| | | | Also Hard Drive, Hard Disk, HD, HDD, although the terms hard disk and hard disk drive are not strictly interchangeable. The hard disk drive (HDD) is the mechanism that reads and writes data to and from a hard disk (HD). Originally used exclusively in computers, hard disk drives are now to be found in games consoles, video recorders and even, in "micro-drive" format, as a removeable storage medium for use in digital cameras, MP3 players, PDAs and more. Consisting of a sealed unit containing a number of magnetic platters (the hard disks) mounted on a spindle that are spun by a motor, data is stored by a HDD magnetically, meaning that it remains safe after the disk is powered-down, in contrast to other forms of storage such as RAM that lose their data when the power is turned off. The hard disk drive is (correctly) the mechanism that reads and writes data, spins the disks and provides the connectivity to the rest of the machine it is a part of. The hard disks that the data is stored on are made from a non-magnetic material such as glass or aluminium coated with a thin layer of magnetic material applied to the surface. They spin at very high speeds - typically from 5,400 RPM in notebook HDDs up to the 15,000 RPM and beyond in the SCSI drives used in servers and other enterprise storage solutions. Early drives had what we would consider today to be minute storage capacities, a few megabytes, whereas current models can be terabytes in size. This has made the use of HDDs viable in such applications as the consumer digital video recorder mentioned above that require large file sizes - simply too large to fit on previous generations of hard disk drive. In addition, continual improvements in design and manufacturing have meant that access and writing times have improved in step with capacity. | | | |
|
