cylinder

cylinder, in mathematics, surface generated by a line moving parallel to a given fixed line and continually intersecting a given fixed curve called the directrix; each line of the family of lines forming the cylinder is called a ruling, or generator. If the directrix is a conic section (e.g., a circle or a parabola), the cylinder is called a quadric cylinder. The commonest type of cylinder is the right circular cylinder, in which the directrix is a circle and the lines forming the cylinder are all perpendicular to the plane of the circle. The solid bounded by a cylindrical surface and two parallel planes intersecting the surface in closed curves is also called a cylinder. The perpendicular distance between the planes is the altitude of the cylinder. The volume of the cylinder is equal to the product of the altitude and the area of the base (the area enclosed by either closed curve).

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The aggregate of all tracks that reside in the same location on every disk surface. On multiple-platter disks, the cylinder is the sum total of every track with the same track number on every surface. On a floppy disk, a cylinder comprises the top and corresponding bottom track.

When storing data, the operating system fills an entire cylinder before moving to the next one. The access arm remains stationary until all the tracks in the cylinder have been read or written.

Cylinder

The cylinder is the aggregate of the same track number on every platter used for recording.

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(storage)

cylinder - The set of tracks on a multi-headed disk that may be accessed without head movement. That is, the collection of disk tracks which are the same distance from the spindle about which the disks rotate. Each such group forms the shape of a cylinder. Placing data that are likely to be accessed together in cylinders reduces the access significantly as head movement (seeking) is slow compared to disk rotation and switching between heads.