cd /var/lib/lxc/$NAME/
tar --numeric-owner -czvf /root/container_fs-$(date +%Y%m%d).tar.gz ./*

From one partition to another:

cp -a /data2/lxc/agencyreports /data/lxc/

• Change ulimits on unprivileged containers
• Create container
• lxc troubleshooting
• Change privileged to unprivileged container in Proxmox

• http://stackoverflow.com/questions/23427129/how-do-i-backup-move-lxc-containers