2 .TH MDADM 8 "" v2.0-devel-3
4 mdadm \- manage MD devices
10 .BI mdadm " [mode] <raiddevice> [options] <component-devices>"
13 RAID devices are virtual devices created from two or more
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.
17 Some RAID levels include redundancy and so can survive some degree of
20 Linux Software RAID devices are implemented through the md (Multiple
21 Devices) device driver.
23 Currently, Linux supports
37 .B MULTIPATH is not a Software RAID mechanism, but does involve
40 each device is a path to one common physical storage device.
42 .B FAULTY is also no true RAID, and it only involves one device. It
43 provides a layer over a true device that can be used to inject faults.
46 is a program that can be used to create, manage, and monitor
48 such it provides a similar set of functionality to the
51 The key differences between
58 is a single program and not a collection of programs.
61 can perform (almost) all of its functions without having a
62 configuration file and does not use one by default. Also
64 helps with management of the configuration
68 can provide information about your arrays (through Query, Detail, and Examine)
78 configuration file, at all. It has a different configuration file
79 with a different format and an different purpose.
82 mdadm has 7 major modes of operation:
85 Assemble the parts of a previously created
86 array into an active array. Components can be explicitly given
87 or can be searched for.
89 checks that the components
90 do form a bona fide array, and can, on request, fiddle superblock
91 information so as to assemble a faulty array.
95 Build an array without per-device superblocks.
99 Create a new array with per-device superblocks.
101 '''in several step create-add-add-run or it can all happen with one command.
105 This is for doing things to specific components of an array such as
106 adding new spares and removing faulty devices.
110 This mode allows operations on independent devices such as examine MD
111 superblocks, erasing old superblocks and stopping active arrays.
114 .B "Follow or Monitor"
115 Monitor one or more md devices and act on any state changes. This is
116 only meaningful for raid1, 4, 5, 6 or multipath arrays as
117 only these have interesting state. raid0 or linear never have
118 missing, spare, or failed drives, so there is nothing to monitor.
122 Grow (or shrink) an array, or otherwise reshape it in some way.
123 Currently supported growth options including changing the active size
124 of componenet devices in RAID level 1/4/5/6 and changing the number of
125 active devices in RAID1.
129 Available options are:
132 .BR -A ", " --assemble
133 Assemble a pre-existing array.
137 Build a legacy array without superblocks.
145 Examine a device to see
146 (1) if it is an md device and (2) if it is a component of an md
148 Information about what is discovered is presented.
152 Print detail of one or more md devices.
155 .BR -E ", " --examine
156 Print content of md superblock on device(s).
159 .BR -F ", " --follow ", " --monitor
166 Change the size or shape of an active array.
169 .BR -X ", " --examine-bitmap
170 Report information about a bitmap file.
174 Display help message or, after above option, mode specific help
179 Display more detailed help about command line parsing and some commonly
183 .BR -V ", " --version
184 Print version information for mdadm.
187 .BR -v ", " --verbose
188 Be more verbose about what is happening. This can be used twice to be
190 This currently only affects
193 .BR "--examine --scan" .
197 Avoid printing purely informative messages. With this,
199 will be silent unless there is something really important to report.
203 Be less verbose. This is used with
211 gives an intermediate level of verbosity.
214 .BR -W ", " --write-mostly
215 subsequent devices lists in a
220 command will be flagged as 'write-mostly'. This is valid for RAID1
221 only and means that the 'md' driver will avoid reading from these
222 devices if at all possible. This can be useful if mirroring over a
226 .BR -b ", " --bitmap=
227 Give the name of a bitmap file to use with this array. Can be used
228 with --create (file should not exist) or --assemble (file should
233 Set the Chunksize of the bitmap. Each bit corresponds to that many
234 Kilobytes of storage. Default is 4.
238 Specify that write-behind mode should be enabled (valid for RAID1
239 only). If an argument is specified, it will set the maximum number
240 of outstanding writes allowed. The default value is 256.
241 A write-intent bitmap is required in order to use write-behind
242 mode, and write-behind is only attempted on drives marked as
248 Be more forceful about certain operations. See the various modes of
249 the exact meaning of this option in different contexts.
