Data recovery emergency on a downed server... Help please!!

[Robert Brockway]

On Mon, 29 Dec 2003, Madison Kelly wrote:

Hi Maddy.  I hope you got some sleep last night...

> I know that backups of the superblock are made, do you know by chance how
> to locate them and/or how to tell the OS to use one for mounting? Also, at

No one mentioned this (and I didn't read TLUG yesterday) so here it is:

/sbin/dumpe2fs /dev/hdxy (where xy is a1, b2, etc) will give you this
info.  There is quite a lot of output so redirect it to a file and read it
with less, eg:

/sbin/dumpe2fs /dev/hde3 > /tmp/hde3.info

Search for the word "Superblock"

Now, take that number and use it with e2fsck -b,

Eg I have "Superblock at 163840" listed for /dev/hde3, so I could try:

e2fsck -b 163840 /dev/hde3.

Remember to only work on backup copies! See below.

> least two partitions on the drive have gone bad...

Different filesystems (partitions) being bad makes it far less likely it
is a filesystem problem.

Also, the use of dd was mentioned.  This is good but there is no need to
write it to a physical drive.  You can write the dd to a file and mount it
using loopback and attempt recovery on that.  As long as you keep a good
copy of the filesystem file around you can keep trying things over and
over on copies.

Good luck.

Rob

-- 
Robert Brockway
Senior Technical Consultant, OpenTrend Solutions Ltd.
Phone: 416-669-3073, Email: rbrockway-wgAaPJgzrDxH4x6Dk/4f9A at public.gmane.org, http://www.opentrend.net
OpenTrend Solutions: Reliable, secure solutions to real world problems.
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