-source (C</dev/VG/Original>). To copy less than the whole
-source device, use L</guestfs_copy_size>.
+source (C</dev/VG/Original>). To copy less than the whole source
+device, use the optional C<size> parameter:
+
+ guestfs_copy_device_to_device (g,
+ "/dev/VG/Original", "/dev/VG/Copy",
+ GUESTFS_COPY_DEVICE_TO_DEVICE_SIZE, 10000,
+ -1);