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RE: ASM IO distribution on a SAN

From: <>
Date: Thu, 13 Sep 2007 12:48:40 +0000
Message-Id: <>

ok so I should create 1 ASM disk group for each LUN.

I do not know alot about SANs. Is it possible to map a LUN to a partition or mount point? Is that how you make it visible at the Oracle level?

Also, the SAME article by Juan Loazia talks about only using the outer half of disks. I am assuming this is something a SAN administrator can configure for me?
-------------- Original message --------------
From: "Kurth, Michael J." <>

We use ASM here.  

Each asm disk group consists of several asm disks. Each asm disk is actually a lun from your SAN. Each lun consists of 8 physical disks.  

When you create a tablespace you specify an asm disk group to put the data.  

So when you create a table, it gets striped very evenly across each of the asm disks.  

The more asm disks in your disk group, the more physical disks your tables get spread across. Mike Kurth
Sr Database Administrator
Wheaton Franciscan Healthcare
400 West River Woods Parkway
Glendale, WI 53212
Phone: 414-465-4046
Pager: 414-584-0042

From: [] On Behalf Of Sent: Wednesday, September 12, 2007 9:56 PM To:
Subject: ASM IO distribution on a SAN  

The Oracle docs state that ASM can perform striping and mirroring. If I use ASM on a SAN how is it able to stripe? All it will see are mount points? My understanding is that it is possible create LUN(logical Units) and map them to individual disks or sets of disks and then possibly map those to mount points. Would this make it easier for ASM to handle IO distribution?  

The project I am working will fully deploy with 5 billion inserts(all bulk loads using external tables) and have 4 million OLTP type queries/day (average query returns over 100 rows, but they are all index scans and the queries are not that complex). No updates or deletes.  

I am trying to find ways to optimize our physical IO. We are using RAC so if I need more CPU we can add nodes. Privileged/Confidential information may be contained in this message. The information contained in this message is intended only for the use of the recipient(s) named above and their co-workers who are working on the same matter. The recipient of this information is prohibited from disclosing the information to any other party unless this disclosure has been authorized in advance.

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-- Received on Thu Sep 13 2007 - 07:48:40 CDT

Original text of this message