In the context of computer hardware, a sector is a sub-division of a track on a magnetic disk or optical disc. Each sector stores a fixed amount of data. The typical formatting of these media provide space for 512 bytes (for hard disks and diskettes) or 2048 bytes (for optical discs) of user accessible data per sector. A BlueGene supercomputer cabinet. ... Hardware is the general term that is used to describe physical artifacts of a technology. ... Magnetic storage is a term from engineering referring to the storage of data on a magnetised medium. ... The optical lens of a compact disc drive. ...

Technically, the word sector, as in the sector of a circle, has always meant something resembling a 2-dimensional slice (like a piece of pie), rather than an angular sub-division of only one circular track or strip. Early on in various computing fields, the term block was used for this small chunk of data, but sector appears to have become more prevalent. One quite probable reason for this is the fact block has often been used to speak of data chunks of any size, rather than being limited to the smallest accessible amount on a medium. For example, the Linux program dd allows one to set the block size to be used during execution with the parameter, bs=bytes. Doing so, never changes the actual sector size of a medium though, only the size of the blocks dd will manipulate. A circular sector or circle sector also known as a pie piece is the portion of a circle enclosed by two radii and an arc. ... In computing (specifically data transmission and data storage), block size indicates a nominal size, usually expressed in bytes or bits, of a block of data. ... dd is a common UNIX program whose primary purpose is the low-level copying and conversion of files. ...

See also

• Cylinder-head-sector
• block_(data_storage)
• Disk storage
• Hard disk drive partitioning
• File Allocation Table