The present data storage subsystem includes a data stream optimization system that optimizes its data throughput performance for a particular type of data that is stored therein, such as video on demand data. The data stream optimization system manages the retrieval of the stored video data to more efficiently use the cache memory. This is accomplished by creating a data stream entry into a table for each viewer that requests access to a stored video file. The data stream optimization system also records the storage extent of each video file so that the identity of the next successive segment of the video file that is being accessed is known. The data stream optimization system monitors the amount of data stored in the cache memory for each of the data streams and identifies the next of these data streams that requires replenishment. The data stream optimization system then accesses the next segment of this video file to ensure that adequate data is stored in the cache memory for the uninterrupted viewing of this video file.