Do virtual machines need a paging file?

Question

I have read this, which has confused me a little:

Virtual Machines require physical not virtual memory so you do not need to count the memory allocated to your VM's when calculating your paging file size.

Does this mean a VM will only use physical RAM, as a paging file is not possible?

Answer 1

It's not talking about what is happening "inside" the VM. Within the VM you can configure the OS within to use a page file (which would likely go to a virtual disk) or whatever you like/need.

Outside of the VM, from the hypervisor's point of view, you really do not want the RAM that's allocated to the VM to be swapped out - the performance of your VM will suffer greatly.

It may be possible that specific VMs don't allow the memory they've allocated for VM use to be swapped out. The documentation you are reading seems to say that.

So, if you plan to run, for example, a VM with 2Gbyte of RAM continuously, and your host system has 4Gbytes of RAM, you don't need to worry about the RAM that the VM is using ever going to the pagefile when figuring out how big of a pagefile you want.