Using smartctl to detect "scan errors" (like google tells me to do ...)

[Jason Usher]

The big report that google published made it clear that even a single "scan error" in the SMART data of a disk drive is a good predictor of eventual failure...

However, when I run smartctl:

# smartctl -a /dev/da0 | grep -i pre-fail
  1 Raw_Read_Error_Rate     0x000b   100   100   016    Pre-fail  Always       -       0
  2 Throughput_Performance  0x0005   135   135   054    Pre-fail  Offline      -       84
  3 Spin_Up_Time            0x0007   126   126   024    Pre-fail  Always       -       612 (Average 612)
  5 Reallocated_Sector_Ct   0x0033   100   100   005    Pre-fail  Always       -       0
  7 Seek_Error_Rate         0x000b   100   100   067    Pre-fail  Always       -       0
  8 Seek_Time_Performance   0x0005   123   123   020    Pre-fail  Offline      -       31
 10 Spin_Retry_Count        0x0013   100   100   060    Pre-fail  Always       -       0


There is nothing called a "scan error".  Further, the wikipedia page for S.M.A.R.T. has nothing in the error table called a "scan error".


So ...


What is a scan error, and which metric should I tell smartctl to check ?


Thanks.