252 .BR -c ", " --config=
253 Specify the config file. Default is
254 .BR /etc/mdadm.conf .
255 If the config file given is
257 then nothing will be read, but
259 will act as though the config file contained exactly
260 .B "DEVICE partitions"
263 to find a list of devices to scan.
266 is given for the config file, then
268 will act as though the config file were empty.
274 for missing information.
275 In general, this option gives
277 permission to get any missing information, like component devices,
278 array devices, array identities, and alert destination from the
280 .BR /etc/mdadm.conf .
281 One exception is MISC mode when using
287 says to get a list of array devices from
291 .B -e ", " --metadata=
292 Declare the style of superblock (raid metadata) to be used. The
293 default is 0.90 for --create, and to guess for other operations.
297 .IP "0, 0.90, default"
298 Use the original 0.90 format superblock. This format limits arrays to
299 28 componenet devices and limits component devices of levels 1 and
300 greater to 2 terabytes.
301 .IP "1, 1.0, 1.1, 1.2"
302 Use the new version-1 format superblock. This has few restrictions.
303 The different subversion store the superblock at different locations
304 on the device, either at the end (for 1.0), at the start (for 1.1) or
305 4K from the start (for 1.2).
308 .SH For create or build:
312 Specify chunk size of kibibytes. The default is 64.
316 Specify rounding factor for linear array (==chunk size)
320 Set raid level. When used with
322 options are: linear, raid0, 0, stripe, raid1, 1, mirror, raid4, 4,
323 raid5, 5, raid6, 6, multipath, mp, fautly. Obviously some of these are synonymous.
327 only linear, raid0, 0, stripe are valid.
330 .BR -p ", " --parity=
331 Set raid5 parity algorithm. Options are:
336 la, ra, ls, rs. The default is left-symmetric.
338 This option is also used to set the failure mode for
356 Each mode can be followed by a number which is used as a period
357 between fault generation. Without a number, the fault is generated
358 once on the first relevant request. With a number, the fault will be
359 generated after that many request, and will continue to be generated
360 every time the period elapses.
362 Multiple failure modes can be current simultaneously by using the
363 "--grow" option to set subsequent failure modes.
365 "clear" or "none" will remove any pending or periodic failure modes,
366 and "flush" will clear any persistant faults.
368 To set the parity with "--grow", the level of the array ("faulty")
369 must be specified before the fault mode is specified.
376 .BR -b ", " --bitmap=
377 Specify a file to store a write-intent bitmap in. The file should not
378 exist unless --force is also given. The same file should be provided
379 when assembling the array.
383 Specifty the chunksize for the bitmap.
386 .BR -n ", " --raid-devices=
387 Specify the number of active devices in the array. This, plus the
388 number of spare devices (see below) must equal the number of
390 (including "\fBmissing\fP" devices)
391 that are listed on the command line for
393 Setting a value of 1 is probably
394 a mistake and so requires that
396 be specified first. A value of 1 will then be allowed for linear,
397 multipath, raid0 and raid1. It is never allowed for raid4 or raid5.
399 This number can only be changed using
401 for RAID1 arrays, and only on kernels which provide necessary support.
404 .BR -x ", " --spare-devices=
405 Specify the number of spare (eXtra) devices in the initial array.
406 Spares can also be added
407 and removed later. The number of component devices listed
408 on the command line must equal the number of raid devices plus the
409 number of spare devices.
414 Amount (in Kibibytes) of space to use from each drive in RAID1/4/5/6.
415 This must be a multiple of the chunk size, and must leave about 128Kb
416 of space at the end of the drive for the RAID superblock.
417 If this is not specified
418 (as it normally is not) the smallest drive (or partition) sets the
419 size, though if there is a variance among the drives of greater than 1%, a warning is
422 This value can be set with
424 for RAID level 1/4/5/6. If the array was created with a size smaller
425 than the currently active drives, the extra space can be accessed
428 The size can be given as
430 which means to choose the largest size that fits all on all current drives.
436 that the array pre-existed and is known to be clean. This is only
437 really useful for Building RAID1 array. Only use this if you really
438 know what you are doing. This is currently only supported for --build.
