I'll guess what may be happening here.
The TSM server runs the 'backup storagepool' and 'migrate' commands on
a "per node" basis. Meaning that if you set it to 4 sessions, TSM will look at
the storage pool, pick the node with the most data and start to duplicate that
data, it will then look for the next node with the largest amount of data and
start up a backup storage pool on that node.
On storagepools where all the data belongs to one node, it will only
start one process eventhough you may set the maxproc to 4. When we had a large
VMS cluster, we encountered the same thing.
One thing you might consider if you have enough drives in your library
is to make the TSM server make the copies at the same time of the backup. Look
at the "update stg" command, paying attention to the "Copystgpool" and
"Copycontinue" options. We are using this to help with a large SAP instance we
have. It slows down the transfer a little, but not by much.
Ben
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Richard Mochnaczewski
Sent: Friday, February 10, 2006 6:54 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Backup stgpool peculiarity
Hi Everybody,
I have one server using a 300Gb storage pool for its Oracle RMAN backups for
one large database. After the backup is done, I want to do a backup storage
pool to my offsite tape pool as quickly as possible by launching the backup
stgpool command and the number of tape drives to use using the the following
command :
backup stg arc_disk arc_dr maxpr=4
After the command is executed, I see 4 processes inititated, but after about 5
minutes, only one process remains using one tape drive and the backup takes a
long time for 300Gb ( 4 hours + ) . I know that the database backup is using 4
channels and there are about 16 files of 16Gb to 20Gb each in the ARC_DISK
storage pool. Why does it always default to one process instead of multiple
sessions as I initiate ?
Server : AIX 4.3.3 , TSM 5.1.6 ( I know I know , old versions of both OS and
TSM. The upgrades to AIX 5.2 and TSM 5.3 are currently in progress ).
Rich Mochnaczewski
Standard Life
(514) 925-7008
Email : richard.mochnaczewski AT standardlife DOT ca
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