Disk Health

https://help.ubuntu.com/community/Smartmontools

• Failure Trends in a Large Disk Drive Population

• Google field study covering 100,000+ consumer-grade drives from 12/2005-08/2006

• correlations between certain S.M.A.R.T. information and annualized failure rates:
  ||||
  |--|--|--|
  |uncorrectable error|198 (0xC6)|after 1^st error drives are 39x more likely to fail within 60 days|
  |reallocation count|5 (0x05)|after 1^st error drives are 14x more likely to fail within 60 days|
  |offline reallocations|196 (0xC4)|after 1^st error drives are 21x more likely to fail within 60 days|
  |probational/current pending sector counts|197 (0xC5)|after 1^st error drives are 14x more likely to fail within 60 days|
  |Temperature||little correlation except at at extremes 40-45°,>45°|
  |Seek Errors||little correlation|
  |CRC Errors||little correlation|
  |Power Cycles||little correlation|
  |Calibration Retries||little correlation|
  |Spin Retries||little correlation|
  |Power-on hours||little correlation|
  |Vibration||little correlation|

[!warning] Large number of drive failures occur with minimal to no warnings

• 56% failed drives: zero counts in major SMART errors (scan errors, reallocation count, offline reallocation, probational count)
• 36% failed drives: zero counts in all SMART errors