Basic knowledge of hard disk and method knowledge of rescuing hard disk

DOS management structure of hard disk

1. Track, sector, cylinder and head number

The most basic component of hard disk is a platter coated with magnetic media made of hard metal materials, and the number of platters of different capacity hard disks varies. Each platter has two sides, which can be

Record information. The platters are divided into many scalloped areas, each region being called a sector, and each sector can store 128x2 N-n=0.1.2.3 bytes of information. In DOS

Each sector of the 128x2 is a 2-second square = 512-byte, the disc is centered on the disc center, concentric circles of different radii are called tracks. The same radius of different platters in the hard disk

The cylinder of the track is called the cylindrical surface. Both the track and the cylinder are circles that represent different radii, and on many occasions, the tracks and cylinders can be used interchangeably, and we know that each magnetic

There are two sides of the disk, each face has a head, the habit of using magnetic number one to distinguish. sector, track (or cylinder) and the number of heads constitute the basic parameters of the hard disk structure, to help these

parameter can get the capacity of the hard disk, the base calculation formula is:

Storage capacity = number of Heads x track (cylinder) x per sector x number of bytes per sector

Main points: (1) The hard disk has several platters, two sides per platter, one head per face

(2) The disc is divided into a plurality of fan areas

(3) Concentric circles with different radii of the same disc are track

(4) cylindrical surface with the same radius of different platters

(5) formula: Storage capacity = number of Heads x track (cylinder) number x per sector x per sector number of bytes

(6) Information records can be expressed as: xx track (cylinder), XX Head, XX sector

2. Cluster

A "cluster" is the smallest unit of DOS allocation. When a small file is created, as a byte, it is not a single byte of space on the disk,

But to occupy a whole cluster. DOS depending on the storage medium (such as floppy disk, hard disk), different capacity of the hard disk, the size of the cluster is also different. The size of the cluster can be called disk

Parameter Block (BPB). The concept of a cluster applies only to data areas.

This point: (1) "Cluster" is the smallest unit of DOS allocation.

(2) Different storage media, different capacity of the hard disk, different DOS version, the size of the cluster is not the same.

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