Re: ASM on SAN
Date: Mon, 22 Feb 2010 08:21:54 -0800 (PST)
Message-ID: <495906.66266.qm_at_web32004.mail.mud.yahoo.com>
I'll second that question- I'm always "I/O bottlenecked" with the amount of data we move daily and any more knowledge I can gleam to help me out in that area is greatly appreciated! :)
~Kellyn
- On Mon, 2/22/10, Martin Bach <development_at_the-playground.de> wrote:
From: Martin Bach <development_at_the-playground.de>
Subject: Re: ASM on SAN
To: greg_at_structureddata.org
Cc: cshapi_at_gmail.com, "oracle-l" <oracle-l_at_freelists.org>
Date: Monday, February 22, 2010, 9:17 AM
Hi Greg,
great reply, I second your approach. May I ask a question about the below paragraph please:
On 02/21/2010 10:23 PM, Greg Rahn wrote:
> The other thing is that most of the storage engineers (people that
> design this stuff) or performance engineers (people that perf test it)
> will tell you there is a sweet spot for the LUN size and
> characteristics. This varies from array to array, but I would seek
> out this information. It usually has to do with things like which
> drives are on what controllers and primary vs secondary IO paths, etc.
I remember a MOS document "Note 810484.1 "Recommendation for 4MB ASM Allocation Unit (AU) size for Oracle 11g" which seems to have disappeared when I tried to look it up is recommending au_size > 1MB. I found reference to it under the exadata best practices but I wondered when you'd set the AU_SIZE to a non-default value.
Our system here isn't too large, 2.5 TB, disk groups ctrllog VRAID 1 for online redo logs and control files, DATA for data (VRAID 5) and FRA with VRAID 5 as well. All ASM LUNs are 250G and use external redundancy. Unfortunately there is a severe lack of spindles and I would have preferred VRAID 1 for DATA but my comments about IO performance and checksum'd writes weren't listened to.
Cheers,
Martin
-- Martin Bach OCM 10g http://martincarstenbach.wordpress.com http://www.linkedin.com/in/martincarstenbach -- http://www.freelists.org/webpage/oracle-l -- http://www.freelists.org/webpage/oracle-lReceived on Mon Feb 22 2010 - 10:21:54 CST