Re: New Disk Setup

From: Mark D Powell <Mark.Powell_at_eds.com>
Date: Thu, 28 May 2009 06:18:52 -0700 (PDT)
Message-ID: <493ebbc3-c462-4f5b-8c3c-1e9c8c7c6049_at_v2g2000vbb.googlegroups.com>



On May 28, 7:55 am, johnbhur..._at_sbcglobal.net wrote:
> On May 28, 5:34 am, billshatne..._at_googlemail.com wrote:
>
>
>
>
>
> > I've got to shift our OLTP production database onto a new server which
> > has 8 disks.
>
> > The layout I've got at the moment is the following.
>
> > Please feel free to flame me if you like but I was wondering if I'm
> > being overly cautious with mirroring and should use striping/
> > mirroring.
>
> > Any suggestions for modifications gratefully received.
>
> > 1 + 2 RAID-1
> > OS
>
> > 3 + 4 RAID-1
> > Datafiles
> > Control file
>
> > 5 + 6 RAID-1
> > Archived Redo Logs
> > Control file
>
> > 7 + 8 RAID-1
> > Oracle Software
> > Control file
> > Backups
>
> Well if you have a system with modest IO requirements almost anything
> will work.
>
> You don't give any details about what kind of server or disks or
> operating system or oracle version or if you are going to use ASM
> etc.  No information on what "kind" of backups either.  Does your os
> support asynchronous writes?  Are you planning on using RAW or using a
> cooked file system?
>
> With 8 disks available you are not going to get to get a lot of
> choices or performance.
>
> How about RAID 1 for disks 1/2 and put the OS + oracle software over
> there.
>
> Disks 7/8 for archive logs and backups in RAID 1.  You really don't
> want rman disk based backups writing to the same disks that the
> operating system is on ... that's guaranteed to cripple performance.
>
> That give you a whole 4 disks to work from eh?
>
> For many OLTP systems especially if they are commit happy the IO
> performance of the oracle online logs ( which you appear to have left
> out of your original description ) is critical.  How are you planning
> on meeting those requirements?- Hide quoted text -
>
> - Show quoted text -

The problem with a dedicated design is that if you have to add a second database to the server at a future date or if the database grows much more rapidly than expected the design does not scale.

Also no mention is made of size so will two disks hold the database? If a flashback recovery area is going to be in use then the area has to be able to hold the entire database, one set of online redo logs, a control file, the flashback logs, and the archived redo logs. Are two disk enough?

With only 8 disks to work with I would consider:

allocating two 4 disk stripes then using the second stripe to mirror the first using RAID-10.

allocating two 4 disk RAID-5 stripes with the database on one and everything else on the other

allocating a single RAID-5 stripe if size demands do not allow dual stripes

Just some things to consider
HTH -- Mark D Powell -- Received on Thu May 28 2009 - 08:18:52 CDT

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