Backblaze’s latest storage reliability figures add SSD boot drive failure rates to the mix

In addition to the quarterly reports on HDD failure rates published by Backblaze, the cloud backup and storage company has now added SSD boot drives to its data starting with Q1 2021. As Backblaze notes, these drives are fairly recent compared to their HDD counterparts (fewer drive days). However, even this preliminary data – for the latest quarter – shows a noticeable difference between annualized failure rate (AFR) for both categories, standing at under 1 percent for SSDs and just over 10 percent for HDDs.

For its latest quarterly report on hard drive reliability, Backblaze notes four models that stood out with zero drive failures through the first three months of 2021. Among these are Seagate’s 6TB and Toshiba’s 4TB disks, which have an average age of almost six years with lifetime annualized failure rates – April 2013 to March 2021 – coming in at under 1 percent.

The other two drives are much newer additions to this testing, and include the Toshiba 16TB MG08 series that have an average age of just over 4 months and Western Digital’s 16TB Ultrastar drives, whose average age across 520 units is just 0.4 months.

Another interesting insight this time around (and going forward) is the addition of reliability data for SSDs, which Backblaze says it started using just over two years ago. Instead of regular HDDs used to store data, and which make for an overwhelming 98 percent majority of the company’s 175,443 total drive count, these SSDs are only used for booting its storage servers, keeping log files, and other diagnostic data.

The failure rate for these drives has been compared with another group of HDDs that Backblaze says have been performing the “same functions in the same environment” over time. An important factor here is the drive age, which can skew the data somewhat in favor of SSDs and was the reason why Backblaze didn’t break them down by their individual models.

“None of the models by themselves had enough drive days to be statistically relevant. In aggregate, the number of drive days is still on the lower side, but the obvious difference in the AFR between the HDD and SSD boot drives is eye-opening.” Going forward, Backblaze says it will take a look at data showing HDD failure rates in their early years of use and compare it with SSDs for a more accurate picture, as well as build a library of SSDs for its storage farm.

Additionally, Backblaze published an updated list of lifetime annualized failure rates for HDDs, noting that lifetime AFR figures across all drives continue to decrease, with the latest average AFR of 1.49 percent being the lowest value on record.