Kevin Closson put out a post yesterday called Critical Analysis Meets Exadata, linking to two awesome videos. It’s well worth spending the time to watch these, even if (like me) you never get so much as a sniff of Exadata.
I was lucky enough to be one of several people asked to review these videos before they were released. I’m sure some of the performance gurus on the Oak Table had a lot to say, but of the several comments I fed back to Kevin, I would just like to post a couple here:
- As a Joe Schmo dba, I almost never get to see what is happening internally in the storage layer (SAN, NAS etc). For the most part the storage is a black box that presents a few LUNs to me. If the storage subsystem and connecting network are capable of pushing enough data to and from my servers, to the point where my RAC node CPUs are the bottleneck, that is awesome. So if I think of the storage grid part of the Exadata configuration like I would judge any other SAN/NAS, then it gets a big gold star because it is good enough to keep my RAC node CPUs/cores, that are ridiculously expensive to license, working at full tilt most of the time.
- I believe the storage cell licensing is sold on a per disk basis, not per CPU core, so the storage grid being full of idle cores does not mean I’m paying for software licensing on idle cores. If Oracle reduced the total number of CPUs/cores, the licensing costs would be unaffected. If on the other hand, the storage cells could perform a lot more of the CPU intensive load and free up the RAC nodes, then I guess the licensing situation would change, because Oracle wouldn’t want to lose those high-cost licenses from the RAC nodes.
Now Kevin is an architecture guy and I can see how from his perspective this setup sucks, because it does. He’s clearly displayed that. Then again, from a DBA perspective, do I really give a damn about some idle CPUs in the storage layer? For all I know, every other storage system out there could be just as stupid, especially now it’s impossible to buy chips with small numbers of cores.
Like I said, you should watch the videos because they are great, but don’t be afraid to have a different opinion because you may be judging things by different standards.