When you use a vhd file for booting, you have no possibilities to reserve space for the pagefile inside the vhd (Windows does not support it). You need to place the file outside of the virtual drive. But what if your vhd has already been encrypted? In this case you have no chance to set virtual memory for the OS due to security reasons. Your pagefile wouldn’t be encrypted, which is not allowed.
Owing to the above mentioned reason, at every startup the following window will be appeared:
If you need the pagefile, in spite of the security risk, of course there is a solution :). The only thing, that you have to do, change a registry value. Under the “HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Memory Management” key you will find the “PagefileOnOsVolume” dword value. Change it from 1 to 0, and after a reboot you are able to set the pagefile outside of the virtual disk.