Declustered data organizations in disk arrays (RAIDs) achieve less-intrusive reconstruction of data after a disk failure. We present PDDL, a new data layout for declustered disk arrays. PDDL layouts exist for a large variety of disk array configurations with a distributed spare disk. PDDL declustered disk arrays have excellent run-time performance under light and heavy workloads. PDDL maximizes access parallelism in the most critical circumstances, namely during reconstruction of data on the spare disk. PDDL occurs minimum address translation overhead compared to all other proposed declustering layouts.
Thomas J. E. Schwarz, Jesse Steinberg, Walter A. B