Every hard drive (built within the last ten years) has secure erase built-in with compliance of the ATA specification.
All it takes is activation. This script by Patrick Verner and Jason Vasquez from Parted Magic which is distributed as free and open source software does just that, with the help of hdparm and one or two other dependencies. The script will totally secure erase user data from each selected drive, so use at your own risk. Please make a backup.
see wiki:
http://en.wikipedia.org/wiki/Parted_Magicand
http://cmrr.ucsd.edu/people/Hughes/SecureErase.shtmlIt's primary use is secure deletion of data from any hard disk drive, lately however has become popular in restoring the performance of Solid State drives. Again, please make a backup. once issued the command will permanently erase all data.
An extension has been submitted, I tried to post the code however it apparently exceeds the 20000 character limit..!!
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Enjoy, but please make a backup, any drive cleaned using this method will irretrievably loose it's data. have I said this enough yet?
having said that, I use this method frequently. Now it's available to tc.