Mechanisms

Abstract

The ultimate backup strategy is to do everything twice at the same time. Systems such as Tandem and Stratus use redundant components at every level of processing; for example, they use arrays of processors, dual I/O buses, multiple banks of random-access memory and duplicate disk storage devices to permit immediate recovery should any computations go awry. Redundant systems use sophisticated communications between processors to assure identity of results. If any computational components fail, processing can continue uninterrupted while the defective components are replaced.