This script is used to back up the main MDTDATA partition to a secondary partition (on another drive!) called MDTDATA2. There is only a single, optional parameter:
This will include the VM VHDX files (which change a lot and are huge) in the backup. Only do this every so often just so that the disk is relatively recent. It's okay if you have to rebuild the VHDXs.
If the VM is running, it will be stopped and then restarted automatically.