Internal hard-drive defect management

Internal hard-drive defect management is a system present in hard drives for handling of bad sectors. The systems are generally proprietary and vary from manufacturer to manufacturer, but typically consist of a "P" (for "permanent" or "primary") list of bad sectors detected in the manufacturing stage and a "G" (for "growth") list of bad sectors that crop up after manufacturing.[1] Many disk/controller subsystems reserve storage to remap defective disk sectors. The drive automatically creates its initial remapping information and has the additional ability to dynamically remap "grown" defects.[2] Because the drive is remapping its own bad sectors, software may not detect growing numbers of bad sectors until later stages of gradual hard-disk failure (which in some cases may not be until after the warranty period has expired.)