This paper describes the design and implementation of an algorithm to manage
continuous media objects stored on a set of video servers. The video servers
are components in a hierarchical distributed video-on-demand system. Media
objects are stored permanently on tertiary storage devices and moved to video
servers. Algorithms are described to 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.