| From: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
|---|---|
| To: | Nikolas Everett <nik9000(at)gmail(dot)com> |
| Cc: | anthony(at)resolution(dot)com, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Speed / Server |
| Date: | 2009-10-06 19:28:59 |
| Message-ID: | dcc563d10910061228h6616a3dmad1fdd92daccb1a5@mail.gmail.com |
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| Lists: | pgsql-performance |
On Tue, Oct 6, 2009 at 8:26 AM, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> wrote:
> On Tue, Oct 6, 2009 at 7:21 AM, Nikolas Everett <nik9000(at)gmail(dot)com> wrote:
>> If my un-word wrapping is correct your running ~90% user cpu. Yikes. Could
>> you get away with fewer disks for this kind of thing?
>
> Probably, but the same workload on a 6 disk RAID-10 is 20% or so
> IOWAIT. So somewhere between 6 and 12 disks we go from significant
> IOWAIT to nearly none. Given that CPU bound workloads deteriorate
> more gracefully than IO Bound, I'm pretty happy having enough extra IO
> bandwidth on this machine.
note that spare IO also means we can subscribe a slony slave midday or
run a query on a large data set midday and not overload our servers.
Spare CPU capacity is nice, spare IO is a necessity.
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