Attaching a VHD in the console
From Support Forums : Accessing file based storage? …, how to actual a VHD disk image in the console for XEv4:
You will need to attach the VDI to dom0 (Please refer to “xe vbd-create”). This will mount the VDI as a device in dom0, which you can then “lomount” to get hold of the exact partition on that disk.