Data Layout for Interactive Video-on-Demand Storage Systems

Interactive video-on-demand applications pose a number of interesting problems such as the support of fast forward and rewind at arbitrary speeds. While it has been shown that no single data layout scheme can support these functions at arbitrary speeds without violating load balance conditions, researchers are now exploring methods to allow at least a wide range of speeds to be supported under load balance conditions. In this paper, we introduce Declustered Mirror, a novel scheme that mirrors a set of striped disks to provide improved performance and fault tolerance for a video-on-demand system. The improved performance is obtained by the use of disk stripping to provide high I/O bandwidth for multimedia data and by the use of Distributed Cyclic Layout (DCL) and Staggered Distributed Cyclic Layout (SDCL) to provide support for a wide range of fast forward and rewind speeds under load balance conditions. Fault tolerance is provided through mirroring.