> Count of reallocated sectors. When the hard drive finds a read/write/verification error, it marks this sector as "reallocated" and transfers data to a special reserved area (spare area).
> Later, when some of these sectors are read successfully, the value is decreased. If errors still occur when reading some sector, the hard drive will try to restore the data, transfer it to the reserved disk area (spare area) and mark this sector as remapped.