Re: RAIDs and Oracle Tablespace layout

Actually, RAID 5 gets a very bad rap for DB use.

The problem is, how many transactions do you need to support per second. There is a formula to calculate how many disks you need to perform the read/writes fast enough across the stripe to sustain that transaction rate.

Unfortunately, only bigger corporations want to spend the money to do it correctly. You may need 30 disks in an array to handle the transaction rate.

Compaq enterprise consulting does this for companies all the time, might want to get in touch, or hunt around their site to find info on sustaining transaction rates if RAID 5 is your choice. Most companies don't want to hear the price tag to truly support the througput. When you hear about SQL or Oracle being able to handle all of these millions of transactions to prove their bravado, they don't mention all of the disks they used in a RAID 5 to accomplish this.

"Doug Coan" <dcoan_at_aegonusa.com> wrote in message news:95v0pv$ct1$1_at_nnrp1.deja.com...
> In article <95uh7l$tqi$1_at_nnrp1.deja.com>,
> mjgusa_at_my-deja.com wrote:
> > Hello:
> >
> > I am implementing a system that will have a fairly large Oracle 8i
> > database on a SUN system that has a RAID file system on it. I am
> > wondering if, since the files are ultimately on a RAID, this spares us
> > from caring about the layout of which tables/indexes go in what files
 or
> > not. I am assuming that no matter what file the data/index is on, the
> > stream comes from all disks anyway so there is no way to affect things
> > either way by putting certain table spaces on certain disks. Does
> > anyone have any experience with this?
> >
> > Thanks,
> > Mike
> >
> > Sent via Deja.com
> > http://www.deja.com/
> >
>
> ouch ouch ouch :-)
>
> There have been a few spirited debates conducted here concerning RAID
> and disk layout. You could be in for a bit of a mess if you are not
> aware of the pros/cons of different raid configurations and how to lay
> things out. It really depends on the size of your db and just how bad
> the RAID is done.
>
> I have seen bad raid layouts (multiple dbs and servers sharing physical
> drives and raid 5) turned into good raid layouts (raid 0+1 with
> dedicated physicals) and the performance improve by 10x or more.
>
> Many of the oracle books I have seen somewhat gloss over raid, but the
> major disk vendors have whitepapers on how to lay out oracle on their
> stuff. I would put the most confidence in some of the discussions that
> have been held here however.
>
> Last comment and personal opinion - NEVER EVER EVER put a database on
> raid 5 unless you really really really hate your clients and if you are
> the DBA don't mind spending all your time watching disk lights.
>
> Good luck....
>
> --
> Doug Coan
> Oracle Certified Professional DBA
>
>
> Sent via Deja.com
> http://www.deja.com/
>
Received on Tue Feb 13 2001 - 20:11:45 CST