[Users] Unable to run VM with "Unable to create cgroup" error message

Hi everyone, I created a Desktop VM1 with all default settings and added a 2G Disk to the VM1 in WebAdmin. But when I run the vm, it returns failure with the follow error message in WebAdmin. "VM VM1 is down. Exit message: Unable to create cgroup for VM1" My DateCenter contains one host(with OS is CentOS 6, VDSM version is 4.9.6 and libvirt version is 0.9.4) and one NFS domain. And The cgroup Directory have already exits on the host. But why cannot I run the VM1? There are some error message in VDSM log -------- File "/usr/lib64/python2.6/site-packages/libvirt.py", line 2087, in createXML if ret is None: raise libvirtError('virDomainCreateXML() failed', conn=self) libvirtError: Unable to create cgroup for VM1: No such file or directory ---------- There are some error message in libvirt log --------- error : virNetClientProgramDispatchError:170 : Unable to create cgroup for VM1: No such file or directory" --------- There are log files in attachment Best wishes, Xuejie Chen