In Windows Server 2008 and Windows Server 2008 R2 – starting a virtual machine would result in Hyper-V creating a .BIN file which matched the size of the memory assigned to the virtual machine. We did this to ensure that we always had enough disk space available to create a saved state (which is particularly critical if the physical computer is shutting down – and the virtual machine is configured to save state when the physical computer shuts down).
However – many people did not like to see their disk space being “wasted” like this. As we have seen memory increase in physical computers – we have started to see systems come out that have more memory than disk space, which obviously causes a problem here.
To address this in Windows “8” we made a simple change:
Now we only pre-create the .BIN file if you choose Save the virtual machine state as the Automatic Stop Action for the virtual machine. If you choose Turn off the virtual machine or Shut down the guest operating system we will only create a .BIN file if you manually choose to save state the virtual machine.