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

In article <385D4887.9482C816_at_nospambigfoot.com>,   Doug Cowles <dcowles_at_nospambigfoot.com> wrote:
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> 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
> >
> > <<<<<<<<<<<<<<<<<<<< * >>>>>>>>>>>>>>>>>>>>
>
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Before you buy. Received on Mon Dec 20 1999 - 10:45:55 CST