ADSM-L

Re: Simultaneous writes to primary and copy stgpools

2004-08-11 12:09:36
Subject: Re: Simultaneous writes to primary and copy stgpools
From: Jin Bae Chi <Jbaechi AT CSCC DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 11 Aug 2004 12:09:02 -0400
Neil and Muthyam.  Got it! Thanks for your kind clarification.


Gus

>>> neil.schofield AT YORKSHIREWATER.CO DOT UK 8/11/2004 11:57:52 AM >>>
Gus

I'm not sure I've understood your setup. Are you saying you have a
primary
disk pool, a primary tape (LTO) pool as the destination for migration
from
the disk pool, and a copy tape (LTO) pool?

My guess is that you want migration processing on the server to
simultaneously write data to both the primary and copy tape pools, but
I
don't believe this is possible. My understanding of simultaneous writes
is
that it is only possible during client operations - a client session
will
mount tapes from multiple storage pools.

The Administrator's reference guide says "the server simultaneously
writes
data when a client backup, archive, or migration operation stores data
to
the primary storage pool". However I believe the reference to migration
in
this context is talking about HSM-style client migrations only.

In order to simultaneously write to both the primary and copy tape
pools,
you are going to have to bypass the disk pool completely and have your
clients write direct to tape. An intermediate solution would be to set
a
maxsize threshold on the disk storage pool, so large files are
simultaneously written to primary and copy tape pools. Small files
would go
to disk and then be migrated to primary tape and separately copied to
copy
tape.

Does anybody else agree?

Regards
Neil Schofield
Yorkhire Water Services Ltd.




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