444 for the array. This is currently only effective when creating an
445 array with a version-1 superblock. The name is a simple textual
446 string that can be used to identify array components when assembling.
452 run the array, even if some of the components
453 appear to be active in another array or filesystem. Normally
455 will ask for confirmation before including such components in an
456 array. This option causes that question to be suppressed.
462 accept the geometry and layout specified without question. Normally
464 will not allow creation of an array with only one device, and will try
465 to create a raid5 array with one missing drive (as this makes the
466 initial resync work faster). With
469 will not try to be so clever.
472 .BR -a ", " "--auto{=no,yes,md,mdp,part,p}{NN}"
473 Instruct mdadm to create the device file if needed, possibly allocating
474 an unused minor number. "md" causes a non-partitionable array
475 to be used. "mdp", "part" or "p" causes a partitionable array (2.6 and
476 later) to be used. "yes" requires the named md device to have a
477 'standard' format, and the type and minor number will be determined
478 from this. See DEVICE NAMES below.
480 The argumentment can also come immediately after
485 is also given, then any
487 entries in the config file will over-ride the
489 instruction given on the command line.
491 For partitionable arrays,
493 will create the device file for the whole array and for the first 4
494 partitions. A different number of partitions can be specified at the
495 end of this option (e.g.
497 If the device name ends with a digit, the partition names add a'p',
498 and a number, e.g. "/dev/home1p3". If there is no
499 trailing digit, then the partition names just have a number added,
500 e.g. "/dev/scratch3".
502 If the md device name is in a 'standard' format as described in DEVICE
503 NAMES, then it will be created, if necessary, with the appropriate
504 number based on that name. If the device name is not in one of these
505 formats, then a unused minor number will be allocted. The minor
506 number will be considered unused if there is no active array for that
507 number, and there is no entry in /dev for that number and with a
514 uuid of array to assemble. Devices which don't have this uuid are
518 .BR -m ", " --super-minor=
519 Minor number of device that array was created for. Devices which
520 don't have this minor number are excluded. If you create an array as
521 /dev/md1, then all superblocks will contain the minor number 1, even if
522 the array is later assembled as /dev/md2.
524 Giving the literal word "dev" for
528 to use the minor number of the md device that is being assembled.
532 will look for super blocks with a minor number of 0.
536 Specify the name of the array to assemble. This must be the name
537 that was specified when creating the array.
541 Assemble the array even if some superblocks appear out-of-date
545 Attempt to start the array even if fewer drives were given than are
546 needed for a full array. Normally if not all drives are found and
548 is not used, then the array will be assembled but not started.
551 an attempt will be made to start it anyway.
554 .BR -a ", " "--auto{=no,yes,md,mdp,part}"
555 See this option under Create and Build options.
558 .BR -b ", " --bitmap=
559 Specify the bitmap file that was given when the array was created.
562 .BR -U ", " --update=
563 Update the superblock on each device while assembling the array. The
564 argument given to this flag can be one of
574 option will adjust the superblock of an array what was created on a Sparc
575 machine running a patched 2.2 Linux kernel. This kernel got the
576 alignment of part of the superblock wrong. You can use the
577 .B "--examine --sparc2.2"
580 to see what effect this would have.
584 option will update the
586 field on each superblock to match the minor number of the array being
587 assembled. This is not needed on 2.6 and later kernels as they make
588 this adjustment automatically.
592 option will cause the array to be marked
594 meaning that any redundancy in the array (e.g. parity for raid5,
595 copies for raid1) may be incorrect. This will cause the raid system
596 to perform a "resync" pass to make sure that all redundant information
601 option allows arrays to be moved between machines with different
603 When assembling such an array for the first time after a move, giving
604 .B "--update=byteorder"
607 to expect superblocks to have their byteorder reversed, and will
608 correct that order before assembling the array. This is only valid
609 with original (Verion 0.90) superblocks.
613 option will correct the summaries in the superblock. That is the
614 counts of total, working, active, failed, and spare devices.
621 hotadd listed devices.
625 remove listed devices. They must not be active. i.e. they should
626 be failed or spare devices.
630 mark listed devices as faulty.
