"It depends", on your environment.
If you have REALLY big tapes, like LTO, so that all the data fits on one or
two tapes, then you are going to have to collocate by filespace to get any
benefit from multiple restores; otherwise multiple restores are all waiting
on the same tape.
But we have a TSM server where we are using 20 GB tapes, and don't collocate
by filespace.
All the data for all filespaces are spread across the same say 10 different
tapes.
If I start a dsm (or dsmc) RESTORE for filespace /a, it mounts tape 1 and
starts doing the restore.
If I start a dsm (or dsmc) RESTORE for filespace /b at the same time, it
waits on the first restore to get access to tape 1, so you get no benefit to
start with.
BUT, once the first restore dismounts tape 1 and mounts tape 2, the second
restore can mount and start using tape 1 at the same time.
So you will get parallel restores for about 80% of the time.
Of course, that's up to the point that you max your network or host adapter
throughput, or (in the case of Windows) the rate at which you can create
files in the NTFS files system -- and assumes you have multiple tape drives
free.
Many ways to skin this cat.
-----Original Message-----
From: Conko, Steven [mailto:sconko AT ADT DOT COM]
Sent: Thursday, July 17, 2003 10:34 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Multi session backup restore question
We have a similar issue too. Is collocation of filespaces the only way
(besides carving your system up in to multiple nodes) to acheive multiple
restore sessions? Will it occur autmatically from a singe dsmc restore or do
you need to manually invoke multiple sessions?
Steve
-----Original Message-----
From: David Longo [mailto:David.Longo AT HEALTH-FIRST DOT ORG]
Sent: Thursday, July 17, 2003 10:25 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Multi session backup restore question
In order to have multi session "simultaneous" restore from tape pool
then you must have this data in a pool that has collocation by filespace.
If you have a big enough disk pool such that if you did a restore
before migration had moved the data, then a multi session restore
would use the disk pool and be multi session.
David B. Longo
System Administrator
Health First, Inc.
3300 Fiske Blvd.
Rockledge, FL 32955-4305
PH 321.434.5536
Pager 321.634.8230
Fax: 321.434.5509
david.longo AT health-first DOT org
>>> Matt.Cooper AT AMGREETINGS DOT COM 07/17/03 09:48AM >>>
Hello all,
I am trying to work in a multi session backup and be able to use a
multi session restore. What I have found is that with the
maxresourceutilization set to 8 that my 350GB 8 processor AIX client is
using only 4 data sessions and 4 control sessions. The data all goes to
the disk pool and then the migration will use only 1 tape drive for this
data. I then assume a multi session restore is not going to work.
1) how can I get this backup to use more sessions for data transfer?
2) Am I correct in believing that the multi-session restore is out
because of the actions of the migration process? MUST this go direct to
tape to have multi session backup and RESTORE?
Thanks in advance,
Matt
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