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BinWondrin 08-08-2009 02:03 PM

Failed HD in Raid0 - which drive failed?
 
I have a failed drive in a software raid-0 assembly. (Fedora release 10 (Cambridge))
I re-added the drive just in case the failure was only a glitch but it failed again a day later.
My raid device is called md0.
The 2 physical drives are sdb1 and sdc1.
When both drives are attached I get a msg that sdc1 has failed.
Question:
- Which drive is sdc?
I detached one drive, booted the machine and it now had only sdb in the array.
Aha, I thought. Let's now swap, detach the current drive and re-add the other one.
Again the system tells me that only sdb is attached.
In both cases the (half) array mounted fine and showed no problems other than a missing drive.
It would be too easy if one of 2 drives was completely dead.

Code:

# mdadm --detail /dev/md0
/dev/md0:
        Version : 0.90
  Creation Time : Tue Jan 20 22:55:07 2009
    Raid Level : raid1
    Array Size : 976759936 (931.51 GiB 1000.20 GB)
  Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
  Raid Devices : 2
  Total Devices : 1
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Sat Aug  8 11:46:09 2009
          State : clean, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

          UUID : b73ecca5:fbea15e3:5014ed2a:67ac9dea
        Events : 0.80080

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

When I run the command with the other drive the output is identical except for the last part:
Code:

          UUID : b73ecca5:fbea15e3:5014ed2a:67ac9dea
        Events : 0.85072

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

So, the question after this looong text (sorry) is, how do I identify the bad disk?
When both disks are attached it identifies /dev/sdc1 as the failed disk.
Which disk is sdc?
Also, is there some way to test if the disk is really bad?

Thanks in advance,

BinWondrin

BinWondrin 08-08-2009 06:24 PM

O.K.
I think, I figured out one possible way.
fdisk gives me an identifier for the actual physical disk:

Quote:

Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000d7a65


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