Physical Security

Lock up the server room:
Even before you lock down the servers, and even before you turn them on for the first time you should always ensure the there are good locks on the server room door. The sever room is the heart of your physical network, and someone with physical access to the servers, switches, router,s, cables and other devices in that room can do enormous damage. 

Use rack mount servers
Rack mount servers not only take up less server room real estate, they are also easier to secure. They are normally smaller and lighter than some tower systems they can easily be locked into closed racks that one loaded with several servers, then can be bolted to the floor, making the entire sever fixture impossible to move, much less to steal. 

Disable the drives
If you don't want employees copying company information to a USB stick, you can disable or remove floppy drives, USB ports and other means of external drives. To do this, you can fill the ports with glue or other substances to permanently prevent their use, although there are software mechanisms that disallow it.