Magnetic storage (English: Magnetic disk) is a secondary storage device most often found on modern computer systems. At the time of the disk is used, the drive motor rotates with a very high speed. There is a read-write head is placed over the disc surface. Disk surface is divided into several tracks that are still divided into several sectors. Fixed-head disks have one head for each track, while the moving-head disks (or often known as a hard disk) has only one head to be movable for access from one track to another track.