Any word that beings with a hash sign (#) starts a comment and that
word together with the remainder of the line is ignored.
+Spaces can be included in a word using quotation characters. Either
+single quotes
+.RB ( ' )
+or double quotes (\fB"\fP)
+may be used. All the characters from one quotation character to
+next identical character are protected and will not be used to
+separate words to start new quoted strings. To include a single quote
+it must be between double quotes. To include a double quote it must
+be between single quotes.
+
Any line that starts with white space (space or tab) is treated as
though it were a continuation of the previous line.
Alternatively, a
.B device
-line can contain either of both of the words
+line can contain either or both of the words
.B containers
and
.BR partitions .
.I mdadm
to look for assembled CONTAINER arrays and included them as a source
for assembling further arrays.
-.PP
+
The word
.I partitions
will cause
.br
DEV /dev/sd*
.br
-DEVICE /dev/discs/disc*/disc
+DEVICE /dev/disk/by-path/pci*
.br
DEVICE partitions
The ARRAY lines identify actual arrays. The second word on the line
may be the name of the device where the array is normally
assembled, such as
-.BR /dev/md1 .
+.B /dev/md1
+or
+.BR /dev/md/backup .
+If the name does not start with a slash
+.RB (' / '),
+it is treated as being in
+.BR /dev/md/ .
Alternately the word
.B <ignore>
(complete with angle brackets) can be given in which case any array
which matches the rest of the line will never be automatically assembled.
If no device name is given,
.I mdadm
-will use various heuristic to determine an appropriate name.
-.PP
+will use various heuristics to determine an appropriate name.
+
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:
-
.RS 4
.TP
.B uuid=
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
+to assemble the array. Note that the devices
listed there must also be listed on a DEVICE line.
.TP
.B level=
-The value is a raid level. This is not normally used to
+The value is a RAID level. This is not normally used to
identify an array, but is supported so that the output of
.B "mdadm \-\-examine \-\-scan"
.TP
.B spares=
The value is a number of spare devices to expect the array to have.
+The sole use of this keyword and value is as follows:
.B mdadm \-\-monitor
will report an array if it is found to have fewer than this number of
spares when
.TP
.B auto=
-This option declares to
+This option is rarely needed with mdadm-3.0, particularly if use with
+the Linux kernel v2.6.28 or later.
+It tells
.I 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.
+whether to use partitionable array or non-partitionable arrays and,
+in the absence of
+.IR udev ,
+how many partition devices to create. From 2.6.28 all md array
+devices are partitionable, hence this option is not needed.
The value of this option can be "yes" or "md" to indicate that a
traditional, non-partitionable md array should be created, or "mdp",
value given can be either a path name in /dev, or a UUID of the
container array.
-.IP
+.TP
.B member=
Specify that this array is a member array of some container. Each
type of container has some way to enumerate member arrays, often a
simple sequence number. The value identifies which member of a
-container the array is. It will usually accompany a 'container=' word.
+container the array is. It will usually accompany a "container=" word.
.RE
.TP
.B \-\-scan
option). There should only be one
.B MAILADDR
-line and it should have only one address.
-
+line and it should have only one address. Any subsequent addresses
+are silently ignored.
.TP
.B MAILFROM
.B CREATE
The
.B create
-line gives default values to be used when creating arrays and device entries for
-arrays.
+line gives default values to be used when creating arrays, new members
+of arrays, and device entries for arrays.
These include:
.RS 4
Give
.B symlinks=no
to suppress this symlink creation.
+
+.TP
+.B names=yes
+Since Linux 2.6.29 it has been possible to create
+.B md
+devices with a name like
+.B md_home
+rather than just a number, like
+.BR md3 .
+.I mdadm
+will use the numeric alternative by default as other tools that interact
+with md arrays may expect only numbers.
+If
+.B names=yes
+is given in
+.I mdadm.conf
+then
+.I mdadm
+will use a name when appropriate.
+If
+.B names=no
+is given, then non-numeric
+.I md
+device names will not be used even if the default changes in a future
+release of
+.IR mdadm .
+
+.TP
+.B bbl=no
+By default,
+.I mdadm
+will reserve space for a bad block list (bbl) on all devices
+included in or added to any array that supports them. Setting
+.B bbl=no
+will prevent this, so newly added devices will not have a bad
+block log.
.RE
.TP
The
.B homehost
line gives a default value for the
-.B --homehost=
-option to mdadm. There should be exactly one other word on the line.
-It should either exactly
-.B <system>
-or a host name.
+.B \-\-homehost=
+option to mdadm. There should normally be only one other word on the line.
+It should either be a host name, or one of the special words
+.BR <system>,
+.B <none>
+and
+.BR <ignore> .
If
.B <system>
is given, then the
.BR gethostname ( 2 )
-systemcall is used to get the host name.
-When arrays are created, this host name will be stored in the
-metadata. When arrays are assembled using auto-assembly, only arrays
-with this host name stored in the metadata will be considered.
+systemcall is used to get the host name. This is the default.
+
+If
+.B <ignore>
+is given, then a flag is set so that when arrays are being
+auto-assembled the checking of the recorded
+.I homehost
+is disabled.
+If
+.B <ignore>
+is given it is also possible to give an explicit name which will be
+used when creating arrays. This is the only case when there can be
+more that one other word on the
+.B HOMEHOST
+line. If there are other words, or other
+.B HOMEHOST
+lines, they are silently ignored.
