Issue No. 07 - July (2003 vol. 52)
S.-H. Gary Chan , IEEE
Fouad A. Tobagi , IEEE
<p><b>Abstract</b>—In order to cost-effectively accommodate a large number of titles in a video system, a hierarchical storage system can be used. In this system, not-so-popular video files are stored in a tertiary level such as a disk/tape library. These files are transferred, or “staged,” to a secondary level composed of magnetic disks before being streamed to the users. This system overcomes the current limitations in using disk/tape libraries to stream videos and resolves the bandwidth difference between staging and streaming. In this paper, we present, via analysis, a model of the system and determine the minimum storage and bandwidth required, at each level, to meet a given user delay goal. We also analyze a number of system operations pertaining to whether or not a file is played while it is being staged (i.e., stage-streaming) and whether or not the displayed segments are deleted (i.e., trail-deletion). We show that stage-streaming and trail-deletion can achieve substantially lower bandwidth and storage requirements. In order to further increase the streaming and storage scalability, a distributed storage system can be used where multiple local servers are put close to user pools and get their files from one of the libraries through a network. We extend the models developed to such a system and specify the resource requirements to meet a given delay goal.</p>
Hierarchical storage systems, video services, tertiary and secondary levels, distributed storage systems, staging and replacement policies, user delay goal.
F. A. Tobagi and S. G. Chan, "Modeling and Dimensioning Hierarchical Storage Systems for Low-Delay Video Services," in IEEE Transactions on Computers, vol. 52, no. , pp. 907-919, 2003.