Chosing processors for Oracle database 10g 64 bits

Question

Hi,
I have a customer that is planning to buy Oracle 10g 64 bits on a server Windows 2003.
My customer is interested in a processor that handles a lot of data in and out in a very effective way and the processor should be able to perform a great number of calculations in the database.
Are there some processors that are better than others for Oracle 10g 64 bits?
For example: Is Itanium better than Xenon? Or is Xenon better that AMD?
Any suggestions will be appreciated.
Thanks in advance.

Answer 1

It's a very long article!
I'm not sure of its relevance, I'm afraid... not enough time to read it!
Kevin Closson's blog has a lot of good stuff about NUMA. Software can be optimised to run on NUMA processors. Oracle is. The parameter means you switch off those optimisations. It means Oracle works fine, but less well than it is theoretically capable of, because you are making it believe it's running on a non-NUMA processor.
From memory, the specific NUMA optimisation that caused the issue is that the buffer cache is divided up internally so that each processor can handle different bits of it, distributing cache management chores amongst all the available cores. Excellent in theory. Unfortunately, the bug meant that a query that runs on one processor core got its data cached in that processor's "bit" of the buffer cache... and if you re-ran the query and happened to end up on a different core, the new core behaved as though no data had been cached, and fetched it all again from hard disk. Performance WITH the NUMA "optimisation" was accordingly abysmal because you effectively had little or no buffer cache. The workaround is to disable the NUMA optimisation and pretend you've only got one core: Oracle then has a monolithic buffer cache -which introduces performance issues of its own, of course, but at least your data gets cached properly!
The bug is allegedly fixed in 10.2.0.3, but we spent over a 16 months getting it sorted, and by that time, we'd given up and gotten the Intel boxes, so I've no idea whether it was really fixed or not... and, of course, you might not be able to patch to that level anyway for internal politics or other reasons.