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

From: Martin Berger <martin.a.berger_at_gmail.com>
Date: Tue, 13 Nov 2012 12:23:56 +0100
Message-ID: <CALH8A920wTr6vGm3NFzUL3H8mV8yk3ZXDowLaFZeCj2VU+aOJA_at_mail.gmail.com>

Sandy,
do if you have proper licenses, can you check v$active_session_history / dba_hist_active_sess_history what the rman sessions are doing during backup?

That should give you a reasonable estimation where they spend their time. (probably better data than a unspecific claim.)

hth
 Martin

On Mon, Nov 12, 2012 at 9:56 PM, Sandra Becker <sbecker6925_at_gmail.com>wrote:

> I have a hunch it's something along those lines, but don't know how to
> prove it. My SA insists there's a setting in the database to "turn on
> multiple CPUs". If it already recognizes there are 5 of them, I'm not sure
> what else I can do.
> Sandy
>
> On Mon, Nov 12, 2012 at 1:53 PM, <Christopher.Taylor2_at_parallon.net> wrote:
>
> > 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?
> >
> > --
> > Sandy
>

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Received on Tue Nov 13 2012 - 12:23:56 CET