Placing TSM DB volumes over multiple physical volumes can improve
performances because the DB is read-oriented, the LVM will spread the load
over the various volumes. if the number of volumes is too high, though,
your performance will be hit by the overhead on the Logical Volume Manager.
the opposite is true for the recovery log which is predominantly
write-oriented.writes are done in a moving cursor format which cannot be
optimized for multiple volumes.

I don't know if I recall correctly and someone was asking this, I'm
thinking about this linked to the DB volume question, but the max TSM DB
size should be 530GB and 13GB for the recovery log.

Cordiali saluti
Gianluca Mariani
Tivoli TSM Global Response Team, Roma
Via Sciangai 53, Roma
 phones : +39(0)659664598
                   +393351270554 (mobile)
gianluca_mariani AT it.ibm DOT com
----------------------------------------------------------------------------------------------------

"The people of Krikkit,are, well, you know, they're just a bunch of real
sweet guys, you know, who just happen to want to kill everybody. Hell, I
feel the same way some mornings..."

"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> wrote on 02/10/2002
16:18:01:

> My experience is the database volumes fill sequentially, no load
balancing.
> This is why I recommend striping on the database to improve backup
> performance.  But, that can be suicide if your bufferpool is not large
> enough to get 98.5%+ hits.  So, there are tradeoffs.  Keep in mind I have
> ESS technology on fiber channel which provides some significant hardware
> caching benefits.
>
> We are still tuning for optimum performance.  I expect to be done in a
> couple of weeks.  The comment on disk storage pools is also my
observation.
>
> Paul D. Seay, Jr.
> Technical Specialist
> Naptheon Inc.
> 757-688-8180
>
>
> -----Original Message-----
> From: Dan Foster [mailto:dsf AT GBLX DOT NET]
> Sent: Wednesday, October 02, 2002 3:08 AM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: Does TSM use all DB Volumes for I/O?
>
>
> Hot Diggety! Kilchenmann Timo was rumored to have written:
> > I would vary much appreciate an answer to the question: Does TSM use
> > all DB volumes for I/O (like round-robin) or does it fill a volume and
> > then goes to the next one?
>
> I do not know for sure, because I don't know of a TSM way to report
> utilization statistics for db or log volumes on a per-volume basis.
>
> But what I can tell you that from my observations, it _DOES_ do some sort
of
> round-robin on the diskpool volumes because it was almost perfectly even
> when I filled up two diskpool volumes for the first time, throughout the
> whole time.
>
> That does not answer your question about dbvols and logvols, I know, but
it
> suggests that it might, since it does seem to do that for diskpool vols.
>
> I'm sure that someone here will know the definite answer. :)
>
> -Dan