Fault Tolerance with Multiple Task Modular Redundancy

The redundant units in a classic N Modular Redundancy (NMR) system are employed solely for fault tolerance, making this technique inefficient. This paper introduces Multiple Task Modular Redundancy that allows an NMR system to have a higher throughput by exploiting, when no faults have occurred, the system’s redundancy. More than one group of replicated tasks are optimistically executed. This method has a 50100% better throughput over NMR but does not jeopardize the fault tolerance of the basic NMR system. Unlike other methods, this technique applies to systems as small as three processors (TMR). Variations on the granularity and dependencies of tasks are considered.