using one dbwr when aio is avaliable is OK, but it does not mean they are
exclusive.
We are using 4 dbwr with disk async io on solaris, both 9.2 and 8.1.7. very
stable.
On 9/10/05, Ranko Mosic <ranko.mosic_at_gmail.com> wrote:
>
> Quote from metalink:
> -------------------
> From: Oracle, Frank Marshall 13-Nov-03 21:38
> Subject: Re : dbwn VS asy io
>
> You can not use multiple DBWR's with asynch IO. You turn off
> asynch_io and use multiple db writers ( up to 10) or you use asynch_io and
> one DBWR. It is an either or situation.
>
> ----------
> Also metalink note Note:97291.1 says:
> If the application is not very write intensive (or even a DSS system) and
> async I/O is available, then consider a single DBWR writer process;
> ------------
> More, there was a bug on Solaris in the past: when both
> db_writer_processes and disk_asynch_io were enabled performance suffered.
> ----
> rm
>
> On 9/9/05, Mladen Gogala <gogala_at_sbcglobal.net> wrote:
> >
> >
> > On 09/09/2005 09:41:37 PM, Lou Fangxin wrote:
> > > We hit some problem on solaris with multiple db writer, and finnaly
> > set it
> > > to one, then the database run well.
> >
> > I'm running with 3 DBWR processes, for more then a year, with async I/O.
> > Slowaris 9,
> > Oracle 9.2.0.5 <http://9.2.0.5>, RAC. My users are storing documents
> > into the database as BLOB's and
> > that is very write-intensive, so I need multiple writers - 1 per I/O
> > controller.
> > No problems. The only thing that is incompatible with async I/O are I/O
> > slaves, which
> > are intended to simulate async I/O. That is explained in the note
> > 97291.1.
> > However, on HP-UX it is not recommended to use multiple DBWR processes
> > and async I/O.
> > This is an old information, from the time that I was working for OXHP,
> > which used to
> > have 4-way OPS (not RAC) system. I remember oracle support guy telling
> > me that it is
> > not advised to use that combo on HP-UX 11.0. It was a brand new system,
> > we finished
> > transition from an old Siemens Reliant Unix to HP-UX on Sunday,
> > 09/09/2001. Tomorrow,
> > on Monday 09/10/2001 I was very busy solving various problems, but
> > everything was successful
> > in the end. I thought that I will relax a bit as of the day after. The
> > day after was, of
> > course, Tuesday 9/11/2001 and the world as I knew it ended that day.
> >
> > --
> > Mladen Gogala
> > http://www.mgogala.com
> >
> >
> >
>
--
Regards
Zhu Chao
www.cnoug.org <http://www.cnoug.org>
--
http://www.freelists.org/webpage/oracle-l
Received on Sat Sep 10 2005 - 10:19:22 CDT
