Strange Cent OS 5 behaviour on failed software raid device

Rickead2000 · 10-26-2010, 05:46 PM

Hi,

I've got a simple software RAID1 configuration (2x250gb disks) running on Centos 5 where one of the devices appears to have failed.

Whilst the system is continuing to run, the ext3 filesystem on the raid device has been placed into read-only mode. Is this normal behaviour? As one of the devices is still operational I can't see why this should have happened. Can anyone explain what may have caused the OS to do this?

Output from /proc/mdstat is:-

Code:

Personalities : [raid1] 
md1 : active raid1 sdb2[2](F) sda2[0]
      16386176 blocks [2/1] [U_]
      
md0 : active raid1 sdb1[1] sda1[2](F)
      227753408 blocks [2/1] [_U]

Output from mdadm --detail /dev/md0 is:-

Code:

/dev/md0:
        Version : 0.90
  Creation Time : Tue Apr 20 18:20:16 2010
     Raid Level : raid1
     Array Size : 227753408 (217.20 GiB 233.22 GB)
  Used Dev Size : 227753408 (217.20 GiB 233.22 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Sun Oct 24 04:22:01 2010
          State : clean, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 1
  Spare Devices : 0

           UUID : a6b83643:464171e0:476dc2f4:af1f75d0
         Events : 0.3904734

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

       2       8        1        -      faulty spare   /dev/sda1

Thanks

Rickead2000 · 10-26-2010, 05:52 PM

Added info....

The problem must have started on 1st Oct as this is in the /var/log/messages (last output there was)

Oct 1 18:33:58 ndb2 smartd[2932]: Device: /dev/sda, 23 Currently unreadable (pending) sectors
Oct 1 18:33:58 ndb2 smartd[2932]: Device: /dev/sdb, 5 Currently unreadable (pending) sectors
Oct 1 19:03:59 ndb2 smartd[2932]: Device: /dev/sda, 23 Currently unreadable (pending) sectors
Oct 1 19:03:59 ndb2 smartd[2932]: Device: /dev/sdb, 5 Currently unreadable (pending) sectors
Oct 1 19:33:59 ndb2 smartd[2932]: Device: /dev/sda, 23 Currently unreadable (pending) sectors
Oct 1 19:33:59 ndb2 smartd[2932]: Device: /dev/sdb, 5 Currently unreadable (pending) sectors
Oct 1 20:03:58 ndb2 smartd[2932]: Device: /dev/sda, 23 Currently unreadable (pending) sectors
Oct 1 20:03:58 ndb2 smartd[2932]: Device: /dev/sdb, 5 Currently unreadable (pending) sectors
Oct 1 20:34:00 ndb2 smartd[2932]: Device: /dev/sda, 23 Currently unreadable (pending) sectors
Oct 1 20:34:00 ndb2 smartd[2932]: Device: /dev/sdb, 5 Currently unreadable (pending) sectors

Surely both drives can't have failed? And that doesn't tally with the mdadm output which suggests there is only 1 drive faulty