What Is a Solid State Drive (SSD)?

The next generation of personal computer storage

Solid state is a term that refers to electronic circuitry that is built entirely out 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 that we have today are built around semiconductors and chips. In terms of a solid state drive, it refers to the fact that the primary storage medium is through semiconductors rather than a magnetic media such as a hard drive.

Now, you might say that this type of storage already exists in the form of flash memory drives that plug into the USB port. This is partially true as solid state drives and USB flash drives both use the same type of non-volatile memory chips that retain their information even when they have 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

So how exactly do they do this? Well, many SSDs on the outside look almost identical to a traditional hard drive. This design allows the SSD drive to be put in a laptop or desktop computer in place of a hard drive. To do this, it needs to have the standard dimension as a 1.8, 2.5 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 have several advantages over the magnetic hard drives. The majority of this comes from the fact that the drive does not have any moving parts. While a traditional drive has drive motors to spin up 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 far less energy than the regular hard drive. Now, the industry has taken steps to address this with drives spinning down and the development of hybrid hard drives, but both of these still use more power. The solid state drive will consistently draw less power than the traditional and hybrid hard drive.

Faster data access will make a number of people happy. Since the drive does not have to spin up the drive platter or move drive heads, the data can be read from the drive near instantly. Hybrid hard drives do 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 very fragile and sensitive. Even small jarring movements from a short drop can cause the drive to have issues. Since the SSD stores all its data in memory chips, there are fewer moving parts to be damaged in any sort of impact. While mechanically SSD drives are better, they do 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 still 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 actually been available for some time now and have come down dramatically in price but they still cost roughly three times or much more the cost of a traditional hard drive for the same rough storage capacity. The higher the capacity the hard drive, the greater the cost differential becomes.

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

Capacity is also a major factor in the adoption of solid-state drives. The average laptop computer equipped with an SSD will have around 512GB to 1TB 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 an even greater disparity between SSD and hard drives, especially when it comes to price of large capacity SSD's.

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