Re: Asynchronous I/O and AIX and jfs = perf ?

Not to be cute.. but can you point me to any resources or white papers on this
very subject? Or can you elaborate more? I'd really like to know, since we
are using asych io on JFS on one of our systems. Any help would be GREATLY appreciated...

• Dc.

epikur_at_my-deja.com wrote:

> In article <385D4887.9482C816_at_nospambigfoot.com>,
> Doug Cowles <dcowles_at_nospambigfoot.com> wrote:
> > This is a multi-part message in MIME format.
> > --------------E01C07E2F296D884F552A6BF
> > Content-Type: text/plain; charset=us-ascii
> > Content-Transfer-Encoding: 7bit
> >
> > But can we go back to the point the first reponder made? Using
> > Asynch I/O with JFS makes no difference at all? Is that true?
> >
> > - Dc.
>
> yes, it is true. aio without raw devices is completely senseless. it
> only eats memory.
>
> best wishes
>
> fs
>
> >
> > Dan Jennings wrote:
> >
> > > Believe it or not, both answers are right, and which one is
> > > better for you depends on how badly you want absolutely all
> > > the performance available for your DB.
> > >
> > > Using raw logical volumes in AIX with Oracle yielded ~18% better
> > > performance in our testing (8 way R50, 4GB RAM, 100 GB database,
> > > 32 mirrored SSA drives=16 spindles for Oracle data, 6 mirrored
> > > SSA drives = 3 spindles for Oracle logging and other admin stuff,
> > > 3 SSA adapters) over JFS. Aynch I/O was used in RLV testing.
> > > We saw much more I/O wait with JFS and longer response times to
> > > our sample SQL queries as opposed to RLV, which had less I/O wait
> > > and faster response times.
> > >
> > > The rub comes when you try to back up a RLV database. If it was
> > > JFS, you just shut down the database and backup the filesystems.
> > > To back up a database that uses RLV's, you have to use the cpio
> > > command and copy from the raw logical volume into file(s) in a
> > > filesystem, then back up the file(s) later on.
> > >
> > > The DB admins I worked with were extremely leery of using the
> > > backup utility in Oracle (this was at version 7.3.2). They
> > > claimed it was unreliable, and that the cpio method was the
> > > only way they would implement production backups of RLV's.
> > >
> > > So the option is really up to you: easier backups with a drop
> > > in performance, or more difficult backups with better
> > > performance.
> > >
> > > Hope this helps,
> > >
> > > Dan
> > >
> > > Emmanuel Cortes wrote:
> > > >
> > > > To increase performance of oracle database 7.3.x.x, is it better
 to use
> > > > Asynchronous I/O on AIX 4.3.x whith jfs file systems or not ?
> > > >
> > > > I read in a redbook (Database Performance on AIX in DB2 UDB ans
 Oracle
> > > > Environnements "SG24-551-00") it's a good thing.
> > > >
> > > > But oracle tell if you don't use raw device is not good idea.
> > > >
> > > > Where is the truth ?
> > > >
> > > > Thanks
> > > >
> > > > Emmanuel Cortes
> > >
> > > --
> > > <<<<<<<<<<<<<<<<<<<< * >>>>>>>>>>>>>>>>>>>>
> > >
> > > Dan Jennings
> > > Speaker to Machines
> > >
> > > When the only tool you have is a hammer,
> > > all problems tend to look like nails.
> > > - Masured
> > >
> > > <<<<<<<<<<<<<<<<<<<< * >>>>>>>>>>>>>>>>>>>>
> >
> > --------------E01C07E2F296D884F552A6BF
> > Content-Type: text/x-vcard; charset=us-ascii; name="vcard.vcf"
> > Content-Transfer-Encoding: 7bit
> > Content-Description: Card for Doug Cowles
> > Content-Disposition: attachment; filename="vcard.vcf"
> >
> > begin: vcard
> > fn: Doug Cowles
> > n: Cowles;Doug
> > org: IBM
> > email;internet: dcowles_at_nospambigfoot.com
> > title: DBA
> > note: Please remove nospam from e-mail to reply.
> > x-mozilla-cpt: ;0
> > x-mozilla-html: FALSE
> > version: 2.1
> > end: vcard
> >
> > --------------E01C07E2F296D884F552A6BF--
> >
> >
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
Received on Tue Dec 21 1999 - 00:00:00 CST