Our standard STORServer build uses two drives at RAID1 (mirroring) for the
OS partition and for the db and log volumes.  We typically build two db vols
on the rest of the partition with a corresponding log volume.  So on a 72 GB
hard drive, we have an 8G OS partion and the rest is used for db and log.

As for the storage pool volumes.  We RAID0 all of these.  That's JBOD (just
a bunch of disk).  We then put two disk pool vols on each disk.  TSM
multi-threads activity.  We have not tried three vols per disk, but believe
that might be slightly better, but not so much that it is worth it.  Perhaps
sometime I'll have time to do an exhaustive study of this.

In some cases, your RAID controller might not let you create as many volumes
as you would like.  In that case, we have use striping a put some number if
disks together.  Note these are not protected as Paul pointed out.

RAID 5 seems a very bad idea for disk pool vols.  For write intensive
activities, RAID5 does not perform well.  This is mitigated somewhat by
large write back caches, but not completely.  We don't recommend it.

Hope this helps!

Kelly J. Lipp
STORServer, Inc.
485-B Elkton Drive
Colorado Springs, CO 80907
lipp AT storsol DOT com or kelly.lipp AT storserver DOT com
www.storsol.com or www.storserver.com
(719)531-5926
Fax: (240)539-7175


-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
Seay, Paul
Sent: Thursday, September 26, 2002 7:24 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Disk volumes


What you do not want is the heads jumping all over the disks servicing many
different files (TSM Volumes).  You have received many responses on this
question.

My lean would be to stripe the database either RAID1 or RAID5 on a given set
of volumes across both arrays (depends on you IO activity).  The reality is
the database does not have that much write activity.  It is mostly read
except during expiration.

For the storage pools disks I would try to use 1 physical disk per volume
and go RAID1, TSM Mirroring, (RAID0 if you can deal with the non
protection).  Or a RAID-5 if you need the space and use a JFS file system.

Others have better experience with this than myself.  I have IBM ESS with a
non-volatile cache, so it is a different ball game.  You may want to try
several things to see what works for you best.

Paul D. Seay, Jr.
Technical Specialist
Naptheon Inc.
757-688-8180


-----Original Message-----
From: Mahesh Tailor [mailto:MTailor AT CARILION DOT COM]
Sent: Thursday, September 26, 2002 8:54 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Disk volumes


Hello,

TSM: 5.1.1.6
OS: AIX 4.3.3
Machine: IBM 6M1

Hopefully this is a simple question:   I have fourteen 36GB drives that
are available for the diskpool and I was wondering whether it is better to
have seven 5GB files or three 10GB files or one 35GB file or something else?
The drives are mounted in two IBM-2014 Ultra-Wide SCSI disk drawers with
separate Ultra-Wide contollers.  The other 14 drives are used for DB, LOG,
and spare.

Thanks.

Mahesh