

Then, cover the hole and try formatting it. Do this until you have gone over the entire disk.

Pass it over the disk radially outward from the center to the edges, like the spokes on a bike wheel. Something else that MIGHT be a good idea (but perhaps not absolutely necessary if I am mis-remembering my facts) is to demagnetize the improperly-formatted disks first using a strong neodymium magnet. The only exception to the above is if you use them exclusively in DD-only drives, in which case it's a moot point since they don't have the switch detecting the second drilled hole anyway and thus won't even care if it's there or not. Or, even if you do manage to get them formatted without covering the hole, the drive might refuse to properly read them afterwards and say the disk isn't formatted properly. More than likely, you'll get the infamous "Invalid media or Track 0 bad" if you try to format them without covering the hole. You likely will need to cover the drilled holes on the DD disks, as some drives may refuse to format them at 720K even with the /f:720 parameter if they have reason to think the disk isn't a DD disk. I tried using some of the other options like /1, or /f:360, but format just said 'yeah, your hardware can't do that'. I'd expect basically 50% (or 100%) bad sectors if one side was totally unwritable.
