How to determine location of a VHD image using using its mounted drive letter?

Hi,

I have a VHD boot based on Window 8.1 Enterprise, starting my laptop in a live manner from a USB drive. The problem is to find out a way to determine the exact location of this VHD image; that is, the drive letter of the USB disk drive containing that image.

Another question is that when I list the disks in the powershell environment, I need to know which of the disks are actually mounted Virtual Hard Disks. Powershell normally shows them as fixed disks.

Thanks