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Re: ASM and RAW Devices on RHEL 4

From: Sanjay Mishra <>
Date: Tue, 7 Mar 2006 11:34:49 -0800 (PST)
Message-ID: <>


  I think question is to use ASM with ASMLIB I/O API or ASM with Linux I/O API. In both cases, it is using RAW.    

  OCR and Voting disk has to go in RAW devices as ASM is not meant for these files. We need OCR and Voting before ASM is started. I don't think that it is possible to store OCR/Voting disk on OCFS2. OCFS2 use differnt config files than OCFS and so Oracle installer cannot verify the cluster file location as it is trying to read from OCFS location. Even if you create symlink for OCFS and OCFS2 location , it will still not work as OCFS2 configuration doesn't have any GUID information.    

  I am catching on RAC and reading extensively and so this is just mine view        

Raj S <> wrote:
  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.


  On 3/7/06, LiShan Cheng <> 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.


LSC      On 3/7/06, johan Eriksson <> 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

> 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)


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Received on Tue Mar 07 2006 - 13:34:49 CST

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