1. The physical drive itself usually comprises several actual disks of which both sides are used. The sides are labelled 0, 1, 2, 3, and so on, and are also called heads because one magnetic head per side does the actual reading and writing. Each side/head has tracks, and each track is divided into segments called sectors. Each sector typically holds 512 bytes. The total amount of space on the drive in bytes is therefore: 512 x (sectors-per-track) x (tracks-per-side) x (number-of-sides) A single track and all the tracks of the same diameter (on all the sides) are called a cylinder. Disks are normally talked about in terms of ``cylinders and sectors'' instead of ``sides, tracks, and sectors.'' Partitions are (usually) divided along cylinder boundaries. Hence, disks do not have arbitrarily sized partitions; rather, the size of the partition is usually a multiple of the amount of data held in a single cylinder. Partitions therefore have a definite inner and outer diameter. From Rute-Users-Guide