What is the Difference Between Hard Disk Drives, Hybrid Hard Drives and Solid State Drives SSD

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Hard disk drives were introduced by IBM in 1956, when they were used in a real-time transactions processing computer. As time passed they became smaller and smaller and the capacity went up drastically. Today almost all computers have a hard disk drive, which is now transforming into a solid state drive SSD.

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Hard Disk Drives

Here are a few features that describe hard disk drives:

  • Hard drives are electromechanical devices.
  • The data is stored on a disk that is covered by ferromagnetic material.
  • When reading, the data is processed on a logic board inside the hard drive converting data from analog to digital.
  • Data is read and written with a so-called head which is positioned on the disk with a coil.
  • All hard drives are designed to last a long time, but mechanical stress, temperature and other factors shorten the lifespan considerably.
  • They have error correction algorithms that enable error correction on the fly and help to read the data from the disk.

Hybrid Hard Drives or Solid State Hybrid Drives (SSHD)

Here are features of SSHD:

  • As usual hard drives they have a disk where the data is stored.
  • They also have a memory where the most used data is stored.
  • They should be faster than a usual hard drives, but in reality their speed varies.
  • There are two types of hybrid drives: dual-drive hybrid systems and solid state hybrid drives (SSHD).

Here is an illustration explaining what a dual-drive is and what SSHD is

As the name suggests, dual-drive systems have two drives – one is a solid state drive (SSD) and another is a usual hard disk drive. If we connect a SSD or mSATA and a hard disk drive to our computer we will then have a dual-drive system.
On the other hand, solid state hybrid drives (SSHD) have both of the above drives inside one device.

Seagate SSHD

As users are reporting, it takes some time for a SSHD to reach its maximum speed. And this is natural, as it learns what data is used the most.

Solid State Drives (SSD)

As memory got cheaper and cheaper it became economical to make storage devices from it. Today solid state disks are still expensive, but the future definitely belongs to them.

  • They are made only from electronics (with no moving parts);
  • The reliability is still unknown as this is very young technology.
  • They are made only from electronics (with no moving parts);
  • The reliability is still unknown as this is very young technology.
  • They also have error correction code as the data written to cells is not perfect, as we may think.
  • They are fast. They also have a different speed that depends on whether there a cache memory inside.
  • Sometimes they are not compatible with older computer models.

Samsung SSD

What are the similarities?

  • All hard drives share the same interface, which is SATA.
  • Earlier hard drives used to have a ATA interface
  • They drive almost the same amount of power.


SSDs not only store data differently from hard disk drives, but also employ new interfaces. For example, there are SSDs with PCIe and NVMe interfaces. Both interfaces allow for transferring data at much higher speeds. Some laptops have an option to use PCIe SSD in the place where the Wi-Fi card is connected.


The future definitely belongs to solid state drives (SSD), not just because they are faster, but they are simple as they do not contain any mechanical parts. As the electronics get cheaper we will see more and more SSD in our computers.

Words like “amazing speed” is the right way to describe SSDs. They read the data at very high speeds. However, their data writing speed is a bit slower.

My experience with SSDs has been positive. There was just one SSD that refused to run on an old Dell laptop, but that was probably because of the laptop’s incompatibility.

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