12 years of HDD analysis brings insight to the bathtub curve’s reliability

Backblaze is a cloud backup and storage company that has been tracking annualized failure rates (AFR) of hard drives in its data center since 2013. As you can imagine, this has brought the company a lot of data. And this data led the company to conclude that hard drives “last longer” and have fewer errors.

This conclusion came from a blog post published this week by Stephanie Doyle, Backblaze’s editor and blog operations specialist, and Pat Patterson, Backblaze’s chief technical evangelist. The authors compared the AFRs for the roughly 317,230 drives in Backblaze’s data center to the AFRs the company recorded when examining the 21,195 drives it had in 2013 and 206,928 drives in 2021. Doyle and Patterson said they identified “a pretty solid gap in drive failure age and peak AFR compared to the last two times we ran the analyses.” “.

As Doyle and Patterson wrote, the high failure percentage peaks for the drives tested this year were 4.25% at 10 years and three months, compared to 13.73% at about three years and three months in 2013 and 14.24% at seven years and nine months in 2021.

“Not only does this represent a significant improvement in drive longevity, but it is also the first time we have seen a spike in drive failure rates at the hairier end of the drive curve. And this represents about a third of each of the other failure peaks,” Doyle and Patterson wrote.

You can check out Paterson and Doyle’s August blog post for more information on the drives they analyzed this year. The drives came from HGST, Seagate, Toshiba and WDC and had an average age of 3.7 months to 103.9 months (approximately 8.7 years). Drives ranged from 4TB to 24TB. In 2021, Backblaze’s sample included drives from the same vendors, and drives tested for each model had an average age of 3.57 to 80.85 months (approximately 6.7 years). The drives ranged from 4TB to 16TB.

As Backblaze has done in the past, Doyle and Paterson compared the behavior of Backblaze’s data center hard drives with the bathtub curve, an engineering principle in which component failure rates tend to follow a U-shape over time, with more failures occurring early in life before the rate drops, stabilizes, and then picks up again as the component gets old.