Write a short note on disk structure

Modern disk drives are initiate as large one dimensional array of logical blocks where the logical block is the smallest unit of transfer. The size of the logical block is typically 512 bytes and the one dimensional array of logical block is mapped onto the sectors of disk sequentially. Sector 0 is the initially first sector of the track on the outermost cylinder the mapping proceeds in order through that track after that through the rest of the tracks in that cylinder and then through rest of the cylinder from outermost to innermost. The faster a track is from the centre of disk that the greater its length so the more sectors it can hold. While we move from outer zone to inner zone the number of sectors per track decreases. Tracks in the outermost zone usually hold 40 percent more sectors than do tracks in the innermost zone. The drive enhance its rotation speed as the head moves from the outer to the inner track to keep the same rate of data moving under the head.