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RE: Oracle Rac and IBM P-series machines

From: Pete Sharman <>
Date: Thu, 16 Feb 2006 05:46:53 +1100
Message-ID: <20060216054653077.00000002740@psharman-au>

Generator Microsoft Word 11 (filtered) Tom

No, it is not true that you need to use raw devices because of RAC. You need to use raw devices ONLY where the OS can' t share files between nodes. If you were on a real operating system (also known as VAX) this wouldn' t be a problem.

OK, OK, I' m biased! J

Honestly though, this is an OS limitation that RAC has to work with, rather than necessarily a RAC limitation. If the OS you use supports a CFS, you can use that instead. Alternatively, you could use ASM if you' re looking at 10g.

We do have customers with systems that are further apart than a mile, mostly I think using dark fibre (or dark fiber for you Yanks). Again, the limitation here is more of an OS one. If you can cluster the boxes, RAC should work on top of that. Having said that, there is of course a latency issue that gets worse as you move the boxes further apart. Only testing of your specific app in that environment can tell whether that latency is acceptable or not.

HTH. Pete

"Controlling developers is like herding cats."
Kevin Loney, Oracle DBA Handbook

"Oh no, it's not. It's much harder than that!"
Bruce Pihlamae, long-term Oracle DBA
From: [] On Behalf Of Mercadante, Thomas F (LABOR) Sent: Wednesday, 15 February 2006 6:10 AM To: Subject: Oracle Rac and IBM P-series machines

We have a pair IBM P690 machines running AIX 5.3.

I was wondering if anyone is running RAC on these machines.

Is it true I would need to use RAW devices because of RAC? " Normal" file systems would not work for RAC.

And can the machines be geographically apart from each other (like within a mile)? Last I heard the physical distance was a problem, but things change fast around here.

Tom Mercadante

Received on Wed Feb 15 2006 - 12:46:53 CST

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