mdadm.conf
MDADM.CONF(5) MDADM.CONF(5)
NAME
mdadm.conf - configuration for management of Software Raid with mdadm
SYNOPSIS
/etc/mdadm.conf
DESCRIPTION
mdadm is a tool for creating, managing, and monitoring RAID devices
using the md driver in Linux.
Some common tasks, such as assembling all arrays, can be simplified by
describing the devices and arrays in this configuration file.
SYNTAX
The file should be seen as a collection of words separated by white
space (space, tab, or newline). Any word that beings with a hash sign
(#) starts a comment and that word together with the remainder of the
line is ignored.
Any line that starts with white space (space or tab) is treated as
though it were a continuation of the previous line.
Empty lines are ignored, but otherwise each (non continuation) line
must start with a keyword as listed below. The keywords are case
insensitive and can be abbreviated to 3 characters.
The keywords are:
DEVICE A device line lists the devices (whole devices or partitions)
that might contain a component of an MD array. When looking
for the components of an array, mdadm will scan these devices
(or any devices listed on the command line).
The device line may contain a number of different devices (sep-
arated by spaces) and each device name can contain wild cards
as defined by glob(7).
Also, there may be several device lines present in the file.
Alternatively, a device line can contain the word partitions.
This will cause mdadm to read /proc/partitions and include all
devices and partitions found there-in. mdadm does not use the
names from /proc/partitions but only the major and minor device
numbers. It scans /dev to find the name that matches the num-
bers.
For example:
DEVICE /dev/hda* /dev/hdc*
DEV /dev/sd*
DEVICE /dev/discs/disc*/disc
DEVICE partitions
ARRAY The ARRAY lines identify actual arrays. The second word on the
line should be the name of the device where the array is nor-
mally assembled, such as /dev/md1. Subsequent words identify
the array, or identify the array as a member of a group. If
multiple identities are given, then a component device must
match ALL identities to be considered a match. Each identity
word has a tag, and equals sign, and some value. The tags are:
uuid= The value should be a 128 bit uuid in hexadecimal, with
punctuation interspersed if desired. This must match the
uuid stored in the superblock.
super-minor=
The value is an integer which indicates the minor number
that was stored in the superblock when the array was cre-
ated. When an array is created as /dev/mdX, then the minor
number X is stored.
devices=
The value is a comma separated list of device names or
device name patterns. Only devices with names which match
one entry in the list will be used to assemble the array.
Note that the devices listed there must also be listed on a
DEVICE line.
level= The value is a raid level. This is not normally used to
identify an array, but is supported so that the output of
mdadm --examine --scan
can be use directly in the configuration file.
num-devices=
The value is the number of devices in a complete active
array. As with level= this is mainly for compatibility
with the output of
mdadm --examine --scan.
spare-group=
The value is a textual name for a group of arrays. All
arrays with the same spare-group name are considered to be
part of the same group. The significance of a group of
arrays is that mdadm will, when monitoring the arrays, move
a spare drive from one array in a group to another array in
that group if the first array had a failed or missing drive
but no spare.
auto= This option declares to mdadm that it should try to create
the device file of the array if it doesn’t already exist,
or exists but with the wrong device number.
The value of this option can be "yes" or "md" to indicate
that a traditional, non-partitionable md array should be
created, or "mdp", "part" or "partition" to indicate that a
partitionable md array (only available in linux 2.6 and
later) should be used. This later set can also have a num-
ber appended to indicate how many partitions to create
device files for, e.g. auto=mdp5. The default is 4.
MAILADDR
The mailaddr line gives an E-mail address that alerts should be
sent to when is running in --monitor mode (and was given the
--scan option). There should only be one MAILADDR line and it
should have only one address.
PROGRAM
The program line gives the name of a program to be run when
mdadm --monitor detects potentially interesting events on any
of the arrays that it is monitoring. This program gets run
with two or three arguments, they being the Event, the md
device, and possibly the related component device.
There should only be one program line and it should be give
only one program.
EXAMPLE
DEVICE /dev/sd[bcdjkl]1
DEVICE /dev/hda1 /dev/hdb1
# /dev/md0 is known by it’s UID.
ARRAY /dev/md0 UUID=3aaa0122:29827cfa:5331ad66:ca767371
# /dev/md1 contains all devices with a minor number of
# 1 in the superblock.
ARRAY /dev/md1 superminor=1
# /dev/md2 is made from precisey these two devices
ARRAY /dev/md2 devices=/dev/hda1,/dev/hdb1
# /dev/md4 and /dev/md5 are a spare-group and spares
# can be moved between them
ARRAY /dev/md4 uuid=b23f3c6d:aec43a9f:fd65db85:369432df
spare-group=group1
ARRAY /dev/md5 uuid=19464854:03f71b1b:e0df2edd:246cc977
spare-group=group1
# /dev/md/home is created if need to be a partitionable md array
# any spare device number is allocated.
ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b
auto=part
MAILADDR root@mydomain.tld
PROGRAM /usr/sbin/handle-mdadm-events
SEE ALSO
mdadm(8), md(4).
MDADM.CONF(5)
