If you are using Hyper-V on computers on which you want to install this service pack, you should be aware of the following considerations:

  • You can import and export virtual machines freely between virtualization servers running Windows Server 2008 R2 and Windows Server 2008 R2 with SP1 as long as neither Microsoft RemoteFX nor Dynamic Memory are enabled on the virtual machine
  • Virtual machines running Windows as a guest operating system that have R2 integration services installed will run normally on virtualization servers that are running Windows Server 2008 R2 with SP1. The Dynamic Memory and RemoteFX features, however, require the SP1 version of integration services, which includes other updates and enhancements as well. To get the SP1 version of these services, either install SP1 on the guest operating system or user Hyper-V Manager (see http://technet.microsoft.com/en-us/library/cc732470(WS.10).aspx for details).
  • Once you have installed this service pack, you will have to uninstall it prior to installing a later release of this service pack. The settings of any virtual machines will remain intact during the uninstallation and installation, but virtual machines that have RemoteFX or Dynamic Memory enabled will not appear in Hyper-V Manager while the service pack is removed. In addition, any snapshots taken when RemoteFX of Dynamic Memory was enabled will not appear in Hyper-V Manager. They will reappear and functional normally once the later release of SP1 is installed.

A Windows Server 2008 R2 Hyper-V Cluster can run as a mixed cluster of nodes running Windows Server 2008 R2 and Windows Server 2008 R2 with SP1. For information about installing a service pack in a cluster, see http://support.microsoft.com/kb/174799/en-us. Before you install the service pack on a cluster, you should be aware of the following considerations:

  • Do not enable either RemoteFX or Dynamic Memory until the entire cluster is upgraded to Windows Server 2008 R2 with SP1.
  • Migration of virtual machines that have Dynamic Memory enabled to a node that does not have Dynamic Memory support will fail
  • Migration of virtual machines that have RemoteFX enabled to a node that does not have RemoteFX enabled will fail.
    To live-migrate virtual machines that have RemoteFX enabled, all nodes must be capable of supporting RemoteFX, all nodes must use identical graphics processing units, and all nodes must have RemoteFX enabled. For details of the CPU requirements for RemoteFX, see see “Hardware Considerations for RemoteFX” at http://technet.microsoft.com/en-us/library/ff817602(WS.10).aspx