 | | | help fixing corrupted RAID array | help fixing corrupted RAID array 2005-06-23 - By Naoki
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Hi,
Because it's raid 5 the file system is spread over the disks, so you
can't mount one of them ( unlike if it was a mirror which would have a
full copy of the FS ).
So you need to get the three disks to play nice together..
I'm not suggesting you try this without first assessing it yourself but
here are some tools :
"ckraid" I guess like a fsck for raid 3/5 devices.
"mdadm --assemble --force" this will try and get your superblocks back
in sync.
"mkraid /dev/md0 --force-resync --really-force" seems to be the
recommendation with the newer raid tools.
"mdadm --force" this will rewrite the raid superblocks but be warned, if
the disk ordering /device names is different for any reason it will blow
away your data.
All info ripped from :
http://www.tldp.org/HOWTO/Software-RAID-HOWTO-8.html#ss8.1
and
http://www.linux.com/howtos/Software-RAID-0.4x-HOWTO-4.shtml
Just sorry I don't have one I can test on.
On Wed, 2005-06-22 at 06:31 -0400, Reuben D. Budiardja wrote:
> 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
>
...............................................................................
.......
Mark "Naoki" Rogers /VP - Systems Engineering
Systems
ValueCommerce Co., Ltd.
Tokyo Bldg 4F 3-32-7 Hongo Bunkyo-ku Tokyo 113-0033 Japan
Tel. +81.3.3817.8995 Fax. +81.3.3812.4051
mailto:naoki@(protected)
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