Data centers are arranged in alternating ‘hot’ and ‘cold’ rows, with the cold rows generally serving as human-access points, where the hot rows are generally for fan exhaust. The ‘extreme changes’ described in the report above were caused by an accidental feedback loop of high temperature and low humidity air from the hot rows entering a water-based evaporative cooling system. When this air returned to the servers on the cold rows, it was so wet that it condensed. A cloud was raining on the cloud.
Tweeted by @GrahamStarr https://twitter.com/GrahamStarr/status/1009181791322869761