Re: optimal hardware for postgres?

peter pilsl wrote:
> I was now wondering which hardware would fit this server best. I think
> about 2GB RAM, a fast Raid1 and now I'm not sure about the CPU.
> I was considering 64-bit AMD : A Athlon 64 FX-51 or a Opteron 2.2GHz.
> The hosting system will be a 64-Bit linux.

While the A64 and Opteron are two sides of the same coin, I'd avoid
using A64s because you need ECC reg memory to keep your server stable.

To get fast RAID, you need fast I/O connections. Up to just a month ago,
that probably meant you had to get a hefty Dual Opteron MB in order to
get PCI-X slots. The other option now is use PCIe. Ordinarily, most
people use fast graphics cards in PCIe slots but you could pop in a PCIe
RAID controller instead. This gives you the option of looking at
"workstation-class" platforms versus a more expensive server platform.

On other note -- if you are thinking about SMP Opteron, you may actually
get better performance from 1x275 (Dual Core 2.2ghz) versus 2x248
(2.2ghz). Full duals have twice the bandwidth but without good NUMA
support, memory has to be interleaved between CPUs. This means when
reading chunks of continous memory, CPUs have to continually request
data from the other CPU. Because the CPU<->CPU requests on DC Opterons
are so much faster, AMD's own performance optimization guide says to put
2 threads onto a single DC chip leaving other CPUs in the system idle
versus trying to fully balance between chips.

> Does postgres benefit from 64-bit AMD's or would I be better off with a
> cheaper AthlonXP or even with a Pentium or a more expensive Xeon?
> Or is my question faulty at all, cause CPU is only 20% of the whole system.

My experience going from RH9 32-bit to FCx 64-bit was huge increases in
speed.