MODELING AND PERFORMANCE ANALYSIS OF DUAL HEAD DISK STRUCTURE

A disk model with dual read/write heads is proposed to improve disk sy stem performance. Dual head disk model can reduce the average seek dis tance either by selecting the closer of the two heads or by dividing t he disk surface into two separated regions, one for each head. And als o, because the reduced seek time can decrease any queuing delay, disk I/O response time can be reduced significantly. To compare the perform ance of the dual head disk model with the conventional disk model, a d isk simulator in which four disk scheduling algorithms are implemented is developed. Both synthetically generated random workload and two ot her workloads constructed by accessing patterns traced are used for pe rformance evaluation. Simulation results show that a higher performanc e by the proposed disk system as compared to the conventional disk sys tem can be obtained under both light and heavy workloads. The dual hea d disk model can give better performance in the application environmen t that has a relatively high seek time ratio.