@InProceedings{schwabe:layouts,
  author = {Eric J. Schwabe and Ian M. Sutherland and Bruce K. Holmer},
  title = {Evaluating Approximately Balanced Parity-Declustered Data Layouts
  for Disk Arrays},
  booktitle = {Proceedings of the Fourth Workshop on Input/Output in Parallel
  and Distributed Systems},
  year = {1996},
  month = {May},
  pages = {41--54},
  publisher = {ACM Press},
  address = {Philadelphia},
  later = {schwabe:jlayouts},
  keywords = {parallel I/O, disk array, parity, RAID, pario-bib},
  abstract = {Parity declustering has been used to reduce the time required to
  reconstruct a failed disk in a disk array. Most existing work on parity
  declustering uses BIBD-based data layouts, which distribute the workload of
  reconstructing a failed disk over the remaining disks of the array with
  perfect balance. For certain array sizes, however, there is no known
  BIBD-based layout. In this paper, we evaluate data layouts that are
  approximately balanced --- that is, that distribute the reconstruction
  workload over the disks of the array with only approximate balance.
  Approximately balanced layouts are considerably easier to construct than
  perfectly balanced layouts. We consider three methods for generating
  approximately balanced layouts: randomization, simulated annealing, and
  perturbing a BIBD-based layout whose size is near the desired size. We
  compare the performance of these approximately balanced layouts with that of
  perfectly balanced layouts using a disk array simulator. We conclude that, on
  uniform workloads, approximately balanced data layouts have performance
  nearly identical to that of perfectly balanced layouts. Approximately
  balanced layouts therefore provide the reconstruction performance benefits of
  perfectly balanced layouts for arrays where perfectly balanced layouts are
  either not known, or do not exist.}
}