David,

My preference for disk pools is to use a lot of smaller volumes. In our
case we use 500 MB volumes in whatever quantity is required to get the disk
pool to its desired size.  The reason is that sessions lock volumes.  A
small number of disk volumes works the same as a small number of tape
drives.  More volumes means more simultaneous sessions.

As for database volumes, my database (~21 GB) is spread across four pairs
of mirrored disks.  You can use Q DBV F=D to see the percent utilization of
each DB volume.  If they are unbalanced, you can use *SM's feature of
copying DB pages elsewhere when deleting DB volumes to force balance the
volume utilization.  I've done that and I have the DB volume utilization
almost perfectly balanced between the four pairs of disks.

Good luck.

Tab Trepagnier
TSM Administrator
Laitram Corporation







David Longo <David.Longo AT HEALTH-FIRST DOT ORG>@VM.MARIST.EDU> on 08/30/2001
09:27:04 AM

Please respond to "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>

Sent by:  "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>


To:   ADSM-L AT VM.MARIST DOT EDU
cc:
Subject:  TSM DB/Disk Pool - Disk tuning question


I have TSM Server 3.7.4.0 on AIX 4.3.3.  I am going to be redoing my disk
storage for this machine and have basically two questions. if someone
knows the details of how this works.

1.  The Disk Storage pool I have is 110GB.  Most of the time it is between
20 and 70 percent full - mostly less than 50 percent.  If I have this split
into say 10 volumes, each on a separate hard disk, does most of the
activity stay on the lower volumes and rarely on the higher ones?

Logically I see this as a coffee cup with a slow leak.  The bottom is
almost always wet, the top rarely.  Is my assumption correct?

Basically I would spread the volumes over the hard disks to even out disk
access.

2.  Same basic question about TSM DB.  It is 13GB and 65% utilized.  I
imagine like a regular database it is spread out over the 13GB and has
more or less even access if spread out over several disks.  Correct?

(With my current system the way everything is laid out now I can't use
things like "iostat" to prove/disprove this, and I didn't seem to find this
"specific" topic mentioned in manuals.)

Thanks,


David B. Longo
System Administrator
Health First, Inc.
3300 Fiske Blvd.
Rockledge, FL 32955-4305
PH      321.434.5536
Pager  321.634.8230
Fax:    321.434.5525
david.longo AT health-first DOT org



"MMS <health-first.org>" made the following
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