Disk Scheduling

Topics: Software testing, Integration testing, Software engineering Pages: 37 (10706 words) Published: June 9, 2013
A Project Report On
SIMULATION OF DISK SCHEDULING
(Using C++ and Graphics)

Index
ABSTRACT…………………………………………………………………………………… 2 PROBLEM DEFINITION…………..…………………………………………………..….. 3 HARDWARE REQUIREMENT….……………………………………………………….. 4 SOFTWARE REQUIREMENT………………….………………………………………… 5 ALGORITHM EXPLANATION/CONCEPT …………………………………………… 6 PROJECT DIAGRAM …………………………………………………………………….. 7 SAMPLE CODE …………………………………………………………………………….. 9 SCREEN SHOTS ………………………..……………………………………………….. 10 TESTING ………………………….……………………………………………………….. 11 CONCLUSION ……………………………………………………………………..……… 12 BIBLIOGRAPHY ….……………………………………………………………………… 13

List of Tables

Sl No| Name| Description|
1| Table 1| Hardware Requirements|
2| Table 2| Software Requirements|

List of Figures
Sl No| Name| Description|
1| Figure 1| Operating system operation|
2| Figure 2| Logical structure of a 1.44 MB disk|
3| Figure 3| First Come First Serve|
4| Figure 4| Last In First Out|
5| Figure 5| Shortest Seek Time First|
6| Figure 6| SCAN|

Abstract

The project entitled “DISK SCHEDULING” is developed by under Turbo C. The main objective of this project is to obtain information regarding the disk scheduling using some algorithms for checking the efficient among them during different situation. These scheduling techniques have been implemented on the floppy disk. By using this project, suitable disk scheduling algorithms can be used to improve both the access time and the band width. The project which is developed will give a brief idea about which disk scheduler is the most efficient one add also deals with the performance of strategies for scheduling the servicing of disk requests.

The main function of an operating system is to use the hardware resources efficiently. The increase in the speed of processors and the main memory has far outstripped that for disk access, with processor and main memory speeds increasing by about the orders of 2:1 magnitude compared to the magnitude for disk which are currently being accessing at slower magnitude. For this reason only we are using disk scheduling.

In this project we have four disk scheduling algorithms. By applying that we can easily know which algorithm is best among the remaining algorithm. The four algorithms used are:

1) FCFS (First Come First serve)
2) LIFO (Last In First Out)
3) SSTF (Short seek job first)
4) SCAN.

The study considers the problem of evaluating the expected disk head movement when the SCAN disk scheduling policy is used to answer a batch of queries. The two cases examined are:

(a) The batched queries are based on primary key values, and (b) Each query in the batch is bas on secondary key values.

Earlier works assumed that hit cylinders are non-distinct and derived an exact (approximate) formula for the first (second) case. In this paper, both replacement and non-replacement models are examined and new exact (exact and approximate) formulae are derived for the first (second) case. It is shown that earlier and new approximate results may be used instead of the computationally expensive exact formulae. formula for the first (second) case. In this paper, both replacement and non-replacement models are examined and new exact (exact and approximate) formulae are derived for the first (second) case. It is shown that earlier and new approximate results may be used instead of the computationally Expensive exact formulae.

Problem Definition:

One of the important responsibilities of the operating system is to efficiently use the hardware resources. The disk drives need a fast access time and disk bandwidth to meet this responsibility. The access time has two major components,

٠seek time
٠rotational latency

The seek time is the time for the disk arm to move the head to the cylinder containing the desired sector. The rotational latency is the additional time waiting for the disk to rotate the desired sector to...
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