Measurements
Analyses
Over 56% of failed drives in the Google production population of more than 100,000 consumer-grade serial and parallel ATA drives (December 2005–August 2006) had no count in any of the four strong SMART signals (scan errors, reallocation count, offline reallocation, and probational count), so models based only on those signals can never predict more than half of the failed drives.
2026-10-09
Over 56% of failed drives had no count on the four strong SMART signals
over 56 percent of failed drives
Four SMART counts — scan errors, reallocation count, offline reallocation, and probational count — and the share of failures that stayed at zero on all of them. Population, window, and the ratio table are on the note. Other open questions stay on theresearch index.