A method of operating a supercomputer having N computing elements each connected to a fast communications link is disclosed, the method comprising the steps of: operating the supercomputer to perform a computing operation; upon failure of a fast communications link transferring state from a computing element which, as a result of the fast communications link failure, is no longer able to communicate, to a spare computing element not previously engaged in the computing operation, and continuing the computing operation with the spare computing element, wherein the number of redundant elements M is chosen to satisfy the expression B.sub.M[N, (1-P.sup.T)]>S where S is a desired probability of successful completion of the computing operation within a time T and P is the probability of successful operation per unit time of a fast communications link.