Hi, I'm running OpenStack to manage LXC instance through libvirt. The same setting runs perfectly well on Ubuntu 12.04, while on CentOS 6u3, libvirt dumped following message when starting lxc instance. virsh -c lxc:/// start instance-00000032 error: internal error The 'cpuacct', 'devices' & 'memory' cgroups controllers must be mounted Really appreciated if someone could shed some lights. Seems to some libvirt / cgroup settings related. $ cat /proc/mounts .. none /cgroup cgroup rw,relatime,net_prio,perf_event,blkio,net_cls,freezer,devices,memory,cpuacct,cpu,ns,cpuset 0 0 .. $ chkconfig --list | grep cg cgconfig 0:off 1:off 2:off 3:off 4:off 5:off 6:off cgred 0:off 1:off 2:off 3:off 4:off 5:off 6:off xml definition -- <domain type="lxc"> <uuid>252a2dc5-452c-4e9c-a593-8c386c9f47e6</uuid> <name>instance-00000032</name> <memory>524288</memory> <vcpu>2</vcpu> <os> <type>exe</type> <cmdline>console=ttyS0</cmdline> <init>/sbin/init</init> </os> <clock offset="utc"/> <devices> <filesystem type="mount"> <source dir="/home/stack/nova_state/instances/instance-00000032/rootfs"/> <target dir="/"/> </filesystem> <interface type="bridge"> <mac address="fa:16:3e:73:67:54"/> <source bridge="br100"/> <filterref filter="nova-instance-instance-00000032-fa163e736754"> <parameter name="IP" value="10.0.0.8"/> <parameter name="DHCPSERVER" value="10.0.0.1"/> <parameter name="PROJNET" value="10.0.0.0"/> <parameter name="PROJMASK" value="255.255.255.0"/> </filterref> </interface> <console type="pty"/> </devices> </domain> Log message with LIBVIRT_DEBUG=1 if that is helpful. http://pastebin.com/LjZ6Euma -- Qiu Yu