Re: Are db_writer_processes and disk_asynch_io mutually exclusive on Solaris ? Thanks, rm.

  • From: Mladen Gogala <gogala@xxxxxxxxxxxxx>
  • To: anysql@xxxxxxxxx
  • Date: Sat, 10 Sep 2005 02:12:03 +0000

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, RAC. My users are storing documents into the database as BLOB's 
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, 
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 
transition from an old Siemens Reliant Unix to HP-UX on Sunday, 09/09/2001. 
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


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