dd if=/dev/zero of=/dev/hda dd if=dev/urandom of=/dev/hda dd if=/dev/random of=/dev/hda
- Using /dev/zero is a load quicker, but not as thorough.
- /dev/urandom takes longer but is more thorough and doesn’t require you to be doing anything on the machine to help create the random data.
- /dev/random is slower and more thorough still and requires monitoring the system to generate entropy.
Excellent explanation here: http://superuser.com/questions/359599/why-is-my-dev-random-so-slow-when-using-dd
Logan's Lab 