In a recent post, I stated that I would circle back around and give you an update on Oracle 11g performance once we had tested the 64 bit version. I have done so at this point, and I must admit that I am rather disappointed.
To remind you of our approach to performance, we do not do any exotic tunings. We simply tune in a manner which a typical customer would find reasonable. No hidden leading underbar parameters, or that sort of thing. This is very, very different from the typical TPC-C you see posted on the TPC.org website.
On 10g, what we found was that tuning memory is easy. We set the parameters SGA_TARGET and SGA_MAX_TARGET and we are away to the races. Of course, we tune Huge Pages appropriately as well. For more information on that, see the excellent article on the Puschitz website.
We got a lot of improvement by tuning Huge Pages. Even as a storage company, who make money by selling disks, we recognize the scalability improvements from adding memory. In general, memory is our number one scaling bottleneck. We never recommend that customers add disk before we have investigated memory first.
So, needless to say the issue of memory is very central to our methodology on tuning Oracle.
When the 32 bit version of Oracle 11g came out, as I stated previously, the memory model was the main reason that we were not able to scale as well as we did on the 64 bit version of 10g. Hence, I had high hopes that the 64 bit version of 11g would scale well. In fact, I hypothesized that we could transition our entire program to 11g.
Wrong. The memory model on the 64 bit version of 11g is no better than the 32 bit version. I find this very strange, and honestly consider it to be a bug. The bottom line is that we have not been able to scale the 64 bit version of 11g any better than we did the 32 bit version.
For this reason, again, we cannot really assess the performance impact of dNFS in a real-world performance workload. (Very contrived testing could be conducted to prove that dNFS saves CPU cost, but what would that prove? Others have done that testing and we have no interest in doing so.) Our focus is on a real-world workload running on a real-world configuration. In this situation, 11g over dNFS does not perform better than 10g over kernel NFS.
We have gone back to 10g Release 2 for now. I will come back to 11g later, perhaps when Release 2 is available (although I have been told I may wait a while for that). In the meantime, I will continue to update you on what we find out in our testing. Our current focus is on the use of VMware in the Oracle context. More on that later.