Buffer Management For Continuous Media Sharing In Multimedia Databse Systems

• Authors: Mohan Kamath;Krithi Ramamritham;Don Towsley
• Venue: Buffer Management For Continuous Media Sharing In Multimedia Databse Systems
• Year: 1994

Buffer management in database systems deals with allocation, search and replacement of buffers for the data to be accessed so as to promote data sharing and reduce the number of disk accesses. These activities are much more complex in multimedia database systems (MMDBS) which handle time variant data. Mul- timedia data have timeliness and synchronization requirements and hence traditional buffer management schemes like FIFO and LRU are not quite suitable for multimedia buffer management. Since the data rates involved are very high, despite the development of ef- ficient storage and retrieval strategies, disk I/O is likely to be a bottleneck, thereby limiting the number of concurrent ses- sions supported by a system. This calls for better use of data that has already been brought into the buffer by exploiting shar- ing whenever possible using advance knowledge of the multimedia stream to be accessed. Since most of the research work in mul- timedia data management has concentrated on data modeling and storage management, no work has been done to explore the benefits of data sharing when concurrent users are accessing multimedia data. In this paper, by considering the specific application of News- On-Demand-Service (NODS) where extensive sharing of continuous media data is possible, we explore the potential benefits of con- tinuous media sharing. We first introduce the notion of {\m con- tinuous media caching} which is a simple and novel technique where buffers that have been played back by a user are preserved in a controlled fashion for use by subsequent users requesting the same data. We then propose new buffer management schemes that use this technique to utilize the available buffer space ef- fectively to promote sharing, thereby reducing the number of disk I/Os. Finally we compare our schemes with traditional buffer management schemes through simulation. Our results indicate that buffer management schemes that utilize continuous media caching outperform the other schemes in environments where sharing is possible. This indicates that for improved performance, it is essential to develop new MMDBS-specific buffer management schemes that exploit the characteristics of multimedia applications.