Re: gcs log flush sync
- From: John D Parker <orclwzrd@xxxxxxxxx>
- To: K Gopalakrishnan <kaygopal@xxxxxxxxx>
- Date: Thu, 9 Oct 2008 19:26:55 -0700 (PDT)
We were in the midst of a huge performance problem today on a 6 way RAC and
this occurred enough times to be both unusual and interesting. Even more
interesting is that this wait looks like it's related to I/O some way. Even
more interesting, we had identified writes as a real issue, especially redo
writes.
Thanks for the explanation!! Always good to hear from the folks that wrote the
book on waits!
Thanks again
John
----- Original Message ----
From: K Gopalakrishnan <kaygopal@xxxxxxxxx>
To: orclwzrd@xxxxxxxxx
Cc: oracle-l <oracle-l@xxxxxxxxxxxxx>
Sent: Thursday, October 9, 2008 5:18:12 PM
Subject: Re: gcs log flush sync
John,
I don't discount this as an idle wait. Basically you (LMS) are/is
waiting for LGWR to flush the pending redo during CR fabrication.
Without going too much in to details, you can turn off the behaviour
by setting _cr_server_log_flush to false.
Are you looking for the details on this wait event or having a
performance problem and suspecting the wait?
On Thu, Oct 9, 2008 at 12:22 PM, John D Parker <orclwzrd@xxxxxxxxx> wrote:
> Anyone have any solid information on this wait event? The 10.2 docs indicate
> it's an idle event, but it's name is far too ominous to just be an idle
> event of the same pedigree as null event...
>
> Thanks,
> John
>
> PS. I'm seeing it on a 6 way 10.2.0.4 RAC on RHEL ES 4
>
>
--
Best Regards,
K Gopalakrishnan
Co-Author: Oracle Wait Interface, Oracle Press 2004
http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/
Author: Oracle Database 10g RAC Handbook, Oracle Press 2006
http://www.amazon.com/gp/product/007146509X/
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