Who makes the most reliable hard drives?

It’s the eternal question for PC owners: Which manufacturer makes the most reliable hard drives? Backblaze, the unlimited online backup company, has been following this story for years now, and its latest 2015 data sheds some new light on the subject. Backblaze currently has over 41,000 hard drives powered up and constantly spinning. And as you can imagine, it is very much in Backblaze’s interests to ensure that it buys reliable hard drives. Every time a drive fails, it takes considerable time and effort to pull the drive, slot in a new one, and rebuild the RAID array.

So while it’s generally known how long hard drives actually live for, it stands to reason that some manufacturers make drives that are more reliable than others. But whose?

Which hard drive manufacturer is the most reliable?

To answer that question, we took a look at Backblaze’s latest numbers. The company breaks down its data in two ways — by manufacturer, and by specific drive. The data is fairly complex, but we’ll try to break it down into bits of easy-to-digest, actionable information. (Read: How a hard drive works.)

As of the end of December 2014, Backblaze had 15,528 Seagate drives, 22,902 Hitachi drives, 1,174 Western Digital drives, and 47 Toshiba drives. These drives are not all the same age — some are several years old, while many were installed in the past year, including thousands of brand new 4TB and even a few 6TB models.

The odd numbers are because Backblaze basically buys whatever drive offers the most competitive dollar-per-gigabyte ratio, with reliability being a secondary factor. For most of the last five years, Seagate and Hitachi have offered the best price-per-gig, with Western Digital Red and Toshiba DT01ACA drives only recently becoming viable (although there are too few Toshiba drives to draw any conclusions yet).

As you can see from the graph above, Hitachi drives are by far the most reliable. Even though many of Backblaze’s Hitachi drives are several years old, they only have an annual failure rate of 2% or so on average. And the latest HGST drives have a failure rate of just 1.4%. The “annual failure rate” is the chance of a drive dying within a 12-month period.

Western Digital is worse, but still impressive: After three years of operation, 92.4% of Western Digital Red 3TB drives are still running — not terrific, but still good.

Seagate 3TB drives turned out to be a disaster, with over 40% failing throughout 2014. In 2013, the failure rate was 9.6% — high, and a kind of foreshadowing, in retrospect. Thanks to the new 4TB version, the numbers improve tremendously, as the second graph indicates below, with an excellent failure rate of just 2.6% — indicating that even a few years out, they should do much better than the 3TB models.

Which single hard drive is the most reliable? (And which is the least?)

In general, then, if you want a reliable hard drive, you should stay with 4TB for the best value and reliability, and go with either Hitachi or Seagate. If you’re looking for a specific drive model that has good longevity, the numbers break down interestingly.

The Hitachi GST Deskstar 5K3000 3TB has proven very reliable, but expensive compared with other HGST models. Get one of these drives and you’re almost guaranteed (97-98%) to make it through three years without a dead drive. If you want a 4TB drive, the Hitachi Deskstar 5K4000 is your best bet — it has a slightly higher failure rate, but still below WD and Seagate’s offerings. As far as poor reliability goes, Seagate had some nasty offenders, particularly the 3TB 7200.14 model. But the latest 4TB 7200.15 drives are turning out to be a solid way to go.

Backblaze also notes that some drives (the Western Digital Green 3TB and Seagate Barracuda LP 2TB) start producing errors as soon as they’re slotted into a storage pod. They think this is due to the large amounts of vibration caused by thousands of other hard drives. (They also think that their aggressive spin-down setting, which is ostensibly to save power, causes a lot of wear to the drive.)

Hit up Backblaze’s website for a full list of hard drives and their statistics.

Samsung, Toshiba, 6TB, and beyond

Unfortunately, Backblaze doesn’t have a statistically significant number of Samsung or Toshiba drives installed. Even so, because Seagate acquired Samsung’s hard drive division in 2011, it’s hard to say if an older, pre-acquisition Samsung drive would be more or less reliable than a post-acquisition drive. Toshiba and Fujitsu still have a reasonable wedge (~10%) of the market share pie. But unfortunately we’ll have to wait for another study to see how they compare with Seagate, Western Digital, and Hitachi.

Otherwise, the next stop is the 6TB tier. Backblaze expects to have plenty of data on the subject come early next year, as it’s busy buying up thousands of new drives at that capacity. We can’t wait for those results.