Optimal response time retrieval of replicated data (extended abstract)

This work deals with the problem of finding efficient access plans for retrieving a set of pages from a multi-disk system with replicated data. This paper contains two results related to this problem: (a) We solve the problem of finding an optimal access path by transforming it into a network flow problem. We also indicate how our method may be employed in dynamic environments where some (or all) of the disks have a preexisting load, are heterogeneous, and reside on different servers. (b) We present a lower bound for the worst case response time of a request under all replication schemes, and also discuss the replication scheme that results in this lower bound. We then use simulation to show how this replication scheme can also greatly reduce the average case response time.