Magnetic disk drives have been the primary means of storing information on computers since 1957 when IBM introduced the RAMAC, the first disk drive. As opposed to semiconductor random access memory, magnetic disk drives provide long-term storage of information in the absence of electrical power; i.e., they provide non-volatile storage. Because of the disk format and the relatively short access time, which disks provide to data, they are used extensively for online storage of information.

Although sometimes taken for granted because of its long history of continual advancement, magnetic disk drives have been critical to the information technology revolution we have been experiencing. The software programs which companies such as Microsoft have been introducing would not be useable if large capacity, high performance disk drives were not available. Moreover the trend toward the storage of more graphical information including video would not be possible without the large data storage capacity and low cost of magnetic disk drives. Indeed, the growth of the Internet and computer networking in general would not be possible without the higher capacities of disk drives and the lower cost of storing information that they make possible. Magnetic disk drive sales are currently over $30 billion per year, but, as was illustrated in Fig. ES.1, are projected to grow to over $75 billion in 2000. This growth is expected to come largely from the more widespread use of computer networks to access data warehouses of information and to store it locally for future use.

U.S. companies have been the major producers of disk drives, as illustrated in Fig. 2.2; however, the U.S. share of the market has been declining over the past three years. The majority of non-U.S. manufactured drives are from Japan. As will be made clear below in the section on magnetic disk drives, although the majority of drives are manufactured by U.S. companies, Japanese companies are making an increasingly large number of the components used in those drives and have increased their market share steadily over the past three years.

Fig. 2.2. A bar graph showing the market share of non-U.S. and U.S. manufacturers of disk drives (Disk/Trend).

Published: June 1999; WTEC Hyper-Librarian