Are SSDs more reliable than hard disk drives? This research may have the answer

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Solid-state drives (SSDs) are more reliable than hard disk drives (HDDs) — at least in certain use cases, according to cloud storage company Backblaze. But this may not actually make much difference when deciding what type of storage you should buy.

This year the company was looking to settle a discussion about whether HDDs or SSDs are more reliable. Backblaze provides cloud backup service for laptops, computers and Offers B2 cloud storage for businesses.

It uses a mixture of SSDs and hard disk drives as boot drives for the storage server in the Backblaze Cloud Storage platform. Since 2018, HDD failed boot drives have been replaced by mostly 2.5-inch SSD drives (some of which are M.2 form factor drives). Backblaze’s SSD/HDD drives boot their storage servers as well as store log files and temporary files produced by the storage server. Today, Backblaze owns more than 2,500 SSDs (a combination of Crucial, Dell, Micron, Seagate, and Western Digital) and stores more than two exabytes of data.

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The company measures SSD and HDD reliability by tracking the annual failure rate (AFR) of SSDs and HDDs to shed light on the “previously mysterious world of hard drive failure rates” and, obviously, to stir debate about the technologies behind its service.

To account for the age differences between older hard drives and newer SSDs that were being compared, last year I published Control for Life SSD and HDD AFRs. And I found that SSD hard drives failed more often, but only slightly. (The problem with her data was that hard drive failure rates increased dramatically after five years, and she didn’t yet have the equivalent of five years of data for hard drives.)

“The difference certainly wasn’t enough by itself to justify the additional cost of buying an SSD versus an HDD,” I finished At that time, noting the best factors to consider when purchasing either technology cost, speed required, electricity and form factor.

Now, with a year’s worth of data on our five-year-old SSDs, we’ve come to a different conclusion—albeit with some caution.

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The lifetime AFR for HDD and SSD in year 4 was 1.83% and 1.05%, respectively, while the gap grew in year 5: 3.55% for HDD versus 0.92% for HDD. The average life span of hard disk drives in the sixth, seventh, and eighth years was 5.23%, 6.26%, and 6.93%, respectively. How do SSDs work these years?

“At this point we can reasonably claim that SSDs are more reliable than hard disk drives, at least when used as boot drives in our environment,” she says.

Backblaze adds: “It’s absolutely certain that the failure rate of SSDs will eventually start to rise. It is also possible at some point that SSDs will hit a wall, perhaps when they start to reach their media wear limits.”

However, this only eliminates one of the variables that consumers need to evaluate when purchasing storage, with price remaining a key factor given that a 1TB SSD costs at least twice as much as an equivalent capacity hard drive.


Source: Backblaze

Backblaze notes that in fact, using the failure rate as a factor in your decision is questionable. Once you controlled for age and driving days, the two types of drive were similar and the difference was definitely not enough by itself to justify the additional cost of buying an SSD versus a hard drive. “At this point, it is best to decide based on other factors: cost, speed required, electricity, form factor requirements, and so on,” he suggested.