RE: ASM and RAW Devices on RHEL 4

Hi,  

I'd advise using devlabel to map rawdevices rather than using /etc/sysconfig/rawdevices. devlabel provides persistency across reboots/storage reorgs. I've been using for a while now without any issues.  

By the way, a major plus for asmlib vs. raw for ASM is that it provides labeling of the disks and therefore persistency against storage changes and easier setup in multinode installations (much like devlabel in this respect). Another interesting fact about asmlib is that it reduces the amount of open file descriptors per process (only 1 is used) which can increase the overall manageability (and scalability) when you map several tens of LUNs.  

Cheers,
Luca

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Raj S Sent: Tuesday, March 07, 2006 8:16 PM
To: exriscer_at_gmail.com
Cc: johan Eriksson; Oracle-L Freelists
Subject: Re: ASM and RAW Devices on RHEL 4

There are no issues using rawdevices for ocr.dbf and votingdisk. They work just fine. Put them in your /etc/sysconfig/rawdevices and create the necessary mapping to the shared storage. We have several of these running fine on raw devices with 10G R2 on RHEL4.

Raj

On 3/7/06, LiShan Cheng <exriscer_at_gmail.com> wrote:

        Hi         

        That test is comparing LVM + EXT3 vs ASM + RAW. My comparison would be ASM + RAW + LINUX I/O API vs ASM + RAW + ASMLIB I/O API.         

        I am not sure if ASMLib is better or ASM and RAW is enough.                  

        Cheers         

        LSC                                             On 3/7/06, johan Eriksson < johan.eriksson_at_bossmedia.se <mailto:johan.eriksson_at_bossmedia.se> > wrote:

		On Tue, 2006-03-07 at 10:54 +0100, LiShan Cheng wrote:


		> Hi

		>

		> I am going to install a 10gR2 RAC in a couple of

weeks. It will be


		> RHEL 4 Update 2 and I will be using ASM for all

database files. 


		> However I have some doubts, I am wondering if ASMLib

API gives better


		> performance than Linux standard I/O API? Anyone with

both ASMLib


		> experience and ASM + RAW + Linux I/O API?

		>

		We have just installed this combination but I haven't
tested the 
		performance yet.
		One test is at http://www.linuxjournal.com/article/8539
		


		> I also read this note, Note: 357492.1, Linux 2.6

kernel deprecation of


		> raw devices. I was planning to use RAW Devices for the

voting disk and 


		> OCR files. If raw devices are deprecated does it mean

I must use


		> OCFS2?

		>

		Linux 2.6 and OCFS2 aren't yet cerified so I think you
have to use raw
		for ocr and voting (if you care about support) 
		
		/johan
		

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