1 .\" Copyright Neil Brown and others.
2 .\" This program is free software; you can redistribute it and/or modify
3 .\" it under the terms of the GNU General Public License as published by
4 .\" the Free Software Foundation; either version 2 of the License, or
5 .\" (at your option) any later version.
6 .\" See file COPYING in distribution for details.
9 mdadm.conf \- configuration for management of Software RAID with mdadm
15 is a tool for creating, managing, and monitoring RAID devices using the
19 Some common tasks, such as assembling all arrays, can be simplified
20 by describing the devices and arrays in this configuration file.
23 The file should be seen as a collection of words separated by white
24 space (space, tab, or newline).
25 Any word that beings with a hash sign (#) starts a comment and that
26 word together with the remainder of the line is ignored.
28 Spaces can be included in a word using quotation characters. Either
31 or double quotes (\fB"\fP)
32 may be used. All the characters from one quotation character to
33 next identical character are protected and will not be used to
34 separate words to start new quoted strings. To include a single quote
35 it must be between double quotes. To include a double quote it must
36 be between single quotes.
38 Any line that starts with white space (space or tab) is treated as
39 though it were a continuation of the previous line.
41 Empty lines are ignored, but otherwise each (non continuation) line
42 must start with a keyword as listed below. The keywords are case
43 insensitive and can be abbreviated to 3 characters.
50 line lists the devices (whole devices or partitions) that might contain
51 a component of an MD array. When looking for the components of an
54 will scan these devices (or any devices listed on the command line).
58 line may contain a number of different devices (separated by spaces)
59 and each device name can contain wild cards as defined by
62 Also, there may be several device lines present in the file.
66 line can contain either or both of the words
74 to look for assembled CONTAINER arrays and included them as a source
75 for assembling further arrays.
83 and include all devices and partitions found therein.
85 does not use the names from
87 but only the major and minor device numbers. It scans
89 to find the name that matches the numbers.
91 If no DEVICE line is present in any config file,
92 then "DEVICE partitions containers" is assumed.
96 DEVICE /dev/hda* /dev/hdc*
100 DEVICE /dev/disk/by-path/pci*
106 The ARRAY lines identify actual arrays. The second word on the line
107 may be the name of the device where the array is normally
112 If the name does not start with a slash
114 it is treated as being in
118 (complete with angle brackets) can be given in which case any array
119 which matches the rest of the line will never be automatically assembled.
120 If no device name is given,
122 will use various heuristics to determine an appropriate name.
124 Subsequent words identify the array, or identify the array as a member
125 of a group. If multiple identities are given,
126 then a component device must match ALL identities to be considered a
127 match. Each identity word has a tag, and equals sign, and some value.
132 The value should be a 128 bit uuid in hexadecimal, with punctuation
133 interspersed if desired. This must match the uuid stored in the
137 The value is an integer which indicates the minor number that was
138 stored in the superblock when the array was created. When an array is
139 created as /dev/mdX, then the minor number X is stored.
142 The value is a comma separated list of device names or device name
144 Only devices with names which match one entry in the list will be used
145 to assemble the array. Note that the devices
146 listed there must also be listed on a DEVICE line.
149 The value is a RAID level. This is not normally used to
150 identify an array, but is supported so that the output of
152 .B "mdadm \-\-examine \-\-scan"
154 can be use directly in the configuration file.
157 The value is the number of devices in a complete active array. As with
159 this is mainly for compatibility with the output of
161 .BR "mdadm \-\-examine \-\-scan" .
165 The value is a number of spare devices to expect the array to have.
166 The sole use of this keyword and value is as follows:
168 will report an array if it is found to have fewer than this number of
177 The value is a textual name for a group of arrays. All arrays with
180 name are considered to be part of the same group. The significance of
181 a group of arrays is that
183 will, when monitoring the arrays, move a spare drive from one array in
184 a group to another array in that group if the first array had a failed
185 or missing drive but no spare.
189 This option is rarely needed with mdadm-3.0, particularly if use with
190 the Linux kernel v2.6.28 or later.
193 whether to use partitionable array or non-partitionable arrays and,
196 how many partition devices to create. From 2.6.28 all md array
197 devices are partitionable, hence this option is not needed.
199 The value of this option can be "yes" or "md" to indicate that a
200 traditional, non-partitionable md array should be created, or "mdp",
201 "part" or "partition" to indicate that a partitionable md array (only
202 available in linux 2.6 and later) should be used. This later set can
203 also have a number appended to indicate how many partitions to create
204 device files for, e.g.
210 The option specifies a file in which a write-intent bitmap should be
211 found. When assembling the array,
213 will provide this file to the
215 driver as the bitmap file. This has the same function as the
222 Specify the metadata format that the array has. This is mainly
223 recognised for comparability with the output of
228 Specify that this array is a member array of some container. The
229 value given can be either a path name in /dev, or a UUID of the
234 Specify that this array is a member array of some container. Each
235 type of container has some way to enumerate member arrays, often a
236 simple sequence number. The value identifies which member of a
237 container the array is. It will usually accompany a "container=" word.
