How to Delete and Reformat Hard Drives

So, you've got a drive you need to clear for some reason. Maybe you just want to reinstall your operating system, or maybe you are getting rid of your old PC and want to make sure you've taken your data off of it. Don't worry, deleting data securely from a drive, or reformatting a drive for re-use, are both simple operations that even a tech novice can do.

First, a little clarification on these terms:

Format:  Technically, the only time you format a disk is the first time it is used.  Formatting a disk lays down the address space so that data can be written to the disk.

Reformat:  Formatting a disk any time after the first time.  Formatting and reformatting do not remove the data from the disk - let's say that again:

Formatting and reformatting do not remove data from the disk!

Formatting/reformatting writes new address space to the disk, but does not remove the disk data.  In essence, it removes the old directory structure, but leaves the data intact.  If you are just wanting to reinstall an OS, this is sufficient.  However, if you are disposing of your computer and want to secure your data, you need to go further.

Wipe:  Wiping is the process of overwriting the data on a disk.  This insures data security; after your drive is wiped, you can send your computer out in confidence that your personal data has been destroyed.

If you are reinstalling your OS, this is very easy.  All  versions of Windows, when booted from their install disk, will give you the option to delete your old partitions and reformat your disk as part of the reinstall process.  Just follow the wizards and they will walk you through it.  There is no need for a seperate reformatting step - it is integrated into the OS install.

If you are wiping a drive instead, you will need third party software to do so, as Windows does not integrate this function. The good news is that there are some great free programs for wiping a hard disk completely.

Darik's Boot and Nuke is an open-source (free) program that has been used by computer technicians for years.

And it is extremely easy to use. Just go to the DBAN website and download the latest version. It is an extremely small program in .iso (disk image) format. Use whichever software package you use to burn CDs to make a CD copy of the file.

(If you don't have a program for burning .iso images to CD, I recommend imgburn, a small free utility you can download here.)

Once you have your DBAN CD, boot your computer with the CD. Once you are given a command prompt type "autonuke".

That's literally it. Just wait for DBAN to finish, it will let you know when it is done. (Please note it may took 2-3 hours for DBAN to completely wipe your hard disks).

DBAN with the "autonuke" command will overwrite all hard drives in your system with a three pass wipe. This means it will overwrite each sector on your disk with random data three times. This method of data erasure is so secure it is referred to as "DOD standard", meaning it has been approved by the Department of Defense as a standard sufficient for data wiping on DOD computers holding classified data.

Congratulations - you now know more than a lot of users.  Most importantly, when the time comes to dispose of your old PC, you know how to be certain you have destroyed your personal data, and don't have to lose any sleep over someone stealing your identity.