[CentOS] Drive recovery?

Wed May 11 01:52:15 UTC 2011
Dag Wieers <dag at wieers.com>

On Tue, 10 May 2011, Ashley M. Kirchner wrote:

> On 5/10/2011 2:00 PM, Ljubomir Ljubojevic wrote:
>> I will byte and actually say it: Use Backups for important data you can
>> not afford to lose. rsync or similar tool can be used via cron to make
>> sure important files are saved.
>     And this is normally done, except I was in the middle of working on
> something when I needed to reboot for non-related reasons.  So for the
> most part I have a backup, but it's about 24 hours behind where I was.
> That's 24 hours I don't necessarily want to lose.

If you finished your dd_rescue/ddrescue copy, you may want to look into 
the testdisk utility to see if somehow the partition-table was not 
tampered with. testdisk can provide you with different layouts based on 
filesystem patterns. And it also saves the original layout so you can 
restore that as well.

Also beware that a complete image includes the partition table, and 
loop-back mounting by default expects the filesystem image. So you may 
have to provide also an offset= option to tell mount where to look for the 
actual filesystem on the image !

If the files on the disk are a common format and the filesystem for some 
reason is nuked, photorec might help recover data from the disk. But 
beware, it may be very time-consuming to restore whatever photorec thinks 
it can identify. For simple digital camera media this works much better 
than a full disk with eg. operating system.

Before trying an fsck on a backup copy, first try an fsck -n and see if 
the output is only minimal or not. Possibly try with different 
superblocks as well. You don't want to have to make another copy just 
because the filesystem is so broken, it can never be restored using fsck.

Good luck, and provide feedback, we might learn a trick or two :)
-- dag wieers, dag at wieers.com, http://dag.wieers.com/
-- dagit linux solutions, info at dagit.net, http://dagit.net/

[Any errors in spelling, tact or fact are transmission errors]