What Is a Solid State Drive (SSD)?

The next generation of personal computer storage

Solid state refers to electronic circuitry that is built entirely of semiconductors. The term was originally used to define those electronics, such as a transistor radio that used semiconductors rather than vacuum tubes in its construction.

Most electronics today are built around semiconductors and chips. A solid state drive uses, as its primary storage medium, semiconductors rather than the magnetic platters of a conventional hard drive.

Solid state drives and USB flash drives use the same type of non-volatile memory chips that retain information when there is no power. The difference is in the form factor and capacity of the drives. While a flash drive is designed to be external to the computer system, an SSD is designed to reside inside the computer in place of a more traditional hard drive.

Samsung 970 EVO SSD.
Arshane88 / CC BY-SA 4.0 / Wikimedia Commons

Many SSDs on the outside look almost identical to a conventional hard drive. This design allows the SSD drive to be put into a laptop or desktop computer in place of a hard drive. To do this, it needs to have the same standard dimension as a 1.8-inch, 2.5-inch, or 3.5-inch hard drive. It also uses the common SATA interface so that it can easily be placed into any PC as a hard drive would. There are several new form factors such as M.2 that look more like a memory module.

What We Like
  • Less power usage.

  • Faster data access.

  • Higher reliability.

What We Don't Like
  • Costs more than a traditional hard drive.

  • Shorter lifespan.

  • Smaller capacity availability.

Why Use a Solid State Drive?

Solid state drives offer several advantages over magnetic hard drives. First, the SSD does not have moving parts. While a magnetic drive uses drive motors to spin the magnetic platters and the drive heads, all the storage on a solid state drive is handled by flash memory chips.

A hard drive and a solid state drive.
Santeri Viinamäki / CC BY-SA 4.0 / Wikimedia Commons

The power usage is a key role in the use of solid-state drives in portable computers. Because there is no power draw for the motors, the drive uses less energy than the regular hard drive. The industry has taken steps to address this discrepancy with drives spinning down and the development of hybrid hard drives. However, both of these use more power. The solid state drive consistently draws less power than the magnetic and hybrid hard drives.

Because the drive does not spin the drive platter or move drive heads, the data reads from the drive more quickly. Hybrid hard drives tend to mitigate the speed aspect when it comes to frequently used drives. Similarly, Intel's new Smart Response Technology is a similar method of caching on a small solid state drive to produce similar results.

Reliability is also a key factor for portable drives. Hard drive platters are fragile and sensitive. Small jarring movements from a short drop can break the drive. Since the SSD stores its data in memory chips, there are fewer moving parts to be damaged in an impact. While, mechanically, SSD drives are better, these have a limited lifespan. This comes from a fixed number of write cycles that can be done on a drive before the cells become unusable. For most consumers, however, the write cycle limits tend to allow the drives to last longer than the average computer system.

Why Aren't SSDs Used for All PCs?

As with most computer technologies, the primary limiting factor of using the solid state drives in laptop and desktop computers is cost. These drives have been available for some time and have come down in price. However, these cost roughly three times or more than a traditional hard drive for the same storage capacity. The higher the capacity the hard drive, the greater the cost difference becomes.

Laptop and cellphone sitting on a wooden surface.
veeterzy / Pexels 

Capacity is also a factor in the adoption of solid state drives. The average laptop computer equipped with an SSD has around 512 GB to 1 TB of storage. This is roughly equivalent to what laptops of several years ago with magnetic drives came equipped with. Today, laptops can feature several TB's of storage with a hard drive. Desktop systems have a greater disparity between SSD and hard drives, especially when it comes to the price of large-capacity SSDs.

Even with the difference in capacity, most computers have more storage capacity than previous models. Only a large collection of raw digital photo files and high definition video files will likely fill up a hard drive quickly. As a result, solid state drives generally offer a sufficient level of storage for most laptop computers. Additionally, high-performance external options from USB 3.0, USB 3.1, and Thunderbolt make adding extra storage space with an external hard drive quick and easy for non-essential files.