Sunday, June 28, 2009

Disk Partition Alignment - best-kept secret related to SQL Server performance

Briefly,
By default there is no disk partition alignment on
Windows 2003 Server. This cause accessing 2 tracks of
HDD instead of 1 for each & every I/O request!

It happens due to wrong partition start offset value.
In combination with stripe unit size & file allocation unit size,

it is possible to increase the SQL Server I/O throughput
by 10%, 15%, 30% or more.




Check the Jimmy May`s blog,he describes it very good:
http://blogs.msdn.com/jimmymay/archive/2008/10/14/disk-partition-alignment-for-sql-server-slide-deck.aspx


For more information:
http://support.microsoft.com/kb/929491


Disk Partition Alignment Best Practices for SQL Server:
http://msdn.microsoft.com/en-us/library/dd758814.aspx

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