An Online Diagnosable Fault-Tolerant Redundancy System

This paper presents an online diagnosable fault-tolerant system: N-unit t-fault tolerablesystem. The number of units N in the system can be either odd or even. The relationshipbetween N and t (the number of faulty units which can be tolerated) is presented. The approachof an optimum N- unit t-fault tolerable system is also given. As an example, a 4-unit 2-faulttolerable system is discussed. The reliability and mean time to failure of 4-unit 2-fault tolerablesystem are shown to be higher than 5MR (5-modular redundancy) and TMR (Triple ModulerRedundancy) system reliabilities. The amount of hardware components in a 4-unit t-faulttolerable system is simpler than 5MR. The complexity of switching circuit for N-unit t-faulttolerable system increases only linearly with respect of the number of modules. Our scheme isalso simpler than the hybrid redundancy system. Some theorems for the online diagnosis of N-unit t-fault systems are given and proved.