conf/assemble: new config line "auto".

The line 'auto' in mdadm.conf can be used to disable assembly
of specific metadata types, or of all arrays.

This does not affect assembly of arrays listed in mdadm.conf
or on command line.

 auto -all

will disable all auto-assembly.

 auto -ddf

will cause mdadm to ignore ddf arrays that are not explicitly
mentioned, and auto assemble anything else it finds.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 35 insertions, 0 deletions

diff --git a/mdadm.conf.5 b/mdadm.conf.5
index 7654f5f9..f69c0b0f 100644
--- a/mdadm.conf.5
+++ b/mdadm.conf.5
@@ -339,6 +339,39 @@ 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.
 
+.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
 .br
@@ -385,6 +418,8 @@ PROGRAM /usr/sbin/handle\-mdadm\-events
 CREATE group=system mode=0640 auto=part\-8
 .br
 HOMEHOST <system>
+.br
+AUTO +1.x -all
 
 .SH SEE ALSO
 .BR mdadm (8),