.... I'd look at adding more disks first. Depending on what type of query load you get, that box sounds like it will be very much I/O bound....
Given a a 13G database on a 12G system, with a low growth rate, it is likely that there is almost no I/O for most activities. The exception is checkpointing. The first thing I'd do is try to build a spreadsheet model of: - select frequency, and # logical and physical reads involved - insert/delete/update frequency, and # logical and physical read and writes involved - commit frequency, etc. (start out with simplistic assumptions, and do it for peak load) - system events (checkpoints, vacuum) I assume that the only high I/O you will see will be for logging. The RAID issue there is basically obviated by the sequential write nature of WAL. If that is the case, EMC is not the most cost effective or obvious solution - since the value they provide is mostly manageability for disaster recovery. The goal in this case is to write at the application max speed, and with mimimal latency. Any responsible battery backed up write through (mirrored) cached controller can do that for you. On the other hand, if your requests are not *all* trivial, you are going to test the hardware and scheduling algorithms of OS and pg. Even if 0.1% of 3,000 tps take a second - that ends up generating 3 seconds of load.... Any, even slightly, slow transactions will generate enormous queues which slow down everything. In most systems of this volume I've seen, the mix of activities is constantly invalidating cache, making L2 caching less important. Memory to CPU bus speed is a limiting factor, as well as raw CPU speed in processing the requests. Xeon is not a great architecture for this because of FSB contention; I suspect a 4-way will be completely FSB bottlenecked so a more than 4 way would likely not change performance. I would try to get a simple model/benchmark going and test against it. You should be talking to the big iron vendors for their take on your issues and get their capacity benchmarks. __________________________________ Do you Yahoo!? Yahoo! Search - Find what you’re looking for faster http://search.yahoo.com ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
