At a data center in Seattle, a CRAC unit was running amok. The $60,000 air-conditioning and air-purifying machine was spewing coolant at a rate of more than a pint an hour all over the pristine white floor. It was heading for a meltdown, and so were the racks of servers it was designed to protect from the heat of their operation. But, perversely, it continued to report to the remote technicians responsible for running the data center that all was well.

It wasn’t quite a 2001 moment, where a murderous but unfailingly polite computer visits death and destruction on a deep-space crew. But for Digital Fortress—one of hundreds of thousands of data centers around the world responsible for the safety of the exabytes of email, industrial data, software-as-service applications, websites, and other data sources that are the lifeblood of the digital economy—the consequences could have been disastrous.