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 If the name does not start with a slash
103 it is treated as being in
107 (complete with angle brackets) can be given in which case any array
108 which matches the rest of the line will never be automatically assembled.
109 If no device name is given,
111 will use various heuristics to determine an appropriate name.
113 Subsequent words identify the array, or identify the array as a member
114 of a group. If multiple identities are given,
115 then a component device must match ALL identities to be considered a
116 match. Each identity word has a tag, and equals sign, and some value.
122 The value should be a 128 bit uuid in hexadecimal, with punctuation
123 interspersed if desired. This must match the uuid stored in the
127 The value should be a simple textual name as was given to
129 when the array was created. This must match the name stored in the
130 superblock on a device for that device to be included in the array.
131 Not all superblock formats support names.
134 The value is an integer which indicates the minor number that was
135 stored in the superblock when the array was created. When an array is
136 created as /dev/mdX, then the minor number X is stored.
139 The value is a comma separated list of device names or device name
141 Only devices with names which match one entry in the list will be used
142 to assemble the array. Note that the devices
143 listed there must also be listed on a DEVICE line.
146 The value is a raid level. This is not normally used to
147 identify an array, but is supported so that the output of
149 .B "mdadm \-\-examine \-\-scan"
151 can be use directly in the configuration file.
154 The value is the number of devices in a complete active array. As with
156 this is mainly for compatibility with the output of
158 .BR "mdadm \-\-examine \-\-scan" .
162 The value is a number of spare devices to expect the array to have.
164 will report an array if it is found to have fewer than this number of
173 The value is a textual name for a group of arrays. All arrays with
176 name are considered to be part of the same group. The significance of
177 a group of arrays is that
179 will, when monitoring the arrays, move a spare drive from one array in
180 a group to another array in that group if the first array had a failed
181 or missing drive but no spare.
185 This option declares to
187 that it should try to create the device file of the array if it
188 doesn't already exist, or exists but with the wrong device number.
190 The value of this option can be "yes" or "md" to indicate that a
191 traditional, non-partitionable md array should be created, or "mdp",
192 "part" or "partition" to indicate that a partitionable md array (only
193 available in linux 2.6 and later) should be used. This later set can
194 also have a number appended to indicate how many partitions to create
195 device files for, e.g.
201 The option specifies a file in which a write-intent bitmap should be
202 found. When assembling the array,
204 will provide this file to the
206 driver as the bitmap file. This has the same function as the
213 Specify the metadata format that the array has. This is mainly
214 recognised for comparability with the output of
219 Specify that this array is a member array of some container. The
220 value given can be either a path name in /dev, or a UUID of the
225 Specify that this array is a member array of some container. Each
226 type of container has some way to enumerate member arrays, often a
227 simple sequence number. The value identifies which member of a
228 container the array is. It will usually accompany a 'container=' word.
235 line gives an E-mail address that alerts should be
240 mode (and was given the
242 option). There should only be one
244 line and it should have only one address.
251 line (which can only be abbreviated to at least 5 characters) gives an
252 address to appear in the "From" address for alert mails. This can be
253 useful if you want to explicitly set a domain, as the default from
254 address is "root" with no domain. All words on this line are
255 catenated with spaces to form the address.
257 Note that this value cannot be set via the
259 commandline. It is only settable via the config file.
265 line gives the name of a program to be run when
266 .B "mdadm \-\-monitor"
267 detects potentially interesting events on any of the arrays that it
268 is monitoring. This program gets run with two or three arguments, they
269 being the Event, the md device, and possibly the related component
272 There should only be one
274 line and it should be give only one program.
281 line gives default values to be used when creating arrays and device entries for
290 These can give user/group ids or names to use instead of system
291 defaults (root/wheel or root/disk).
294 An octal file mode such as 0660 can be given to override the default
298 This corresponds to the
305 \(em possibly followed by a number of partitions \(em to indicate how
306 missing device entries should be created.
310 The name of the metadata format to use if none is explicitly given.
311 This can be useful to impose a system-wide default of version-1 superblocks.
315 Normally when creating devices in
318 will create a matching symlink from
326 to suppress this symlink creation.
333 line gives a default value for the
335 option to mdadm. There should be exactly one other word on the line.
336 It should either be a host name, or one of the special words
343 .BR gethostname ( 2 )
344 systemcall is used to get the host name.
348 is given, then a flag is set so that when arrays are being
349 auto-assemble the checking of the recorded
353 When arrays are created, this host name will be stored in the
354 metadata. When arrays are assembled using auto-assembly, arrays which
355 do not record the correct homehost name in their metadata will be
356 assembled using a 'foreign' name. A 'foreign' name alway ends with a
357 digit string (possibly preceded by an underscore) to differentiate it
358 from any possible local name. e.g.
364 A list of names of metadata format can be given, each preceded by a
365 plus or minus sign. Also the word
367 preceded by plus or minus is allowed and is usually last.
371 is auto-assembling an array, with via
375 and it finds metadata of a given type, it checks that metadata type
376 against those listed in this line. The first match wins, where
379 If a match is found that was preceded by a plus sign, the auto
380 assembly is allowed. If the match was preceded by a minus sign, the
381 auto assembly is disallowed. If no match is found, the auto assembly
384 This can be used to disable all auto-assembly (so that only arrays
385 explicitly listed in mdadm.conf or on the command line are assembled),
386 or to disable assembly of certain metadata types which might be
387 handled by other software.
389 The known metadata types are
396 DEVICE /dev/sd[bcdjkl]1
398 DEVICE /dev/hda1 /dev/hdb1
400 # /dev/md0 is known by its UUID.
402 ARRAY /dev/md0 UUID=3aaa0122:29827cfa:5331ad66:ca767371
404 # /dev/md1 contains all devices with a minor number of
406 # 1 in the superblock.
408 ARRAY /dev/md1 superminor=1
410 # /dev/md2 is made from precisely these two devices
412 ARRAY /dev/md2 devices=/dev/hda1,/dev/hdb1
414 # /dev/md4 and /dev/md5 are a spare-group and spares
416 # can be moved between them
418 ARRAY /dev/md4 uuid=b23f3c6d:aec43a9f:fd65db85:369432df
422 ARRAY /dev/md5 uuid=19464854:03f71b1b:e0df2edd:246cc977
426 # /dev/md/home is created if need to be a partitionable md array
428 # any spare device number is allocated.
430 ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b
434 MAILADDR root@mydomain.tld
436 PROGRAM /usr/sbin/handle\-mdadm\-events
438 CREATE group=system mode=0640 auto=part\-8
projects / thirdparty / mdadm.git / blob