Backblaze's Geriatric Hard Drives Kicked The Bucket More In 2023

Cloud backup and storage provider Backblaze has published a report on hard drive failures for 2023, finding that rates increased during the year due to aging drives that it plans to upgrade.

Backblaze, which focuses on cloud-based storage services, claims to have more than three exabytes of data storage under its management.

As of the end of last year, the company monitored 270,222 hard drives used for data storage, some of which are excluded from the statistics because they are still being evaluated. That still left a collection of 269,756 hard drives comprised of 35 drive models. Statistics on SSDs used as boot drives are reported separately.

Backblaze found one drive model exhibited zero failures for all of 2023, the Seagate 8 TB ST8000NM000A. However, this came with the caveat that there are only 204 examples in service, and these were deployed only since Q3 2022, so have accumulated a limited number of drive days (total time operational).

Nevertheless, as Backblaze's principal cloud storage evangelist Andy Klein pointed out: "Zero failures over 18 months is a nice start."

Backblaze 2023 failure rates

For the year, 4,189 drives failed for an overall annualized failure rate (AFR) of 1.7 percent. This was the equivalent of the company having to replace a failed drive every two hours and five minutes, Backblaze said.

A comparison of the overall AFR Backblaze for each of the past three years confirmed that the rate was up in 2023, with an AFR for all drives listed in 2022 of 1.37 percent and just 1.01 percent in 2021. The table shown includes only those drive models that had more than 200,000 drive days during 2023.

According to Backblaze, the AFR increase appears to go hand in hand with the average age of the drive fleet increasing. It said there are currently nine drive models with an average age of six years or more, and these models make up nearly 20 percent of all the drives in production, meaning the rising failure rate can be attributed to aging drives.

Backblaze three-year comparison

In response to this trend, Backblaze said it has hastened the migration program from older drive models, typically 4 TB in size, to new drive models, typically 16 TB in size, which is set to continue throughout 2024.

Backblaze has also produced a chart showing failure rates for each drive size over the past three years. As the company notes, the AFR for 10 TB drives (gold line) has obviously increased during the period, as with the 8 TB drives (gray line) and 12 TB drives (purple line).

The AFR for Backblaze's 4 TB fleet (blue line) peaked in 2022 and has since decreased, which the company attributes to the policy just mentioned of migrating off the older 4 TB drives to 16 TB drives during 2023.

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In general, the company migrates the oldest drives first, as you would expect, because those are the units more likely to fail in the near future.

However, Klein noted "not all drive models play along," pointing out that it has 6 TB Seagate drives which, on average, are older than eight years, yet have the lowest AFR for any drive size group during 2023.

Backblaze failure by drive size

Backblaze also tracks data for the lifetime of its drives. The table shown is for all drive models active at the end of 2023 that can boast two million drive days or more over their lifetime in the company's datacenter.

Klein said the trend lines for the data indicate that drive failure consistently increases with age once the figures for the 4 TB drives are removed. This held for both HGST and Seagate drives, for example.

He said this data makes it clear Backblaze should continue its policy of migrating off its 4 TB drives, although there are other factors such as server age, server size (45 vs 60 drives), and server failure rates that guide its decisions.

Backblaze liftetime failure rates

You don't have to take Backblaze's word for it as the company makes the entire data set available from its website for anyone to download and analyze. Backblaze asks that anyone doing so credits the company as the source of the data and does not sell it on. ®