I have found recently I can't boot any VMs which have a CD attached to it. I get the following error. VM Test is down with error. Exit message: internal error: qemu unexpectedly closed the monitor: 2018-10-04T11:53:07.031875Z qemu-kvm: -device ide-cd,bus=ide.1,unit=0,drive=drive-ua-5ccd6310-a1e5-4019-b989-795529c70794,id=ua-5ccd6310-a1e5-4019-b989-795529c70794,bootindex=2: Failed to lock byte 100 2018-10-04T11:53:07.032264Z qemu-kvm: -device ide-cd,bus=ide.1,unit=0,drive=drive-ua-5ccd6310-a1e5-4019-b989-795529c70794,id=ua-5ccd6310-a1e5-4019-b989-795529c70794,bootindex=2: Failed to lock byte 100 2018-10-04T11:53:07.032285Z qemu-kvm: -device ide-cd,bus=ide.1,unit=0,drive=drive-ua-5ccd6310-a1e5-4019-b989-795529c70794,id=ua-5ccd6310-a1e5-4019-b989-795529c70794,bootindex=2: Failed to lock byte 100 Unexpected error in raw_apply_lock_bytes() at block/file-posix.c:642: 2018-10-04T11:53:07.032665Z qemu-kvm: -device ide-cd,bus=ide.1,unit=0,drive=drive-ua-5ccd6310-a1e5-4019-b989-795529c70794,id=ua-5ccd6310-a1e5-4019-b989-795529c70794,bootindex=2: Failed to lock byte 100. I have tried relaxing the permissions on the iSO NFS share and even removed the iSO domain and added a new one, but I still get the problem. Regards Simon