"Handling Updates and Crashes in VoD Systems"

Though there have been several recent efforts to develop disk based video servers, these approaches have all ignored the topic of updates and disk server crashes. In this paper, we present a priority based model for building video servers that handle two classes of events: user events that could include enter, play, pause, rewind, fast-forward, exit, as well as system events such as insert, delete, server-down, server-up that correspond to uploading new movie blocks onto the disk(s), eliminating existing blocks from the disk(s), and/or experiencing a disk server crash. We will present algorithms to handle such events. Our algorithms are provably correct, and computable in polynomial time. Furthermore, we guarantee that under certain reasonable conditions, continuing clients experience jitter free presentations. We further justify the efficiency of our techniques with a prototype implementation and experimental results. (Also cross-referenced as UMIACS-TR-97-47

Placement Of Continuous Media In Multi-Zone Disks

For applications with large data sets, e.g., video servers, magnetic disks have established themselves as the mass storage device of choice. A technique to increase the storage capacity of disks is zoning. A side-effect of zoning is that it introduces a disk drive with variable transfer rates. This chapter describes techniques to support a continuous display of constant-bit rate video and audio objects using a multi-zone disk drive. As compared to previous approaches, the proposed techniques harness the average transfer rate of each magnetic disk (instead of its minimum transfer rate). In addition, we describe a configuration planner that logically manipulates the zoning information of a disk drive to support the performance criteria of an application. We present performance numbers from an experimental prototype to demonstrate the feasibility of our approach