Also, some (flash) drives are compressing data on the fly. Writing zeroes to such a drive might just not actually write anything at all to the flash cells except for some run length descriptors (numbers).<p>Since the worry seems to be speed, here&#x27;s a tool I wrote to get random bytes about as fast as drives can accept (well, at least spinning disk drives, there might be some flash drives that are faster):<p><a href="https:&#x2F;&#x2F;github.com&#x2F;pflanze&#x2F;fastrandom" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;pflanze&#x2F;fastrandom</a><p>I&#x27;m expecting you to figure out where this tool goes wrong and produces predictable bytes yourself. Also, please tell me if you do :)<p>Anyway, even if it isn&#x27;t secure, it will be enough to foil compression algorithms.