[libvirt] How to use live migration of kvm with non-shared storage

non-shared storage. But I don't know how to use it. In the qemu monitor, "migrate -d tcp:10.1.10.42:444" which is based on shared storage is going well. I don't know how to use the command of "-b or -i" or maybe I don't know the correct format of uri. the source and destination system is Fedora-13, and the version of kvm is qemu-kvm-0.12.3. When I use the "migrate -d -b tcp:10.1.10.42:4444", the qemu monitor don't show nothing. When I use "info migrate",there shows "migrate status: failed". I don't know why? I hope someone who used this command successfully would help me, thank you