+If
+.B <none>
+is given, then the default of using
+.BR gethostname ( 2 )
+is over-ridden and no homehost name is assumed.
+
+When arrays are created, this host name will be stored in the
+metadata. When arrays are assembled using auto-assembly, arrays which
+do not record the correct homehost name in their metadata will be
+assembled using a "foreign" name. A "foreign" name alway ends with a
+digit string preceded by an underscore to differentiate it
+from any possible local name. e.g.
+.B /dev/md/1_1
+or
+.BR /dev/md/home_0 .
.TP
.B AUTO
A list of names of metadata format can be given, each preceded by a
plus or minus sign. Also the word
+.I homehost
+is allowed as is
+.I all
+preceded by plus or minus sign.
.I all
-preceded by plus or minus is allowed and is usually last.
+is usually last.
When
.I mdadm
-is auto-assembling an array, with via
-.I --assemble
+is auto-assembling an array, either via
+.I \-\-assemble
or
-.I --incremental
+.I \-\-incremental
and it finds metadata of a given type, it checks that metadata type
against those listed in this line. The first match wins, where
.I all
auto assembly is disallowed. If no match is found, the auto assembly
is allowed.
+If the metadata indicates that the array was created for
+.I this
+host, and the word
+.I homehost
+appears before any other match, then the array is treated as a valid
+candidate for auto-assembly.
+
This can be used to disable all auto-assembly (so that only arrays
explicitly listed in mdadm.conf or on the command line are assembled),
or to disable assembly of certain metadata types which might be
-handled by other software.
+handled by other software. It can also be used to disable assembly of
+all foreign arrays - normally such arrays are assembled but given a
+non-deterministic name in
+.BR /dev/md/ .
The known metadata types are
.BR 0.90 ,
.BR ddf ,
.BR imsm .
+.B AUTO
+should be given at most once. Subsequent lines are silently ignored.
+Thus an earlier config file in a config directory will over-ride
+the setting in a later config file.
+
+.TP
+.B POLICY
+This is used to specify what automatic behavior is allowed on devices
+newly appearing in the system and provides a way of marking spares that can
+be moved to other arrays as well as the migration domains.
+.I Domain
+can be defined through
+.I policy
+line by specifying a domain name for a number of paths from
+.BR /dev/disk/by-path/ .
+A device may belong to several domains. The domain of an array is a union
+of domains of all devices in that array. A spare can be automatically
+moved from one array to another if the set of the destination array's
+.I domains
+contains all the
+.I domains
+of the new disk or if both arrays have the same
+.IR spare-group .
+
+To update hot plug configuration it is necessary to execute
+.B mdadm \-\-udev\-rules
+command after changing the config file
+
+Key words used in the
+.I POLICY
+line and supported values are:
+
+.RS 7
+.TP
+.B domain=
+any arbitrary string
+.TP
+.B metadata=
+0.9 1.x ddf or imsm
+.TP
+.B path=
+file glob matching anything from
+.B /dev/disk/by-path
+.TP
+.B type=
+either
+.B disk
+or
+.BR part .
+.TP
+.B action=
+include, re-add, spare, spare-same-slot, or force-spare
+.TP
+.B auto=
+yes, no, or homehost.
+
+.P
+The
+.I action
+item determines the automatic behavior allowed for devices matching the
+.I path
+and
+.I type
+in the same line. If a device matches several lines with different
+.I actions
+then the most permissive will apply. The ordering of policy lines
+is irrelevant to the end result.
+.TP
+.B include
+allows adding a disk to an array if metadata on that disk matches that array
+.TP
+.B re\-add
+will include the device in the array if it appears to be a current member
+or a member that was recently removed and the array has a
+write-intent-bitmap to allow the
+.B re\-add
+functionality.
+.TP
+.B spare
+as above and additionally: if the device is bare it can
+become a spare if there is any array that it is a candidate for based
+on domains and metadata.
+.TP
+.B spare\-same\-slot
+as above and additionally if given slot was used by an array that went
+degraded recently and the device plugged in has no metadata then it will
+be automatically added to that array (or it's container)
+.TP
+.B force\-spare
+as above and the disk will become a spare in remaining cases
+.RE
+
.SH EXAMPLE
DEVICE /dev/sd[bcdjkl]1
.br
ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b
.br
auto=part
-
+.br
+# The name of this array contains a space.
+.br
+ARRAY /dev/md9 name='Data Storage'
+.sp
+POLICY domain=domain1 metadata=imsm path=pci-0000:00:1f.2-scsi-*
+.br
+ action=spare
+.br
+POLICY domain=domain1 metadata=imsm path=pci-0000:04:00.0-scsi-[01]*
+.br
+ action=include
+.br
+# One domain comprising of devices attached to specified paths is defined.
+.br
+# Bare device matching first path will be made an imsm spare on hot plug.
+.br
+# If more than one array is created on devices belonging to domain1 and
+.br
+# one of them becomes degraded, then any imsm spare matching any path for
+.br
+# given domain name can be migrated.
+.br
MAILADDR root@mydomain.tld
.br
PROGRAM /usr/sbin/handle\-mdadm\-events
.br
HOMEHOST <system>
.br
-AUTO +1.x -all
+AUTO +1.x homehost \-all
.SH SEE ALSO
.BR mdadm (8),
.BR md (4).
-
projects / thirdparty / mdadm.git / blobdiff