RE: direct IO

Sorry, 10.2.0.4.

We have AIO-MAX-NR=3145728 but the messages are still there.    

De: Mohammad Rafiq [mailto:rafiq9857_at_hotmail.com] Enviado el: sábado, 27 de noviembre de 2010 17:27 Para: Juan Cruz Miranda Vigo; przemolicc_at_poczta.fm; oracle list Asunto: RE: direct IO  

You did not mention oracle version. Try to get it set aio-max-nr to 1048576 (default is 65536). If it is 10.2.0.5 then it must be 1048576 as a work around.  

Regards
Rafiq  

> From: jcmiranda_at_oesia.com
> To: przemolicc_at_poczta.fm; oracle-l_at_freelists.org
> Date: Fri, 26 Nov 2010 12:58:22 +0100
> Subject: RE: direct IO
>
>
> We are getting
>
> WARNING:io_submit failed due to kernel limitations MAXAIO for process=128
pending aio=110
> WARNING:asynch I/O kernel limits is set at AIO-MAX-NR=3145728 AIO-NR=77074
> WARNING:Oracle process running out of OS kernel I/O resources (1)
> WARNING:Oracle process running out of OS kernel I/O resources (1)
> WARNING:Oracle process running out of OS kernel I/O resources (1)
>
> on several systems with linux pppc64 and it seems there are no patch for
this error on this platform.
> I can´t tell if direct i/o is slower.
>
> Anyone know how to solve this problem?
>
> ________________________________________
> De: oracle-l-bounce_at_freelists.org [oracle-l-bounce_at_freelists.org] En
nombre de przemolicc_at_poczta.fm [przemolicc_at_poczta.fm]
> Enviado el: viernes, 26 de noviembre de 2010 10:21
> Para: oracle-l_at_freelists.org
> Asunto: Re: direct IO
>
> On Thu, Nov 25, 2010 at 05:32:02PM +0200, Laimutis.Nedzinskas_at_seb.lt
wrote:
> > Looking for experiences/advices of others regarding one issue with
direct
> > IO.
> >
> > Recently we switched to another data center and some databases reported
> > increased IO time.
> > After investigating we found that IO is slower on file systems (Veritas,
> > Solaris 10) mounted with direct io options.
> > AWR shows more time on scattered reads but for the same number of blocks
> > too.
> > We are going to switch of direct IO and test but for the time beeing I
am
> > wandering why direct IO is bad in our case.
> >
> > We've got seriously increased times for statistics gathering which does
> > full scan naturally - we've found 2 full scan sqls on the same table
> > clearly comming from dbms_stats package . Full scan is not cached by
> > oracle. But file system cache can help in that particular case.
>
> Do you have exactly the same storage configuration in both data centers ?
>
> We found that _usually_ switching from buffered filesystem to direct IO
won't
> help unless you increase also Oracle buffers (so Oracle uses memory which
> had been used previously for filesystem buffering).
> Also on Veritas/UFS I recommend to turn on direct IO in Oracle
(FILESYSTEMIO_OPTIONS=SETALL)
> and not in Veritas (we don't set any mount options in /etc/vfstab for
Veritas filesystems).
>
> If you bought Veritas ODM - just use it.
>
> Regards
> Przemyslaw Bak (przemol)
> --
> http://przemol.blogspot.com/
>
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