1. Introduction
Computer hard disk drives are storage devices for digital data. The digital data is stored on high-speed rotating magnetic surfaces. They are non-volatile and use the random access technique to access data stored on them. It consists of fast rotating discs which have magnetic surfaces onto which data is stored. They are permanently mounted on the computers and cannot be easily detached like floppy disks. It is known as hard disk drive as both the disk and the drive are contained inside the same unit. The costs of hard disk drives have fallen in the last few years and ...