There is a middle ground here.
If you set COLLOCATION=NO, it will drastically affect your RESTORE
performance.
Over time, you could in theory have to mount EVERY TAPE to do a full
restore of a client.
That is why collocation is a good thing.
But collocation will, by default, put each client on its own tape,
thereby using a LOT of tapes.
The alternative is to control collocation by setting the MAXSCRATCH
value for your TAPEPOOL.
Assume you are starting out with a new TSM server; if you have 80
clients and set MAXSCRATCH to 40,
TSM will stack 2 clients per tape.
This is a good thing, too.
You get 90% of the benefits of collocation, with only half the tapes.
This is a very common thing to do; there are plenty of sites that have
more clients than slots in their library!
The drawback is that you have to check on the value of MAXSCRATCH often.
As you get more tapes in FULL status (assuming you are like the rest of
us and your site is CONSTANTLY growing its storage farm), you have to
keep increasing the value of MAXSCRATCH. That's easy: update stgpool
TAPEPOOL maxscratch=xxx. Or do it from the admin GUI.
What I do is:
1) Decide whether you want to stack 2, 3, etc. clients per tape. For
example, pick TWO.
2) Then the number of TAPEPOOL tapes you wand to be in FILLING status is
#clients/TWO.
3) Count the number of tapes in TAPEPOOL that are already FULL.
3) Set TAPEPOOL MAXSCRATCH to: DESIRED FILLING + ALREADY FULL.
Check it one a week (or more often if you fill up a lot of tapes daily)
and add more to MAXSCRATCH as tapes get full.
Regarding COPYPOOL, I don't see any reason to collocate that at all.
Wanda Prather
"I/O, I/O, It's all about I/O" -(me)
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Roark Ludwig
Sent: Thursday, August 25, 2005 7:56 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Question about Space Reclamation..
I have been handed a TSM system in the past week that has been running
for
a year. IT has collocation = yes for TAPEPOOL and COPYPOOLS. this
system
is running TSM 5.2.2.
We have run out of tapes as the setting for collocation (yes) is trying
to
use a tape for each node (as I understand it, ,,please correct me if I
am
wrong)..
We have decided that since we have about 80 volumes with less then 1%
utilized and 20 or so with large utilization %'s to set COLLOCATION=NO
for
the TAPEPOOL and COPYPOOLS.
We are expecting to add another set of nodes and don't wish to consume
more
of our volumes (with small percent utilization) as we add the nodes.
Question ..
Will this setting COLLOCATION=NO stop the addition of volumes? (I
expect
the answer is YES,, please correct me if I am wrong.)
Now to the second question.
I see no easy way to have Space Reclamation condense the volumes
included
in the two pools as it will only process "FULL" volumes. (Again Please
jump
in here).
QUESTION: is it acceptable to set the status from "FILLING" to "FULL"
for
the volumes with low percentage utilized to force Space Reclamation ?
OR
is there an easier way to accomplish the GOAL of reducing the number of
volumes needed for the pools? (given that we have set COLLOCATION=NO)
or should we simply wait out the natural filling of the volumes and
allow
normal Space Reclamation as time proceeds?
Has anyone done this in the past?
How have others dealt with this??
Thanks for any input.
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