636 .SH For Examine mode:
640 In an array was created on a 2.2 Linux kernel patched with RAID
641 support, the superblock will have been created incorrectly, or at
642 least incompatibly with 2.4 and later kernels. Using the
646 will fix the superblock before displaying it. If this appears to do
647 the right thing, then the array can be successfully assembled using
648 .BR "--assemble --update=sparc2.2" .
654 start a partially built array.
658 deactivate array, releasing all resources.
661 .BR -o ", " --readonly
662 mark array as readonly.
665 .BR -w ", " --readwrite
666 mark array as readwrite.
670 If the device contains a valid md superblock, the block is
671 over-written with zeros. With
673 the block where the superblock would be is over-written even if it
674 doesn't appear to be valid.
682 is set to reflect the status of the device.
684 .SH For Monitor mode:
687 Give a mail address to send alerts to.
690 .BR -p ", " --program ", " --alert
691 Give a program to be run whenever an event is detected.
695 Give a delay in seconds.
697 polls the md arrays and then waits this many seconds before polling
698 again. The default is 60 seconds.
701 .BR -f ", " --daemonise
704 to run as a background daemon if it decides to monitor anything. This
705 causes it to fork and run in the child, and to disconnect form the
706 terminal. The process id of the child is written to stdout.
709 which will only continue monitoring if a mail address or alert program
710 is found in the config file.
713 .BR -i ", " --pid-file
716 is running in daemon mode, write the pid of the daemon process to
717 the specified file, instead of printing it on standard output.
720 .BR -1 ", " --oneshot
721 Check arrays only once. This will generate
723 events and more significantly
727 .B " mdadm --monitor --scan -1"
729 from a cron script will ensure regular notification of any degraded arrays.
735 alert for every array found at startup. This alert gets mailed and
736 passed to the alert program. This can be used for testing that alert
737 message to get through successfully.
744 .I md-device options-and-component-devices...
747 .B mdadm --assemble --scan
748 .I md-devices-and-options...
751 .B mdadm --assemble --scan
755 This usage assembles one or more raid arrays from pre-existing components.
756 For each array, mdadm needs to know the md device, the identity of the
757 array, and a number of component-devices. These can be found in a number of ways.
759 In the first usage example (without the
761 the first device given is the md device.
762 In the second usage example, all devices listed are treated as md
763 devices and assembly is attempted.
764 In the third (where no devices are listed) all md devices that are
765 listed in the configuration file are assembled.
767 If precisely one device is listed, but
773 was given and identify information is extracted from the configuration file.
775 The identity can be given with the
779 option, can be found in the config file, or will be taken from the
780 super block on the first component-device listed on the command line.
782 Devices can be given on the
784 command line or in the config file. Only devices which have an md
785 superblock which contains the right identity will be considered for
788 The config file is only used if explicitly named with
790 or requested with (a possibly implicit)
798 is not given, then the config file will only be used to find the
799 identity of md arrays.
801 Normally the array will be started after it is assembled. However if
803 is not given and insufficient drives were listed to start a complete
804 (non-degraded) array, then the array is not started (to guard against
805 usage errors). To insist that the array be started in this case (as
806 may work for RAID1, 4, 5 or 6), give the
812 option is given, either on the command line (--auto) or in the
813 configuration file (e.g. auto=part), then
815 will create the md device if necessary or will re-create it if it
816 doesn't look usable as it is.
818 This can be useful for handling partitioned devices (which don't have
819 a stable device number - it can change after a reboot) and when using
820 "udev" to manage your
822 tree (udev cannot handle md devices because of the unusual device
823 initialisation conventions).
825 If the option to "auto" is "mdp" or "part" or (on the command line
826 only) "p", then mdadm will create a partitionable array, using the
827 first free one that is not inuse, and does not already have an entry
828 in /dev (apart from numeric /dev/md* entries).
830 If the option to "auto" is "yes" or "md" or (on the command line)
831 nothing, then mdadm will create a traditional, non-partitionable md
834 It is expected that the "auto" functionality will be used to create
835 device entries with meaningful names such as "/dev/md/home" or
836 "/dev/md/root", rather than names based on the numerical array number.
