Evaluating approximately balanced parity-declustered data layouts for disk arrays
Eric J. Schwabe, Ian M. Sutherland, Bruce K. Holmer · 1996
Parity-declustered data layouts were developed to reduce the time for on-line failure recovery in disk arrays. They generally require perfect balancing of reconstruction workload among the disks; this restrictive balance condition makes such data layouts difficult to construct. In this paper, we consider approximately balanced data layouts, where some variation in the reconstruction workload over the disks is permitted. Such layouts are considerably easier to construct than perfectly balanced layouts. We consider three methods for constructing approximately balanced data layouts, and analyze their performance both theoretically and experimentally. We conclude that on uniform workloads, approximately balanced layouts have performance nearly identical to that of perfectly balanced layouts. A preliminary version of this paper appears in the Proceedings of the Fourth Annual Workshop on I/O in Parallel and Distributed Systems, pp. 41--54, May 1996. y [email protected]. Supported by N...