Physical security 

In most cases, physical access translates to a total loss of security. Even if they can't access your data, an attacker can do a lot of damage. We'll take a look at the most essential security measures everyone should implement, if they haven't already been done:

• Lock up the server room: The server room is the power station of your physical network, and someone with physical access to the servers, switches, routers, cables, and other devices in that room can do enormous damage.
• Set up surveillance: You need a way to monitor who goes in and out, what they do and when they do it. A better solution is to set up biometric scanners that are required in order to unlock the doors, and the identity of each technician is then recorded. Surveillance cameras can monitor continuously, or they can use motion detection technology to record a person's movement. They can even send an email or cell phone notification if motion is detected when it shouldn't be.
• Disable the drives: Of course...