[SWLUG] RAID Array data recovery

[justin]

On Thu, 2009-09-24 at 21:55 +0100, Matthew Moore wrote:
> justin wrote:
> > On Thu, 2009-09-24 at 21:30 +0100, Matthew Moore wrote:
> >> Hi all,
> >>
> >> I've been having a few problems with my RAID 5 array this evening.  The
> >> array is three 500gb drives in a RAID 5 config, using MDADM.  /dev/sdb.
> >> /dev/sdc & /dev/sdd and the array is /dev/md0.  This morning in a bit of
> >> a hurry I forced a power down, which seems to have corrupted the
> >> superblock of the array.  I've been unable to create a backup superblock
> >> (e2fsck -b 32768 /dev/md0) and /dev/sdd doesn't have a valid partition
> >> table.  So while the array runs fine, it won't mount.  I've tried to
> >> create a new Raid autodetect partition on /dev/sdd, but that doesn't
> >> seem to work.  So in rough order I've done:
> > 
> > you have added whole disk devices to the array, none of them will have
> > valid partition tables as youve used whole disks not partitons within
> > the disks.  any partition table you can see is an artefact.
> > 
> > does md0 appear to have a valid partition table ?
> > if it does then that might be why you cant fsck it, because the
> > filesystem doesnt appear at the start of the disk, you have to access
> > the sub partiton of it,  is there a /dev/md0p1 or similar ?
> > 
> > or did you put LVM on md0 ?  (try pvdisplay)
> > 
> 
> root at hugh:/home/matt# fdisk -l /dev/md0
> 
> Disk /dev/md0: 1000.2 GB, 1000215543808 bytes
> 255 heads, 63 sectors/track, 121602 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> 
>     Device Boot      Start         End      Blocks   Id  System
> /dev/md0p1               1       60801   488384001   fd  Linux raid
> autodetect
> 
> Which is odd, as it ought to be a ext3 partition.  Is it possible to
> recover the ext3 partition that is on there?
try fsck and/or mounting the device it says there, see if thats where
you ext3 partiton has gone.

the partition type label shouldnt affect the commands.


> Haven't used LVM at all.
oh good as that tends to make things worse.


if all else fails and you cant find a valid filesystem then there are
some free forensics tools around that will search a raw block device for
the tell-tale signatures of certain file types and try to recover them