A fast data placement scheme for video server with zoned-disks
Journal
Proceedings of SPIE - The International Society for Optical Engineering
Journal Volume
3229
Pages
92-102
Date Issued
1997
Author(s)
Abstract
Recently, zoning technique has been applied to disk technology to increase disk capacities. As a side effect, data transfer rates from outer zones of a hard disk are much higher than those from inner zones. Unfortunately, either VBR nature of video streams or the effects of disk zoning are neglected by previous studies on data placement of VBR video streams on a zoned- disk. Our objective is to minimize server buffer size and to maximize disk utilization subject to the capacity constraints of disk zones. To solve the problem, we adopt the concept of constant read time in which a constant period of time is allocated to retrieve a variable-sized disk block. Blocks retrieved from the same disk zone have the same size. This problem is then formulated as a constrained combinatorial optimization problem. In a previous paper, we present an optimum algorithm to solve the data placement problem based on dynamic programming. In this paper, we present suboptimum heuristics to reduce time and space complexities. The algorithms are implemented in C language and run on Linux operating system and Pentium Pro 200. Preliminary experimental results show that our solutions are very effective. For example, our approach guarantees 100 percent of disk storage efficiency and bandwidth utilization and its buffer size requirement is no more than 3 disk blocks for practical examples. We also run our program on MPEG/1 encoded movie 'Star War', the optimized buffer size is slightly more than 2 disk blocks, e.g., 500KBytes for 140-220KBytes variable-sized disk blocks, with 70 utilization. Preliminary performance studies also shows that the proposed CRT scheme is very promising in maximizing system throughput.
Type
conference paper