From: Richard Huxton <dev@archonet.com>
To: Ralph Mason <ralph.mason@telogis.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Ever Increasing IOWAIT
Date: Fri, 18 May 2007 10:12:01 +0100
Message-ID: <464D6DE1.6040001@archonet.com> (raw)
In-Reply-To: <011b01c798d5$141365a0$3c3a30e0$@mason@telogis.com>
References: <011b01c798d5$141365a0$3c3a30e0$@mason@telogis.com>
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 itÂ’s fine for hours but over
> time it goes bad again.
>
> (CPU usage graph here HYPERLINK
> "http://www.flickr.com/photos/8347741@N02/502596262/"http://www.flickr.com/p
> hotos/8347741@N02/502596262/ ) You can clearly see where the restart
> happens in the IO area
I'm assuming here we're talking about that big block of iowait at about
4-6am?
I take it vmstat/iostat show a corresponding increase in disk activity
at that time.
The question is - what?
Does the number of PG processes increase at that time? If that's not
intentional then you might need to see what your applications are up to.
Do you have a vacuum/backup scheduled for that time? Do you have some
other process doing a lot of file I/O at that time?
> This is Postgres 8.1.4 64bit.
You'll want to upgrade to the latest patch release - you're missing 5
lots of bug-fixes there.
--
Richard Huxton
Archonet Ltd
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To: pgsql-performance@postgresql.org
Cc: dev@archonet.com, ralph.mason@telogis.com
Subject: Re: Ever Increasing IOWAIT
In-Reply-To: <464D6DE1.6040001@archonet.com>
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