Data Storage on Magnetic Disks

Hard disk drives (HDDs) have been used as storage devices in computers for more than 50 years. Although the first HDD of 1956, which was three to four times bigger than a fridge, had a capacity of 5 × 10⁶ bytes, recent HDDs that are as big as a paperback book have a capacity of 1 × 10¹² bytes. In addition to capacity, HDDs can also outdo their competitors in terms of price. Because of cost and capacity advantage, HDDs have also found a significant place in the consumer electronic devices, such as in video cameras and video recorders that require huge storage requirements. Entry of HDDs in consumer electronic devices was possible because of the tremendous progress that was made in almost all the technologies associated with the HDDs. This article will provide an overview of HDDs, with more emphasis on the magnetic disks that store the information.

Keywords: hard disk drive; magnetic recording; recording media; perpendicular recording; data storage; electron spin; sputtering; magnetic recording medium; patterned media; heat assisted magnetic recording