using virt-df is simple as writing df on your terminal.
Below a real life example:
# virsh list --all Id Name State ---------------------------------------------------- 1 win2003 running 4 win2008 running # virt-df -d win2008 -h Filesystem Size Used Available Use% win2008:/dev/sda1 40G 38G 1.9G 96%
Tag(s):
virt-df