The hard disk drive (HDD) is one of the most important and yet mysterious parts of a computer system. HDDs are sealed units used for nonvolatile data storage. Nonvolatile, or semi-permanent, storage means that the storage device retains the data even when no power is supplied to the computer. Because HDDs store crucial programming and data, the consequences of any failures are usually very serious. To maintain, service, and upgrade a PC system properly, it is important to know how hard disks function.
Hard disk drives contain rigid, disk-shaped platters, usually constructed of aluminum or glass. Unlike floppy disks, the platters can’t bend or flex—hence the term hard disk. In most drives you can’t remove the platters, which is why they are sometimes called fixed disk drives. Removable hard disk drives are also available.
Problems that plague well-known hard drive brands:
