Yeah.. Not sure if the root cause was ever determined but at my previous job we had issues with Xen guests shutting down but the blkback device would go D and n

Yeah.. Not sure if the root cause was ever determined but at my previous job we had issues with Xen guests shutting down but the blkback device would go D and never quit. This would prevent the VM from starting because the LV was busy. lvm commands would freeze. And of course the system would end up needing a hard reboot because the lvm teardown scripts would not complete on shutdown due to the busy device. Good times :|