http://www.tomcoughlin.com/Techpapers/Secure%20Erase%20Article%20for%20IDEMA,%20042502.pdf Actually this paper makes it seem like there are actual exotic attacks that using random data in the wipe helps protect from in the end they do conclude that one pass is enough to make data unrecoverable, but they also say using random data and putting the head off center can add additional protection from exotic attacks even a very small partial recovery of data can be enough to do a full recovery in some cases, let's say you have the anarchists cookbook and you erase your drive but they get a few 512 bit segments of it from the track edges, that is potentially enough for a fuzzy hash match to identify it (provided they have a reference) hm seems like if they don't know the overwrite pattern then they can't do it ATA-SE has two versions standard and enhanced. The standard version does a single pass wipe, enhanced does on track and off track wipe, and it can do this because it is firmware.