Re: ASM IO distribution on a SAN

From: K Gopalakrishnan <kaygopal_at_gmail.com>
Date: Wed, 12 Sep 2007 21:54:55 -0700
Message-ID: <3b0f44a10709122154q60aeb387pbbbaba8c212de300@mail.gmail.com>

Ryan,

In simple terms (when you are using external redundancy) ASM is like RAID 0 (plain striping) with 1MB stripes. So all it needs is a JBOD and it stripes equally in all the available disks (based on the volume of the data) and at present ASM do not have any control over I/O volume. It is Stripe and Mirror Everything (SAME).

In a SAN environment, you just get bunch of disks (or something exposed as DISKS) and use ASM to stripe the data in all available disks. It could be either mount points, or disk partitions or disk itself. Of course the assumption is all the available disks are having same I/O characteristics.

-Gopal

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Best Regards,
K Gopalakrishnan
Co-Author: Oracle Wait Interface, Oracle Press 2004 http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/

Author: Oracle Database 10g RAC Handbook, Oracle Press 2006 http://www.amazon.com/gp/product/007146509X/
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http://www.freelists.org/webpage/oracle-l Received on Wed Sep 12 2007 - 23:54:55 CDT