On the effect of a configuration choice on the performance of a mirrored storage system

In this paper, we study the effect of various configuration choices on the performance of a mirrored disk array. We introduce a large class of semistructured configurations which provide good seek minimization and bandwidth. We study their properties with respect to both online and offline mirroring algorithms. We also prove a theorem concerning the load balancing capabilities of random or semistructured configurations with several data copies. We show that almost the entire bandwidth of the storage system can be exploited once we increase the number of copies. In an appendix we explain a common error which appears in much of the literature concerning this subject.