I have a hard drive that has been rejected by my RAID controller due to it having a bad sector. I want to return it to the manufacturer for a replacement. But I want to make sure it is wiped before I send it out. I tried CopyWipe a few times, and that always froze the machine at the same point during the wipe, so apparently it choked on the bad sector. Then I tried DBAN a few times (including the Guttman method), and that seemed to handle the bad sector better, because it finished all the wipes, and at the end of each wipe it mentioned there were non-fatal errors most likely due to bad sectors. The last wipe I did with DBAN was the one that wrote all zeros to the drive. Now I want to verify that the drive really does have all zeros on it. How can I do that? I tried booting off the Knoppix Linux CD, and used the "cksum" command to try to calculate the checksum of the drive. It should return a zero checksum if the hard drive really does have all zeros on it. But it failed with an "input/output error", so I guess it can't handle the bad sector.