We’ve been investigating an interesting issue for the past several weeks. One of the servers we manage has been restarting without warning every other Sunday morning. Thankfully, no one is on the system, no files are open and nothing is taking place. No VSS snapshots, no backup – nothing.
What’s been so odd about it is there’s been nothing in any of the system logs. And no memory dump either. Just a reboot out of nowhere.
We took a look at the UPS and didn’t see any problems, but once we opened up its web console, we found the answer. The UPS had a self test scheduled for that time. And none of the tests were logged since the problem started. We ran the self-test manually and immediately discovered the self test cycle was resetting the power to the UPS and bringing down the server.
The manual self-test also triggered a bad battery alarm, so we immediately ordered a new battery and replaced it, resolving the problem.