October 21, 2021

HDD vs SSD: What is the Difference Between SSD and HDD

HDD vs SSD Comparison

1. low processing speed1. High processing speed
2. High latency2. Low latency
3. i/o operations per second are lower3. i/o operations per second are higher
4. Heavier in weight4. Lighter in weight
5. Larger in size5. Smaller in size
6. Sequential data transfer6. Randomly accessed data transfer
7. Noise generated when working7. No noise is generated
Table 01: HDD and SSD comparison


The conventional rotating hard drive is the primary non-volatile storage device in a computer. In other words, unlike data stored in RAM, the information there does not go anywhere when the device is turned off. A hard drive is a metal platter with a magnetic coating that holds more types of data. While the platters are spinning, a read/write head on an arm accesses the data.

An SSD is similar to a hard drive in that the data is stored on interconnected flash memory chips that contain the data even though no power is passing through it. These flash chips are distinct from those used in USB drives in that they are faster and more reliable. As a result, SSDs are more expensive than USB drives of similar capacities.

Hard Disc Drive

Figure 01: Hard Disk Drive (By Evan-Amos)

A hard disk drive (HDD) is a non-volatile computer storage system made up of rotating magnetic disks or platters. Random-access memory (RAM) is the main memory unit, and it is a secondary storage device used to store data indefinitely. The term “non-volatile” refers to data that is retained even when the device is turned off.

A hard drive is securely secured inside a computer case with braces and screws to prevent it from being shaken as it spins. It typically spins at a speed of 5,400 to 15,000 rpm. The drive spins at a faster rate, allowing data to be accessed almost instantly. The majority of hard drives use serial ATA (SATA) or serially connected technology to communicate at high speed. An arm with a read/write head extends over the platters as they rotate. The arm writes and reads new data to and from the platters. The majority of hard drives, including motherboard cables and connectors, use Enhanced Integrated Drive Electronics (EIDE). All data is magnetically recorded, allowing it to be recorded even if the power is turned off.

How it Works

Hard drives need a read-only memory (ROM) controller card to tell read/write heads how, when, and where to move through platters. Hard drives have disks stacked up and spin in unison. The read/write heads are controlled by an actuator, which magnetically reads and writes to the platters. The read/write heads float on a film of air above the platters. Both sides of the platters are used to store data. Each side or surface of a disc is called a Head, each divided into sectors and tracks. All tracks are the same distance from the center of the disc. Collectively, they include a cylinder. Data is written to a disc starting with the furthest track. The read/write heads move inward to the next cylinder after the first cylinder is filled.

A hard drive is divided into one or more partitions, which can be divided into logical drives or volumes. Usually, a Master Boot Record (MBR) sits at the start of the hard drive and contains a partition information table. Each logical drive contains a boot record, a file allocation table (FAT), and a root directory for the FAT file system.

Figure 02: Parts of an HDD (By I, Surachit)

Solid state Drive

Figure 03: Solid State Drive (By photo: Qurren (talk))

Integral circuits are used to store data in this solid-state storage, which is used as secondary storage. Flash memory is used to store and retain data even when the power is switched off. SanDisk was the first to launch this, and the size ranges from 250GB to 100TB. These are considered to have higher physical shock resistance, faster access times, and lower latency. SSD properties differ depending on the manufacturer.

This has a much higher read/write speed than a hard disk drive (HDD). Since these don’t have any external moving parts like HDDs, they’re also noise-free. A solid-state drive (SSD) can be more costly than a hard drive. However, if someone chooses a hard disk over an SSD, they can get far more storage for the same price. SSDs are usually much smaller than HDDs, giving PC manufacturers more design versatility. Traditional hard drives are smaller in size and can be placed in a slot or mounted directly on the motherboard.

This allows games, applications, and movies to load faster. SSDs are lighter and better able to withstand movement and dropping due to the technologies they use. Furthermore, solid-state drives use less energy, allowing computers to operate at a lower temperature.

Leave a Reply

Your email address will not be published. Required fields are marked *

Pin It on Pinterest