What is a Hard Disk Drive used for? Hard Disk types

Computer systems possess a repository for storing the data and information that is to be processed by the processor. This storage area, called RAM or volatile memory, can store the data and information temporarily. The data is no more in RAM as soon as the computer shuts down. However, user also wants to store his necessary data and files into the computer system permanently for the later use. For that purpose, computer system consists of a permanent storage area called Hard Disk.

What is a Hard Disk Drive?

Hard disk is defined as: "A permanent storage place that is meant for saving the data and instructions for the later use is called hard disk or hard drive. A hard disk can have the storage capacity of 8 TB or more". Computer Hard disk drive has three main types:

1. Fixed Hard disk drive

This type of hard disk is also known as “fixed disk" as it is fixed in the system unit. This disk is a type of magnetic disk that is composed of several circular disks called "platters" stacked on the top of one another. Each platter consists of two read/write heads. Hard disk allows a user to read and write the data as frequent as he desires. However, hard disk requires formatting before any data can be written on it. What is formatting? "Formatting is a process of creating tracks and sectors on the disk". Tracks are in the form of circles on the surface of hard disk and each track is divided into sectors. Up to 512 bytes of data can be stored by each sector on the disk. A cluster is formed when two or more sectors are combined.

2. External/Removable Hard disk

This is the type of hard disk that is not fixed inside the system unit. Instead it is a separate disk that can be attached to a system unit externally with the help of a usb port. External hard disk is advantageous because it can be installed externally without opening the system unit.

Besides external hard disk, a removable hard disk can also be inserted and removed from a computer system without opening system unit. Storage capacity of removable hard disk drive is up to 1 TB and more. The storage capacity is considerably low in comparison with external or fixed hard disk, however this kind of hard disk is extremely useful when there is a need to transfer big amount of data from one place to another.

3. Miniature hard disk

The smallest type of hard disk called miniature hard disk is available to us in various sizes such as 0.85 inch, 1 inch and 1.8 inch. Miniature sizes are available for both internal and external hard disks. Miniature hard disks are specifically designed for portable devices such as digital cameras, media players and smart phones.