Hyper-V How To: How to tell what physical disk is used for passthrough
Taylor Brown's blog post shows you the WMI that will tell you what physical disk a virtual machine is using when configured for passthough on the host: https://blogs.msdn.com/taylorb/archive/2008/08/21/hyper-v-wmi-what-vhd-s-physical-disks-are-associated-with-a-virtual-machine.aspx.