What is Hard Disk

Hard Disk

Hard Disk Drive is the secondary memory of a computer, it is used to store data on a large scale and can be retrieved at a faster speed. Let's know the physical hard disk The structure.

Physical Structure Of Hard Disk

Basically, a hard disk is made by mixing multiple platters and stacking them on top of each other in an airtight case, i.e a stack of disks. Each platter is made of a thin circular metal plate with a magnetic layer on either side. Magnetic material is coated nowadays, all the platters are of 3.5 inch diameter.

Suppose a computer that uses a hard disk of 80 GB or more capacity has 7 or more disks mounted on a central shaft which rotates at a speed of around 2400 to 7200 rpm, i.e per minute, this plate is connected to each other. At a distance of 1.5 inches, each platter is provided with a reed and right head at the top and bottom, which is connected with a mobbable arm between two platters. Two reeds and right heads carry, so a 6-plate hard disk can also be called a 12-head disk.

All the disks in the hard disk rotate at the same speed and rotate in the same direction, you will be surprised to know that the data does not store on the top and bottom surface of the hard disk, the rest of the disk contains all those surfaces. But data can be stored in each disk. There are many invisible vowels called tracks. These tracks are given a number. The outermost truck. The number is zero.


Now these tracks are given on every disk and all the tracks with the same number form a cylinder, thus in a hard disk that has 10 platters and 18 recording surfaces because the hard disk has the topmost and lowest surface. But the data is not stored, so it is only 18 and thus there are 18 tracks in the cylinder.

Latency time and seek time

Now let's understand what is latency time and seek time. The time it takes to reach a certain track in a disk is called latency time and the time taken to read the record is called the seek time. Is the total time a hard disk's access time is called, including both latency time and seek time.

Now let us know how the data is kept in the hard disk. To keep the data organized, DOS memory divides the disk into two parts, 

1. System Area
2. Data Area

1.System Area

The system area is a total of 2% of the hard disk used to organize the basic structure of the disk. The system area is divided into three parts.

1. Boot Records
2. FAT
3. Root Directory

Boot Records

Boot Records are also called partition sectors. The size of a sector is 512 bytes before the sector is used. These boot actors contain the following information such as where to place the primary partition table of the disk to start the computer. Information of code and instructions required for the process of

FAT

Fat  is a full form file allocation table, called Fat in short. Fat  table is very important because it has a complete record of the data where it is to be stored.

Root Directory

The first directory of the directory number of the computer's file system is the root directory Root Directory, it is also known by the name of the original directory, in which all other files are directory and the sub directory is maintained.

2.Data Area

2% part covers the system area, 98% percent covers the data area. All the types of files and data created by us remains in the same data area, it remains in complete detail or small cluster. 

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