help fixing corrupted RAID array

From: Reuben D. Budiardja (techlist_at_voyager.phys.utk.edu)
Date: 06/21/05

  • Next message: Larry D Sorensen: "Re: Boot disk" 
    To: redhat-list@redhat.com
Date: Tue, 21 Jun 2005 11:11:57 -0400

    Hello,
    I have a machine with software RAID5 enabled. After a power failure, the raid
    wont start, and during booting, this message appears: 

    ---
Starting up RAID devices : raid5 : failed to run raid set md0 
Checking filesystems
/boot : clean, ... 
fsck.ext3 : /dev/md0 :
The superblock could not be read or does not describe a correct ext2 
filesystem. If the device is valid and it really contains an ext2 filesystem 
(and not swap or ufs or something else), then the superblock is corrupt, and 
you might try running e2fsck with an alternate superblock :
e2fsck -b 8193 <device> 
Invalid argument while trying to open /dev/md0  [Failed]
---
In the "repair filesystem" mode, I tried to use "e2fsck /dev/md0" but it gives 
me the same message. I tried running "mke2fs -n /dev/md0" to give me the 
backup superblock and it says that "device size is reported to be zero ... "
I suspect this is because /dev/md0 doesn't actually exists since raidstart 
failed ? 
I tried "mke2fs -n /dev/hde1" to see the individual partitions that make up 
the RAID and it gives me the backup superblock info. But when I feed that to 
e2fsck it complains that the partition is not ext2 (which is correct since 
it's a RAID partition, I thought).
So now I am confused as to what to do. Is there anyway I can recover the data 
in my RAID array ? Below is my /etc/raidtab. Any help is greatly appreciated. 
----------- /etc/raidtab------------
raiddev             /dev/md0
raid-level                  5
nr-raid-disks               3
chunk-size                  64k
persistent-superblock       1
nr-spare-disks              0
    device          /dev/hde1
    raid-disk     0
    device          /dev/hdg1
    raid-disk     1
    device          /dev/hdi1
    raid-disk     2
Thanks.
RDB
-- 
Reuben D. Budiardja
Dept. Physics and Astronomy
University of Tennessee, Knoxville, TN
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