----- Message from sredfern@gmail.com ---------
     Date: Mon, 22 Oct 2007 21:46:08 +1000
     From: Sam Redfern [off-list ref]
Reply-To: Sam Redfern [off-list ref]
  Subject: Fwd: issues rebuilding raid array.
       To: linux-raid@vger.kernel.org

The array was build using 2.6.18-7 Now i'm using  2.6.21-2

I'm trying to recreate the raid array with the following command and
this is the error I get:

mca4:~# mdadm -Av /dev/md1 /dev/sdb /dev/sdc /dev/sdd /dev/sde
/dev/sdf /dev/sdg
mdadm: looking for devices for /dev/md1
mdadm: no RAID superblock on /dev/sdc
mdadm: /dev/sdc has no superblock - assembly aborted

So I figure, oh look the disk sdc has gone cactus, I'll just remove it
from the list. One of the advantages of mdadm.

mca4:~# mdadm -Av /dev/md1 /dev/sdb /dev/sdd /dev/sde /dev/sdf /dev/sdg
mdadm: looking for devices for /dev/md1
mdadm: /dev/sdb is identified as a member of /dev/md1, slot -1.
mdadm: /dev/sdd is identified as a member of /dev/md1, slot 0.
mdadm: /dev/sde is identified as a member of /dev/md1, slot 1.
mdadm: /dev/sdf is identified as a member of /dev/md1, slot 5.
mdadm: /dev/sdg is identified as a member of /dev/md1, slot 4.
mdadm: added /dev/sde to /dev/md1 as 1
mdadm: no uptodate device for slot 2 of /dev/md1
mdadm: no uptodate device for slot 3 of /dev/md1
mdadm: added /dev/sdg to /dev/md1 as 4
mdadm: added /dev/sdf to /dev/md1 as 5
mdadm: failed to add /dev/sdb to /dev/md1: Invalid argument
mdadm: added /dev/sdd to /dev/md1 as 0
mdadm: /dev/md1 assembled from 4 drives - not enough to start the array.

If found this really difficult to understand considering that I can
get the output of mdamd -E /dev/sdb (other disks included to overload
you with information)

mdadm -E /dev/sd[b-h]

/dev/sdb:
          Magic : a92b4efc
        Version : 00.90.00
           UUID : 4e3b82e1:f5604e19:a9c9775f:49745adf
  Creation Time : Fri Oct  5 09:18:25 2007
     Raid Level : raid5
    Device Size : 312571136 (298.09 GiB 320.07 GB)
     Array Size : 1562855680 (1490.46 GiB 1600.36 GB)
   Raid Devices : 6
  Total Devices : 6
Preferred Minor : 1

    Update Time : Tue Oct 16 20:03:13 2007
          State : clean
 Active Devices : 6
Working Devices : 6
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 80d47486 - correct
         Events : 0.623738

         Layout : left-symmetric
     Chunk Size : 64K

      Number   Major   Minor   RaidDevice State
this     6       8       16       -1      spare   /dev/sdb

   0     0       8       80        0      active sync   /dev/sdf
   1     1       8      128        1      active sync   /dev/.static/dev/sdi
   2     2       8      144        2      active sync   /dev/.static/dev/sdj
   3     3       8       16        3      active sync   /dev/sdb
   4     4       8       64        4      active sync   /dev/sde
   5     5       8       96        5      active sync   /dev/sdg

If anyone could offer a solution I'd be forever grateful, also to
prove that supporting open source isn't all free labour I'll send you
can choose one of 1 of 2 Nintendo DS games, the new radiohead album or
a cree flash light. :)

----- End message from sredfern@gmail.com -----

Hey, this looks similar to what I recently had.  
(http://www.mail-archive.com/linux-raid@vger.kernel.org/msg09306.html)
I my case a RAID5 reshape was interrupted and the new devices were  
also marked spare with slot -1.
Apply the attached patch to mdadm-2.6.3, build then do:
  mdadm -S /dev/md1
  ./mdadm -Av /dev/md1 --update=this /dev/sd[b-g]
That should update the slot on /dev/sdb. Then:
  mdadm -S /dev/md1
  ./mdadm -Av /dev/md1 /dev/sd[bcdefg]

should bring back your array in degraded mode.
If it works send your gifts to Neil Brown [off-list ref], he wrote  
the patch! :)
Good luck!


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