3 mdadm.conf \- configuration for management of Software Raid with mdadm
9 is a tool for creating, managing, and monitoring RAID devices using the
13 Some common tasks, such as assembling all arrays, can be simplified
14 by describing the devices and arrays in this configuration file.
17 The file should be seen as a collection of words separated by white
18 space (space, tab, or newline).
19 Any word that beings with a hash sign (#) starts a comment and that
20 word together with the remainder of the line is ignored.
22 Any line that starts with white space (space or tab) is treated as
23 though it were a continuation of the previous line.
25 Empty lines are ignored, but otherwise each (non continuation) line
26 must start with a keyword as listed below. The keywords are case
27 insensitive and can be abbreviated to 3 characters.
34 line lists the devices (whole devices or partitions) that might contain
35 a component of an MD array. When looking for the components of an
38 will scan these devices (or any devices listed on the command line).
42 line may contain a number of different devices (separated by spaces)
43 and each device name can contain wild cards as defined by
46 Also, there may be several device lines present in the file.
50 line can contain the word
56 and include all devices and partitions found there-in.
58 does not use the names from
60 but only the major and minor device numbers. It scans
62 to find the name that matches the numbers.
64 If no DEVICE line is present, then "DEVICE partitions" is assumed.
68 DEVICE /dev/hda* /dev/hdc*
72 DEVICE /dev/discs/disc*/disc
78 The ARRAY lines identify actual arrays. The second word on the line
79 should be the name of the device where the array is normally
82 Subsequent words identify the array, or identify the array as a member
83 of a group. If multiple identities are given,
84 then a component device must match ALL identities to be considered a
85 match. Each identity word has a tag, and equals sign, and some value.
91 The value should be a 128 bit uuid in hexadecimal, with punctuation
92 interspersed if desired. This must match the uuid stored in the
96 The value should be a simple textual name as was given to
98 when the array was created. This must match the name stored in the
99 superblock on a device for that device to be included in the array.
100 Not all superblock-formats support names.
103 The value is an integer which indicates the minor number that was
104 stored in the superblock when the array was created. When an array is
105 created as /dev/mdX, then the minor number X is stored.
108 The value is a comma separated list of device names or device name
110 Only devices with names which match one entry in the list will be used
111 to assemble the array. Note that the devices
112 listed there must also be listed on a DEVICE line.
115 The value is a raid level. This is not normally used to
116 identify an array, but is supported so that the output of
118 .B "mdadm --examine --scan"
120 can be use directly in the configuration file.
123 The value is the number of devices in a complete active array. As with
125 this is mainly for compatibility with the output of
127 .BR "mdadm --examine --scan" .
131 The value is a number of spare devices to expect the array to have.
133 will report an array if it is found to have fewer than this number of
142 The value is a textual name for a group of arrays. All arrays with
145 name are considered to be part of the same group. The significance of
146 a group of arrays is that
148 will, when monitoring the arrays, move a spare drive from one array in
149 a group to another array in that group if the first array had a failed
150 or missing drive but no spare.
154 This option declares to
156 that it should try to create the device file of the array if it
157 doesn't already exist, or exists but with the wrong device number.
159 The value of this option can be "yes" or "md" to indicate that a
160 traditional, non-partitionable md array should be created, or "mdp",
161 "part" or "partition" to indicate that a partitionable md array (only
162 available in linux 2.6 and later) should be used. This later set can
163 also have a number appended to indicate how many partitions to create
164 device files for, e.g.
170 The option specifies a file in which a write-intent bitmap should be
171 found. When assembling the array,
173 will provide this file to the
175 driver as the bitmap file. This has the same function as the
182 Specify the metadata format that the array has. This is mainly
183 recognised for comparability with the output of
192 line gives an E-mail address that alerts should be
197 mode (and was given the
199 option). There should only be one
201 line and it should have only one address.
208 line (which can only be abbreviate at leat 5 characters) gives an
209 address to appear in the "From" address for alert mails. This can be
210 useful if you want to explicitly set a domain, as the default from
211 address is "root" with no domain. All words on this line are
212 catenated with spaces to form the address.
214 Note that this value cannot be set via the
216 commandline. It is only settable via the config file.
222 line gives the name of a program to be run when
224 detects potentially interesting events on any of the arrays that it
225 is monitoring. This program gets run with two or three arguments, they
226 being the Event, the md device, and possibly the related component
229 There should only be one
231 line and it should be give only one program.
238 line gives default values to be used when creating arrays and device entries for
247 These can give user/group ids or names to use instead of system
248 defaults (root/wheel or root/disk).
251 An octal file mode such as 0660 can be given to override the default
255 This corresponds to the
262 - possibly followed by a number of partitions - to indicate how
263 missing device entries should be created.
267 The name of the metadata format to use if none is explicitly given.
268 This can be useful to impose a system-wide default of version-1 superblocks.
274 DEVICE /dev/sd[bcdjkl]1
276 DEVICE /dev/hda1 /dev/hdb1
278 # /dev/md0 is known by it's UID.
280 ARRAY /dev/md0 UUID=3aaa0122:29827cfa:5331ad66:ca767371
282 # /dev/md1 contains all devices with a minor number of
284 # 1 in the superblock.
286 ARRAY /dev/md1 superminor=1
288 # /dev/md2 is made from precisey these two devices
290 ARRAY /dev/md2 devices=/dev/hda1,/dev/hdb1
292 # /dev/md4 and /dev/md5 are a spare-group and spares
294 # can be moved between them
296 ARRAY /dev/md4 uuid=b23f3c6d:aec43a9f:fd65db85:369432df
300 ARRAY /dev/md5 uuid=19464854:03f71b1b:e0df2edd:246cc977
304 # /dev/md/home is created if need to be a partitionable md array
306 # any spare device number is allocated.
308 ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b
312 MAILADDR root@mydomain.tld
314 PROGRAM /usr/sbin/handle-mdadm-events
316 CREATE group=system mode=0640 auto=part-8
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