I think it's even possible to modify that shell script to pipe into nbdkit and from there to ‘qemu-img convert’. I'm too lazy to actually do that right now, but the basic idea is here:
https://rwmj.wordpress.com/2014/10/14/streaming-nbd-server/ You'll probably have to add ‘-m 1’ to the qemu-img convert command line. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org