Browsing by Author "Shyu, IJ"

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A distributed fault-tolerant design for multiple-server VOD systems
(1999-03-01)
Shyu, IJ
;
Shieh, SP
;
資訊工程學系
;
Department of Computer Science
Fault tolerance is an important design criterion for reliable and robust video-on-demand systems. Conventional fault-tolerant designs use either a primary backup or an active replication method to provide system fault tolerance. However, these approaches suffer from low utilization of the backup or replication system. In this paper we propose two playback-recovery schemes for distributed video-on-demand systems called the forward playback-recovery scheme and the backward playback-recovery scheme. Unlike conventional fault-tolerant designs, our schemes use existing playback resources to recover faulty playbacks without allocating new resources, significantly reducing recovery overhead. To use the schemes effectively, we developed a distributed algorithm for determining the order and gap information between the playbacks on the distributed video-on-demand servers so that overhead for recovering from a server failure can be minimized. This algorithm achieves N - 1 fault-tolerant resiliency for N-server video-on-demand systems. In addition, three server-recovery policies are also presented to guide surviving servers in applying the proper scheme to recover faulty playbacks, thus reducing overall recovery costs. Simulation results show that the proposed recovery schemes are effective and useful in designing fault-tolerant multiple-server video-on-demand systems.
Playback dispatch and fault recovery for a clustered video system with multiple servers
(1999-11-01)
Shyu, IJ
;
Shieh, SP
;
資訊工程學系
;
Department of Computer Science
Recent technology advances have made multimedia on-demand services feasible. One of the challenges is to provide fault-tolerant capability at system level for a practical video-on-demand system. The main concern on providing fault recovery is to minimize the consumption of system resources on the surviving servers in the event of server failure. In order to reduce the overhead on recovery, we present three schemes for recovering faulty playbacks through channel merging and sharing techniques on the surviving servers. Furthermore, to evenly distribute the recovery load among the surviving servers, we propose a balanced dispatch policy that ensures load balancing in both the normal server conditions and the presence of a server failure.