Most data center security programs are built around the server hall. Badges, mantraps, cameras, cages and visitor logs all concentrate on the room where the computing equipment sits. The equipment that keeps that room running usually sits somewhere else: in a utility yard, a generator yard, a fuel area, a cooling plant and a set of fiber vaults, often behind nothing more than a fence. If any one of them is lost, the hall goes down with it, however well its doors are controlled.
This note is written for owners, developers, engineers, specifiers and contracting officers planning a data center campus or an expansion of one. It sets out where physical exposure tends to sit outside the building, how to describe the threat for each part of the campus, and what to write into the specification so that protection is designed rather than improvised after the yards are built.
Map the dependency chain before drawing the perimeter
The first step is a list, not a product. Every element whose loss would stop the server hall belongs on it, along with where that element physically sits. On a typical campus the list includes the utility service entrance and its transformers, the switchgear, the standby generators and their radiators, the bulk fuel storage and day tanks, the chillers, cooling towers or dry coolers, the water supply, and the points where fiber enters the property and the building.
For each item, the useful questions are simple. Is it inside or outside the secure perimeter? Can it be seen from a public road or a neighboring parcel? Can a vehicle reach it? Is there a single point where damage would take out more than one of its redundant paths at once? Redundancy on a one-line diagram does not help if both feeds, both fuel lines or both fiber routes pass through the same yard, the same duct bank or the same wall.
Write the threat for each part of the campus
Different parts of a campus face different threats, and each one should be written as a threat rather than as an adjective. A generator yard next to a public road may need to be evaluated against a rifle fired from outside the fence. A gate on a long straight approach may need to be evaluated against a vehicle. A fiber vault or fuel fill point may need to be evaluated against forced entry with hand and power tools. Tampering and sabotage by someone with legitimate access belong on the list as well.
Each threat has its own reference. ASTM F2656 is the usual test standard for vehicle barriers, and it defines the test vehicle, the impact speed and the penetration measured. UL 752 and NIJ-STD-0108.01 are the usual references for ballistic threat definitions, which state the test round and the conditions under which it is fired. The specification should cite the standard and its edition for each threat, and say which part of the campus each one applies to.