
2122 .B " echo 'DEVICE /dev/hd[a\-z] /dev/sd*[a\-z]' > mdadm.conf"
2124 .B " mdadm \-\-examine \-\-scan \-\-config=mdadm.conf >> mdadm.conf"
2126 This will find arrays which could be assembled from existing IDE and
2127 SCSI whole drives (not partitions), and store the information in the
2128 format of a config file.
2129 This file is very likely to contain unwanted detail, particularly
2132 entries. It should be reviewed and edited before being used as an
2135 .B " mdadm \-\-examine \-\-brief \-\-scan \-\-config=partitions"
2137 .B " mdadm \-Ebsc partitions"
2139 Create a list of devices by reading
2140 .BR /proc/partitions ,
2141 scan these for RAID superblocks, and printout a brief listing of all
2144 .B " mdadm \-Ac partitions \-m 0 /dev/md0"
2146 Scan all partitions and devices listed in
2147 .BR /proc/partitions
2150 out of all such devices with a RAID superblock with a minor number of 0.
2152 .B " mdadm \-\-monitor \-\-scan \-\-daemonise > /var/run/mdadm"
2154 If config file contains a mail address or alert program, run mdadm in
2155 the background in monitor mode monitoring all md devices. Also write
2156 pid of mdadm daemon to
2157 .BR /var/run/mdadm .
2159 .B " mdadm \-Iq /dev/somedevice"
2161 Try to incorporate newly discovered device into some array as
2164 .B " mdadm \-\-incremental \-\-rebuild \-\-run \-\-scan"
2166 Rebuild the array map from any current arrays, and then start any that
2169 .B " mdadm /dev/md4 --fail detached --remove detached"
2171 Any devices which are components of /dev/md4 will be marked as faulty
2172 and then remove from the array.
2174 .B " mdadm --create /dev/md/ddf --metadata=ddf --raid-disks 6 /dev/sd[a-f]"
2176 Create a DDF array over 6 devices.
2178 .B " mdadm --create /dev/md/home -n3 -l5 -z 30000000 /dev/md/ddf"
2180 Create a raid5 array over any 3 devices in the given DDF set. Use
2181 only 30 gigabytes of each device.
2183 .B " mdadm -A /dev/md/ddf1 /dev/sd[a-f]"
2185 Assemble a pre-exist ddf array.
2187 .B " mdadm -I /dev/md/ddf1"
2189 Assemble all arrays contained in the ddf array, assigning names as
2192 .B " mdadm \-\-create \-\-help"
2194 Provide help about the Create mode.
2196 .B " mdadm \-\-config \-\-help"
2198 Provide help about the format of the config file.
2200 .B " mdadm \-\-help"
2202 Provide general help.
2213 lists all active md devices with information about them.
2215 uses this to find arrays when
2217 is given in Misc mode, and to monitor array reconstruction
2223 The config file lists which devices may be scanned to see if
2224 they contain MD super block, and gives identifying information
2225 (e.g. UUID) about known MD arrays. See
2229 .SS /var/run/mdadm/map
2232 mode is used, this file gets a list of arrays currently being created.
2235 does not exist as a directory, then
2236 .B /var/run/mdadm.map
2242 understand two sorts of names for array devices.
2244 The first is the so-called 'standard' format name, which matches the
2245 names used by the kernel and which appear in
2248 The second sort can be freely chosen, but must reside in
2250 When giving a device name to
2252 to create or assemble an array, either full path name such as
2256 can be given, or just the suffix of the second sort of name, such as
2262 chooses device names during auto-assembly, it will normally add a
2263 small sequence number to the end of the name to avoid conflicted
2264 between multiple arrays that have the same name. If
2266 can reasonably determine that the array really is meant for this host,
2267 either by a hostname in the metadata, or by the presence of the array
2268 in /etc/mdadm.conf, then it will leave of the suffix if possible.
2270 The standard names for non-partitioned arrays (the only sort of md
2271 array available in 2.4 and earlier) are of the form
2275 where NN is a number.
2276 The standard names for partitionable arrays (as available from 2.6
2277 onwards) are of the form
2281 Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2".
2283 From kernel version, 2.6.28 the "non-partitioned array" can actually
2284 be partitioned. So the "md_dNN" names are no longer needed, and
2285 partitions such as "/dev/mdNNpXX" are possible.
2289 was previously known as
2293 is completely separate from the
2295 package, and does not use the
2297 configuration file at all.
2300 For further information on mdadm usage, MD and the various levels of
2303 .B http://linux\-raid.osdl.org/
2305 (based upon Jakob \(/Ostergaard's Software\-RAID.HOWTO)
2307 .\"for new releases of the RAID driver check out:
2310 .\".UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches
2311 .\"ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches
2316 .\".UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/
2317 .\"http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/
2320 The latest version of
2322 should always be available from
2324 .B http://www.kernel.org/pub/linux/utils/raid/mdadm/
projects / thirdparty / mdadm.git / blob