CentOS - Jun 2012 - mdadm: failed to write superblock to

Hello,

i have a little problem. Our server has an broken RAID.

# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sda1[2](F) sdb1[1]
       2096064 blocks [2/1] [_U]

md2 : active raid1 sda3[2](F) sdb3[1]
       1462516672 blocks [2/1] [_U]

md1 : active raid1 sda2[0] sdb2[1]
       524224 blocks [2/2] [UU]

unused devices: <none>


I have remove the partition:

# mdadm --remove /dev/md0 /dev/sda1
mdadm: hot removed /dev/sda1 from /dev/md0

# mdadm --remove /dev/md2 /dev/sda3
mdadm: hot removed /dev/sda3 from /dev/md2


Now i want to add the old partition (to sync the raid), unfortunately, 
comes an error message:
# mdadm --add /dev/md0 /dev/sda1
mdadm: failed to write superblock to /dev/sda1


What is wrong here? Here some more details:

# mdadm --detail /dev/md0
/dev/md0:
         Version : 0.90
   Creation Time : Fri Sep  2 12:38:17 2011
      Raid Level : raid1
      Array Size : 2096064 (2047.28 MiB 2146.37 MB)
   Used Dev Size : 2096064 (2047.28 MiB 2146.37 MB)
    Raid Devices : 2
   Total Devices : 1
Preferred Minor : 0
     Persistence : Superblock is persistent

     Update Time : Thu Jun  7 08:57:12 2012
           State : clean, degraded
  Active Devices : 1
Working Devices : 1
  Failed Devices : 0
   Spare Devices : 0

            UUID : 9beaf2eb:4b5c7416:776c2c25:004bd7b2
          Events : 0.147

     Number   Major   Minor   RaidDevice State
        0       0        0        0      removed
        1       8       17        1      active sync   /dev/sdb1


Thanks Sebastian

Am 07.06.2012 09:48, schrieb sebastian:
> # cat /proc/mdstat
> Personalities : [raid1]
> md0 : active raid1 sda1[2](F) sdb1[1]
>        2096064 blocks [2/1] [_U]
> 
> md2 : active raid1 sda3[2](F) sdb3[1]
>        1462516672 blocks [2/1] [_U]
> 
> md1 : active raid1 sda2[0] sdb2[1]
>        524224 blocks [2/2] [UU]
> 
> unused devices: <none>
> 
> 
> I have remove the partition:
> 
> # mdadm --remove /dev/md0 /dev/sda1
> mdadm: hot removed /dev/sda1 from /dev/md0
> 
> # mdadm --remove /dev/md2 /dev/sda3
> mdadm: hot removed /dev/sda3 from /dev/md2
> 
> 
> Now i want to add the old partition (to sync the raid), unfortunately, 
> comes an error message:
> # mdadm --add /dev/md0 /dev/sda1
> mdadm: failed to write superblock to /dev/sda1
> 
> 
> What is wrong here?
Looks like a hardware defect to me. That's probably also the reason
why the RAID went degraded in the first place. Better replace that
disk while the other one still holds the line.

HTH
T.

-- 
Tilman Schmidt
Phoenix Software GmbH
Bonn, Germany