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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: (view raw or whole 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 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

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Subject: Re: WAL+Os on a single disk
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Subject: Re: Write performance

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