Hard drive failure rates: what 341,263 drives tell us

Almost everything written about drive reliability is anecdote. Backblaze is the exception: it runs a fleet of over 341,000 hard drives in its data centres and publishes the failure rate of every model, every quarter. This page summarises what that data actually shows.

The headline numbers

In its Q1 2026 report (published 9 July 2026), Backblaze analysed 341,263 drives and recorded an annualised failure rate (AFR) of 1.24% for the quarter, from 1,030 failures across 30,203,180 drive days. Its lifetime AFR, covering 20,212 failures over more than 529 million drive days, stands at 1.39%.

For the 2025 calendar year the fleet-wide AFR was 1.36%, down from 1.55% in 2024. In other words, roughly one drive in seventy fails per year in continuous data-centre use — and the rate is improving.

Bigger drives are currently the most reliable

This is the finding that most contradicts folk wisdom. The received advice has long been to avoid the largest capacity in a range. The current data says the opposite: in Q1 2026 the 20TB-and-above cohort ran at 0.85% AFR, comfortably better than the 1.24% fleet average. Backblaze's first 26TB drive, the WDC WUH722626ALE6L4, posted an AFR of 0.08% in its debut period.

The best performers at meaningful scale

AFR on a small population is close to meaningless — a single failure among 200 drives produces a dramatic-looking number. These are the strongest models from Q1 2026 that Backblaze runs in genuinely large numbers:

Model	Size	Drives	Failures	AFR
Toshiba MG11ACA24TE	24TB	7,203	3	0.22%
WDC WUH721414ALE6L4	14TB	8,640	7	0.33%
WDC WUH722222ALE6L4	22TB	45,638	42	0.38%
Seagate ST16000NM001G	16TB	34,729	44	0.52%
Toshiba MG10ACA20TE	20TB	20,451	42	0.92%
WDC WUH721816ALE6L4	16TB	26,801	64	0.97%

Note the fourth row: the Seagate ST16000NM001G, running at 0.52% across nearly 35,000 drives, is one of the best-performing large populations in the entire fleet — worth remembering next time someone tells you Seagate drives fail.

The weakest performers

The highest Q1 2026 failure rates were the Seagate ST14000NM0138 (14TB) at 4.9%, the ST10000NM0086 (10TB) at 4.63% and the ST12000NM0007 (12TB) at 4.59% — all older, shrinking, end-of-life populations. Among large populations, the HGST HUH721212ALN604 (12TB, 9,780 drives) at 3.98% and the Seagate ST24000NM002H (24TB, 9,605 drives) at 3.29% stand out.

What this means when you are buying

Model matters far more than brand. See Seagate vs WD reliability for the clearest example.
Do not fear high capacities. On current data they are the best performers, and they also give the best price per terabyte.
Remember the context. Backblaze drives run 24/7 in climate-controlled racks with steady workloads and no transport shocks. Your desktop drive gets power-cycled, knocked and run warm. Treat this as excellent evidence about drive mechanisms, not a prediction for your particular machine.
Buy from different batches when filling a NAS, so one bad production run cannot take out the whole array at once.

Source: Backblaze Drive Stats, Q1 2026 (9 July 2026) and the 2025 annual report (12 February 2026). Backblaze publishes model-level figures only — it does not publish a manufacturer-level AFR, so any brand-wide number quoted elsewhere is somebody's interpretation rather than Backblaze's own.

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Frequently asked questions

What is a normal hard drive failure rate?

In Backblaze's fleet of 341,263 drives the annualised failure rate was 1.24% in Q1 2026, with a lifetime figure of 1.39% and a 2025 calendar-year figure of 1.36%. That is roughly one drive in seventy per year under continuous data-centre use. Individual models range from about 0.2% to nearly 5%, so the model you choose matters far more than the average.

Are larger hard drives less reliable?

Not according to current data. In Backblaze's Q1 2026 report the 20TB-and-larger cohort ran at 0.85% AFR against a 1.24% fleet average, and the 24TB Toshiba MG11ACA24TE recorded just 0.22% across 7,203 drives. The belief that the biggest drives are riskiest reflects older generations rather than what is shipping now.

Which hard drive brand is the most reliable?

Backblaze does not publish brand-level failure rates, and its model-level data does not support picking a brand. Seagate spans 0.52% to 4.9% within a single quarter, and two Western Digital 16TB models differ by more than three times. Choose on the specific model, its warranty and its price per terabyte rather than on the badge.