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Re: Write performance

From: Greg Smith <greg(at)2ndquadrant(dot)com>
To: Janning <ml(at)planwerk6(dot)de>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Write performance
Date: 2010-06-24 13:57:50
Message-ID: 4C23645E.5070101@2ndquadrant.com (view raw or flat)
Thread:
Lists: pgsql-performance
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(at)2ndQuadrant(dot)com   www.2ndQuadrant.us


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Next:From: Anj AduDate: 2010-06-24 14:55:04
Subject: Re: WAL+Os on a single disk
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Subject: Re: Write performance

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