Hard sectoring in a magnetic storage or optical disk data storage device is an archaic form of sectoring that uses a physical mark or hole in the recording medium, from which sector locations are referenced.

Hard sectoring was most notably implemented in older 8- and 5¼-inch floppy disks, by punching an index hole in the disk. When the presence of the index hole was recognized by an optical sensor, a reference signal was generated. All sector locations could be referenced from this signal.