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 Any line that starts with white space (space or tab) is treated as
29 though it were a continuation of the previous line.
31 Empty lines are ignored, but otherwise each (non continuation) line
32 must start with a keyword as listed below. The keywords are case
33 insensitive and can be abbreviated to 3 characters.
40 line lists the devices (whole devices or partitions) that might contain
41 a component of an MD array. When looking for the components of an
44 will scan these devices (or any devices listed on the command line).
48 line may contain a number of different devices (separated by spaces)
49 and each device name can contain wild cards as defined by
52 Also, there may be several device lines present in the file.
56 line can contain either of both of the words
64 to look for assembled CONTAINER arrays and included them as a source
65 for assembling further arrays.
73 and include all devices and partitions found therein.
75 does not use the names from
77 but only the major and minor device numbers. It scans
79 to find the name that matches the numbers.
81 If no DEVICE line is present, then "DEVICE partitions containers" is assumed.
85 DEVICE /dev/hda* /dev/hdc*
89 DEVICE /dev/discs/disc*/disc
95 The ARRAY lines identify actual arrays. The second word on the line
96 may be the name of the device where the array is normally
101 (complete with angle brackets) can be given in which case any array
102 which matches the rest of the line will never be automatically assembled.
103 If no device name is given,
105 will use various heuristic to determine an appropriate name.
107 Subsequent words identify the array, or identify the array as a member
108 of a group. If multiple identities are given,
109 then a component device must match ALL identities to be considered a
110 match. Each identity word has a tag, and equals sign, and some value.
116 The value should be a 128 bit uuid in hexadecimal, with punctuation
117 interspersed if desired. This must match the uuid stored in the
121 The value should be a simple textual name as was given to
123 when the array was created. This must match the name stored in the
124 superblock on a device for that device to be included in the array.
125 Not all superblock formats support names.
128 The value is an integer which indicates the minor number that was
129 stored in the superblock when the array was created. When an array is
130 created as /dev/mdX, then the minor number X is stored.
133 The value is a comma separated list of device names or device name
135 Only devices with names which match one entry in the list will be used
136 to assemble the array. Note that the devices
137 listed there must also be listed on a DEVICE line.
140 The value is a raid level. This is not normally used to
141 identify an array, but is supported so that the output of
143 .B "mdadm \-\-examine \-\-scan"
145 can be use directly in the configuration file.
148 The value is the number of devices in a complete active array. As with
150 this is mainly for compatibility with the output of
152 .BR "mdadm \-\-examine \-\-scan" .
156 The value is a number of spare devices to expect the array to have.
158 will report an array if it is found to have fewer than this number of
167 The value is a textual name for a group of arrays. All arrays with
170 name are considered to be part of the same group. The significance of
171 a group of arrays is that
173 will, when monitoring the arrays, move a spare drive from one array in
174 a group to another array in that group if the first array had a failed
175 or missing drive but no spare.
179 This option declares to
181 that it should try to create the device file of the array if it
182 doesn't already exist, or exists but with the wrong device number.
184 The value of this option can be "yes" or "md" to indicate that a
185 traditional, non-partitionable md array should be created, or "mdp",
186 "part" or "partition" to indicate that a partitionable md array (only
187 available in linux 2.6 and later) should be used. This later set can
188 also have a number appended to indicate how many partitions to create
189 device files for, e.g.
195 The option specifies a file in which a write-intent bitmap should be
196 found. When assembling the array,
198 will provide this file to the
200 driver as the bitmap file. This has the same function as the
207 Specify the metadata format that the array has. This is mainly
208 recognised for comparability with the output of
213 Specify that this array is a member array of some container. The
214 value given can be either a path name in /dev, or a UUID of the
219 Specify that this array is a member array of some container. Each
220 type of container has some way to enumerate member arrays, often a
221 simple sequence number. The value identifies which member of a
222 container the array is. It will usually accompany a 'container=' word.
229 line gives an E-mail address that alerts should be
234 mode (and was given the
236 option). There should only be one
238 line and it should have only one address.
245 line (which can only be abbreviated to at least 5 characters) gives an
246 address to appear in the "From" address for alert mails. This can be
247 useful if you want to explicitly set a domain, as the default from
248 address is "root" with no domain. All words on this line are
249 catenated with spaces to form the address.
251 Note that this value cannot be set via the
253 commandline. It is only settable via the config file.
259 line gives the name of a program to be run when
260 .B "mdadm \-\-monitor"
261 detects potentially interesting events on any of the arrays that it
262 is monitoring. This program gets run with two or three arguments, they
263 being the Event, the md device, and possibly the related component
266 There should only be one
268 line and it should be give only one program.
275 line gives default values to be used when creating arrays and device entries for
284 These can give user/group ids or names to use instead of system
285 defaults (root/wheel or root/disk).
288 An octal file mode such as 0660 can be given to override the default
292 This corresponds to the
299 \(em possibly followed by a number of partitions \(em to indicate how
300 missing device entries should be created.
304 The name of the metadata format to use if none is explicitly given.
305 This can be useful to impose a system-wide default of version-1 superblocks.
309 Normally when creating devices in
312 will create a matching symlink from
320 to suppress this symlink creation.
327 line gives a default value for the
329 option to mdadm. There should be exactly one other word on the line.
330 It should either exactly
336 .BR gethostname ( 2 )
337 systemcall is used to get the host name.
338 When arrays are created, this host name will be stored in the
339 metadata. When arrays are assembled using auto-assembly, only arrays
340 with this host name stored in the metadata will be considered.
344 A list of names of metadata format can be given, each preceded by a
345 plus or minus sign. Also the word
347 preceded by plus or minus is allowed and is usually last.
351 is auto-assembling an array, with via
355 and it finds metadata of a given type, it checks that metadata type
356 against those listed in this line. The first match wins, where
359 If a match is found that was preceded by a plus sign, the auto
360 assembly is allowed. If the match was preceded by a minus sign, the
361 auto assembly is disallowed. If no match is found, the auto assembly
364 This can be used to disable all auto-assembly (so that only arrays
365 explicitly listed in mdadm.conf or on the command line are assembled),
366 or to disable assembly of certain metadata types which might be
367 handled by other software.
369 The known metadata types are
376 DEVICE /dev/sd[bcdjkl]1
378 DEVICE /dev/hda1 /dev/hdb1
380 # /dev/md0 is known by its UUID.
382 ARRAY /dev/md0 UUID=3aaa0122:29827cfa:5331ad66:ca767371
384 # /dev/md1 contains all devices with a minor number of
386 # 1 in the superblock.
388 ARRAY /dev/md1 superminor=1
390 # /dev/md2 is made from precisely these two devices
392 ARRAY /dev/md2 devices=/dev/hda1,/dev/hdb1
394 # /dev/md4 and /dev/md5 are a spare-group and spares
396 # can be moved between them
398 ARRAY /dev/md4 uuid=b23f3c6d:aec43a9f:fd65db85:369432df
402 ARRAY /dev/md5 uuid=19464854:03f71b1b:e0df2edd:246cc977
406 # /dev/md/home is created if need to be a partitionable md array
408 # any spare device number is allocated.
410 ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b
414 MAILADDR root@mydomain.tld
416 PROGRAM /usr/sbin/handle\-mdadm\-events
418 CREATE group=system mode=0640 auto=part\-8
projects / thirdparty / mdadm.git / blob