Re: ASM and RAID
From: DA Morgan <damorgan_at_psoug.org>
Date: Thu, 18 Dec 2008 06:42:44 -0800
Message-ID: <1229611362.994431@bubbleator.drizzle.com>
>
> I've no numbers to contribute (though I'm also very interested in the
> collective experience of this group on this).
> But I do have a question: how much would we reasonably *expect*
> performance to be impacted one way or the other by ASM, when we are on a
> high performance SAN?
Date: Thu, 18 Dec 2008 06:42:44 -0800
Message-ID: <1229611362.994431@bubbleator.drizzle.com>
robert wrote:
> Michael Austin wrote:
>> How, in your >> testing and research, does performance either improve or suffer with >> the addition of ASM. The database is scattered across 6 separate disk >> groups with logfiles etc in their own disk group.
>
> I've no numbers to contribute (though I'm also very interested in the
> collective experience of this group on this).
> But I do have a question: how much would we reasonably *expect*
> performance to be impacted one way or the other by ASM, when we are on a
> high performance SAN?
On a high end SAN you are reading and writing to a cache not to disk so the number of spindles becomes less important. This is part of what makes NetApp's RAID4 different from RAID4 from other vendors.
ASM seems to prove either a neutral or slightly positive impact (a few percent) on performance if compared to raw disk with no LVM. If comparing with other LVMs what we see is a substantial drop in CPU utilization. Most LVMs are cpu pigs: ASM is not.
-- Daniel A. Morgan Oracle Ace Director & Instructor University of Washington damorgan_at_x.washington.edu (replace x with u to respond) Puget Sound Oracle Users Group www.psoug.orgReceived on Thu Dec 18 2008 - 08:42:44 CST