Question

What is a cylinder in computer?

Answer 1

Cylinder : A hard disk is usually made up of multiple platters, each of which used two heads to record and read data, one for the top of the platter and one for the bottom (this isn't always the case, but usually is). The heads that access the platters are locked together on an assembly of head arms.

In order to allow synchronised of data, the storage space on the platters must be divided logically into cylinders, tracks and sectors.

A disk drive cylinder is a division of data in a disk drive used in the addressing mode of a hard disk (or floppy disk). The concept is concentric, hollow, cylindrical slices through the physical disk (platters), collecting the respective circular tracks aligned through the stack of platters. (Tracks are subdivided in to sectors).

In other words, the number of cylinders of a disk drive exactly equals the number of tracks on a single surface in the drive. The term cylinder is sometimes prefaced with the word (logical) to emphasise the fact that it is an abstract concept, not a cylinder in the physical sense.