Re: perplexing performance on AIX
- From: "David Barbour" <david.barbour1@xxxxxxxxx>
- To: john40855@xxxxxxxxx
- Date: Tue, 6 May 2008 17:50:17 -0400
John,
What version of AIX, including maintenance level. What is your
filesystemio_options parameter? What HBAs are you using? Raw, or journaled
filesystems? JFS2? How are they mounted?
What do you see with iostat?
On Tue, May 6, 2008 at 4:32 PM, John Smith <john40855@xxxxxxxxx> wrote:
> Not that I want to discourage any potential comedians, but I do understand
> the concept of idle waits. However, the wait event seems excessive, (its
> larger than any other timed event on the system, to include CPU time), which
> makes me suspect that there is a problem.
>
>
> On Tue, May 6, 2008 at 3:11 PM, Baumgartel, Paul <
> paul.baumgartel@xxxxxxxxxxxxxxxxx> wrote:
>
> > On Tue, May 6, 2008 at 2:21 PM, Allen, Brandon <
> > Brandon.Allen@xxxxxxxxxxx> wrote:
> >
> > > If you disabled parallellism, you couldn't get PX wait events. You
> > > might want to try with DOP of 1. I'd also verify CIO is being used if you
> > > aren't sure.
> > >
> >
> >
> > Reminds me of the old Henny Youngman joke: "I went to the doctor. I
> > said 'Doc, it hurts when I do this.' He said 'Don't do that.'"
> >
> > *Paul Baumgartel*
> > *CREDIT SUISSE*
> > Information Technology
> > Prime Services Databases Americas
> > One Madison Avenue
> > New York, NY 10010
> > USA
> > Phone 212.538.1143
> > paul.baumgartel@xxxxxxxxxxxxxxxxx
> > www.credit-suisse.com
> >
> >
> > ------------------------------
> > *From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:
> > oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *John Smith
> > *Sent:* Tuesday, May 06, 2008 3:29 PM
> > *To:* Allen, Brandon; oracle-l@xxxxxxxxxxxxx
> > *Subject:* Re: perplexing performance on AIX
> >
> > We really want to be able to use parallel.
> >
> >
> > > ------------------------------
> > > *From:* John Smith [mailto:john40855@xxxxxxxxx]
> > > *Sent:* Tuesday, May 06, 2008 11:57 AM
> > > *To:* Allen, Brandon
> > > *Subject:* Re: perplexing performance on AIX
> > >
> > > Yes, we tried decreasing the DOP. Didnt really affect the wait
> > > event. I am pretty sure the drives are already mounted w/ CIO. At least
> > > they are supposed to be.
> > >
> > > On Tue, May 6, 2008 at 1:20 PM, Allen, Brandon <
> > > Brandon.Allen@xxxxxxxxxxx> wrote:
> > >
> > > > Have you tried decreasing the degree of parallelism (or maybe
> > > > even disabling it) to see if that helps? Sometimes too muchparallelism
> > > > is
> > > > a bad thing.
> > > >
> > > > You might also want to consider using concurrent IO if you're not
> > > > already.
> > > >
> > > > Regards,
> > > > Brandon
> > > >
> > > >
> > > >
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