Inside the data halls, customers can either purchase a full rack of server space (on the right), or quarter racks. Each has electronic locks with multiple layers of approval that plug into a customer's Active Directory, meaning enterprise IT managers don't have to call facilities around the country to blacklist former employees to prevent access. The blue gates are where cooled air enters the equipment - on the other side is a closed off red corridor that prevents the recirculation of warmed air in the data hall, improving energy efficiency.