ABSTRACT
Fault tolerance is the ability of a system to continue correct performance of its tasks after the occurrence of hardware or software faults. The physical replication of hardware is perhaps the most common form of fault tolerance used in systems. Information redundancy is simply the addition of redundant information to data to allow fault detection, fault masking, or possibly fault tolerance. Software faults are unusual entities. Software does not break as hardware does, but instead software faults are the result of incorrect software designs or coding mistakes. The recovery block approach to software fault tolerance is analogous to the active approaches to hardware fault tolerance, specifically the cold standby sparing approach. An extremely important parameter in the design and analysis of fault-tolerant systems is fault coverage. The fault coverage available in a system can have a tremendous impact on the reliability, safety, and other attributes of the system.
