At present, computer hard disks are divided into mechanical hard disks and solid-state hard disks. The maximum capacity of mechanical hard disks that have come out in the world is 16TB, and the maximum capacity of solid-state hard disks that have come out is 2TB.

Mechanical hard disk: it is a traditional common hard disk, mainly composed of disk, magnetic head, disk spindle and control motor, magnetic head controller, data converter, interface and cache. The magnetic head can move along the radial direction of the disk, and the disk rotates at a high speed of several thousand revolutions per minute, so the magnetic head can be positioned at the designated position of the disk to read and write data. Information is written on the disk by the electromagnetic current of the magnetic head close to the magnetic surface, and information can be read in the opposite way.

Solid-state hard disk: referred to as solid-state hard disk, it is a hard disk made of solid-state electronic memory chip array, and consists of control unit and storage unit. Solid-state hard disk is exactly the same as ordinary hard disk in terms of interface, function and usage, and the product shape and size are also exactly the same as ordinary hard disk. Widely used in military, vehicle, industrial control, video monitoring, network monitoring, network terminals, electric power, medical care, aviation, navigation equipment and other fields.