Never Underestimate The Power of Defrag

Monday, 8 December 2008 21:34 by RanjanBanerji

Very often I hear people make comments like "I have no idea but my servers are running really slow."  A common cause for this magical slow performance is a highly fragmented drive.  High levels of fragmentation will result in excessive disk I/O which will impact the performance of your servers.

A few years ago we were experiencing very slow query responses from an Oracle server.  The DBA laughed at me when I said check the drives.  Eventually when we checked sure enough the drives were extremely fragmented.  Once defragged (if I may use the term) the problems vanished.

Today I happened to be diagnosing why one of our servers running SharePoint and SQL Server was behaving so poorly.  A simple select count(*) from AuditData was taking over 2 minutes to return data.  Granted that the table had 13 million records. I wrote a script to delete records from this table using the SharePoint API and the code just sat there chugging for 4 hours at the end of which I had to terminate it.  A casual glance showed that this appeared to be a problem triggered by poor I/O.  When I checked the drives this is what I found.

defrag

 

That much red is just not good.  So before you get down to lengthy discussions about query optimizations and table indexes please stop and make sure your server is not screaming for help.

 

 

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May 4. 2011 05:38

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