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Message-ID: <878c83960708220922n747c8485r30584d3ef793ec2e@mail.gmail.com>
Date: Wed, 22 Aug 2007 20:22:59 +0400
From: "Dmitry Potapov" <fortune.fish@gmail.com>
To: "Joshua D. Drake" <jd@commandprompt.com>
Subject: Re: io storm on checkpoints, postgresql 8.2.4, linux
Cc: pgsql-performance@postgresql.org
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2007/8/22, Joshua D. Drake <jd@commandprompt.com>:

> >     We've run into an issue of IO storms on checkpoints. Once in 20min
> > (which is checkpoint_interval) the database becomes unresponsive for
> about
> > 4-8 seconds. Query processing is suspended, server does nothing but
> writing
>
> What are your background writer settings?
>
>
bgwriter_delay=100ms
bgwriter_lru_percent=20.0
bgwriter_lru_maxpages=100
bgwriter_all_percent=3
bgwriter_all_maxpages=600


In fact, with dirty_background_ratio > 0 bgwriter even make things a tiny
bit worse.
-- 
Regards,
            Dmitry

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<span class="gmail_quote">2007/8/22, Joshua D. Drake &lt;<a href="mailto:jd@commandprompt.com">jd@commandprompt.com</a>&gt;:</span><br><div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
&gt;&nbsp;&nbsp;&nbsp;&nbsp; We&#39;ve run into an issue of IO storms on checkpoints. Once in 20min<br>&gt; (which is checkpoint_interval) the database becomes unresponsive for about<br>&gt; 4-8 seconds. Query processing is suspended, server does nothing but writing
<br><br>What are your background writer settings?<br><br></blockquote></div><br><pre>bgwriter_delay=100ms<br>bgwriter_lru_percent=20.0<br>bgwriter_lru_maxpages=100<br>bgwriter_all_percent=3<br>bgwriter_all_maxpages=600<br>
</pre><br clear="all">In fact, with dirty_background_ratio &gt; 0 bgwriter even make things a tiny bit worse.<br>-- <br>Regards, <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Dmitry

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