mdadm.conf - configuration for management of Software Raid with mdadm
is a tool for creating, managing, and monitoring RAID devices using the
driver in Linux.
Some common tasks, such as assembling all arrays, can be simplified
by describing the devices and array in this configuation file.
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 are ignored.
Any line that start 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 key words are case
insensitve and can be abbreviated to 3 characters.
The keywords are:
line lists the devices (whole devices or partitions) that might contain
a component of an MD array. When looking for the components of an
will scan these devices and no others.
line may contain a number of different devices (separated by spaces)
and each device name can contain wild cards as defined by
Also, there may be several device lines present in the file.
DEVICE /dev/hda* /dev/hdc*
The ARRAY lines identify actual arrays. The second word on the line
should be the name of the device where the array is normally
assembled, such as
Subsequent words identify the array. If multiple identities are given,
then the array must match ALL identities to be considered a match.
Each identity word has a tag, and equals sign, and some value.
The options are:
The value should be a 128 bit uuid in hexadecimal, with punctuation
interspersed if desired. This must match the uuid stored in the
The value is an integer which indicates the minor number that was
stored in the superblock when the array was created. When an array is
created as /dev/mdX, then the minor number X is stored.
The value is a comma separated list of device names. Precisely these
devices will be used to assemble the array. Note that the devices
listed there must also be listed on a DEVICE line.
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.
The value is the number of disks in a complete active array. As with
this is mainly for compatibility with the output of