The principle of hard drives

Basic principle of hard drives and floppy disks work are almost identical: the data is written and read by the universal read-write heads from the surfaces of the rotating magnetic disk, divided into tracks and sectors (512 bytes each), as in Fig. 1


In storage rings are usually installed multiple drives, and data is written on both sides of each of them. Most drives have at least two or three discs (which can record on four or six sides),
but there are also devices that contain up to 11 or more disks. The same type of (equally spaced) on all sides of the track drives are combined into a cylinder. To each side of each disc provides its own track read / write, but all the heads are mounted on a common shaft or a rack. For this reason, the head can not move independently of each other and move only synchronously.

Hard drives spin faster than flexible. The frequency of their rotation, even in pain in most of the first models was 3600 rev / min (ie 10 times more than in the floppy disk), and until recently was almost a standard for hard drives, but now speed drives increased, for example, on my laptop drive capacity 3.3 GB rotates with a frequency of 4852 rev / min, but there are models with frequencies 5400, 5600, 6400, 7200 and even 10 000 rev / min. The rate of work of a hard drive depends on the frequency of its rotation, the velocity of the system heads, and the number of sectors per track. In addition, due to a combination of all these factors to communicate with hard disk drives is much faster than floppy disks.