An interesting article caught my eye earlier today from CNet. It was all about how iPod hard disk drives write the entire drive before overwriting it and that has lead to several criminal investigations due to the iPods ability to store contact information and not actually loose it.

How does this refer to Macs? Well, I assure you this isn’t going to turn into an iPod binge, but it certainly relates to Macs. There is in essence a list of files the operating system (Mac OS X and previous) can access buried in your operating system files. As with Windows file systems, when you delete a file from your Mac the filename is simply deleted from this list, but the file remains. This does not cause inaccurate readouts of disk space, but it does pose a potential security risk.

When you delete files from the trash, you can either “Empty Trash” or “Secure Empty Trash” from the Finder menu. If you “Secure Empty Trash” then you are overwriting that file data with zeros (nothingness). Secure? Not yet. This only overwrites the file once and it can still be accessed by an expert.

If you really want to be secure with deleted files then you can address the issue much more securely by once again accessing the Disk Utility application either from the Finder window, under Applications>Utilities or by simply doing a Spotlight search for the term “Disk Utility”. Once the application is open, choose the hard disk drive you want to secure from the list on the left and then choose the tab “Erase”. Don’t panic.

Next you will want to Erase Free Space… and then choose the number of passes you wish to make. The more passes you do, the more securely and permanently deleted your files will be, but the longer it will take. In addition, you will find that more available disk space (as listed at the bottom of the window) the longer the process can take; and it can take a long time.

You will not loose any un-deleted data during this process. That said; if you really want to secure your unwanted data (such as when you come to sell you Mac or otherwise destroy your Hard Disk Drive, you don’t want to just hit it or “Zero” it; you will have to take a drill to it (and replace as necessary). This is a little over the top for the typical user, but if you have financial information stored on your drive or something similar, it’s an option worth taking when you come to upgrade (after transferring the data you want to keep, obviously).

[Inspiring Article from CNet.com]