[libvirt] clone "img" on iscsi storage

Hi: I need to clone a vm, the source is "vm1.img",i need to clone the "vm1.img" to a iscsi storage volume, it's said that i can't create volume on a iscsi. I use virStorageVolCreateXMLFrom to do this, can you do me a favor? thank you. the virt-manager can clone the "vm1.img" to overwrite the iscsi "lun",what can i do to do the same thing, i do not understand the python.