Failure distributions for local vs. global and replicate vs. standby redundancies

The paper begins with an arbitrary single-output, discrete-signal, irredundant system consisting of interconnected computing units each of which has the same exponential distribution for failure time. Then it presents several corresponding redundant designs that compute the same function, derives their distributions for failure time, and illustrates them with quantitative examples. None of the straight replicative designs very much improves the original distribution for failure time; nor do the releasing designs do better. The standby designs do best, even after the standby management-system failure distribution is factored into the system failure distribution. Replicate releasing designs, as a group, are better than straight replicate designs; and standby designs are best