Posted 25 May 2011 - 07:46 AM
Agreed. The sectors are physical locations on the disk. They are bad because there is something physically wrong with that sector. The raw materials have impurities, or there was a microscopic defect or damage done during construction.
So in that respect, a bad sector can never be repaired.
However, when the new platters are low-level formatted at the factory, some sectors may be "marked" as bad, when they are not. And in that case, a bad sector, upon further diagnostics, may be determined as good after all, and marked as good again. But this is not common, and not worth the effort when there are millions of sectors on a disk.