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.
+will use various heuristics to determine an appropriate name.
.PP
Subsequent words identify the array, or identify the array as a member
of a group. If multiple identities are given,
.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",
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
+It should either be a host name, or one of the special words
.B <system>
-or a host name.
+and
+.BR <ignore> .
If
.B <system>
is given, then the
.BR gethostname ( 2 )
systemcall is used to get the host name.
+
+If
+.B <ignore>
+is given, then a flag is set so that when arrays are being
+auto-assemble the checking of the recorded
+.I homehost
+is disabled.
+
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.
+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 (possibly preceded by an underscore) to differentiate it
+from any possible local name. e.g.
+.B /dev/md/1_1
+or
+.BR /dev/md/home0 .
+.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 all
+preceded by plus or minus is allowed and is usually last.
+
+When
+.I mdadm
+is auto-assembling an array, with via
+.I --assemble
+or
+.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
+matches anything.
+If a match is found that was preceded by a plus sign, the auto
+assembly is allowed. If the match was preceded by a minus sign, the
+auto assembly is disallowed. If no match is found, the auto assembly
+is allowed.
+
+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.
+
+The known metadata types are
+.BR 0.90 ,
+.BR 1.x ,
+.BR ddf ,
+.BR imsm .
.SH EXAMPLE
DEVICE /dev/sd[bcdjkl]1
CREATE group=system mode=0640 auto=part\-8
.br
HOMEHOST <system>
+.br
+AUTO +1.x -all
.SH SEE ALSO
.BR mdadm (8),
projects / thirdparty / mdadm.git / blobdiff