Fault-tolerance and fault-intolerance

Two complementary methods whìch are employed in order to assure relìable computing are fault-intolerance and fault-tolerance. Fault-intolerance depends on the elìmìnatìon of the causes of unreliability prior to the start of the computing process while fault-tolerance employs protective redunuancy during the computing process in order to detect and to correct unreliable functìoning. A balanced allocation of reliability resources between the two methods appears to offer the best practical solution. The paper reviews current fault-tolerance practices in system architecture and discusses their relevance to software systems.