A Compensatory Retrieval Method of Region-Based Data Placement for Interactive Video-on-Demand Systems

• Main Authors: Tsao, Shiao-Li, 曹孝櫟
• Other Authors: Huang Yueh-Min
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/06420173999009938937

碩士 === 國立成功大學 === 工程科學系 === 84 === By advances in network architecture, compression techniques,and storage devices,video servers are growing rapidly. Themain challenges of designing a video server are real-timeretrieval and delivery of video data and promotion of thestorage throughput to accommodate more users. As indicated,previous studies on improving storage throughput have focusedon the data placement and the disk scheduling. Some dataplacement methods have been researched on limiting theseeking distance in the region of the disk instead of thewhole one. The objective of these approaches is to reduce theseek time overhead and improve the disk throughput. However,they do not consider actual characteristics of hard disks. Oflate, the zoning technique has been applied to increase thedisk capacity for modern disks. As a result of the technique,a disk is partitioned into several zones with differenttransfer rates (bandwidth). The effect of the zoning is thatsince a hard disk has the constant angular velocity, the diskcan have more bandwidth in its outer zones than in its innerzones. In this study, we propose a compensatory retrievalmethod to fully utilize the different bandwidth in each zone.Due to the same reading time of retrieving a data block, inthis manner we can read more data in the outer zones tocompensate for the consumption in the inner zones. In ourdesign,the disk throughput can be promoted to the extreme. From simulation results and the performance testing of theprototype, our proposed method can improve disk throughputby 25%-35%.In addition, we design a frame converting method to reconstructthe MPEG data. Due to the frame converting technique, thecompensatory retrieval method can also provide the fastforward/fast backward function in a video server.