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RE: Disk Layout Document

From: DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Date: Fri, 16 Nov 2001 09:15:49 -0800
Message-ID: <F001.003C790F.20011116084024@fatcity.com>

Jesse - Yes, that is my situation. Most of the textbooks still talk about stand-alone disk drives, while most of us are using RAID. A RAID set handles much more throughput than a stand-alone disk and incorporates many disk drives within itself. So the hardware people certainly won't buy 22 RAID sets. When I start talking about spreading I/O to more RAID sets, the response I receive is that the RAID set isn't anywhere near its I/O capacity. Usually I have 2 RAID sets for the bulk of the data, plus additional drives/sets for redo, etc. If anyone can point me to a document that says there are advantages to more RAID sets, I would be very interested. Thanks.
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Thursday, November 15, 2001 11:40 AM To: Multiple recipients of list ORACLE-L

After many DB copies, loads, reloads, upgrades, etc., I've decided that the 22-disk layout just doesn't work for us. With only two 4-way stripe sets, we get vastly superior I/O thruput that more than compensates for any contention on any of the stripes.

Yes, yes, I understand that with mirroring the total drive count is 16. But since this is only a volatile test system there's no need for mirroring, archiving, or duplexing for recovery. With another stripe/mirror (RAID 10 or 0+1 -- no need to get back to that discussion) of 6 or 8 drives total for the archiving and maybe a duplexed controlfile, I still say that setup will smoke an Oracle-sanctioned Kevin Loney 22-disk layout. At least it does for our DB and environment.

Think about it: If a single drive housing a single datafile can pop 100-200 I/Os/sec, that same datafile on a 4-way stripe can hit in the thousands (w/caching and tuning). Of course, mutiply this by several datafiles, redos, controlfiles, and you've got a really fun physical layout project to minimize contention at peak operating times.

Hey, it can't work for everyone. But some may see the huge performance advantage we've seen by using RAID instead of single drives for physical DB layout.

Just my $.02

Rich Jesse                          System/Database Administrator
Rich.Jesse_at_qtiworld.com             Quad/Tech International, Sussex, WI USA


-----Original Message-----
Sent: Thursday, November 15, 2001 10:21
To: Multiple recipients of list ORACLE-L

Every time they ask for a new database I try that 22 disk thing also. I also settle for 6 mount points (not 6 disks). Its still fun to try though. Especially when we hire new people.

-----Original Message-----
Sent: Wednesday, November 14, 2001 6:45 PM To: Multiple recipients of list ORACLE-L

the very first time I ever saw Kevin present, he was talking about that. I went out and bought the DBA Handbook and came home to the operations people saying "I need 22 disks"

when they picked themselves up off the floor I said "okay, I can get away with 17"

again, I waited until they stopped laughing and said "can I get 9?"

I settled for 6

then I kept reading the book and emailing kevin with the typos I would find. And that dear ones, is how Kevin Loney and I met and became friends.

He got his revenge for my bothering him though -- he got me to co-author a book :)

Rachel

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Received on Fri Nov 16 2001 - 11:15:49 CST

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