Non-removable, magnetic data storage device
with one or more flat
, circular plates (platters) of a hard material
. The platters are coated with a magnetically sensitive material, enclosed in vacuum sealed case with the recording
heads, and connected to a computer's bus through a controller
card. The data is written, erased, and overwritten the same way as voice is recorded, wiped off, and re-recorded on the tape in a cassette recorder. In comparison to CDs or DVDs (which store
data in one long spiral track) hard drives store data in segments (called 'sectors') of concentric circles.
They are suitable for storing large amounts of data (currently available ones can store 100 gigabytes or more), and can be written over again and again for an indefinite number of times. Despite their sturdiness, all hard drives fail sooner or later and require backup
routines for the continuous availability
of stored data. Also called fixed disk, fixed drive
, hard disk, or magnetic disk.