Low-level Formatting the HDD
Marking on sectors in hard disk drives are made during the manufacture of the disk drive by record servo marks which are created using the unique high-precision external mechanical device through a technological window in the hermetic block on magnetic disks; after marking the completion, the technological window is stuck up. The laser gauge of distance is used for the control over the moving of magnetic heads during marking. Servo marks are put on a working surface of a magnetic disk, forming the circular tracks located on the same distance from the center of rotation of a magnetic disk. Each track is formatted on different sectors quantity depending on the length of a circle, providing a constant record density.
At usual operation of a HDD servo marks, being located between sectors, are selected from the data stream of the disk drive and are used for keeping a magnetic head over the required track irrespective of external effects and thermal deformation of elements, and also for identification of sectors and stabilization of frequency of rotation of a magnetic disk by spindle motor. Servo information is a basis of marking of a disk, and in the case of its damage, the hard drive controller cannot restore it by itself. Usually, it is accompanied by positioner knocking at mechanical limiters and disk drive "hanging up".
In the ATA-3 standard, the application of factory marking of a magnetic disk on sectors in hard drives resulted in refusing the command "Format track" with a code 50h. For the same reason, the procedure of low-level formatting (Low-Level format) was eliminated from the BIOS of modern motherboards. In spite of it, a myth about the possibility of low-level program formatting which generates the creation of "Noddy" programs, only filling storage devices with zeros and erasing the information from it, persists in the network.