Re: Ever Increasing IOWAIT

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Ralph Mason" <ralph(dot)mason(at)telogis(dot)com>
Cc: "'Richard Huxton'" <dev(at)archonet(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Ever Increasing IOWAIT
Date: 2007-05-20 21:55:50
Message-ID: 17450.1179698150@sss.pgh.pa.us
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"Ralph Mason" <ralph(dot)mason(at)telogis(dot)com> writes:
> Ralph Mason wrote:
>> We have a database running on a 4 processor machine. As time goes by
>> the IO gets worse and worse peeking at about 200% as the machine loads up.
>>
>> The weird thing is that if we restart postgres it's fine for hours but
>> over time it goes bad again.

Do you by any chance have stats collection enabled and
stats_reset_on_server_start set to true? If so, maybe this is explained
by growth in the size of the stats file over time. It'd be interesting
to keep an eye on the size of $PGDATA/global/pgstat.stat over a fast-to-
slow cycle.

regards, tom lane

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