ADSM-L

Re: Does TSM use all DB Volumes for I/O?

2002-10-02 10:27:05
Subject: Re: Does TSM use all DB Volumes for I/O?
From: "Seay, Paul" <seay_pd AT NAPTHEON DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 2 Oct 2002 10:18:01 -0400
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

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