Important registry setting in Windows Server 2008 R2 SP1

Since SP1 supports ‘Dynamic Memory’, your VMs could consume almost all available memory on the host, and leave 'nothing' for the parent partition.

A new registry key is now available:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Virtualization

REG_DWORD value

Name = MemoryReserve

Setting= amount of MB to reserve for the parent partition (recommend minimum 2GB)

You have to reboot your host to let the changes take effect.