> If stripping in hardware, I would recommend also mirroring that strip in
> the hardware...
>

I agree. Striping combined with mirrorring (usually called Raid 0+1) in
hardware is fast *and* reliable. However, the Stage here is 1 TB - too
small for mirroring if you have a total backup volume of 600 G and if you
have to avoid migrating to tape during the night e.g. due to limited
bandwith to the storage subsystem.

Once again on Striping: If you can guarantee that there is always one
version of the data on the client and one version on the backup server,
depending on your backup strategy
=========================
maybe you can live with the possibility to loose the stage thus loosing
the whole backup of one night?

(Audit of the stage volumes will not work using stripe sets. You would
have to discard the contents of the whole stage - which has the
questionable advantage of being faster than auditing. The MTBF of a
stripe set decreases [linearly?] with the number of disks - so this
possibility should definitely not be neglected.)

So in this case I would still prefer RAID5: Usually you have at least two
controllers in high end systems. In my experience, RAID 5 in harware
RAID systems is not much slower than striping. I would expect at least
20 MByte/s per controller with RAID 5 giving more than 1 TB in 8 hours
which should be enough in this case.

Regards,

Michael


----
Dr. Michael Br"uwer
Dr. Michael Br"uwer
RZ der Univ. Hohenheim     70593 Stuttgart
bruewer AT uni-hohenheim DOT de   www.uni-hohenheim.de/~bruewer
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