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

Dan,

2 questions

1. Was Fast Write Cache enabled ?
2. Was Mirror Write Consistency on ?

Thanks,
John

In article <38545C3E.4C89F059_at_home.com>,   Dan Jennings <dan.jennings_at_home.com> 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
>
> <<<<<<<<<<<<<<<<<<<< * >>>>>>>>>>>>>>>>>>>>
>

Sent via Deja.com http://www.deja.com/
Before you buy. Received on Fri Jan 07 2000 - 12:10:20 CST