Hierarchical storage management in a distributed VOD system

The article describes the storage management algorithms in the Berkeley Video-on-Demand System, a hierarchical storage management system designed to support transparent access to thousands of hours of video material. Storage management algorithms handle continuous media objects stored on video servers within a hierarchical distributed video-on-demand system. Media objects stored permanently on tertiary storage devices are moved to video servers when needed. Algorithms manage the distributed cache in the video servers and select a video server on which to place a requested object. The object-placement algorithm uses server load, network load, and service-wait times to optimize system performance.