Re: Seeking performance advice and explanation for high I/O on 8.3 - Mailing list pgsql-performance

From Andy Colson
Subject Re: Seeking performance advice and explanation for high I/O on 8.3
Date
Msg-id 4A9FDAA0.4010701@squeakycode.net
Whole thread Raw
In response to Seeking performance advice and explanation for high I/O on 8.3  ("Scott Otis" <scott.otis@intand.com>)
List pgsql-performance
Scott Otis wrote:
> Would love to get some advice on how to change my conf settings / setup
> to get better I/O performance.
>
> Total I/O (these number are pretty constant throughout the day):
> Reads: ~ 100 / sec for about 2.6 Mb/sec
> Writes: ~ 400 /sec for about 46.1Mb/sec
>
>
> Most of the SQL happening is selects – very little inserts, updates and
> deletes comparatively.
>

Maybe I'm wrong, but those two don't seem to jive.  You say its mostly selects, but you show higher writes per second.

Does freebsd have a vmstat or iostat?  How did you get the numbers above?  How's the cpu's look?  (are they pegged?)

The io stats above seem low  (reading 2 meg a second is a tiny fraction of what your system should be capable of).
Haveyou tried a dd test? 

-Andy

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