@InProceedings{holland:decluster,
  author = {Mark Holland and Garth Gibson},
  title = {Parity Declustering for Continuous Operation in Redundant Disk
  Arrays},
  booktitle = {Proceedings of the Fifth International Conference on
  Architectural Support for Programming Languages and Operating Systems},
  year = {1992},
  pages = {23--35},
  later = {holland:bdecluster},
  URL =
  {http://www.cs.cmu.edu/afs/cs.cmu.edu/project/pdl/ftp/Declustering/ASPLOS.ps},
  keywords = {parity, declustering, striping, disk array, redundancy,
  reliability, pario-bib},
  abstract = {We describe and evaluate a strategy for declustering the parity
  encoding in a redundant disk array. This declustered parity organization
  balances cost against data reliability and performance during failure
  recovery. It is targeted at highly-available parity-based arrays for use in
  continuous- operation systems. It improves on standard parity organizations
  by reducing the additional load on surviving disks during the reconstruction
  of a failed disk's contents. This yields higher user throughput during
  recovery, and/or shorter recovery time. \par We first address the generalized
  parity layout problem, basing our solution on balanced incomplete and
  complete block designs. A software implementation of declustering is then
  evaluated using a disk array simulator under a highly concurrent workload
  comprised of small user accesses. We show that declustered parity penalizes
  user response time while a disk is being repaired (before and during its
  recovery) less than comparable non-declustered (RAID5) organizations without
  any penalty to user response time in the fault-free state. \par We then show
  that previously proposed modifications to a simple, single-sweep
  reconstruction algorithm further decrease user response times during
  recovery, but, contrary to previous suggestions, the inclusion of these
  modifications may, for many configurations, also slow the reconstruction
  process. This result arises from the simple model of disk access performance
  used in previous work, which did not consider throughput variations due to
  positioning delays.}
}