An online video placement policy based on bandwidth to space ratio (BSR)

In a video-on-demand server, resource reservation is required to guarantee continuous delivery. Hence any given storage device (or a striping group treated as a single logical device) can serve only up to a fixed number of client access streams. Each storage device is also limited by the number of video files it can store. For the reasons of availability, incremental growth, and heterogeneity, there may be multiple storage devices in a video server environment. Hence, one or more copies of a particular video may be placed on different storage devices. Since the access rates to different videos are not uniform, there may be load imbalance among the devices. In this paper, we propose a dynamic placement policy (called the Bandwidth to Space Ratio (BSR) Policy) that creates and/or deletes replica of a video, and mixes hot and cold videos so as to make the best use of bandwidth and space of a storage device. The proposed policy is evaluated using a simulation study.