Re: HORRIBLE ORACLE PERFORMANCE PROBLEM

Yes, logically you can seperate all the tablespaces, but there is no control over where datafiles and redologs physically reside. It will distribute across disks well if the stripe size balances all files, but a large stripe size probably won't seperate the redologs and you could possibly end up with the redologs all on one physical disk. Stripe size must be bigger than the IO block size to minimize the impact of the read overhead and if the stripe size is too large, the controller will be waiting to retrieve more data than the application needs. Also if your system is write intensive, RAID-5 writes typically take twice as long as reads. The bad thing about RAID 0+1 is that it is expensive!

Troy Meyerink
Oracle DBA
Raytheon
Sioux Falls, SD
meyerink_at_usgs.gov

TurkBear wrote:

> Why can't you separate those things...You can specify a tablespace for any
> tables,index, etc at creation time and you can specify which temporary
> tablespaces to use by username or role...If you have those tablespaces on
> separate disks with independent controllers, you can load balance quite well, I
> believe...
>
> Troy Meyerink <meyerink_at_edcmail.cr.usgs.gov> wrote:
>
> >How are you ever sure that you can get an even load balance when you cannot
> >seperate the redologs, indexes, tables, system tablespace, & temp tablespace. I
> >know there is supposed to be data distribution, but you can't control how. This
> >is why I use RAID 0+1 for almost all my databases. Just my 2 cents worth.
> >
> >Troy Meyerink
> >Oracle DBA
> >Raytheon
> >Sioux Falls, SD
> >
> >"Michael D. Long" wrote:
> >
> >> I agree with Nuno. I've worked with a lot of RAID systems,
> >> and the only time that RAID 5 will have heavy I/O on one
> >> drive (by design) is during recovery. Either the RAID is not
> >> properly configured at level 5, or you have a hardware
> >> fault in either the controller or the effected drive.
> >>
> >> --
> >> Michael D. Long
> >> http://extremedna.homestead.com
> >>
> >> "JoLurie" <jolurie_at_aol.com> wrote in message
> >> news:20000718233952.18484.00000057_at_ng-cc1.aol.com...
> >> > Turns out our Raid 5 is setup on 5 disks not 2. Most of the I-O seems to
 be on
> >> > one disk though.
Received on Mon Jul 24 2000 - 00:00:00 CDT