On Thursday, 06.03.2008 at 16:05 -0800, Aaron J. Grier wrote:

> On Tue, Mar 04, 2008 at 08:29:03AM -0500, Chris Hoogendyk wrote:
> > My own preference is to configure the system with separate drives
> > for holding disk. There is no reason for them to be raid.
> 
> all backup data passes through the holding disk: doesn't it follow
> that the holding disk should be as reliable as possible?  and doesn't
> that imply at least a mirrored holding disk?  MTBF may be lowered, but
> failure of a single holding disk will not affect backups.

I'm quite happy to use a fast, RAID-0 bundle for speed and size.  The
data is transient, spending at most a couple of hours on the disk before
being flushed to tape.

Remember that this is a *backup* - the 'real' data being elsewhere - so
the increased likelihood of disk failure resulting in a failed backup is
not really very important.  On the other hand, having a fast enough disk
system with a high capacity helps tremendously.

Dave.
-- 
Dave Ewart
davee AT ceu.ox.ac DOT uk
Computing Manager, Cancer Epidemiology Unit
University of Oxford / Cancer Research UK
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