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[oracle-l] Re: The Holy War: Disks

From: Koivu, Lisa <Lisa.Koivu_at_Cendant-TRG.com>
Date: Tue, 27 Jan 2004 11:59:03 -0500
Message-ID: <840C139B79E7CC4496B2594E9E35E96704192542@floexmailbe2.ffci.com>


Hi Dennis,=20

Sorry. Raid 10. =20

I am lucky enough to work with an engineer who truly believes that RAID5 is not worth it. As long as it isn't Raid 5, I don't care. I have bigger fish to fry than to get into the details of other raid configurations.

LK

-----Original Message-----
From: DENNIS WILLIAMS [mailto:DWILLIAMS_at_LIFETOUCH.COM]=20 Sent: Tuesday, January 27, 2004 11:31 AM To: 'oracle-l_at_freelists.org'
Subject: [oracle-l] Re: The Holy War: Disks

Lisa

   RAID5? Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com=20

-----Original Message-----
From: Koivu, Lisa [mailto:Lisa.Koivu_at_Cendant-TRG.com] Sent: Tuesday, January 27, 2004 10:11 AM To: oracle-l_at_freelists.org
Subject: [oracle-l] The Holy War: Disks

Hello everyone,=20
=20

Windows 2003, v9204, 2 Clariion SANs=20

=20

I have just been given ~1tb of disk on a new SAN. The engineer wanted to give me 3 huge (maxed out) disks, 2 350GB and a third with the remainder. I argued for 6 disks similarly sized. =20

=20

My fellow DBA supported my argument. The engineer and the dw architect wanted 3 disks. =20

=20

I am going to have i/o problems no matter what. Concatenating 10 physical disks into 1 logical disk is going to have as much i/o latency percentagewise as 6 physical disks concatenated into 1 logical disk. =20

=20

Each disk has 1 bus, so to speak. These buses are concatenated together into 1 "device". (I'm being told that "device" is a unix term and it doesn't apply in Windows). So, concatenating 10 disks (and buses) together for 1 high speed disk is going to result in having even more data on the other side of the "straw". =20

=20

I strongly feel if I have 3 disks instead of 6, my options for alleviating i/o contention are very limited. Any i/o balancing would be messier and more difficult. We are going with 6 disks instead of 3 with the understanding that when we add more disk to this server, we'll evaluate performance of the 6 disks and reconsider. =20

=20

As far as I know, the Clariion SANs don't have the whizbang functionality of the Symmetrix that allows moving datafiles at the physical level within the SAN to alleviate i/o hotspots. I also don't buy the argument that the SAN cache should alleviate i/o problems. This is a data warehouse that has the potential to become enormous and it will blow the size of any SAN cache during data loads, guaranteed.

=20

Is anyone in this type of environment? What have your experiences been? Any and all comments are welcome. =20

=20

Thank you

=20

Lisa Koivu
Senior Monkey

Cendant Timeshare Resort Group

Orlando, FL, USA

=20

=20

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Received on Tue Jan 27 2004 - 10:59:03 CST

Original text of this message

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