Datavolume doesn't exist ! message

Well, it’s not looking good.

Twice now it’s failed during the rebuild process, leaving me with:

~ $ mdadm -D /dev/md2
/dev/md2:
        Version : 00.90.01
  Creation Time : Fri Apr  3 13:54:17 2009
     Raid Level : raid5
     Array Size : 5854981248 (5583.75 GiB 5995.50 GB)
    Device Size : 1951660416 (1861.25 GiB 1998.50 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 2
    Persistence : Superblock is persistent

    Update Time : Fri Apr 29 14:17:52 2011
          State : clean, degraded
 Active Devices : 2
Working Devices : 3
 Failed Devices : 1
  Spare Devices : 1

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : b2c561ae:9acfcff0:2594d787:fb4eb047
         Events : 0.4283852

    Number   Major   Minor   RaidDevice State
       0       8        4        0      active sync   /dev/sda4
       1       0        0        1      removed
       2       8       36        2      active sync   /dev/sdc4
       3       0        0        3      removed

       4       8       20        -      spare   /dev/sdb4
       5       8       52        -      faulty spare   /dev/sdd4

Any suggestions (and thanks for the typo pickup earlier…)