RE: DBWR, Direct I/O and the Devil

  • From: "Hameed, Amir" <Amir.Hameed@xxxxxxxxx>
  • To: <don@xxxxxxxxx>, "Taylor, Chris David" <Chris.Taylor@xxxxxxxxxxxxxxx>
  • Date: Wed, 28 Nov 2007 16:00:20 -0500

You can remove the dbwriter parameter and let Oracle set it
automatically based on the number of CPUs on your system.

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Don Seiler
Sent: Wednesday, November 28, 2007 2:39 PM
To: Taylor, Chris David
Cc: Oracle-L Freelists
Subject: Re: DBWR, Direct I/O and the Devil

On Nov 28, 2007 1:32 PM, Taylor, Chris David
<Chris.Taylor@xxxxxxxxxxxxxxx> wrote:
> Do you believe you have an I/O issue or are you just trying to
"squeeze"
> more out of your I/O subsystem?

Right now I just want to know that I don't have some horribly obvious
(to everyone else) misconfiguration.  Obviously having a stable setup is
paramount, I'll worry about tuning again after that.  With my recent
rash of performance issues, I'm going through any and all configuration
changes that I made in the past 3 months and questioning everything.

> Having played with db_writer_processes, I haven't really seen much 
> improvement or negative impact from increasing/decreasing them.  But 
> that is probably more due to the load (or lack thereof to notice any 
> difference).

As I said, I'm all in favor of dropping down to 1, maybe back up to 2 if
need be.  I just wanted to know if there's any concerns to be aware of
with the number of DBWR processes in direct vs. asynch I/O.

--
Don Seiler
http://seilerwerks.wordpress.com
ultimate: http://www.mufc.us
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