Analysis on disk scheduling for special user functions

Previous studies on disk scheduling for video services were usually based o n computer simulation. In this paper, we present analysis on disk schedulin g for video services, This paper first gives a short review on the various disk-scheduling algorithms. It then concentrates on the analysis of two maj or disk-scheduling algorithms, namely, CLOOK and LOOK. The purpose of the a nal-sis is to obtain the maximum number of simultaneous users supported by systems using these two algorithms, The results of the analysis show that t he CLOOK algorithm performs slightly better than LOOK algorithm in video ap plications. Then, this paper discusses disk scheduling for supporting speci al user functions such as "forward search" and "reverse search." It is show n that the maximum number of user streams supported drops dramatically when such user functions are used. A technique call ed redundancy for special u ser functions (RESUF) is then studied in this paper. Analysis of the techni que shows that it can keep the I/O demands to almost constant under all use r request conditions.