ADSM-L

Re: Collocate for Exchange agent client?

1998-09-28 16:59:36
Subject: Re: Collocate for Exchange agent client?
From: Chris Zaremba <zaremba AT US.IBM DOT COM>
Date: Mon, 28 Sep 1998 16:59:36 -0400
James,

>I have NT ADSM server V3.1.1.3 and using the Exchange agent to backup
>Exchange servers with information stores of about 20Gig.  I have a file size
>threshold of 500Meg before it goes to tape (DLT7000).  Would I gain anything
>by enabling collocation for these clients?  I fugure that they are already
>going directly to tape and a restore should call up only 1 or 2 tapes at
>most.

Given your setup, you can benefit from colocation because not all exchange
objects are necessarily
going directly to tape with a 500MB threshhold on the disk pool.  Even though
the IS is about 20GB, there
are actually 3 separate objects stored in ADSM storage pools:

  1.   the Public IS dbfile
  2.   the Private IS dbfile
  3.   the transaction logs for the IS (accumulated into a single object)

For a 20GB IS, the two DBs are most likely larger than the 500MB size limit on
the disk pool but
that may not necessarily be the case for the transaction logs.  So, without
colocation, it is possible
that the logs go to the disk pool and eventually migrate to a tape other than
the one(s) on which the
dbfiles are written.  With colocation, the log file object will eventually be
written to tapes storing
other objects for that node...but not necessarily contiguous to those objects.

You would probably benefit more from sending all exchange backup data directly
to tape (via the
backup copy group) rather than relying on the max file size on the disk pool
and colocation.  Going
directly to tape via the copy group settings will result in the objects from a
single backup being stored
contiguosly.

Chris Zaremba
ADSM Agent Development
internet  zaremba AT us.ibm DOT com
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