Differences between Hard disks and SSDs Explained

There are two types of hard disks: HDD and SSD. HDD uses mechanical parts to store data. SSD uses integrated circuits to store data. SSD drives are costly but provide higher data transfer speeds.


HDD stands for Hard Disk Drive. A hard disk contains spinning platters and a moving needle. Platters are circular disks made of a nonmagnetic material such as aluminum alloy, glass, or ceramic. They are coated with a thin layer of magnetic material on both sides that is used to store data.

The moving needle is called the head. It is used to perform read and write operations on platters. During this operation, the platters rotate at tremendous speed. The speed is measured in RPM. More RPM means more speed and cost.

hard disk

Advantages of Hard disks

  • Hard disks are much cheaper than SSDs. At the price of a 256 GB SSD, you can buy a 1 TB HDD.
  • Hard disks are available in much bigger sizes than SSDs. You can easily buy an 8TB or a 16 TB hard disk from any local retailer or online store.
  • Hard disks contain mechanical parts that you can replace at any repair shop. For example, if a hard disk's head is damaged, you do not need to change the entire hard disk. You can replace only the head.
  • Hard disks provide a slower data transfer speed compared to SSDs.

Disadvantages of hard disks

  • Since hard disks use rotatory platters to save data, they make noise during reading and writing operations.
  • They are vulnerable to shock and sudden movement, which makes them a poor choice for laptops.
  • Since they contain moving parts, they are prone to damage.

This tutorial is the first part of the tutorial series "Hard Disk Type, Data Transmission Technology and Interfaces Explained.". Other parts of this series are the following.

Why Do Hard Disks use Serial Transmission?

SCSI, PATA, SATA, and NVMe Explained


SSD stands for Solid State Drive. SSDs use integrated circuits to store data. They do not contain any moving or magnetic parts. They use ICs that are fixed on PCBs. It makes them more durable, faster, and less prone to damage and corruption.

There are two types of SSD: SATA SSD and NVme SSD. SATA SSD uses a SATA interface. NVMe SSD uses an NVMe interface. The SATA interface uses a SATA cable to connect the SSD drive to the motherboard. NVMe interfaces are directly mounted on the motherboard. You can call them NVMe slots. You need to attach NVMe SSD disks directly to these slots.

ssd disk

Advantages of SSD

  • SSDs provide much higher data transfer speeds than HDDs.
  • Since they do not contain any moving or magnetic parts, they are less prone to damage.
  • They are more secure than the traditional HDDs.

Disadvantages of SSD

  • They are more expensive than HDDs.
  • Bigger size SSDs are not easily available. You have to purchase them directly from manufacturers or distributors.
  • Since it does not contain any repairable parts, you have to replace the entire disk if it is damaged.

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