RE: Solaris 8 and asynch IO
- From: thump604@xxxxxxxxxxx
- To: oracle-l@xxxxxxxxxxxxx
- Date: Fri, 19 Mar 2004 20:21:17 +0000
In this thread raw and Quick IO are not an option.
I have read the papers on ixora that touch on the subject, but was wanting to
hear from others. I have read most of what is out there on the subject
although I dont claim to remember it all.
--
- David / Thump
Life is what happens while waiting
or planning for the future.
> 1.) If you can do kaio, (raw or VxFS+QIO), set disk_async_io=TRUE and be
> happy.
> 2.) If you can't do kaio, set disk_async_io=FALSE. As to slaves vs.
> multiple
> writers, it depends on your environment and the type of load you're
> supporting.
> I'll just direct you to Steve Adams' site, http://www.ixora.com.au/ for more
> details. Do a search on 'dwbr io slave', and you'll find lots to read.
> 3.) If you have a combination of raw and filesystem files, you should also
> investigate the 'filesystemio_options' parameter. Again, a good explanation
> is
> available on Steve's site.
>
>
>
> -----Original Message-----
> From: thump604@xxxxxxxxxxx [mailto:thump604@xxxxxxxxxxx]
> Sent: Friday, March 19, 2004 2:40 PM
> To: oracle-l@xxxxxxxxxxxxx
> Subject: Solaris 8 and asynch IO
>
>
> Happy Friday everyone!
>
> I would like to hear from some others regarding their opinions and feedback
> in
> terms of asynch IO on Solaris when Veritas is not in the mix.
> OS Solaris 8
> DB 8174
>
> We know that if Quick IO or raw devices are not available that Solaris only
> simulates asynch IO with a failed kaio call and then the use of light weight
> threaded processes if disk_asycnh_io is set to true. If disk_asynch_io is
> set
> to false and dbwr_io_slaves are employed, then asycnh IO is simulated, but
> this
> time at the database level. My understanding is that IO slaves in terms of
> simulating asycnh IO can setrvice IO requests for most of the Oracle internal
> processes, where as OS pwrite/pread calls are more limited in what requests
> they
> can service.
>
> With that, the question remains is there a hard answer or actual best
> practice
> in terms of disk_asycnch_io=false/true combined with db_writer_processes VS
> dwr_io_slaves?
>
> I believe that the setting of false and 4 dbwr_io_slaves is optimal.
> I would like to hear what others think or have found on this matter.
> --
> - David / Thump
> Life is what happens while waiting
> or planning for the future.
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