While I couldn't find out how or why this happened, I did find the way 
to 'repair':

|mdadm --grow -n X /dev/md1|

Where 'X'  is the actual number of devices in my array.

    Regards, Danilo







On 11/18/2011 08:45 AM, Danilo Godec wrote:

I have three hard drives in my machine and on installation, I 
configured two 3-partition RAID1 arrays for /boot and /. The third 
array is a RAID3 and this one is OK.

Somehow both RAID1 arrays are now 'degraded' with three devices active 
and one 'removed':

quoted

/dev/md0:
        Version : 1.0
  Creation Time : Mon May 23 11:33:58 2011
     Raid Level : raid1
     Array Size : 530100 (517.76 MiB 542.82 MB)
  Used Dev Size : 530100 (517.76 MiB 542.82 MB)
   Raid Devices : 4
  Total Devices : 3
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Fri Nov 18 08:36:11 2011
          State : active, degraded
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

           Name : linux:0
           UUID : be28253b:04ef7513:53ddc8e4:4417a480
         Events : 751

    Number   Major   Minor   RaidDevice State
       0       8       33        0      active sync   /dev/sdc1
       1       0        0        1      removed
       2       8        1        2      active sync   /dev/sda1
       3       8       17        3      active sync   /dev/sdb1

quoted

/dev/md2:
        Version : 1.0
  Creation Time : Mon May 23 11:34:06 2011
     Raid Level : raid1
     Array Size : 41945640 (40.00 GiB 42.95 GB)
  Used Dev Size : 41945640 (40.00 GiB 42.95 GB)
   Raid Devices : 4
  Total Devices : 3
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Fri Nov 18 08:43:32 2011
          State : active, degraded
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

           Name : linux:2
           UUID : 3889bec9:12aa98b3:81df75b8:c87832bc
         Events : 66961

    Number   Major   Minor   RaidDevice State
       0       8       35        0      active sync   /dev/sdc3
       1       0        0        1      removed
       2       8        3        2      active sync   /dev/sda3
       3       8       19        3      active sync   /dev/sdb3

Can this be resolved without re-creating the array?


  Danilo