mdadm.conf.5

   1 .TH MDADM.CONF 5
   2 .SH NAME
   3 mdadm.conf \- configuration for management of Software Raid with mdadm
   4 .SH SYNOPSIS
   5 /etc/mdadm.conf
   6 .SH DESCRIPTION
   7 .PP
   8 .B mdadm
   9 is a tool for creating, managing, and monitoring RAID devices using the
  10 .B md
  11 driver in Linux.
  12 .PP
  13 Some common tasks, such as assembling all arrays, can be simplified
  14 by describing the devices and arrays in this configuration file.
  15
  16 .SS SYNTAX
  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.
  21
  22 Any line that starts with white space (space or tab) is treated as
  23 though it were a continuation of the previous line.
  24
  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.
  28
  29 The keywords are:
  30 .TP
  31 .B DEVICE
  32 A
  33 .B device
  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
  36 array,
  37 .B mdadm
  38 will scan these devices (or any devices listed on the command line).
  39
  40 The
  41 .B device
  42 line may contain a number of different devices (separated by spaces)
  43 and each device name can contain wild cards as defined by
  44 .BR glob (7).
  45
  46 Also, there may be several device lines present in the file.
  47
  48 Alternatively, a
  49 .B device
  50 line can contain the word
  51 .BR partitions .
  52 This will cause
  53 .I mdadm
  54 to read
  55 .I /proc/partitions
  56 and include all devices and partitions found there-in.
  57 .I mdadm
  58 does not use the names from
  59 .I /proc/partitions
  60 but only the major and minor device numbers.  It scans
  61 .I /dev
  62 to find the name that matches the numbers.
  63
  64 For example:
  65 .IP
  66 DEVICE /dev/hda* /dev/hdc*
  67 .br
  68 DEV    /dev/sd*
  69 .br
  70 DEVICE /dev/discs/disc*/disc
  71 .br
  72 DEVICE partitions
  73
  74 .TP
  75 .B ARRAY
  76 The ARRAY lines identify actual arrays.  The second word on the line
  77 should be the name of the device where the array is normally
  78 assembled, such as
  79 .BR  /dev/md1 .
  80 Subsequent words identify the array, or identify the array as a member
  81 of a group. If multiple identities are given,
  82 then a component device must match ALL identities to be considered a
  83 match.  Each identity word has a tag, and equals sign, and some value.
  84 The tags are:
  85
  86 .RS 4
  87 .TP
  88 .B uuid=
  89 The value should be a 128 bit uuid in hexadecimal, with punctuation
  90 interspersed if desired.  This must match the uuid stored in the
  91 superblock.
  92 .TP
  93 .B super-minor=
  94 The value is an integer which indicates the minor number that was
  95 stored in the superblock when the array was created. When an array is
  96 created as /dev/mdX, then the minor number X is stored.
  97 .TP
  98 .B devices=
  99 The value is a comma separated list of device names or device name
 100 patterns.
 101 Only devices with names which match one entry in the list will be used
 102 to assemble the array.  Note that the devices
 103 listed there must also be listed on a DEVICE line.
 104 .TP
 105 .B level=
 106 The value is a raid level.  This is not normally used to
 107 identify an array, but is supported so that the output of
 108
 109 .B "mdadm --examine --scan"
 110
 111 can be use directly in the configuration file.
 112 .TP
 113 .B num-devices=
 114 The value is the number of devices in a complete active array.  As with
 115 .B level=
 116 this is mainly for compatibility with the output of
 117
 118 .BR "mdadm --examine --scan" .
 119
 120 .TP
 121 .B spare-group=
 122 The value is a textual name for a group of arrays.  All arrays with
 123 the same
 124 .B spare-group
 125 name are considered to be part of the same group.  The significance of
 126 a group of arrays is that
 127 .B mdadm
 128 will, when monitoring the arrays, move a spare drive from one array in
 129 a group to another array in that group if the first array had a failed
 130 or missing drive but no spare.
 131
 132 .TP
 133 .B auto=
 134 This option declares to
 135 .B mdadm
 136 that it should try to create the device file of the array if it
 137 doesn't already exist, or exists but with the wrong device number.
 138
 139 The value of this option can be "yes" or "md" to indicate that a
 140 traditional, non-partitionable md array should be created, or "mdp",
 141 "part" or "partition" to indicate that a partitionable md array (only
 142 available in linux 2.6 and later) should be used.  This later set can
 143 also have a number appended to indicate how many partitions to create
 144 device files for, e.g.
 145 .BR auto=mdp5 .
 146 The default is 4.
 147 .RE
 148
 149 .TP
 150 .B MAILADDR
 151 The
 152 .B mailaddr
 153 line gives an E-mail address that alerts should be
 154 sent to when
 155 .M mdadm
 156 is running in
 157 .B --monitor
 158 mode (and was given the
 159 .B --scan
 160 option).  There should only be one
 161 .B MAILADDR
 162 line and it should have only one address.
 163
 164
 165 .TP
 166 .B PROGRAM
 167 The
 168 .B program
 169 line gives the name of a program to be run when
 170 .B "mdadm --monitor"
 171 detects potentially interesting events on any of the arrays that it
 172 is monitoring.  This program gets run with two or three arguments, they
 173 being the Event, the md device, and possibly the related component
 174 device.
 175
 176 There should only be one
 177 .B program
 178 line and it should be give only one program.
 179
 180 .SH EXAMPLE
 181 DEVICE /dev/sd[bcdjkl]1
 182 .br
 183 DEVICE /dev/hda1 /dev/hdb1
 184
 185 # /dev/md0 is known by it's UID.
 186 .br
 187 ARRAY /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
 193 ARRAY /dev/md1 superminor=1
 194 .br
 195 # /dev/md2 is made from precisey these two devices
 196 .br
 197 ARRAY /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
 203 ARRAY /dev/md4 uuid=b23f3c6d:aec43a9f:fd65db85:369432df
 204 .br
 205            spare-group=group1
 206 .br
 207 ARRAY /dev/md5 uuid=19464854:03f71b1b:e0df2edd:246cc977
 208 .br
 209            spare-group=group1
 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
 215 ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b
 216 .br
 217            auto=part
 218
 219 MAILADDR root@mydomain.tld
 220 .br
 221 PROGRAM /usr/sbin/handle-mdadm-events
 222
 223
 224 .SH SEE ALSO
 225 .BR mdadm (8),
 226 .BR md (4).
 227