Backblaze Billion-Hour Hard Drive Reliability Report Shows Consistently Low HGST Failure Rates

Cloud storage company Backblaze is at it again with its latest report on failure rates for hard drives. Backblaze’s early 2015 study showed alarmingly high Seagate 3TB failure rates. For the first quarter of 2016, the overall failure rate for Seagate drives has fallen to a somewhat more respectable level, but Western Digital HDDs haven’t improved nearly as much overall. HDDs are still one of the most cost-effective ways to store large quantities of data, and Backblaze’s analysis is quite thorough and of great use for enthusiasts as the company almost exclusively uses consumer-grade 3.5-inch HDDs.

When it comes to hours in service, over 51 percent of Backblaze’s HDD fleet is serviced by HGST drives, with Seagate coming in a close second at just over 45.5 percent. Western Digital drives make up a mere 3.4 percent of the tally, while Toshiba is just a blip on the radar with 0.3 percent.

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There’s good reason for this discrepancy according to Backblaze:

These days we need to purchase drives in reasonably large quantities, 5,000 to 10,000 at a time… For Toshiba we have not been able to find their drives in sufficient quantities at a reasonable price. For WDC, we sometimes get offered a good price for the quantities we need, but before the deal gets done something goes sideways and the deal doesn’t happen… We would be happy to buy more drives from Toshiba and WDC, if we could, until then we’ll continue to buy our drives from Seagate and HGST.

The good news from Backblaze’s analysis of over 61,000 HDDs during the January 1st, 2016 to March 31st, 2016 period is that the overall annualized rate of failure for HDDs has continually dropped over the past three years, reaching an overall low of 1.84 percent for the quarter.

Out of 61,523 HDDs in service during the first quarter, Backblaze reported 266 total failures. The bulk of that figure came from the 4TB Seagate Barracuda ST4000DM000, which had 198 total failures during the period. But the ST4000DM000 is by far the most prevalent HDD in the study with 34,729 units in service — more than 10 times the next closest HDD. So even with the seemingly high number of failures, the annual failure rate is still just 2.54 percent.

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Failure rates for the newer Western Digital 6TB drives were a bit higher than average and there were a high number of failures (annual failure rate) for older Western Digital 2TB drives. On the other hand, Seagate’s 6TB drive experienced zero failures during Q1 despite the fact that there are over four times as many of those drives in service compared to its Western Digital counterpart.

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The big takeaway, however, is Backblaze’s hard drive failure rate broken down by manufacturer for the past three years. Although HGST drives have racked up the largest number of hours overall in Backblaze’s testing, its annualized failure rate has hovered around 1 percent each year. Seagate lingered in the 9 to 11 percent range for 2014 and 2015, but fell to 3.48 percent for 2016 (mainly because Backblaze yanked the failure-prone 3TB Barracuda drives from service). Toshiba has fallen from 4.53 percent to 4.23 percent on down to its current 3.06 percent failure rate. Western Digital has also made advances in its failure rates, but its 2016 failure rate of 6.55 percent is still the highest among the four studied HDD manufacturers.