I'm having the same problem here and I think it's not a virt-manager nor libvirt problem, but a D-I problem.
When a fresh install finishes and the system reboots, it doesn't find the SCSI disk, not even to start grub. If I change the disk to IDE, grub shows up. Squeeze works like a charm. -- Estêvão Samuel Procópio Amaral Diamantina, MG, Brasil
