Two Intel E5-2643 (4 cores each) or single E5-2690 (8 cores) for Oracle 11.2.0.3 on Oracle Linux

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I have quite specific question about Oracle database (11.2.0.3) and Intel processors. We just upgraded our main database server to big Linux box with 192GB of RAM (150 GB dedicated for Oracle). After the upgrade we found that the system is now CPU constrained (it was IO constrained before).

The machine is DELL R620 with single Intel Xeon E5-2643 processor and 192GB or RAM.

We want to go to 8 cores, so now we have two options:
1. We can buy second E5-2643
2. We can buy a single 8 core processor, e.g. E5-2690.

We don't have experience with multi cpu systems, so decision is not easy for us.

After analysis we found that second E5-2643 could be better because:

  • it is faster (3.3GHz vs 2.9GHZ of E5-2690)
  • we get two memory controllers – so we double the theoretical memory bandwidth

E5-2690 could be better because:

  • we have a single processor, so all memory would be local, so access to memory would be equally fast for all requests, whereas in case of two E5-2643 we would have to split memory between two processors (NUMA nodes), so for each processor half of memory would be remote, so access to this memory would be slower (please keep in mind that our SGA is 140GB, so it would be located on both NUMA nodes).

Do you have any suggestions, which configuration should behave better with Oracle (the price of processor or power consumption does not matter).

Best Answer

Performance will be very similar. GHz difference is not essential because e.g. E5-2690 has 3.8GHz Max Turbo Frequency vs 3.5GHz on E5-2643. You can find full comparision here:

http://ark.intel.com/compare/64596,64587

The big thing may be licensing. If you are using Standard Edition or Standard Edition One per CPU licensing they are licensed per socket. So in case you buy second E5-2643 you will also have to buy one more Oracle license. Of course that it not the case with the Enterprise Edition.

If licensing is also not an issue then you still have two decide between two choices:

  • buying 2nd E5-2643 will be just cheaper now. Why not to save some money if everything else is the same?
  • if you buy E5-2690 and after some time you will hit CPU bottleneck again you will have an option to buy 2nd E5-2690 and once again double the performance.

Also with such amount of memory you really really should use Huge Pages. Of course that means no more AMM and back to ASMM. But especially if you have many connections to Oracle the difference can be really big. You can read about configuring Huge Pages e.g. here:

http://www.oracle-base.com/articles/linux/configuring-huge-pages-for-oracle-on-linux-64.php

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