Hard disk drive
A hard disk drive is a physical device that contains hard disk platters, a spindle, read and write heads, read and write arms, electrical motors, integrated electronics and an enclosure.
A typical hard disk drive design consists of a central axis, i.e., a spindle upon which several hard disk platters spin, each spinning at the same rate of speed. Between each hard disk platter are read and write arms that contain read and write heads. These arms can move randomly either from the outer edge of a hard disk platter toward the center of a hard disk platter or from the center of a hard disk platter toward the outer edge of a hard disk platter. This random movement allows the read and write heads to access all areas of any given hard disk platter.
The integrated electronics control the movement of the read and write arms to specific areas of the hard disk platters and allow the reading and writing of data to occur.
The sealed enclosure contains the sub-systems of a hard disk drive. Containing the sub-systems within a sealed enclosure prevents contaminating substances, e.g., dirt, from coming into contact with the read and write heads. Contamination of the read and write heads can cause a collision, i.e., a "head crash" between a read and write head and a hard disk platter. This kind of contamination can damage the hard disk platter surface.
For a technical explanation, see hard disk drive functioning
see also hard disk drive partitioning, Master boot record, disk storage, storage device,