Storage alternatives for video service

In the next decade, video-on-demand (VOD) services will be widely available to customers and potentially highly profitable to service providers. In order to provide access to many movies, video storage servers may contain not only magnetic disks but also high-capacity tertiary storage devices. In this paper, we study two storage device alternatives: an array of magnetic disks and an array of magnetic tapes. Magnetic disk arrays provide high-bandwidth, low-latency retrieval and moderate storage capacity at high cost. Magnetic tape arrays provide low-bandwidth, high-latency retrieval and high storage capacity at low cost. We evaluate these two storage system alternatives to determine the number of users that each can support. Our simulations show that magnetic disk arrays can support considerably more users, at a lower cost per user, than magnetic tape arrays