838 When using this option to create a partitionable array, the device
839 files for the first 4 partitions are also created. If a different
840 number is required it can be simply appended to the auto option.
841 e.g. "auto=part8". Partition names are created by appending a digit
842 string to the device name, with an intervening "_p" if the device name
847 option is also available in Build and Create modes. As those modes do
848 not use a config file, the "auto=" config option does not apply to
859 .BI --raid-devices= Z
863 This usage is similar to
865 The difference is that it creates a legacy array without a superblock. With
866 these arrays there is no difference between initially creating the array and
867 subsequently assembling the array, except that hopefully there is useful
868 data there in the second case.
870 The level may only be 0, raid0, or linear. All devices must be listed
871 and the array will be started once complete.
882 .BI --raid-devices= Z
886 This usage will initialise a new md array, associate some devices with
887 it, and activate the array.
891 option is given (as described in more detail in the section on
892 Assemble mode), then the md device will be created with a suitable
893 device number if necessary.
895 As devices are added, they are checked to see if they contain raid
896 superblocks or filesystems. They are also checked to see if the variance in
897 device size exceeds 1%.
899 If any discrepancy is found, the array will not automatically be run, though
902 can override this caution.
904 To create a "degraded" array in which some devices are missing, simply
905 give the word "\fBmissing\fP"
906 in place of a device name. This will cause
908 to leave the corresponding slot in the array empty.
909 For a RAID4 or RAID5 array at most one slot can be
910 "\fBmissing\fP"; for a RAID6 array at most two slots.
911 For a RAID1 array, only one real device needs to be given. All of the
915 When creating a RAID5 array,
917 will automatically create a degraded array with an extra spare drive.
918 This is because building the spare into a degraded array is in general faster than resyncing
919 the parity on a non-degraded, but not clean, array. This feature can
920 be over-ridden with the
926 '''option is given, it is not necessary to list any component-devices in this command.
927 '''They can be added later, before a
931 '''is given, the apparent size of the smallest drive given is used.
933 The General Management options that are valid with --create are:
936 insist on running the array even if some devices look like they might
941 start the array readonly - not supported yet.
948 .I options... devices...
951 This usage will allow individual devices in an array to be failed,
952 removed or added. It is possible to perform multiple operations with
953 on command. For example:
955 .B " mdadm /dev/md0 -f /dev/hda1 -r /dev/hda1 -a /dev/hda1"
961 and will then remove it from the array and finally add it back
962 in as a spare. However only one md array can be affected by a single
973 MISC mode includes a number of distinct operations that
974 operate on distinct devices. The operations are:
977 The device is examined to see if it is
978 (1) an active md array, or
979 (2) a component of an md array.
980 The information discovered is reported.
984 The device should be an active md device.
986 will display a detailed description of the array.
990 will cause the output to be less detailed and the format to be
991 suitable for inclusion in
992 .BR /etc/mdadm.conf .
995 will normally be 0 unless
997 failed to get useful information about the device(s). However if the
999 option is given, then the exit status will be:
1003 The array is functioning normally.
1006 The array has at least one failed device.
1009 The array has multiple failed devices and hence is unusable (raid4 or
1013 There was an error while trying to get information about the device.
1018 The device should be a component of an md array.
1020 will read the md superblock of the device and display the contents.
1025 then multiple devices that are components of the one array
1026 are grouped together and reported in a single entry suitable
1028 .BR /etc/mdadm.conf .
1032 without listing any devices will cause all devices listed in the
1033 config file to be examined.
1037 The devices should be active md arrays which will be deactivated, as
1038 long as they are not currently in use.
1042 This will fully activate a partially assembled md array.
1046 This will mark an active array as read-only, providing that it is
1047 not currently being used.
1053 array back to being read/write.
1057 For all operations except
1060 will cause the operation to be applied to all arrays listed in
1065 causes all devices listed in the config file to be examined.
1073 .I options... devices...
1078 to periodically poll a number of md arrays and to report on any events
1081 will never exit once it decides that there are arrays to be checked,
1082 so it should normally be run in the background.
1084 As well as reporting events,
1086 may move a spare drive from one array to another if they are in the
1089 and if the destination array has a failed drive but not spares.
