Gardenia?
Collocation directs TSM to store the data for a particular group of
nodes, node, or filespace on as few volumes as possible.  As Medhi
Salehi noted, it keeps tape mounts to a minimum for restores, but it
opens many more tapes.

In primary pools if you collocate by Node, each Client will open a tape
and write to that tape until it is full.  As long as MaxScratch has
sufficient volumes, no other Client will use that tape.  If you have 300
clients using that pool, you will have 300 filling tapes.

Collocated storage pools will use more tapes and more tape mounts for
processes that write to tape, whether that is backup-direct-to-tape or
migrations from disk to tape.  (Reclamation also honors collocation.) I
am not sure if collocating a copy pool is beneficial.  It seems like the
copy pool as a disaster recovery pool would be ideal to collocate, but
if you send off tapes every day you end up with a fragmented set of
tapes for each collocation unit anyway.  To clean that up would require
bringing offsite tapes back onsite, exposing you to risk.  It is
possible to do a Move Nodedata in a copy pool, but the tapes have to be
onsite.  Perhaps there are better ways.

Search this mailing list.  There has been a lot of discussion about
collocation's benefits and costs in the past.
http://www.adsm.org/lists/html/ADSM-L/
http://www.adsm.org/lists/html/ADSM-L/2009-03/msg00263.html

What are you trying to achieve with collocation?

I hope this helps!


-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
gardenia28
Sent: Tuesday, November 24, 2009 12:37 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] collocation increases tape mounts while backup

Hi,

I find by applying collocation concept, the no.of tape mount increases
while taking backup...

Could anyone justify it or explain me why it is so?

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