The following video from Google covers most major aspects of physical security and cybersecurity measures for the Internet search monolith's data center operations. Topics including IP-based key access and video monitoring are covered, as are fire-suppression and data backup technologies.
See Also:
Google's 10 tips for better data center design
Google reveals detailed look into data center infrastructure
Google Fiber headhunting network ops center experts
Google clue reveals public HP printers may spawn serious network threats