Ok, between your answer and David Spearman's, I've determined that
perhaps I'm better off doing a straight mirror.  I don't have a hardware
based raid5 controller, and thus I would take a hit both on the
write-performance of the disks, and the high cpu utilizations caused by
the demands raid5 puts on the cpus.

thanks for your clarification.

robert

Doug Braden wrote:
> 
> Robert,
> 
> Regarding Raid5...
> 
> Raid5 as I understand it has stronger read performance than write
> performance.  Some of that may be negated by caching on either your
> software-based or hardware controller based Raid5.  So that write hit may or
> may not have an effect on you.
> 
> The write performance hit would be most apparent if you have full NetBackup
> logging enabled on your servers.  Especially if they are set to verbose. So
> keep that in mind.
> 
> Regards,
> 
> Doug Braden
> VERITAS Impact Team
> 
> -----Original Message-----
> From: Robert Johannes [mailto:ROBERT_JOHANNES AT udlp DOT com]
> Sent: Friday, November 02, 2001 9:40 AM
> To: nb
> Subject: [Veritas-bu] Raid5 or mirrored?
> 
> I'm setting up a file system for /usr/openv using volume manager with
> four disks, and I'm wondering if it would be better to make it a raid5
> system, or a concatenated mirror.  If I use mirroring, then my disk
> space is limited to that of the two disks, but with raid5, I get an
> extra disk space.  For performance reasons, what would be the best
> layout of disks?
> 
> thanks
> robert
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