Are hard drives getting better?

Summary

If you’ve hung around Backblaze for a while (and especially if you’re a Drive Stats fan), you may have heard us talking about the bathtub curve. In Drive Failure Over Time: The Bathtub Curve Is Leaking, we challenged one of reliability engineering’s oldest ideas—the notion that drive failures trace a predictable U-shaped curve over time. But, the data didn’t agree. Our fleet showed dips, spikes, and plateaus that refused to behave. Now, after 13 years of continuous data, the picture is clearer—and stranger. The bathtub curve isn’t just leaking, and the shape of reliability might look more like an ankle-high wall at the entrance to a walk-in shower. The neat story of early failures, calm middle age, and gentle decline no longer fits the world our drives inhabit. Drives are getting better—or, more precisely, the Drive Stats dataset says that our drives are performing better in data center environments. So, let’s talk about what our current “bathtub curve” looks like, and how it compares to earlier generations of the analysis. The TL;DR: Hard drives are getting better, and lasting longer. The intro: Let’s talk bathtub curve If you’ve spent any time around hardware reliability, you’ve seen it: a smooth U-shaped line called the bathtub curve. It promises order in the chaos of failure—a story where devices begin life with a burst of defects, settle into steady performance, and finally wear out in predictable decline. And, this is what it looks like: The classic bathtub curve. For decades, it’s been engineering shorthand for how things die. But as our dataset has grown—more than a decade of drive telemetry and millions of drive-days—the data is clear: Our real drive population is more complicated. What the bathtub curve looked like then The first time we ran this analysis was in 2013, and when we updated the article in 2021, we shared this chart: It shows the annualized failure rate (AFR) of the full drive pool over time (in years) at two different look-back points—2013 an...