While we have identified what rebooted the server, we still have not gotten to the root cause of the issue. We still need to figure out what caused the high load average. Unfortunately, this would classify as information that is lost during a reboot.
If the system was still experiencing a high load average, we would simply be able to use
ps to figure out which processes are using the most CPU time. Once the system was rebooted however, any process that was causing a high load average would have been restarted.
Unless these processes started causing a high load average again, we have no way of identifying the source.
$ w 02:13:07 up 23 min, 1 user, load average: 0.00, 0.01, 0.05 USER TTY LOGIN@ IDLE JCPU ...