We use an external RAID-5  cabinet for our storage pools, database, and
primary log copy.
I mirror the log on a physically separate internal disk though, and keep the
log in ROLLFORWARD mode.

That way I know I can recover, even if we lose the whole RAID set.

We haven't tested to see how much performance gain we would get using
independent drives.

The RAID has a lot of cache, so performance is not usually a problem for us,
and we want the reliability of RAID-5.


***************************************************************
Wanda Prather
The Johns Hopkins Applied Physics Lab
443-778-8769
wanda_prather AT jhuapl DOT edu

"Intelligence has much less practical application than you'd think" -
Scott Adams/Dilbert
***************************************************************



> -----Original Message-----
> From: Doug Thorneycroft [SMTP:dthorneycroft AT LACSD DOT ORG]
> Sent: Monday, December 07, 1998 2:10 PM
> To:   ADSM-L AT VM.MARIST DOT EDU
> Subject:      Re: Raid or no?
>
> We run 3 18.2 GB drives set up for raid5, used for our storage pools,
> database and log files. Everything works fine, but we haven't tested to
> see how much performance gain we would get with multiple independent
> drives.
>
> Adam Slesinger wrote:
> >
> > Fellow Adsmers,
> >
> > We are starting to set up adsm and we are trying to decide whether or
> > not to set up our eight 9GB drives as a raid array or whether we should
> > treat them as regular disks.  The adsm consultant says that it would be
> > best to put the database and log on one disk and then, through adsm,
> > have it mirrored on another disk.  The remaining 6 disks would be used
> > for the client data which would be migrated to tape soon after going to
> > disk.  The other option is to set 7 disks in a raid array and have the
> > eight as a hot spare.  I am under the impression that this option is not
> > recommended by IBM but cannot be sure.  Has anyone out there had
> > experiences using a raid array as a primary storage pool?  Thanks!
> >
> > adam