RAID 5 - serious problem

[Dieter]

> FreeBSD 7.0-Release
> Intel D975XBX2 motherboard (Intel Matrix Storage Technology)
> 3 WD Raptor 74 GB in a RAID 5 array
> 1 WD Raptor 150 GB as a standalone disk
> / and /var mounted on the standalone,, /usr on the RAID 5
> I believe what happened was that one of the disks didn't respond for such a
> long time, that is was marked "bad". And afterwards the same thing happened
> for the other disks. When I try to boot the system, all three disks are
> marked "Offline".

> I am very desperate not to lose my data,

In that case, step one is to use dd(1) to make a bit-for-bit copy of the
three drives to some trusted media.  Since they are marked bad/offline,
you might need to move them to a controller that doesn't know anything
about RAID.  (Note that there is risk here, and in almost anything you do
at this point.)  Once you have this bit-for-bit backup, you can run any
experiment you like to attempt to recover your data.  If the experiment
goes bad, you can dd the exact original contents back using dd, then
try a different experiment.  While you're at it, make a normal backup
using dump(8) or whatever you normally use, of / and /var.  Once you have
*everything* backed up, you can do risky experiments like booting linux.

My personal approach to avoiding data loss is (a) avoid buggy things like
inthell and linux. (b) FFS with softdeps and the disk write cache turned off,
(c) full backups.  I don't have enough ports to run RAID.  :-(  The downside
is that FreeBSD doesn't have NCQ support yet (when? when? when?) so writes
are slow.  :-(