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 name=
  94 The value should be a simple textual name as was given to
  95 .I mdadm
  96 when the array was created.  This must match the name stored in the
  97 superblock on a device for that device to be included in the array.
  98 Not all superblock-formats support names.
  99 .TP
 100 .B super-minor=
 101 The value is an integer which indicates the minor number that was
 102 stored in the superblock when the array was created. When an array is
 103 created as /dev/mdX, then the minor number X is stored.
 104 .TP
 105 .B devices=
 106 The value is a comma separated list of device names or device name
 107 patterns.
 108 Only devices with names which match one entry in the list will be used
 109 to assemble the array.  Note that the devices
 110 listed there must also be listed on a DEVICE line.
 111 .TP
 112 .B level=
 113 The value is a raid level.  This is not normally used to
 114 identify an array, but is supported so that the output of
 115
 116 .B "mdadm --examine --scan"
 117
 118 can be use directly in the configuration file.
 119 .TP
 120 .B num-devices=
 121 The value is the number of devices in a complete active array.  As with
 122 .B level=
 123 this is mainly for compatibility with the output of
 124
 125 .BR "mdadm --examine --scan" .
 126
 127 .TP
 128 .B spare-group=
 129 The value is a textual name for a group of arrays.  All arrays with
 130 the same
 131 .B spare-group
 132 name are considered to be part of the same group.  The significance of
 133 a group of arrays is that
 134 .B mdadm
 135 will, when monitoring the arrays, move a spare drive from one array in
 136 a group to another array in that group if the first array had a failed
 137 or missing drive but no spare.
 138
 139 .TP
 140 .B auto=
 141 This option declares to
 142 .B mdadm
 143 that it should try to create the device file of the array if it
 144 doesn't already exist, or exists but with the wrong device number.
 145
 146 The value of this option can be "yes" or "md" to indicate that a
 147 traditional, non-partitionable md array should be created, or "mdp",
 148 "part" or "partition" to indicate that a partitionable md array (only
 149 available in linux 2.6 and later) should be used.  This later set can
 150 also have a number appended to indicate how many partitions to create
 151 device files for, e.g.
 152 .BR auto=mdp5 .
 153 The default is 4.
 154
 155 .TP
 156 .B bitmap=
 157 The option specifies a file in which a write-intent bitmap should be
 158 found.  When assembling the array,
 159 .I mdadm
 160 will provide this file to the
 161 .B md
 162 driver as the bitmap file.  This has the same function as the
 163 .B --bitmap-file
 164 option to
 165 .BR --assemble .
 166 .RE
 167
 168 .TP
 169 .B MAILADDR
 170 The
 171 .B mailaddr
 172 line gives an E-mail address that alerts should be
 173 sent to when
 174 .M mdadm
 175 is running in
 176 .B --monitor
 177 mode (and was given the
 178 .B --scan
 179 option).  There should only be one
 180 .B MAILADDR
 181 line and it should have only one address.
 182
 183
 184 .TP
 185 .B PROGRAM
 186 The
 187 .B program
 188 line gives the name of a program to be run when
 189 .B "mdadm --monitor"
 190 detects potentially interesting events on any of the arrays that it
 191 is monitoring.  This program gets run with two or three arguments, they
 192 being the Event, the md device, and possibly the related component
 193 device.
 194
 195 There should only be one
 196 .B program
 197 line and it should be give only one program.
 198
 199 .SH EXAMPLE
 200 DEVICE /dev/sd[bcdjkl]1
 201 .br
 202 DEVICE /dev/hda1 /dev/hdb1
 203
 204 # /dev/md0 is known by it's UID.
 205 .br
 206 ARRAY /dev/md0 UUID=3aaa0122:29827cfa:5331ad66:ca767371
 207 .br
 208 # /dev/md1 contains all devices with a minor number of
 209 .br
 210 #   1 in the superblock.
 211 .br
 212 ARRAY /dev/md1 superminor=1
 213 .br
 214 # /dev/md2 is made from precisey these two devices
 215 .br
 216 ARRAY /dev/md2 devices=/dev/hda1,/dev/hdb1
 217
 218 # /dev/md4 and /dev/md5 are a spare-group and spares
 219 .br
 220 #  can be moved between them
 221 .br
 222 ARRAY /dev/md4 uuid=b23f3c6d:aec43a9f:fd65db85:369432df
 223 .br
 224            spare-group=group1
 225 .br
 226 ARRAY /dev/md5 uuid=19464854:03f71b1b:e0df2edd:246cc977
 227 .br
 228            spare-group=group1
 229 .br
 230 # /dev/md/home is created if need to be a partitionable md array
 231 .br
 232 # any spare device number is allocated.
 233 .br
 234 ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b
 235 .br
 236            auto=part
 237
 238 MAILADDR root@mydomain.tld
 239 .br
 240 PROGRAM /usr/sbin/handle-mdadm-events
 241
 242
 243 .SH SEE ALSO
 244 .BR mdadm (8),
 245 .BR md (4).
 246