RE: ASM+internal disks

From: Vishal Gupta <vishal_at_vishalgupta.com>
Date: Tue, 26 Apr 2011 17:16:33 +0100
Message-ID: <787DD2F284E39D4FA3C2ABD2DAF1AB2D179E36_at_MAIL.vishalgupta.co.uk>

On RHEL5, CFQ i/o scheduler is broken. Under heavy load performance improves with deadline i/o scheduler. On RHEL4 it does not give much benefit. There is linux bug for broken CFQ on RHEL5.  

http://www.google.co.uk/url?sa=t&source=web&cd=1&sqi=2&ved=0CBYQFjAA&url=https%3A%2F%2Fbugzilla.redhat.com%2Fshow_bug.cgi%3Fid%3D456181&ei=tDaKTcvzNeWG0QHYybzoDQ&usg=AFQjCNEKaFfKVmLhVeoMgJzoaGyeRXS15w

http://www.google.co.uk/url?sa=t&source=web&cd=2&sqi=2&ved=0CBwQFjAB&url=https%3A%2F%2Fbugzilla.redhat.com%2Fshow_bug.cgi%3Fid%3D427709&ei=tDaKTcvzNeWG0QHYybzoDQ&usg=AFQjCNEZHzLC3u7lkB3nE-1ZNbI7hvboFQ

http://www.google.co.uk/url?sa=t&source=web&cd=3&sqi=2&ved=0CCIQFjAC&url=https%3A%2F%2Fbugzilla.redhat.com%2Fshow_bug.cgi%3Fid%3D448130&rct=j&q=redhat%20cfq%20bug%20i%2Fo%20slow&ei=tDaKTcvzNeWG0QHYybzoDQ&usg=AFQjCNGdlO8BfKyUeWrifJLtybLszRGsBg    

Regards,
Vishal Gupta
http://www.vishalgupta.com

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From: oracle-l-bounce_at_freelists.org on behalf of Kevin Closson Sent: Tue 26/04/2011 16:45
To: Oracle-L
Subject: Re: ASM+internal disks

Here's how I look at this. The following are true 1) there is no networked storage so all disks are the same, 2) the database is important and 3) the Oracle software and OS are equally important. Also, in spite of the fact that I got no information back regarding how the disks are attached (e.g., the make and model of the RAID card) I think we can all be quite certain that the card supports HW raid. To that end, I would simply configure all 8 drives in a HW raid configuration. I see no benefit in the slice and dice. I also see no value in ASM in such a situation but I suppose this could be standard edition or some other such software that forces its use?

So, Niall, we agree: "...software RAID? Seriously?" :-)

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From: Niall Litchfield <niall.litchfield_at_gmail.com> To: oracle.tutorials_at_gmail.com
Cc: Oracle-L <oracle-l_at_freelists.org> Sent: Tue, April 26, 2011 12:10:01 AM
Subject: Re: ASM+internal disks

Deepak, I'm with you on the mirrored pair for the o/s - availability trumps the performance that Kevin refers to. But software RAID? Seriously? Does the server not have a decent controller? You can of course keep any oracle files outside of ASM.

        On 25 Apr 2011 19:28, "DBA Deepak" <oracle.tutorials_at_gmail.com> wrote:         

        Hi,                  

        We have a server with 8 SAS internal disks. The OS is going to be RHEL 5 x86_64         

        We plan to mirror disk 1 and 2 using software RAID -- OS and Oracle software will be kept on this         

        Remaining 6 disks will be used for ASM.                  

        Need your expert opinion on how to use the disks efficiently to maximize the available space without loosing ASM performance benefits much.                  

        Our main worry is that if we spare 2 disks for storing online REDO logs (different ASM diskgroup with fine striping) then it will be a loss of space as well as we will have only 4 disks to store remaining oracle database files hence loosing performance a bit.                  

        Please suggest how should we layout the various files under ASM.         

	-- 
	Regards,
	
	Deepak
	Oracle DBA
	

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Received on Tue Apr 26 2011 - 11:16:33 CDT