Re: Seeking performance advice and explanation for high I/O on 8.3

From: Andy Colson <andy(at)squeakycode(dot)net>
To: Scott Otis <scott(dot)otis(at)intand(dot)com>
Subject: Re: Seeking performance advice and explanation for high I/O on 8.3
Date: 2009-09-03 15:02:56
Message-ID: 4A9FDAA0.4010701@squeakycode.net
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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). Have you tried a dd test?

-Andy

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