We've run our data center for over seven years (www.esnet.com) and we didn't have armed security measures until after Hurricane Katrina in New Orleans, Louisiana. There was one colo facility that stayed up and running during Hurricane Katrina. After all that settled down some, we visited with their operations staff and they discussed the importance of armed security to prevent from looting and stealing equipment.

Computer equipment and data is very valuable and malicious people have reason to attempt to steal it or gain unauthorized access. Trained security staff go a long way to ensure customer security and discourage malicious behavior.