Re: optimum postgres server configuration

On Thu, 24 Jul 2003, tom dyson wrote:

> We're about to buy a new server for dedicated Postgres serving. It'll be
> serving 4 - 10 databases (average dump size 20Gb) for various web
> applications. What is the list's advice on optimum configuration of hardware
> and software, given a smallish fixed budget (around $US 2000)? In
> particular, should we prioritise
>
> * Disk speed
> * Hardware RAID
> * Memory
> * Processor speed
> * Processor type
> * Multiple processors

This really kinda depends.

Will these databases see much writing?  Or will they be mostly read?

Generally, the more writing, the faster you want your disk subsystem to
be, and the more reading, the more memory / CPU horsepower you want.
Especially if you'll be munging tables against each other a lot.

I like having dual CPUs, as they aren't very expensive compared to single
ones, and provide a very noticeable performance gain for me.  I'd rather
have dual 1400MHz CPUs than one 2800MHz CPU.

You can't have too much memory.

Hardware RAID is overrated.  It's good, but software RAID on fast machines
is every bit a match for hardware RAID in performance, the only issue
being support for hot swapping and what not some hardware RAID cards have.

On Linux sw RAID however, stacking RAID levels doesn't provide as much
gain as it does with a hardware controller, so if you're looking at RAID
1+0, hardware is probably a better choice.

64 bit CPUs are nice if you're gonna use tons o ram to cache your
databases.

> And does the list have any observations regarding Postgres performance on
> different platforms? Our webservers run Linux (RedHat 8), but we're willing
> to experiment with alternatives.

BSD is generally considered the best performer, with Linux a close second.
Solaris is not so fast, but it does scale out to dozens and dozens of
CPUs, and Sparc boxes tend to have pretty fast I/O (the real ones, not the
IDE based workstations.)  Note that many folks consider BSD or Linux on
Sparc to be a nice solution for speed and expandability.