University of Essex and Sungkyunkwan University researchers published a peer-reviewed IEEE study re-analyzing 12 years of Backblaze public drive data covering 443,156 hard drives and 1.66 million drive-years from 2013 through Q2 2025. The analysis, which controlled for drive age, capacity, form factor, and operating temperature, found that HGST drives fail at roughly 41% of Seagate's failure rate, while WD comes in at 52% of Seagate's rate. Toshiba ranked last at 107% of Seagate's failure rate.
Toshiba showed a dramatic failure-rate spike after 60 months in service, with monthly failure rates quintupling to five to six per 1,000 drives monthly—far exceeding the 2.5-per-1,000 monthly rate seen across other brands. Each additional degree Celsius of drive temperature raised failure rates by 2.1%, compounding to roughly 23% over a 10-degree increase. Each extra terabyte of capacity cut failure rates by about 3.4%, attributed partly to helium-filled enclosures and newer head-fabrication processes in higher-capacity designs.
The study notes important caveats: the dataset comprises only enterprise drives from Backblaze data centers with limited comparable workload data across manufacturers, and just 0.52% of sampled drives operated longer than a decade, so estimates reflect short- to medium-term reliability. The authors suggest WD's ownership of HGST since 2012 may explain their close proximity in rankings due to shared technology. Backblaze reported a fleet-wide annualized failure rate of 1.36% for 2025.