A hard disk drive (HDD) is an old-school storage device that uses mechanical platters and a moving read/write head to access data. A solid-state drive (SSD) is a newer, faster type of device that stores data on instantly-accessible memory chips.

Until the late 2000s, the world was simpler. When you bought a new hard disk drive or personal computer, your hard disk storage choices were limited to size and perhaps speed (such as 5,400 or 7,200 rotations per minute). But today, when you buy a new PC you’re confronted with two very different options: In the example above, the laptop on the left comes with a traditional hard disk drive (HDD), while the one on the right contains a more modern solid-state drive (SSD). Fundamentally, their purpose is the same: These storage devices preserve your memories, music, documents, and programs. But the technology behind them couldn’t be more different:

HDDs : An enclosure contains a series of platters covered by a ferromagnetic coating. The direction of the magnetization represents the individual bits. Data is read and written by a head (similar to the way vinyl record albums work) that moves extremely fast from one area of the disk to another. Since all of these pieces are “mechanical,” the hard disk is the slowest component of any computer – and the most fragile.

SSD: These newer types of disks store information on flash memory, which consists of individual memory cells storing bits that are instantly accessible by the controller. Learn all about SSDs here.

Why are SSDs useful for laptops?

While lower-priced laptops still come with traditional hard drives (it’s one way for manufacturers to minimize their costs), most midrange to high-end machines come with an SSD.

Due to their non-mechanical nature, SSDs require less power, which translates into better battery life.

They’re also shock-resistant. Hard disks have moving parts. If you drop your laptop, chances are that the read/write head of an old-school hard drive is in motion, which could lead to data failure. This doesn’t apply to SSDs.

It isn’t always an either/or choice. In some cases, you find “hybrid” computers. The system partition that contains the operating system, application programs, and the most-used files are installed on an SSD. Other data, such as movies, photos, and documents, are stored on a traditional HDD, which is larger and less expensive.

How much faster are solid-state drives compared to hard disk drives?

The speed difference is significant. SSDs are extremely fast in all areas, but the speed difference is more pronounced when performing certain tasks, such as:

Sequential read/write operations : Copying and moving huge files (such as movies) is where the difference is most apparent. On old-school HDDs, the copying process takes 30-150 MB per second (MB/s), where the same action takes about 500 MB/s on normal SSD, or even 3,000-3,500 MB/s on new NVME SSDs. In this example, copying a 20 GB movie is complete in less than 10 seconds with an SSD, while a hard disk would need at least two minutes.

Small “4K” read/write operations: Most of the time, when you run Windows (or MacOS), open programs, or browse the web, you’re actually opening and manipulating thousands of smaller files, which are stored in small blocks of data (usually sized at 4K). The faster your disk can read (and write) these 4K blocks, the faster and snappier your system seems. With HDDs, the speed ranges from 0.1 to 1.7 megabytes per second (MB/s). SSDs and NVME SSDs, however, operate at much faster speeds of 50-250 MB/s in 4K reads/writes.

To demonstrate the difference, compare these benchmarks. On the left (using CrystalDiskMark) are numbers from a 6-year-old HP 630 laptop:

In terms of personal perception, this system is painfully slow. Every click in Windows is accompanied by a massive delay; boot time takes four minutes to fully complete; launching Chrome takes about 15 seconds. It isn’t fun.

In comparison, the test on the right was performed on a MacBook Pro 2017 running Windows 10 and sporting a fast NVMe SSD. Sequential reads are nearly 56 times faster (fifty-six times faster!) and small 4K read operations are about 226 times faster. As you might expect from the improved performance numbers, Windows takes 10 seconds to boot. There is no visible delay when launching Chrome; it’s just there. Night and day. So sure, upgrading to an SSD on PCs or macOS makes a lot of sense.

What’s the lifespan of an SSD

There are lots of myths surrounding SSD life spans, and the assumptions go back to the early days of SSDs in the 1990s and early 2000s. It is true that SSD cells have a limited lifespan, but today this is not really an issue.

In theory, the more data written to a cell, the faster it wears out. Nowadays, an SSD cell survives about 3,000 write cycles, which doesn’t sound like much at first. But thanks to the principle of wear leveling, the SSD controller makes sure that write operations are spread evenly across all cells in order to minimize “cell death.” Additionally, modern SSDs contain spare cells that will replace cells that go bad. This is called bad block management, and it’s why the larger the SSD, the longer its lifespan.

However, even if you were to constantly write data on to a hard disk, 24 hours a day, you’d still have decades until the disk eventually dies. (Read more about the myths and facts of SSD endurance)

What about capacity differences between HDDs and SSDs?

If you are concerned about how much information you can store on each type of drive, be reassured. There are no differences in storage capacity. You can get HDDs and SSDs in similar sizes. Usually the range is 128 GB to 2 TB.

However, larger SSDs are still more expensive, so let’s talk about…

Price differences between HDDs and SSDs

The market for flash storage is volatile, and it varies based on supply and demand. While the price for SSDs has decreased a lot, there is still a significant price difference. A 500 GB HDD costs between $25 and $50 (for faster, higher-end models), whereas a 500 GB SSD costs from around $60 to $150. Naturally, these numbers will change over time.

A good source for direct price comparison of popular disk sizes can be found at PCPartPicker.com:

In this example from April 2019, you can see that the old-school HDDs either remained around the same price point or they experienced sudden spikes. In contrast, the price for a 1 TB SSD dropped from around $400 to slightly above $200 (with some discounted models at $100-150).

Is an HDD or an SDD better for gaming?

Given the huge amounts of data a game has to shuffle back and forth (loading levels, character models, etc), an SSD helps games load and run faster. You’ll also experience less stutter when playing games, as the rest of your PC doesn’t need to wait for game data to load – which can give you quite an advantage, especially in the eSports arena.

Here’s a simple example: Loading the world of GTA V takes about 25 seconds on my Samsung 970 Evo Plus with SSD, compared to more than two minutes when using an old mechanical hard disk. A game changer.

Summary

If you’re simply looking for a cheap way to store files, then you can still get a great deal with HDDs. They offer lots of terabytes for budget prices.

But for your “primary” drive (your operating system, application programs, and most-used files), you should upgrade to an SSD, as it offers dramatically improved speeds.

In all cases, SSD or HDD, you’ll need to keep your drive clean. Your operating system requires a lot of disk space to operate – and running low on space can cause extreme slowdowns and even crashes.

To prevent this from happening, try Avast Cleanup or Avast Cleanup for Mac, which keep your computer clean and running its best.