How To Use DBAN To Securely Erase A Hard Drive
In my computer repair business it can be hard to convince people of the need to destroy their data properly before disposing of a computer by selling it, giving it away or taking it to the dump…
Why Securely Erase A Hard Drive?
Even if you empty the recycle bin after deleting files, they are still stored on your hard drive. When you delete a file, Windows does not actually delete it – the first letter of each file name is just changed to a ‘?’
Because Windows ignores any files that start with a ‘?’ it looks in Windows as if the file has been deleted – but the file itself is still on the hard drive.
With the right software, these ‘deleted’ files can be retrieved if the space they occupy has not subsequently been overwritten by a new file – a godsend if you deleted files by accident but a security nightmare if someone disreputable gains access to your drive…
Can I Just Format the Hard Drive or Reinstall Windows?
Formatting a drive does not permanently erase files stored on it – it just makes it look as if they’re not there.
Reinstalling Windows might overwrite some old files (making them unreadable) but, with the huge sizes of modern hard drives, there is a good chance that most of your old files will not be overwritten, so they could still be retrieved later.
How To Use DBAN To Securely Erase a Hard Drive
DBAN (Darik’s Boot And Nuke) is a popular free program to delete all information stored on hard disk drives in a PC or laptop.
Step 1 – download the free version of DBAN from the button at the top of the page here.
It is an ISO image file so, once downloaded, you need to burn it to a CD as an image – see how to burn an ISO to CD. After you have burned the CD, insert it in the computer containing the hard drive to be securely erased.
Warning: Make sure there is only 1 hard drive (the one you want to securely erase) in the computer as DBAN will erase all hard drives it finds – double check this as you will not be able to recover files after DBAN has securely erased them!
Step 2 – Boot (start) the computer from the DBAN CD. If you don’t know how to do this see how to Boot from a CD. Once DBAN has loaded up you should see the following screen – press the ENTER key to start DBAN in interactive (normal) mode:
Step 3 – The main menu shown below should display your hard drive to be erased – if there is more than 1 drive displayed (and you don’t want to erase them all) please refer to the earlier warning, switch off the computer and take the second hard drive out of the PC before running DBAN again.
Step 4 – Press the Space key to select the hard drive for wiping – it should now say [wipe] to the left of the drive as shown below:
Note: the default Method of erasing the drive is a DoD Short wipe – if you have a large drive such as 500GB or more, be aware that the erasing process may take up to 24 hours or more using the DoD Short wipe method.
So I’d recommend that you change to the DBAN Quick Erase method by continuing to Step 5. However, if you’re a little paranoid, or have incredibly confidential data on your hard drive, then skip to Step 6.
Step 5 – To change to the DBAN Quick Erase method for a quicker finish (recommended) press the M key to display the Wipe Method menu shown below:
The default (arrowed) method is DoD Short wipe. Use the J or Up-Arrow key on your keyboard to move up to Quick Erase then press the Space bar to select it and return to the main menu.
Step 6 – In the main menu, press the F10 key to start and the DBAN secure erase will begin, displaying progress and time remaining as shown below:
Step 7 – When the process is complete, a confirmation screen appears as shown below – remove the CD from your computer and then power off by pressing and holding down the power (on/off) button until the computer switches off.
Congratulations, you have now securely erased your hard drive :-)
Alternative DBAN Erase Methods
DBAN Quick Erase writes once over every part of the hard drive, whereas the default DoD Short method overwrites three times.
Many IT professionals, including me, believe that the Quick Erase method is probably sufficient to erase hard drives that contain only personal home user data.
I couldn’t retrieve any data after a Quick Erase and it’s likely that only law enforcement agencies and specialist security companies would have much success.
But, if you really want to proceed with the more secure DBAN DoD Short method then ignore Step 5 – and be prepared for it to take a day or more to finish…
Note that if you are throwing away the computer then you could just take the hard drive out and (taking usual safety precautions) give it a good hammering – or drop it from height onto a concrete floor a few times…
Then when you shake the drive you should be able to hear the tinkling that indicates a shattered hard disc inside.