RE: Backup using only one CPU - SA wants to know why

From: <Christopher.Taylor2_at_parallon.net>
Date: Mon, 12 Nov 2012 14:53:25 -0600
Message-ID: <F05D8DF1FB25F44085DB74CB916678E88564FBE0DE_at_NADCWPMSGCMS10.hca.corpad.net>



According to my AIX admin (on a similar question I asked him about active sessions) he said its because of the way IBM does CPU scheduling.

I wish I had more info on that.

Chris

-----Original Message-----

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Sandra Becker Sent: Monday, November 12, 2012 1:39 PM
To: oracle-l
Subject: Backup using only one CPU - SA wants to know why

Oracle 11.2.0.2
SLES11 on IBM mainframe
DB size - just below 1T
I run an incremental 0 backup on my production OLTP once a week, incrementals the rest of the week. Recently changed the disk_asynch_io to TRUE and the filesystemio_options to SETALL, per recommendations from Oracle. I then added a channel to the backup scripts so it uses 4 channels. These changes shaved 35 pecent off the time it takes to run the incr0 backup, which I am very happy with.

The SA monitoring the performance of the mainframe says the incremental 0 backup of our production OLTP is pegging a single CPU, out of 5 available.  He thinks the backup would run even faster if it used more CPUs and suggested setting the PARALLELISM parameter to more than 1. Unbeknownst to him, it had been set to 3 for the past 6 years. He wants to know why the backup isn't using more CPUs. Any ideas/suggestions?

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Sandy
Transzap, Inc.

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http://www.freelists.org/webpage/oracle-l Received on Mon Nov 12 2012 - 21:53:25 CET

Original text of this message