OS X Tip #22
Do you think you erased that old hard drive? Are you really sure? Did you know that it is not that hard for a “hacker” armed with a UNIX machine and using a “grep” command to find all sorts of data from your old hard drive you think you erased. I read a story a few years ago that some college students did a report where they collected old hard drives from garage sales and were able to easily retrieve peoples private data. Even recovering thousands of peoples bank account information from what might have been an old ATM machine hard drive!

The reason is a simple erase only erases the FAT (File Allocation Table) from the hard drive and NOT the actual data. Since we are dealing with magnetics. Even a Zero Data Erase still leaves the possibility that specialized software can recover much of the data on a hard drive that you thought was erased.

So let me show you how to really erase that hard drive. At least the best way you can today using OS X.

To start really erase your hard drive
To erase your boot drive. Put in the Mac OS X Tiger DVD, run the installer, and your Mac will reboot. Then, run the Disk Utility before you re-install Mac OS X Tiger.

Or in the case of erasing an external hard drive or a hard drive other then your boot disk, launch the Disk Utility located in the Applications -> Utilities folder. In the Disk Utility, choose the hard drive you want to erase on the left.

Then go to the “Erase” tab. Click on the “Options” button, and you will see three different erase options:
Zero Out Data – this is simple and faster, but not necessarily that secure
7-pass – which is very secure
35-pass – which is very very secure!

What do you give up for this extra security? Time.
The 7-pass secure erase may take approximately 4 hours on a 30 GB hard drive. The 35-pass secure erase may take over 18 hours on a 30 GB hard drive. Experts claim that at least 7-pass is needed to be secure from most software disk utility software or forensic computer software. Do you need this? You must decide how important this to you and your data’s privacy.

    | Tags: mac tips, security