1091 If any devices are listed on the command line,
1093 will only monitor those devices. Otherwise all arrays listed in the
1094 configuration file will be monitored. Further, if
1096 is given, then any other md devices that appear in
1098 will also be monitored.
1100 The result of monitoring the arrays is the generation of events.
1101 These events are passed to a separate program (if specified) and may
1102 be mailed to a given E-mail address.
1104 When passing event to program, the program is run once for each event
1105 and is given 2 or 3 command-line arguements. The first is the
1106 name of the event (see below). The second is the name of the
1107 md device which is affected, and the third is the name of a related
1108 device if relevant, such as a component device that has failed.
1112 is given, then a program or an E-mail address must be specified on the
1113 command line or in the config file. If neither are available, then
1115 will not monitor anything.
1119 will continue monitoring as long as something was found to monitor. If
1120 no program or email is given, then each event is reported to
1123 The different events are:
1127 .B DeviceDisappeared
1128 An md array which previously was configured appears to no longer be
1133 was told to monitor an array which is RAID0 or Linear, then it will
1135 .B DeviceDisappeared
1136 with the extra information
1138 This is because RAID0 and Linear do not support the device-failed,
1139 hot-spare and resync operations which are monitored.
1143 An md array started reconstruction.
1149 is 20, 40, 60, or 80, this indicates that rebuild has passed that many
1150 percentage of the total.
1154 An md array that was rebuilding, isn't any more, either because it
1155 finished normally or was aborted.
1159 An active component device of an array has been marked as faulty.
1163 A spare component device which was being rebuilt to replace a faulty
1168 A spare component device which was being rebuilt to replace a faulty
1169 device as been successfully rebuild and has been made active.
1173 A new md array has been detected in the
1179 A newly noticed array appears to be degraded. This message is not
1182 notices a drive failure which causes degradation, but only when
1184 notices that an array is degraded when it first sees the array.
1188 A spare drive has been moved from one array in a
1190 to another to allow a failed drive to be replaced.
1196 has been told, via the config file, that an array should have a certain
1197 number of spare devices, and
1199 detects that it has fewer that this number when it first sees the
1200 array, it will report a
1206 An array was found at startup, and the
1217 cause Email to be sent. All events cause the program to be run.
1218 The program is run with two or three arguments, they being the event
1219 name, the array device and possibly a second device.
1221 Each event has an associated array device (e.g.
1223 and possibly a second device. For
1228 the second device is the relevant component device.
1231 the second device is the array that the spare was moved from.
1235 to move spares from one array to another, the different arrays need to
1236 be labelled with the same
1238 in the configuration file. The
1240 name can be any string. It is only necessary that different spare
1241 groups use different names.
1245 detects that an array which is in a spare group has fewer active
1246 devices than necessary for the complete array, and has no spare
1247 devices, it will look for another array in the same spare group that
1248 has a full complement of working drive and a spare. It will then
1249 attempt to remove the spare from the second drive and add it to the
1251 If the removal succeeds but the adding fails, then it is added back to
1255 The GROW mode is used for changing the size or shape of an active
1257 For this to work, the kernel must support the necessary change.
1258 Various types of growth may be added during 2.6 development, possibly
1259 including restructuring a raid5 array to have more active devices.
1261 Currently the only support available is to
1263 change the "size" attribute
1264 for RAID1, RAID5 and RAID6.
1266 change the "raid-disks" attribute of RAID1.
1268 add a write-intent bitmap to a RAID1 array.
1271 Normally when an array is build the "size" it taken from the smallest
1272 of the drives. If all the small drives in an arrays are, one at a
1273 time, removed and replaced with larger drives, then you could have an
1274 array of large drives with only a small amount used. In this
1275 situation, changing the "size" with "GROW" mode will allow the extra
1276 space to start being used. If the size is increased in this way, a
1277 "resync" process will start to make sure the new parts of the array
1280 Note that when an array changes size, any filesystem that may be
1281 stored in the array will not automatically grow to use the space. The
1282 filesystem will need to be explicitly told to use the extra space.
