Research & analyses

2026-10-09 / Statistical analysis

What fails most often: unreadable data on disks, uncorrectable reads on SSDs, and bus errors on the link

The most frequent field fault is not a dead drive but data that cannot be read: 3.45% of 1.53 million hard disks developed at least one latent sector error in 32 months, and 20.3–90.5% of Google's flash drives (ten models, first 4 years; 3 for eMLC) had at least one uncorrectable error and 19.1–62.7% a final read error, while 4.2–34.1% of Facebook's SSD platforms reported at least one uncorrectable error. Link faults show up separately as CRC counts (about 2% of Google's disks), and the public counters miss a large share of failed drives: over 56% of failed drives in the Google study and 23.3% in Backblaze's 2016 log showed no signal on the SMART attributes each used.