Hi ,John , You are right , this problem is solved when use the default driver, But I found the blktap in xen4.5 was not a module, it seems a library, am I right? And the VM also cannot start, I am not familiar whit xen, did you ever meet the below error, Thanks for helping me so much! 328 libxl: debug: libxl_event.c:606:libxl__ev_xswatch_deregister: watch w=0x7f102c0b9518 wpath=/local/domain/0/device-model/12/state token=3/0: deregister slotnum=3 329 libxl: error: libxl_dm.c:1371:device_model_spawn_outcome: domain 12 device model: spawn failed (rc=-3) 330 libxl: error: libxl_create.c:1194:domcreate_devmodel_started: device model did not start: -3 331 libxl: error: libxl_dm.c:1475:kill_device_model: Device Model already exited 332 libxl: debug: libxl_event.c:618:libxl__ev_xswatch_deregister: watch w=0x7f102c0cb640: deregister unregistered 333 libxl: debug: libxl_event.c:618:libxl__ev_xswatch_deregister: watch w=0x7f102c0cb850: deregister unregistered 334 libxl: debug: libxl_event.c:618:libxl__ev_xswatch_deregister: watch w=0x7f102c0cb220: deregister unregistered 335 libxl: debug: libxl_event.c:1739:libxl__ao_complete: ao 0x7f102c0c8820: complete, rc=-3 336 libxl: debug: libxl_event.c:1711:libxl__ao__destroy: ao 0x7f102c0c8820: destroy -----Original Message----- From: John Haxby [mailto:john.haxby@xxxxxxxxxx] Sent: Thursday, April 17, 2014 10:31 PM To: Tian, Shuangtai; libvir-list@xxxxxxxxxx Subject: Re: libvirt-libxl driver defaulting to tap disk and not working (ubuntu 12.10 + xen 4.5 + libvirt 1.2.3 + openstack) On 17/04/14 10:51, Tian, Shuangtai wrote: > <driver name="tap2" type="raw" cache="none"/> > As I recall, tap2 is deprecated and libxl will fail with it. Perhaps try tap or just leaving the driver as default? jch -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list