On Tue, Oct 6, 2009 at 8:26 AM, Scott Marlowe <scott.marlowe@gmail.com> wrote:
> On Tue, Oct 6, 2009 at 7:21 AM, Nikolas Everett <nik9000@gmail.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.