Microsoft has recently released the beta of the eagerly awaited service pack 1 for Windows 7 and Windows Server 2008 R2. This service pack is unusual because it can be applied to either operating system. The service pack includes many new and improved capabilities for Windows Server 2008 R2. On such new feature is Dynamic Memory. Servers running Hyper-V role can now better manage allocations of memory to Virtual Machines.
In Hyper-V the memory allocation of a Virtual Machine could only be modified if the VM was shut down. This would cause an interruption of services for any network connected users. System Administrators would have to specify an amount of RAM that was sufficient during periods of peak demand. This meant that often memory was unused on a VM most of the time but was still not available for other, busier VMs. This leads to a situation where a significant percentage of the memory resources of a Hyper-V server is wasted.
When Service Pack 1 for Windows Server 2008 R2 is installed a VM can be configured with Dynamic Memory. An administrator can assign a range of memory to a VM that can change based on an increase to a VM’s workload. This range consists of a Startup RAM allocation and can increase to a Maximum RAM value. A percentage of RAM can also be reserved, based on a VM’s workload, to be used as a buffer if memory demand increases suddenly. Each Virtual Machine running on a Hyper-V server can also be assigned Memory Priority ranging from low to high relative to the other VMs. I if multiple VMs need more memory at the same time those that have a higher priority will receive more Dynamic Memory.
The Windows 7 and Server 2008 R2 Service Pack is still in beta and is intended for testing and evaluation only. The final version is expected to be released in early 2011. Check out Dynamic Memory by down loading the beta version of the service pack at: http://technet.microsoft.com/en-us/evalcenter/ff183870.aspx
Author: Mark Menges