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RE: 10g RAC Install with Raw Devices

From: Kerber, Andrew W. <>
Date: Thu, 29 Mar 2007 13:12:37 -0500
Message-ID: <>

I was working on a home project drawing to build a rac cluster, and ran into exactly that issue. Linux, at least fedora, has desupported raw devices. Since the objective of the project was to learn more about linux and rac, at that point I switched the project over to suse 10.2, which still supports raw. However, the project isn't complete (since I am doing it in my spare time), so I cant really tell you about how well the suse will work. Basically, as near as I could determine, the choices were asm or raw devices for the voting disk and quorum disk, and asm isn't available for current versions of fedora (5 or 6), that left raw devices, which also were not supported. I haven't seen anything that says that supports o_direct, but I haven't seen anything that says it doesn't either.

-----Original Message-----
[] On Behalf Of William Wagman Sent: Thursday, March 29, 2007 11:08 AM
To:; Cc:; Subject: RE: 10g RAC Install with Raw Devices


Can you provide some pointers to further information on this subject.


Bill Wagman
Univ. of California at Davis
IET Campus Data Center
(530) 754-6208
-----Original Message-----
[] On Behalf Of Alex Gorbachev Sent: Wednesday, March 28, 2007 8:07 PM
Cc:; Subject: Re: 10g RAC Install with Raw Devices

Don't use raw devices if you are running Oracle (or 3?) on Linux.
* Raw devices are being kind of depreciated in Linux. * Additional level of complexity (bind + permissions) so more likely to fail.

The problem with block devices (/dev/sd*) is that IO to block devices is buffered IO - going via OS cache. Unless you open them with O_DIRECT flag. Starting with 10.1 (IIRC) Oracle adds this to datafile open call (filesystemio_options must be at least directio?). With the same is done for OCR - it's opened with O_DIRECT. However, voting disks open call still have a bug so during installation of you will need to bind voting disks at least. After upgrade to later patchset (I think is enough but don't remember - need to check list of bugs fixed), voting disk is also opened with O_DIRECT.

On 3/28/07, Naqi Mirza <> wrote: >
> How did you setup the raw devices ? Did you bind raw partitions to
your raw
> devices. I'm not an expert on linux but I see you're specifying
/dev/sda2 -
> once bound shouldnt this be something like /dev/raw/raw1 ?
> I haven't had the installer complain about devices, but I have had
> fail on the shared storage check - but that was specific to the hp-ux
> platform.

Best regards,
Alex Gorbachev


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Received on Thu Mar 29 2007 - 13:12:37 CDT

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