Simplicity in design always assures simplicity in implementation and simplicity in response to problems.
Compartmentalization assumes (as should be assumed) in all designs that there will be failures and that, when they occur, they will have limited consequences.
Redundancy assumes we live in a physical world and that it is not a question of if something will break, but when it will break.
Maintainability must be part of every design. One of the basic laws of thermodynamics is that all things deteriorate with time. Systems must therefore be designed to allow for maintenance without disruption to data processing operations.
Testability is the only way to verify that all systems are operating properly including all backup systems. The infrastructure must be designed so that testing can be carried out without disruption to data processing operations
Intelligent monitoring must be part of all infrastructure designs for high-reliability operation. Early warning of problems, remaining levels of backup, specific instructions to operations, and maintenance personnel are all essential if the reliability originally designed into the system is to be maintained throughout the life of the facility.