Hi, I'm facing following issue ( or misunderstanding from my side) I try to attach a device to a running guest ; I want to do it persistently and without having to restart the GUEST . By using options "-live - persistent" , I got following error : [root@ldc01omv01 data]# virsh attach-device VM_RHEL7-1 "../data/channel_omnivision_to_be_used.xml" --live --persistent Please enter your authentication name: root@ldc01omv01 Please enter your password: error: Failed to attach device from ../data/channel_omnivision_to_be_used.xml error: Requested operation is not valid: cannot modify device on transient domain [root@ldc01omv01 data]# virsh -r list --all Id Name State ---------------------------------------------------- 8 VM_RHEL7-2 running 11 W2008R2-2 running 12 VM_RHEL7-1 running By using options "-live " , I got following error : [root@ldc01omv01 data]# virsh attach-device VM_RHEL7-1 "../data/channel_omnivision_to_be_used.xml" --live Please enter your authentication name: root@ldc01omv01 Please enter your password: error: Failed to attach device from ../data/channel_omnivision_to_be_used.xml error: Unable to read from monitor: Connection reset by peer [root@ldc01omv01 data]# virsh -r list --all Id Name State ---------------------------------------------------- 8 VM_RHEL7-2 running 11 W2008R2-2 running [root@ldc01omv01 data]# And then the Guest is powered off !! If I try to attach device when the Guest is off , then : [root@ldc01omv01 data]# virsh attach-device VM_RHEL7-1 "../data/channel_omnivision_to_be_used_1.xml" --config --persistent Please enter your authentication name: root@ldc01omv01 Please enter your password: error: failed to get domain 'VM_RHEL7-1' error: Domain not found: no domain with matching name 'VM_RHEL7-1' FYI , xml file contents is : <channel type='unix'> <source mode='bind' path='//var/lib/libvirt/qemu/VM_RHEL7-1_omnivision_1.agent'/> <target type='virtio' name='omnivision_1.agent'/> </channel> I'm using libvirt-1.2.17-13.el7.x86_64 Any help is welcome. Thanks. Regards, J.P. Ribeauville P: +33.(0).1.47.17.20.49 . Puteaux 3 Etage 5 Bureau 4 jpribeauville@axway.com<mailto:jpribeauville@axway.com> http://www.axway.com<http://www.axway.com/> P Pensez à l'environnement avant d'imprimer.