Backblaze: Our bet on consumer hard drives looks good so far

After measuring failure rates for four years, the online backup service is optimistic that buying cheaper consumer-grade hard drives was the right choice.

Stephen Shankland Former Principal Writer
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Stephen Shankland
2 min read
Backblaze's hard drive failure rate increases after the third year, but after four years, more than three quarters of its hard drives are still working.
Backblaze's hard drive failure rate increases after the third year, but after four years, more than three quarters of its hard drives are still working. Backblaze

For years, hard drive makers have manufactured premium enterprise models that are more reliable but more expensive. Online backup service Backblaze, though, chose to use consumer-oriented drives, and now it's releasing statistics about just how reliable they are.

The company now has 75 petabytes of data stored on 25,000 drives, and it's been tracking failure rates since 2009. So far, 76 percent of drives live past their fourth birthday, said Backblaze distinguished engineer Brian Beach in a blog post Tuesday. Beach just joined Backblaze after 15 years at TiVo, where he was vice president of research and development.

The Backblaze drive failure rate isn't constant. In the first year and a half, it's relatively high -- 5.1 percent -- likely because of manufacturing defects. The second year and a half is the honeymoon period, with a 1.4 percent annual failure rate. Then the hardware starts bombing, with a much higher 11.8 percent failure rate in the fourth year.

Extrapolating the fourth-year failure rate, Backblaze calculates the that half its hard drives will last six years. And though it doesn't have enough data to say whether it will reach that point, it's an encouraging statistic for the startup.

"When Backblaze started, there were some concerns that consumer-grade disk drives wouldn't hold up in a data center," Beach said. "If this six-year median lifespan is true, it means that more than half the drives will last six years, and those concerns were unfounded."

The company plans to update the study results quarterly -- including with details on which manufacturers and drive models are most reliable, if the company can make statistically significant conclusions.

"We are looking forward to finding out what will happen when drives become 5, 6, 7, and 8 years old," Beach said.