1284 A RAID1 array can work with any number of devices from 1 upwards
1285 (though 1 is not very useful). There may be times which you want to
1286 increase or decrease the number of active devices. Note that this is
1287 different to hot-add or hot-remove which changes the number of
1290 When reducing the number of devices in a RAID1 array, the slots which
1291 are to be removed from the array must already be vacant. That is, the
1292 devices that which were in those slots must be failed and removed.
1294 When the number of devices is increased, any hot spares that are
1295 present may be activated immediately.
1299 .B " mdadm --query /dev/name-of-device"
1301 This will find out if a given device is a raid array, or is part of
1302 one, and will provide brief information about the device.
1304 .B " mdadm --assemble --scan"
1306 This will assemble and start all arrays listed in the standard confile
1307 file. This command will typically go in a system startup file.
1309 .B " mdadm --stop --scan"
1311 This will shut down all array that can be shut down (i.e. are not
1312 currently in use). This will typically go in a system shutdown script.
1314 .B " mdadm --follow --scan --delay=120"
1316 If (and only if) there is an Email address or program given in the
1317 standard config file, then
1318 monitor the status of all arrays listed in that file by
1319 polling them ever 2 minutes.
1321 .B " mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/hd[ac]1"
1323 Create /dev/md0 as a RAID1 array consisting of /dev/hda1 and /dev/hdc1.
1326 .B " echo 'DEVICE /dev/hd*[0-9] /dev/sd*[0-9]' > mdadm.conf"
1328 .B " mdadm --detail --scan >> mdadm.conf"
1330 This will create a prototype config file that describes currently
1331 active arrays that are known to be made from partitions of IDE or SCSI drives.
1332 This file should be reviewed before being used as it may
1333 contain unwanted detail.
1335 .B " echo 'DEVICE /dev/hd[a-z] /dev/sd*[a-z]' > mdadm.conf"
1337 .B " mdadm --examine --scan --config=mdadm.conf >> mdadm.conf"
1339 This will find what arrays could be assembled from existign IDE and
1340 SCSI whole drives (not partitions) and store the information is the
1341 format of a config file.
1342 This file is very likely to contain unwanted detail, particularly
1345 entries. It should be reviewed and edited before being used as an
1348 .B " mdadm --examine --brief --scan --config=partitions"
1350 .B " mdadm -Ebsc partitions"
1352 Create a list of devices by reading
1353 .BR /proc/partitions ,
1354 scan these for RAID superblocks, and printout a brief listing of all
1357 .B " mdadm -Ac partitions -m 0 /dev/md0"
1359 Scan all partitions and devices listed in
1360 .BR /proc/partitions
1363 out of all such devices with a RAID superblock with a minor number of 0.
1365 .B " mdadm --monitor --scan --daemonise > /var/run/mdadm"
1367 If config file contains a mail address or alert program, run mdadm in
1368 the background in monitor mode monitoring all md devices. Also write
1369 pid of mdadm daemon to
1370 .BR /var/run/mdadm .
1372 .B " mdadm --create --help"
1374 Providew help about the Create mode.
1376 .B " mdadm --config --help"
1378 Provide help about the format of the config file.
1382 Provide general help.
1393 lists all active md devices with information about them.
1395 uses this to find arrays when
1397 is given in Misc mode, and to monitor array reconstruction
1403 The config file lists which devices may be scanned to see if
1404 they contain MD super block, and gives identifying information
1405 (e.g. UUID) about known MD arrays. See
1411 While entries in the /dev directory can have any format you like,
1413 has an understanding of 'standard' formats which it uses to guide its
1414 behaviour when creating device files via the
1418 The standard names for non-partitioned arrays (the only sort of md
1419 array available in 2.4 and earlier) either of
1425 where NN is a number.
1426 The standard names for partitionable arrays (as available from 2.6
1433 Partition numbers should be indicated by added "pMM" to these, thus "/dev/md/d1p2".
1437 was previously known as
1441 For information on the various levels of
1445 .UR http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/
1446 http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/
1449 for new releases of the RAID driver check out:
1452 .UR ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches
1453 ftp://ftp.kernel.org/pub/linux/kernel/people/mingo/raid-patches
1458 .UR http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/
1459 http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/
projects / thirdparty / mdadm.git / blob