将rootfs放置于aufs上可以节省不少空间（template）:
create a linux container named “p1” with template “ubuntu” on a 32bit pc
1. mkdir -p /var/lib/lxc/p1/rw /var/lib/lxc/p1/rootfs
2. mount -t aufs -o br=/var/lib/lxc/p1/rw:/var/cache/lxc/saucy/rootfs-i386 none /var/lib/lxc/p1/rootfs
3. lxc-create -t ubuntu -n p1