Customers report loss of their I/O performance (network and storage) when enabling the Microsoft HyperV* role on an Intel® Compute Module MFS5520VI with an Intel® Xeon® Processor 5600 Series and more than 32GB memory installed.
This issue is caused by the way the processor presents its memory capabilities to HyperV and the way HyperV looks at the system memory, and fixes are available from both Microsoft and Intel.
Upgrade the Intel® Modular Server to firmware 6.7 or higher, set BIOS defaults, and then enter the BIOS and make the following settings change:
On advanced PCIe* configuration screen go to maximize/minimize memory below 4GB and set it to MIN.
Go to the Microsoft Web site and download and apply the following Microsoft hotfix:
Performance decreases in Windows Server 2008* R2 when the Hyper-V role is installed on a computer that uses Intel Westmere or Sandy Bridge processors
You cannot run a Windows 8*-based or Windows Server 2012*-based virtual machine in Windows Server 2008* or in Windows Server 2008 R2.