Doing 'virsh migrate --copy-storage-all' currently isn't very end user friendly because it requires initial stub storage files to exist on the destination host. 

Trying to automatically do this is likely difficult and error prone given all the possible storage configurations available, but IMO as is the feature is pretty uninteresting to end users.

I think we should add a migration API flag that will have the destination libvirt create storage stubs for disk images, if required. Even if a first attempt just handles image files that would go a long way.

Without this, we would _have_ to implement something similar just to expose this in virt-manager, so IMO it's better to do this at the libvirt level first, so all clients (particularly virsh) can benefit.