FWIW to follow up to this old thread, I made the change in nbdkit: https://github.com/libguestfs/nbdkit/commit/acc37af9989aae708e8acad3535e1491931e6bdb Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html