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Old 05-28-2010, 02:39 AM   #1
Sjonnie48
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Registered: Jun 2005
Location: Earth
Distribution: Ubuntu10.04
Posts: 308

Rep: Reputation: 43
Ubuntu10.04. Raid5 array: No md superblock ...


After a system crash caused by faulty memory I detected a problem with my raid array. Nevertheless it works for reading and writing, but I cannot get it mounted at start-up. When I wanted to examine the raid:

Code:
#mdadm -E /dev/md0 
mdadm: No md superblock detected on /dev/md0.
Then I tried:

Code:
#mdadm --detail /dev/md0
/dev/md0:
        Version : 00.90
  Creation Time : Fri Sep  4 12:05:37 2009
     Raid Level : raid5
     Array Size : 2500516864 (2384.68 GiB 2560.53 GB)
  Used Dev Size : 625129216 (596.17 GiB 640.13 GB)
   Raid Devices : 5
  Total Devices : 5
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Fri May 28 09:12:42 2010
          State : clean
 Active Devices : 5
Working Devices : 5
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 64K

           UUID : 8be5b829:959e()e00d:01f9e43d:ac30fbff (local to host server)
         Events : 0.5261

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1
       2       8       33        2      active sync   /dev/sdc1
       3       8       49        3      active sync   /dev/sdd1
       4       8       65        4      active sync   /dev/sde1
So far everything looks fine but there is something wrong with the UUID.
On the position marked with the brackets there is a character missing.
See code below which shows the UUIDs of the five disks in the raid array.

Code:
#blkid -o value -s UUID
8be5b829-959e-e00d-01f9-e43dac30fbff
8be5b829-959e-e00d-01f9-e43dac30fbff
8be5b829-959e-e00d-01f9-e43dac30fbff
8be5b829-959e-e00d-01f9-e43dac30fbff
8be5b829-959e-e00d-01f9-e43dac30fbff
The array is not partitioned and it contains an xfs file system.
I like to know how this problem can be solved.
 
Old 06-01-2010, 04:45 PM   #2
javaunixsolaris
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Registered: Jan 2007
Location: Colorado
Distribution: Kubuntu
Posts: 53

Rep: Reputation: 15
I'm in the middle of investigating a boot problem (not raid) and I think UUID generation might be the culprit, this is on 10.04 as well.
 
  


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mdadm, raid5, xfs



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