What I have noticed over the years (in AIX environments) is that TSM spreads
the load out across its direct access volumes.
Say you have 9 logical volumes across 3 physical and you have 3 inbound
client sessions...
TSM will spread that inbound traffic across 3 of its (locical) volumes.
If you have 3 logical volumes per physical volumes, the inbound work might
be going all to the same physical volume.
So there is a possibility of a slight performance problem by having multiple
logical volumes per physical volume, I say slight because I very rarely see
small numbers of inbound sessions (or activity) on the tsm servers.
If you resize to a 1 logical per physical, you might see a slight increase
in performance...
just my 2 cents worth based on general observations over the past 7 years.

Dwight


-----Original Message-----
From: David Browne [mailto:dbrowne AT HUMANA DOT COM]
Sent: Monday, January 13, 2003 8:19 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject:


We are running TSM 4.2.2.0 on OS390/2.10 and we are in the process of
replacing our mod 3 dasd with mod 9's.

Currently I have a disk storagepool with a mixture of mod 3 and mod 9 dasd
volumes, however when I define my dasd storage pool volumes I sized  them
as mod 3.
 I also have my database volumes broken in to mod 3 size volumes if they
reside  on a mod 9.

My question is will I see a performance issue if I resize all of my storage
pool volumes  and database volumes to a full mod 9 in size?