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Hard Disk Drive (HDD) – Storage, Components of HDD

September 5, 2022

Hard Disk drives are the storage devices for data in computers. HDDs store information magnetically in tracks on rotating disks. HDDs use heads to read and write data onto the disks. HDDs have been around since the 1970s and have become smaller over time. Today’s HDDs are much faster than older models and can hold many times more data.

Working of Hard Disk Drive

Hard disks are mechanical hardware devices that contain platters coated with magnetic material. When a current passes through the coil, it creates a magnetic field that causes the platter to spin at high speeds. This spinning motion causes the head to read or write information from the surface of the platter.

They come in various sizes, from 2.5 inches to 15 inches. The smaller ones are commonly found in laptops and tablets, whereas larger models are usually found in desktop computers.

A hard disk drive (HDD) is a device that stores data on a rotating storage medium such as a hard disk or solid-state drive. HDDs are widely used in personal computers and other electronic devices.

Characteristics of Hard Disk

  • Hard disk provides large storage capacity. The capacity of a personal computer hard disk is from 160GB to 2 TB and more.
  • It is much faster than a floppy disk.
  • It is the primary media for storing data and programs.
  • It is more reliable than a floppy disk.
  • Data stored on a hard disk is safer than a floppy disk.

Storage Capacity of HDD

The three main storage size ranges for HDDs are 16-64 GB, 120-256 GB, and 500 GB to 2 TB. The first group is among the lowest for HDD storage and is found in older devices. The second group is considered the entry point for laptops and computers.

The third group is considered decent for average users with enough space to store music, photos, videos, and other files. 1 TB to 2 TB is suitable for gamers with large file sizes.

Components of HDD

An HDD consists of several components, including the read/write head, actuator arm, spindle motor, platter, and enclosure.

image showing the Components of HDD


The motor is the heart of the hard drive. It contains the spindle and actuator assembly that spins the disk at high speeds. The actuator moves the magnetic heads over the surface of the disk to read and write data.

Read/Write Head

A read/write head uses electromagnetic induction to detect changes in the magnetic field of the disk. When the head passes over a magnetized area of the disk, it detects these changes and interprets them as binary ones and zeros.


The platter is the spinning metal disc that holds the information written to the disk. A single platter can hold thousands of gigabytes of data.

Spindle motor

The spindle is the rotating hub that holds the platters. It is powered by a motor and rotates at high speed.


The actuator is the arm that carries the read/write head over the surface of the platter.


The disk is the flat surface that stores the data. There are two types of disks: Hard disks and Solid State Drives (SSD).


The controller is the brain of the hard drive. Its job is to manage the flow of data between the computer and the hard drive.

Frequently Asked Questions (FAQs)

What is the importance of hard disk?

The hard disk drive (HDD) is the main storage device for your computer. It stores all of your data, including your operating system, applications, documents, music, videos, pictures, and much more.

What part of the hard drive stores data?

In HDD data is stored on a platter. The platter is a circular disk. It is a fixed, rapidly rotating disk in a hard drive. High-capacity hard drives typically have two or more platters.

What are the 5 components of a hard drive?

Read/write head
Spindle motor

What are the three types of hard disk?

Serial Advanced Technology Attachment (Sata)
Small Computer System Interface(SCSI)
Serial Attached SCSI(SAS)