Download SP1 from http://www.microsoft.com/ and install it on the Windows 2008 R2.
SP1 was not installed on the Windows 2008 R2. This led to a significant storage performance fluctuation when a LUN was processing small data block sequential reads.
Storage performance fluctuates significantly when Windows 2008 R2 works with QFMA HBAs. It is not recommended that performance-demanding services such as VOD run on such a system. For details about SP1, contact Microsoft technical support personnel.