On Fri, Oct 17, 2008 at 3:19 PM, Brian Modra <epailty@googlemail.com> wrote:
> Hi,
> I have a server in production running postgresql, receiving 110 rows
> inserted per second, with some pretty intense queries involving long
> plpgsql.
> This server has 4Gigs of RAM and dual processor. Disk is Raid 5.
You've hamstrung your RAID array right there with RAID-5, unless it's
almost all reads, in which case it might be ok, but not great.
> I need more power, and am wondering what is the place really I need to put
> more emphasis? CPU, RAM, or disk?
Ram > disk > cpu
> I'm thinking of a 4xCPU and 20 Gigs and one of those large ram disks which
> has its own battery and writes all RAM to hard disk in the event of power
> failure.
Hard to say if a RAM disk would help. If your dataset already fits in
ram and you don't write much then a ram disk won't help. What do
vmstat and iostat have to say on the issue?
> Obviously I need to first get a good sysadmin guy to configure postgres
> properly, but I am sure I also need a bigger host.
> Any advice will be appreciated.
Well, don't buy anything before you've identified your biggest
performance killer, memory, io, or CPU. Memory is cheap, you might
find that putting 16 Gigs into your current server the performance
improves enough to keep you from needing a big shiny new server. If
you do decide to get a shiny new server, get it with enough RAM to
cache your dataset, and a RAID controller with as many disks as you
can afford. 4 to 8 cpus are usually plenty unless you have a really
large parallel workload going on.
--
When fascism comes to America, it will be draped in a flag and
carrying a cross - Sinclair Lewis
