Edit: see section 3.2.2 in the PDF (and the corresponding table 2):
> In most cases, overwriting the entire disk twice was sufficient to sanitize the disk, regardless of the previous state of the drive. There were three exceptions: about 1% (1 GB) of the data remained on Drive A after twenty passes
This is about normal overwriting, however. The fastest random overwriting program on Linux I know of is `shred`