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Re: Hard Disk selections

From: Paul Drake <>
Date: Thu, 22 Sep 2005 11:20:22 -0400
Message-ID: <>

On 9/22/05, Bryan Wells <> wrote:
> Let me apologize in advance if i leave any good facts out and have to
> restate...
> I am in process of migrating an existing windows 2k,<>test environment to some beefier hardware attached to IBM FastT SAN (?). The
> current environment is a Dell Poweredge 6400 p3 4x500 MHz/ with internal and
> external disk being 76GB 15k RAID 5. The new environment will be a blade
> with 2x2.5Ghz, at least, attached to the san. My question; will
> performance, Oracle that is, suffer going with a bigger disk (146Gb) on the
> SAN, or should I stay with the 76GB disk? The requirement is to not allow
> the performance to degrade below the existing SLA, however, we will have
> more users hitting this test instance once the cut over has been made.
> Because the hardware will not be over 4+ years old, my gut feel is that the
> bigger disk should not be an issue in this type of environment any more than
> that seen with the 76Gb in the existing environment, however, how do I prove
> this?
> Any links to help Green DBA Man understand Oracle and disk selections?
> As always, thanks for your help and patience.
> --
> Bryan Wells
> Oracle DBA hopeful


It depends.
What you have going for you is:

CPU bogomips (500 MHz to likely 3.4 GHz) Memory bandwidth (100 MHz FSB to 800 MHz effective) Newer disks tend to have faster interfaces, larger cache, higher RPMs and shorter seek times.
The SAN will likely have some form of cache.

If you're only loading up data into the buffer cache at instance startup and only writing to disk for redo, controlfile and archived redo logs, you may not notice the fewer disks.

If you find that the CBO wants to do all table scans, you're in trouble.

The only way to know for sure is to test. Get as much memory in the box as your budget allows and only use half of it. Use w2k advanced server instead of w2k server, as it has the /PAE and /3GB options.
W2k3 server standard edition supports the /3GB option.



Received on Thu Sep 22 2005 - 10:22:42 CDT

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