On-Demand Data Elevation in a Hierarchical Multimedia Storage Server

摘要

Given the present cost of memories and the very large storage and bandwidth requirements of large-scale multimedia databases, hierarchical storage servers (which consist of RAM, disk storage, and robot-based tertiary libraries) are becoming increasingly popular. However, related research is scarce and employs tertiary storage for storage augmentation purposes only. This work, exploiting the ever-increasing performance offered by (particularly) modern tape library products, aims to utilize tertiary storage in order to augment the system's performance. We consider the issue of elevating continuous data from its permanent place in tertiary for display purposes. Our primary goals are to save on the secondary storage bandwidth that traditional techniques require for the display of continuous objects, while requiring no additional RAM buffer space. To this end we develop algorithms for sharing the responsibility forrnthe playback between the secondary and tertiary devices and for placing the blocks of continuous objects on tapes, and show how they achieve the above goals. We study these issues for different commercial tape library products with different bandwidth and tape capacity and in environments with and without the multiplexing of tape libraries.