Hello,

We have been seeing rather poor throughput to our 8mm drives (8500C with
compression enabled) while doing reclaim or move data processes.  We are
seeing less than 100KB/s.  We do keep the drives cleaned, so I don't think
that is the problem (though it is possible that the heads are wearing out).
However, I suspect that the problem may be database throughput, since each
file moved requires updating of the database.  While we have 3 database
extents spread across 3 disks on 2 different scsi channels, I suspect that
ADSM is not spreading database pages evenly across these 3 extents.  Indeed,
I suspect it is attempting to fill up the first extent before using the
second one, etc.

I guess what I am looking for, is some way to improve our database
performance, so that we can get better throughput to our tape drives.  If
anyone has ideas on this, I'd like to hear them.  In particular, I am curious
if anyone has thought about using disk striping under AIX v4 for database
volumes.  We have 9 drives on 2 channels.  I know that disk striping is
usually targetted at serial file accesses, and the ADSM database is not a
serial file, but I'm still curious if there might be some benefit by
spreading the database accesses across multiple disk drives.

Any thoughts, or experiences?  Thanks!

..Paul

Paul Zarnowski                     Phone:   607/255-4757
Cornell Information Technologies   Fax:     607/255-6523
Cornell University                 US Mail: 315 CCC, Ithaca, NY 14853-2601