What happened: I used SeaTools for DOS v2.20 to try remapping the bad sectors on a Seagate hard disk which had approx. 250 of them. (Yes I know that this makes little sense as such a drive will probably fail in the coming days or months anyway … but I was experimenting.)
Now when you run “Basic Tests -> Long Test” in this tool, it will scan the whole drive and at the end show you a list of bad sectors and the option to fix all of them. I did so, and finally the program said “Long Test passed after Repair”. But afterwards the Short Test still failed due to an unreadable block after the last repaired one. So I let the Long Test run again, and it found again many bad blocks. Why? Wasn’t it supposed to find and fix them all during the first run?
Seemingly not. It seems that the number of blocks that this tool finds and repairs at once is at most 98, as that is the number reported in the progress window when the Long Test will stop proceeding and instead show the list of bad sectors to repair (strange enough, this window contains only 90 item, and also it does not seem that the 8 remaining ones are fixed and just not shown). So if you have to repair a really large amount of bad blocks, you will need to run the “Long Test” several times in a row. Or you could do the same with other tools.