244 line gives an E-mail address that alerts should be
249 mode (and was given the
251 option). There should only be one
253 line and it should have only one address. Any subsequent addresses
254 are silently ignored.
260 line (which can only be abbreviated to at least 5 characters) gives an
261 address to appear in the "From" address for alert mails. This can be
262 useful if you want to explicitly set a domain, as the default from
263 address is "root" with no domain. All words on this line are
264 catenated with spaces to form the address.
266 Note that this value cannot be set via the
268 commandline. It is only settable via the config file.
269 There should only be one
271 line and it should have only one address. Any subsequent addresses
272 are silently ignored.
278 line gives the name of a program to be run when
279 .B "mdadm \-\-monitor"
280 detects potentially interesting events on any of the arrays that it
281 is monitoring. This program gets run with two or three arguments, they
282 being the Event, the md device, and possibly the related component
285 There should only be one
287 line and it should be given only one program. Any subsequent programs
288 are silently ignored.
295 line gives default values to be used when creating arrays, new members
296 of arrays, and device entries for arrays.
298 There should only be one
300 line. Any subsequent lines will override the previous settings.
304 line and supported values are:
311 These can give user/group ids or names to use instead of system
312 defaults (root/wheel or root/disk).
315 An octal file mode such as 0660 can be given to override the default
319 This corresponds to the
326 \(em possibly followed by a number of partitions \(em to indicate how
327 missing device entries should be created.
331 The name of the metadata format to use if none is explicitly given.
332 This can be useful to impose a system-wide default of version-1 superblocks.
336 Since Linux 2.6.29 it has been possible to create
338 devices with a name like
340 rather than just a number, like
343 will use the numeric alternative by default as other tools that interact
344 with md arrays may expect only numbers.
351 will use a name when appropriate.
354 is given, then non-numeric
356 device names will not be used even if the default changes in a future
364 will reserve space for a bad block list (bbl) on all devices
365 included in or added to any array that supports them. Setting
367 will prevent this, so newly added devices will not have a bad
375 line gives a default value for the
377 option to mdadm. There should normally be only one other word on the line.
378 It should either be a host name, or one of the special words
386 .BR gethostname ( 2 )
387 systemcall is used to get the host name. This is the default.
391 is given, then a flag is set so that when arrays are being
392 auto-assembled the checking of the recorded
397 is given it is also possible to give an explicit name which will be
398 used when creating arrays. This is the only case when there can be
399 more that one other word on the
401 line. If there are other words, or other
403 lines, they are silently ignored.
407 is given, then the default of using
408 .BR gethostname ( 2 )
409 is over-ridden and no homehost name is assumed.
411 When arrays are created, this host name will be stored in the
412 metadata. When arrays are assembled using auto-assembly, arrays which
413 do not record the correct homehost name in their metadata will be
414 assembled using a "foreign" name. A "foreign" name alway ends with a
415 digit string preceded by an underscore to differentiate it
416 from any possible local name. e.g.
425 line gives a default value for the
427 option to mdadm. It specifies the cluster name for the md device.
428 The md device can be assembled only on the cluster which matches
429 the name specified. If
431 is not provided, mdadm tries to detect the cluster name automatically.
433 There should only be one
435 line. Any subsequent lines will be silently ignored.
439 A list of names of metadata format can be given, each preceded by a
440 plus or minus sign. Also the word
444 preceded by plus or minus sign.
450 is auto-assembling an array, either via
454 and it finds metadata of a given type, it checks that metadata type
455 against those listed in this line. The first match wins, where
458 If a match is found that was preceded by a plus sign, the auto
459 assembly is allowed. If the match was preceded by a minus sign, the
460 auto assembly is disallowed. If no match is found, the auto assembly
463 If the metadata indicates that the array was created for
467 appears before any other match, then the array is treated as a valid
468 candidate for auto-assembly.
470 This can be used to disable all auto-assembly (so that only arrays
471 explicitly listed in mdadm.conf or on the command line are assembled),
472 or to disable assembly of certain metadata types which might be
473 handled by other software. It can also be used to disable assembly of
474 all foreign arrays - normally such arrays are assembled but given a
475 non-deterministic name in
478 The known metadata types are
485 should be given at most once. Subsequent lines are silently ignored.
486 Thus a later config file in a config directory will not overwrite
487 the setting in an earlier config file.
491 This is used to specify what automatic behavior is allowed on devices
492 newly appearing in the system and provides a way of marking spares that can
493 be moved to other arrays as well as the migration domains.
495 can be defined through
497 line by specifying a domain name for a number of paths from
498 .BR /dev/disk/by-path/ .
