Disk Partition Alignment Best Practices for SQL Server 2008

       The SQL Server Team has released guidance on Disk Partitioning Alignment Best Practices for SQL 2008.  This was a topic discussed at length at the Microsoft Management Summit 2009 (MMS2009) in Las Vegas, and Best Practices for SQL 2005 and SQL 2008 have been hotly debated.

You can read the entire whitepaper here.

“Summary: Disk partition alignment is a powerful tool for improving SQL Server performance. Configuring optimal disk performance is often viewed as much art as science. A best practice that is essential yet often overlooked is disk partition alignment. Windows Server 2008 attempts to align new partitions out-of-the-box, yet disk partition alignment remains a relevant technology for partitions created on prior versions of Windows.

This paper documents performance for aligned and nonaligned storage and why nonaligned partitions can negatively impact I/O performance; it explains disk partition alignment for storage configured on Windows Server 2003, including analysis, diagnosis, and remediation; and it describes how Windows Server 2008 attempts to remedy challenges related to partition alignment for new partitions yet does not correct the configuration of preexisting partitions.

The following topics are also included: background information, implementation, vendor considerations, two essential correlations, valid starting partition offsets, and the simple protocol to align partitions, define file allocation unit size, and assign drive letters. It includes results from tests that show how partition alignment can affect performance for SQL Server 2008.”