A Cost-effective Near-line Storage Server for Multimedia System

In this paper, we consider a storage server architecture for multimedia information systems. While most other works on multimedia storage servers assume on-line disk storage [12, 11, 15, 8, 2], we consider a two-tier storage architecture with a robotic tape library as the vast near-line storage and on-line disks as the front-line storage. Magnetic tapes are cheaper, more robust, and have a larger capacity; hence they are more cost e ective for large scale storage systems (e.g., video on demand (VOD) systems [7] may store tens of thousands of videos). We study in details the design issues of the tape subsystem and propose some novel tape scheduling algorithms which give faster response and require less disk bu ering. We also study the disk striping policy and the disk space organization in order to fully utilize the throughput of the robotic tape system and to minimize the size of on-line disk storage.