About drive wiping: You&#x27;re probably better off using the ATA Secure Erase command, which is very quick and does the entire disc.  dd and other tools risk not doing blocks marked as bad, for example.<p>He&#x27;s right that a single overwrite of zero is probably good enough to make sure that data is gone, but it&#x27;s probably not enough to persuade other people that it&#x27;s gone. A few passes of pseudo random data is probably better if you need to persuade other people that the data has gone.<p>But if it&#x27;s really important drive wiping is what you do to protect the drives until you get a change to grind them.