On Sun, Aug 06, 2006 at 09:41:39AM +0200, Geert Uytterhoeven wrote:
> > I've had quite good luck doing poor man's data recovery.  Boot the
> > machine into Knoppix or like ilk and use dd_rescue to copy the disk to
> > an image file or another disk.  dd_rescue is smart about skipping
> > areas of the disk it cannot read instead of giving up.  It can take a
> > long time, but I've recovered quite a bit of data with that sucker.
> 
> But this simple methods won't work, as the disk used to be part of a RAID0
> setup, and thus contains only half of the data. Then it depends on the stripe
> size: the larger it is, the more likely you can find useful pieces of data
> (e.g. a complete password or credit card number).

Well, no reason you couldn't apply this principle to the RAID0 data.
Suppose your disks are /dev/sda1 and /dev/sdb1, sdb has failed:

# dd_rescue /dev/sdb1 some_file_or_device
(wait a long time)
(if you're using a file # losetup /dev/loop/0 some_file)
# mdadm --assemble /dev/md0 /dev/sda1 /dev/whatever

If the superblock of the second disk is intact, mdadm should be able
to assemble the array with no problems.  Of course you'll run into
files with corrupt data, as you know one half of the stuff is damaged.
If you're unlucky, the filesystem data was damaged and you'll have
either lost everything or will need to run fsck...


-- 
Ross Vandegrift
ross AT kallisti DOT us

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
        --St. Augustine, De Genesi ad Litteram, Book II, xviii, 37