The Supremacy of Embedded Redundancy over Redundancy at System Level in Mission Critical Facilities

The reliability of a mission critical facility such as a data center infrastructure is strongly influenced by decisions made during the design, modifications and upgrades of the electrical and mechanical systems. Deficiencies in design, affect all aspects of data center maintenance and operation and are increasingly more expensive to correct. Consequently, proper and failure-free design concept, has a crucial impact throughout the life of the data center. It is essential that suitable design processes being followed to minimize the possibility of operation failure and allow the design deficiencies being detected before the facility goes to live operation. One of the most important design decisions in any data center is the level of redundancy for its infrastructure systems. It is customary that "external redundancy", such as 2N systems, being treated as a superior type of redundancy, however, this may not be true for all systems, and there are cases that embedded redundancy provides greater reliability over redundancy at system level. The objective of this paper is reviewing those cases starting with mathematical proof along with detailed overview and two case studies.