Q:Why does VCR scanning show only a few bad sectors while online scanning show a lot?

A: Because softwares like VCR/MHDD do not scan a single LBA at a time, by default it scans 256 LBAs at a time. If there is a bad block in 256 LBAs, one error log is displayed. So this means, one bad block can be 1 LBA or 256 LBAs. Two consecutive bad blocks can never mean consecutive LBAs, so if VCR reports 3 bad blocks while online sanning reports hundreds, it is possible. Besides, oneline scanning is facotry level scanning, which is more accurate and strict than third party softwares. 10 thousands bad sectors entries can show only a few entries when added to P list, because P list adds bad sectors in the way of cylinders, one cylinder can hold up to 10 thousand entries, so P list have no problem containing all the bad sectors entries.