ext3 corrupted

[Lennart Sorensen]

On Mon, Jul 23, 2007 at 09:32:38AM -0400, Madison Kelly wrote:
> These are good suggestions, specially the 'dd' one.
> 
> One trouble with any journaled file system is that data recovery is very 
> difficult. An ext2 partition is simple to recover, by comparison. It's 
> to the point now where if I have an ext3 (or other journaled) FS, I get 
> paranoid about backups. My personal view/experience is that it's just 
> not possible, but I am also not an expert.
> 
> I would suggest that, if your data is critical, do not attempt anything 
> beyond the 'dd' yourself.
> 
> Ontrack (http://www.ontrackdatarecovery.com/ontrack) was the DR house 
> I've used in the past. They're very talented, and recovered a physically 
> defective drive a client had (whose tape backup had silently failed, 
> ending my trust of tape backups ever since). I believe it was about 
> $1,700 and they were unable to recover the directory structure, but all 
> the data was there. It took about two more days to recreate the 
> directory structure, but in the end we got all the data back. I believe 
> they will look at your drive and give you an idea of the likely hood of 
> recovering your data before doing billable work. At least they did back 
> when I last needed them.
> 
> I would *only* suggest trying anything further on your defective disk if 
> you get a quote from them (or another DR house) and you decide it's too 
> expensive (ie: 'nothing to lose'). If you do manage to make a dd image, 
> try doing data recovery on a copy of the image. You really do not want 
> to touch the source drive *any* more than you have to.
> 
> I wish I had better news. :( Journaling is a double-edged sword.

Any time you are trying to recover data, the first thing you do is make
a raw copy of the device to an image somewhere else.  Then you put the
original device away and don't touch it anymore.

You then copy the image onto a spare device, and do your filesystem
recovery there.  If you screw up, copy the image to the device again.

You should never mess with the original data since you may end up
causing more harm than good with one of your attemps, and then you can't
try again with something else because you already ruined what you had
left.

--
Len Sorensen
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