499 A device may belong to several domains. The domain of an array is a union
500 of domains of all devices in that array. A spare can be automatically
501 moved from one array to another if the set of the destination array's
505 of the new disk or if both arrays have the same
508 To update hot plug configuration it is necessary to execute
509 .B mdadm \-\-udev\-rules
510 command after changing the config file
514 line and supported values are:
525 file glob matching anything from
535 include, re-add, spare, spare-same-slot, or force-spare
538 yes, no, or homehost.
543 item determines the automatic behavior allowed for devices matching the
547 in the same line. If a device matches several lines with different
549 then the most permissive will apply. The ordering of policy lines
550 is irrelevant to the end result.
553 allows adding a disk to an array if metadata on that disk matches that array
556 will include the device in the array if it appears to be a current member
557 or a member that was recently removed and the array has a
558 write-intent-bitmap to allow the
563 as above and additionally: if the device is bare it can
564 become a spare if there is any array that it is a candidate for based
565 on domains and metadata.
568 as above and additionally if given slot was used by an array that went
569 degraded recently and the device plugged in has no metadata then it will
570 be automatically added to that array (or it's container)
573 as above and the disk will become a spare in remaining cases
580 and accepts the same keyword assignments. It allows a consistent set
581 of policies to applied to each of the partitions of a device.
587 and identify the path to one or more disk devices. Each partition on
588 these disks will be treated according to the
590 setting from this line. If a
592 is set in the line, then the domain associated with each patition will
593 be based on the domain, but with
595 appended, when N is the partition number for the partition that was
602 line lists custom values of MD device's sysfs attributes which will be
603 stored in sysfs after the array is assembled. Multiple lines are allowed and each
604 line has to contain the uuid or the name of the device to which it relates.
605 Lines are applied in reverse order.
609 hexadecimal identifier of MD device. This has to match the uuid stored in the
613 name of the MD device as was given to
615 when the array was created. It will be ignored if
624 line gives a delay in seconds
626 shall wait before pooling md arrays
633 command line argument takes precedence over the config file.
637 lines are provided, only first non-zero value is considered.
640 .B ENCRYPTION_NO_VERIFY
642 .B ENCRYPTION_NO_VERIFY
643 disables encryption verification for devices with particular encryption support detected.
644 Currently, only verification of SATA OPAL encryption can be disabled.
645 It does not disable ATA security encryption verification.
654 The default config file location, used when
656 is running without --config option.
660 The default directory with config files. Used when
662 is running without --config option, after successful reading of the
664 default config file. Files in that directory
665 are read in lexical order.
670 Alternative config file that is read, when
672 is running without --config option and the
674 default config file was not opened successfully.
678 The alternative directory with config files. Used when
680 is runninng without --config option, after reading the
682 alternative config file whether it was successful or not. Files in
683 that directory are read in lexical order.
686 DEVICE /dev/sd[bcdjkl]1
688 DEVICE /dev/hda1 /dev/hdb1
690 # /dev/md0 is known by its UUID.
692 ARRAY /dev/md0 UUID=3aaa0122:29827cfa:5331ad66:ca767371
694 # /dev/md1 contains all devices with a minor number of
696 # 1 in the superblock.
698 ARRAY /dev/md1 superminor=1
700 # /dev/md2 is made from precisely these two devices
702 ARRAY /dev/md2 devices=/dev/hda1,/dev/hdb1
704 # /dev/md4 and /dev/md5 are a spare-group and spares
706 # can be moved between them
708 ARRAY /dev/md4 uuid=b23f3c6d:aec43a9f:fd65db85:369432df
712 ARRAY /dev/md5 uuid=19464854:03f71b1b:e0df2edd:246cc977
716 # /dev/md/home is created if need to be a partitionable md array
718 # any spare device number is allocated.
720 ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b
724 POLICY domain=domain1 metadata=imsm path=pci-0000:00:1f.2-scsi-*
728 POLICY domain=domain1 metadata=imsm path=pci-0000:04:00.0-scsi-[01]*
732 # One domain comprising of devices attached to specified paths is defined.
734 # Bare device matching first path will be made an imsm spare on hot plug.
736 # If more than one array is created on devices belonging to domain1 and
738 # one of them becomes degraded, then any imsm spare matching any path for
740 # given domain name can be migrated.
742 MAILADDR root@mydomain.tld
744 PROGRAM /usr/sbin/handle\-mdadm\-events
746 CREATE group=system mode=0640 auto=part\-8
750 AUTO +1.x homehost \-all
752 SYSFS name=/dev/md/raid5 group_thread_cnt=4 sync_speed_max=1000000
754 SYSFS uuid=bead5eb6:31c17a27:da120ba2:7dfda40d group_thread_cnt=4
755 sync_speed_max=1000000
759 ENCRYPTION_NO_VERIFY sata_opal
projects / thirdparty / mdadm.git / blob