Performance study of data layout schemes for a SAN-based video server

We describe the design and performance of storage area network multimedia server (SAM), which manages a set of parallel storage devices connected by a storage area network. SAM is geared towards providing multiple concurrent services such as interactive video-on-demand and video games. The challenge, therefore, is twofold: provide a high throughput in order to service the maximum number of users possible, with a small response time that is necessary for interactive applications.The primary focus of this paper is on the data layout scheme for SAM. The problem of out-of-order delivery of video frames is described, and a scheme to transmit the frames in order is presented. A data layout scheme called constrained random striping (CRS) is developed for the logical loop model. Using a simulation model, the performance of this scheme is compared with several other data layout strategies. It is shown that CRS reduces the start-up latency of clients. The performance gains and tradeoffs of the different strategies are discussed in detail.