mdadm-1.6.0
[thirdparty/mdadm.git] / mdadm.conf.5
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1.TH MDADM.CONF 5
2.SH NAME
3mdadm.conf \- configuration for management of Software Raid with mdadm
4.SH SYNOPSIS
5/etc/mdadm.conf
6.SH DESCRIPTION
7.PP
8.B mdadm
11a3e71d 9is a tool for creating, managing, and monitoring RAID devices using the
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10.B md
11driver in Linux.
12.PP
13Some common tasks, such as assembling all arrays, can be simplified
2d465520 14by describing the devices and arrays in this configuration file.
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15
16.SS SYNTAX
17The file should be seen as a collection of words separated by white
18space (space, tab, or newline).
11a3e71d 19Any word that beings with a hash sign (#) starts a comment and that
2d465520 20word together with the remainder of the line is ignored.
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2d465520 22Any line that starts with white space (space or tab) is treated as
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23though it were a continuation of the previous line.
24
25Empty lines are ignored, but otherwise each (non continuation) line
2d465520 26must start with a keyword as listed below. The keywords are case
e0d19036 27insensitive and can be abbreviated to 3 characters.
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28
29The keywords are:
30.TP
31.B DEVICE
32A
33.B device
34line lists the devices (whole devices or partitions) that might contain
35a component of an MD array. When looking for the components of an
36array,
37.B mdadm
2d465520 38will scan these devices (or any devices listed on the command line).
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39
40The
41.B device
42line may contain a number of different devices (separated by spaces)
43and each device name can contain wild cards as defined by
44.BR glob (7).
45
46Also, there may be several device lines present in the file.
47
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48Alternatively, a
49.B device
50line can contain the word
51.BR partitions .
52This will cause
53.I mdadm
54to read
55.I /proc/partitions
56and include all devices and partitions found there-in.
57.I mdadm
58does not use the names from
59.I /proc/partitions
60but only the major and minor device numbers. It scans
61.I /dev
62to find the name that matches the numbers.
63
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64For example:
65.IP
66DEVICE /dev/hda* /dev/hdc*
67.br
68DEV /dev/sd*
69.br
70DEVICE /dev/discs/disc*/disc
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71.br
72DEVICE partitions
11a3e71d 73
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74.TP
75.B ARRAY
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76The ARRAY lines identify actual arrays. The second word on the line
77should be the name of the device where the array is normally
78assembled, such as
79.BR /dev/md1 .
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80Subsequent words identify the array, or identify the array as a member
81of a group. If multiple identities are given,
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82then a component device must match ALL identities to be considered a
83match. Each identity word has a tag, and equals sign, and some value.
84The tags are:
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85
86.RS 4
87.TP
88.B uuid=
89The value should be a 128 bit uuid in hexadecimal, with punctuation
90interspersed if desired. This must match the uuid stored in the
91superblock.
92.TP
93.B super-minor=
94The value is an integer which indicates the minor number that was
95stored in the superblock when the array was created. When an array is
96created as /dev/mdX, then the minor number X is stored.
97.TP
98.B devices=
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99The value is a comma separated list of device names or device name
100patterns.
101Only devices with names which match one entry in the list will be used
102to assemble the array. Note that the devices
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103listed there must also be listed on a DEVICE line.
104.TP
105.B level=
106The value is a raid level. This is not normally used to
107identify an array, but is supported so that the output of
108
109.B "mdadm --examine --scan"
110
111can be use directly in the configuration file.
112.TP
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113.B num-devices=
114The value is the number of devices in a complete active array. As with
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115.B level=
116this is mainly for compatibility with the output of
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11a3e71d 118.BR "mdadm --examine --scan" .
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119
120.TP
121.B spare-group=
122The value is a textual name for a group of arrays. All arrays with
123the same
124.B spare-group
125name are considered to be part of the same group. The significance of
126a group of arrays is that
127.B mdadm
128will, when monitoring the arrays, move a spare drive from one array in
129a group to another array in that group if the first array had a failed
130or missing drive but no spare.
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131
132.TP
133.B auto=
134This option declares to
135.B mdadm
136that it should try to create the device file of the array if it
137doesn't already exist, or exists but with the wrong device number.
138
139The value of this option can be "yes" or "md" to indicate that a
140traditional, non-partitionable md array should be created, or "mdp",
141"part" or "partition" to indicate that a partitionable md array (only
142available in linux 2.6 and later) should be used. This later set can
143also have a number appended to indicate how many partitions to create
144device files for, e.g.
145.BR auto=mdp5 .
146The default is 4.
11a3e71d 147.RE
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148
149.TP
150.B MAILADDR
151The
152.B mailaddr
153line gives an E-mail address that alerts should be
154sent to when
155.M mdadm
156is running in
157.B --monitor
158mode (and was given the
159.B --scan
160option). There should only be one
161.B MAILADDR
162line and it should have only one address.
163
164
165.TP
166.B PROGRAM
167The
168.B program
169line gives the name of a program to be run when
170.B "mdadm --monitor"
171detects potentially interesting events on any of the arrays that it
172is monitoring. This program gets run with two or three arguments, they
173being the Event, the md device, and possibly the related component
174device.
175
176There should only be one
177.B program
178line and it should be give only one program.
179
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180.SH EXAMPLE
181DEVICE /dev/sd[bcdjkl]1
182.br
183DEVICE /dev/hda1 /dev/hdb1
184
185# /dev/md0 is known by it's UID.
186.br
187ARRAY /dev/md0 UUID=3aaa0122:29827cfa:5331ad66:ca767371
188.br
189# /dev/md1 contains all devices with a minor number of
190.br
191# 1 in the superblock.
192.br
193ARRAY /dev/md1 superminor=1
194.br
195# /dev/md2 is made from precisey these two devices
196.br
197ARRAY /dev/md2 devices=/dev/hda1,/dev/hda2
198
199# /dev/md4 and /dev/md5 are a spare-group and spares
200.br
201# can be moved between them
202.br
203ARRAY /dev/md4 uuid=b23f3c6d:aec43a9f:fd65db85:369432df
204.br
205 spare-group=group1
206.br
207ARRAY /dev/md5 uuid=19464854:03f71b1b:e0df2edd:246cc977
208.br
209 spare-group=group1
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210.br
211# /dev/md/home is created if need to be a partitionable md array
212.br
213# any spare device number is allocated.
214.br
215ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b
216.br
217 auto=part
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218
219MAILADDR root@mydomain.tld
220.br
221PROGRAM /usr/sbin/handle-mdadm-events
222
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56eb10c0 224.SH SEE ALSO
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225.BR mdadm (8),
226.BR md (4).
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