Using rotational mirrored declustering for replica placement in a disk-array-based video server

  • Authors:

  • Ming-Syan Chen;Hui-I Hsiao;Chung-Sheng Li;Philip S. Yu

  • Affiliations:

  • -;-;-;-

  • Venue:
  • Multimedia Systems
  • Year:
  • 1997

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Abstract

In a video-on-demand (VOD) environment, diskarrays are often used to support the disk bandwidth requirement. This can pose serious problems on available disk bandwidth upon disk failure. In this paper, we explore the approach of replicating frequently accessed movies to providehigh data bandwidth and fault tolerance required in a disk-array-based video server. An isochronous continuous videostream imposes different requirements from a random accesspattern on databases or files. Explicitly, we propose a newreplica placement method, called rotational mirrored declustering (RMD), to support high data availability for disk arrays in a VOD environment. In essence, RMD is similar tothe conventional mirrored declustering in that replicas arestored in different disk arrays. However, it is different fromthe latter in that the replica placements in different disk arrays under RMD are properly rotated. Combining the meritsof prior chained and mirrored declustering methods, RMD isparticularly suitable for storing multiple movie copies to support VOD applications. To assess the performance of RMD,we conduct a series of experiments by emulating the storage and delivery of movies in a VOD system. Our resultsshow that RMD consistently outperforms the conventionalmethods in terms of load-balancing and fault-tolerance capability after disk failure, and is deemed a viable approachto supporting replica placement in a disk-array-based videoserver.