Sectors marked Defective no longer show defective on next run

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Active member
Feb 6, 2024
I have a 1TB external USB drive that I decided to scan for maintenance purposes. I disassembled the drive from its housing to get direct access to the SATA connector and ran a level 4 scan. It completed in a little over 10 hours. There were three sectors that were marked DEFECTIVE (black B on the "wall of dots" display). There were no other issues with the drive. I reran the drive under level 2 and those 3 sectors are no longer being marked DEFECTIVE. What is the explanation? Were the defective sectors swapped out with spares?

Were the defective sectors swapped out with spares?


When Level 3 does it's read and write sequencing, a bad sector will be swapped out by the drive's firmware. That sector will then never been seen again by SpinRite, any OS, any file system, or any App.

SpinRite doing it's thing - "repairing" the drive! :)
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