Unit number 7 is kind of special. It's reserved for SCSI controller. The comment in virDomainSCSIDriveAddressIsUsed() summarizes that pretty nicely. Libvirt would never generate such address. Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Tested-by: Daniel Henrique Barboza <danielhb413@gmail.com> Reviewed-by: Jim Fehlig <jfehlig@suse.com>