On Thu, 19 Aug 2010 17:00:13 -0400
Joe Landman [off-list ref] wrote:

Hi folks

   Moved an array to a new machine.  For a number or reasons, the arrays 
which were md0 and md1, are now md1 and md2.

   I can force the assembly of the arrays, but can't force them to 
autoassemble, and it looks like the minors are wrong.

  ~ # mdadm --assemble /dev/md2 --update=super-minor  /dev/sdc2 /dev/sde2
mdadm: /dev/md2 has been started with 2 drives.

  ~ # mdadm --assemble --update=super-minor /dev/md1 /dev/sdd2 /dev/sdf2
mdadm: /dev/md1 has been started with 2 drives.

  ~ # mdadm --examine --scan
ARRAY /dev/md/0 metadata=1.0 UUID=6ddbf291:a7344bb6:375a9f38:89b409e9 
name=jr5.scalableinformatics.com:0
ARRAY /dev/md/0 metadata=1.2 UUID=2e8b8744:16f038fa:9c4ba1b1:d4a7ee79 name=0
ARRAY /dev/md/1 metadata=1.2 UUID=04251ae2:ef750917:f71c67b8:152b985b name=1

1.x metadata doesn't store a 'minor number', it stores a name.
So you want
   mdadm --assemble --update=name --name=1 /dev/md1 /dev/sdd2 /dev/sdf2

(assuming you like the name '1' and don't want to use - say - ImportantStuff..

I've made a note to see if I can get '--update=super-minor' to complain when
used on v1.x metadata

NeilBrown

~ # cat /proc/mdstat
Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md1 : active raid0 sdf2[0] sdd2[1]
       14352793600 blocks super 1.2 2048k chunks

md2 : active raid0 sde2[0] sdc2[1]
       1923825664 blocks super 1.2 1024k chunks

md0 : active raid1 sda1[0] sdb1[1]
       26217400 blocks super 1.0 [2/2] [UU]
       bitmap: 0/201 pages [0KB], 64KB chunk

unused devices: <none>

How do I force the md1 and md2 to accept the new minors?  The 
--update=super-minor isn't working on assembly.

Also, for completeness

~ # cat /etc/mdadm.conf
DEVICE containers partitions
ARRAY /dev/md0 UUID=6ddbf291:a7344bb6:375a9f38:89b409e9
name=jr5.scalableinformatics.com:0
ARRAY /dev/md1 metadata=1.2 UUID=2e8b8744:16f038fa:9c4ba1b1:d4a7ee79 name=1
ARRAY /dev/md2 metadata=1.2 UUID=04251ae2:ef750917:f71c67b8:152b985b name=2

~ # mdadm --examine /dev/sdf2
/dev/sdf2:
           Magic : a92b4efc
         Version : 1.2
     Feature Map : 0x0
      Array UUID : 04251ae2:ef750917:f71c67b8:152b985b
            Name : 1
   Creation Time : Sun Feb 15 06:21:14 2009
      Raid Level : raid0
    Raid Devices : 2

  Avail Dev Size : 14352796387 (6843.95 GiB 7348.63 GB)
   Used Dev Size : 0
     Data Offset : 16 sectors
    Super Offset : 8 sectors
           State : active
     Device UUID : 80406a02:959d30ee:9d090fd5:c570c9f7

     Update Time : Sun Feb 15 06:21:14 2009
        Checksum : 5e70dc7e - correct
          Events : 0

      Chunk Size : 2048K

    Device Role : Active device 0
    Array State : AA ('A' == active, '.' == missing)