From: Greg Smith <greg@2ndquadrant.com>
To: Janning <ml@planwerk6.de>
Cc: pgsql-performance@postgresql.org
Subject: Re: Write performance
Date: Thu, 24 Jun 2010 09:57:50 -0400
Message-ID: <4C23645E.5070101@2ndquadrant.com> (raw)
In-Reply-To: <201006241443.33296.ml@planwerk6.de>
References: <201006241443.33296.ml@planwerk6.de>
As others have already pointed out, your disk performance here is
completely typical of a single pair of drives doing random read/write
activity. So the question you should be asking is how to reduce the
amount of reading and writing needed to run your application. The
suggestions at
http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server address
that. Increases to shared_buffers and checkpoint_segments in particular
can dramatically reduce the amount of I/O needed to run an application.
On the last server I turned, random reads went from a constant stream of
1MB/s (with default value of shared_buffers at 32MB) to an average of
0.1MB/s just by adjusting those two parameters upwards via those guidelines.
If you haven't already made large increases to those values, I'd suggest
starting there before presuming you must get a different disk setup.
--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com www.2ndQuadrant.us
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To: pgsql-performance@postgresql.org
Cc: greg@2ndquadrant.com, ml@planwerk6.de
Subject: Re: Write performance
In-Reply-To: <4C23645E.5070101@2ndquadrant.com>
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