Hard disk is a common data storage used in computers. Data is stored on the hard disk in the form of 0 and 1. Through this article we will find out how actually data is stored on the hard disk drive. The part of the hard disk that stores the data is known as platter. Platters are circular disk made of a non magnetic material typically aluminum alloy, glass or ceramic and are coated with a thin layer (10-20nm) of a magnetic material. Platters are further separated in to the tracks and sectors where tracks are concentric circles while sectors are pie shaped wedges on the track.
Hard disk stores information in the form of magnetic fields. Data is stored digitally in the form of tiny magnetized regions on the platter where each region represents a bit. To write a data on the hard disk, a magnetic field is placed on the tiny field in one of these two polarities: N-S – If North Pole arrives before the south pole and S-N – if the south pole arrives before the north pole while the field is accessed. An orientation in the one direction (like N-S) can represent the ‘1’ while the opposite orientation (S-N) represents “0”. This polarity is sensed by integrated controllers built within the hard disk.