Backblaze published its Drive Stats for Q2 2021 report yesterday, and despite an overall increase in failure rates, the company found three HDDs that didn't fail once. But don't take that as a ringing (or would it be spinning?) endorsement quite yet. There are some important caveats regarding the reliability of these particular drives.
The models in question are the Seagate ST6000DX000, HGST HUH721212ALE600, and Western Digital WUH721816ALE6L0. Of those, only the Seagate drives have been in use for over two years, and the company only gathered stats for 886 of them. That pales in comparison to the 177,935 drives that were examined for this report.
The Seagate drives' performance is still notable, however, because those HDDs have been in use for 74 months on average with a lifetime failure rate of 0.92 percent. The WD and HGST drives have been in use for three and 21 months, respectively, so their 0 (WD) and 0.41 percent (HGST) failure rates could rise as they continue to age.
Those rates are still low compared to the average. Backblaze said the annual failure rate for all of its drives rose from 0.81 percent to 1.01 percent year-over-year. "The increase is within our confidence interval, the company said, "but bears watching going forward." It didn't attribute the rise in drive failures to anything in particular.
Backblaze also updated its comparison of HDD and SSD boot drive failure rates. The company said its first attempt "was suspect as each type of drive was at a different point in its life cycle," so it "took the HDD boot drives that were in use at the end of Q4 2020 and went back in time to see where their average age and cumulative drive days would be similar to those same attributes for the SDDs at the end of Q4 2020."
That led the company to examine HDD boot drive information from the end of 2015. It found that "when we control using the same drive models, the same average drive age, and a similar number of drive days" the 10x failure rate for HDDs it reported in the first quarter comparison dropped to a failure rate just under 2x that of SSDs. That's still a compelling reason to consider one of the best SSDs as your boot drive, rather than using a mechanical hard drive.