For nearly the past five years, Backblaze has been recording hard drive statistics at its data centers, noting which drives failed, when they died, and how long they lasted. Backblaze’s sample size of thousands of drives means it gives us solid, actionable data in its reports, which is why when it notes that some manufacturers make much more reliable drives than others, it’s noteworthy.
That’s certainly the case following this latest report. In the fourth quarter of 2017, just 22 of 23,265 HGST drives failed. Extrapolating that data over a full 12-month period, the worst failure rate Backblaze expects of its HGST drives is 0.45 percent.
That same annualized failure rate for Western Digital drives was slightly worse, though with a sample size of 662 drives, those statistics are not quite as compelling.
Seagate’s statistics however, paint a far grimmer picture. Although the most popular drives used by Backblaze, with a total of 67,787 drives tracked by the study, it also saw the highest failure rates. In the case of one of the 8TB Seagate drives, 44 failed from around 14,000, equating to an annualized failure rate of 1.22 percent. Other annualized failure rates saw two percent and even nearly three percent in one category.
Although other drives had estimated rates of as high as 29 percent, those were far smaller sample sizes, so are arguably not as accurate.
It’s not all bleak for Seagate however. Although its drives did experience the highest failure rate of Backblaze hard drives in the last quarter, drive reliability does appear to be gradually improving. While the number of 6TB Seagate drives used by Backblaze has remained constant for the past three years, the failure rate has fallen from 2.2 percent to 0.7 percent. Western Digital has also seen improvements with its 6TB models.
HGST has been consistently the most reliable over the years though, especially at the 4TB level, wherein each of the past three years it has achieved a sub-one percent failure rate.
If you’d like to look at more data from Backblaze, its entire back catalogue of reliability tests is archived on its website.
