Which metric indicates progressive failure requiring drive replacement?

• A. VALUE
• B. THRESH
• C. Reallocated_Sector_Ct (ID 5)
• D. Current_Pending_Sector

Answer: (C)

Progressive failure is most clearly shown by sectors that have been found unrecoverable and remapped to spare sectors. In S.M.A.R.T., Reallocated_Sector_Ct (ID 5) counts how many sectors have been relocated because they could not be read or written reliably. A rising Reallocated_Sector_Ct means the drive is continually losing good sectors, which signals ongoing deterioration and a strong indication that the drive should be replaced.

Other metrics can be informative but are less definitive for requiring replacement. Current_Pending_Sector shows sectors that had read errors but have not yet been remapped; those can sometimes be resolved on retry, so they don’t prove progressive failure as directly. VALUE and THRESH pertain to the attribute’s value and its failure threshold rather than illustrating a accumulated history of bad sectors.