At this point, we have covered some basic rules and tips on how to implement a safe data center. Let's move to the next step: the security inside the data center.
As we have already mentioned in the preceding paragraphs, we can split the servers with secure doors for more granular access. Why should we do this? Isn't it enough to be sure that all people entering the data center are authorized? Very often this is not enough because all the people who are authorized to enter in the data center will be allowed to touch every single device in it so we are still not compliant with the Principle of Least Privilege.
Some companies solve this problem with a locked rack, while others resolve it with segmented data centers, or even with both approaches. Both the approaches have ups and downs, for instance, you might prefer a segmented data center approach because:
Rack doors are often uncomfortable and require a wider aisle
Open racks have a better air flow than locked racks (this is not always true)
Open racks are way cheaper than locked racks
This approach also has some disadvantages:
Less flexible (the person has or has not access to multiple racks)
Walls and doors have to be placed during the data center construction and cannot be moved later
A combined solution can solve some of these disadvantages. Another mixed option is the locking cages, which are easier to install than walls but are often easier to break in.
To implement more, the Separation of Duties principle is possible to require two authorized people to be present at the same time to unlock a door or it could require a badge of type A for unlocking the doors in the data center and a badge of type B to unlock the racks.