HOW THE DATA STORES IN PHYSICAL DISKS?

Data on the disk is recorded on tracks, which are concentric rings on the platter around the spindle. The tracks are numbered, starting from zero, from the outer edge of the platter. Each track is divided into smaller units called sectors. A sector is the smallest, individually addressable unit of storage. The track and sector structure is written on the platter by the drive manufacturer using a low-level formatting operation. The number of sectors per track varies according to the drive type. There can be thousands of tracks on a platter, depending on the physical dimensions and the recording density of the platter. Typically, a sector holds 512 bytes of user data; although some disks can be formatted with larger sector sizes. In addition to user data, a sector also stores other information, such as the sector number, head number or platter number, and track number. This information helps the disk controller to locate the data on the drive.