Since Oneiric, /var/lock is a symlink to /run/lock and /run/lock are tmpfs filesystems.
#mount | grep /run
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
On first start/install from source , the directory /var/lock/one is create. But after a reboot, it desapear.
So we get this error on start:
oned: Error: Cannot start oned, opening lock file /var/lock/one/one
Be careful . You need to create the directory before starting opennebula