How-To Erase Deleted Files and Wipe Free Space in OSX

So far we have written articles about how to recover accidentally deleted files, how to secure erase data from your mac hard drive and how to import recovered data to applications like Apple Mail. Missing from this equation is an article on how to actually delete or overwrite data that you have already deleted, or in other words: “wipe free space”.

Traces of Data

When you actually empty the trash in OSX, unless you explicitly force OSX to secure delete the data, the system will merely remove any reference to the file in the catalog database it uses to track what is where on your hard disk. This might be beneficial in terms of speed when you are deleting large volumes of data but in reality its not particularly secure, especially when you have information you are bound to protect.

Wiping Free Space: Disk Utility & Shredit X

There is no in-built Finder method, in the same way that you can secure erase trash to actually go back and zero out any free space on any memory storage device, be it an internal or external, but that doesn’t mean that the ability to erase your deleted data is still only a few clicks away.

Disk Utility to Erase Free Space

Apple’s offering is the “Erase Free Space” under “Erase” in disk utility that appears having selected the desired volume in the left device menu. This then brings up a drop down option list providing the user with 3 options:

• Zero Out Deleted Files
• 7-Pass Erase Deleted Files
• 35-Pass Erase Deleted Files

Needless to say the larger the amount of free space and the more passes desired the longer the process will take.This is the quickest and cheapest option for anyone wanting to clear up the “ghost” data sitting on their hard drive and which one might not want prying eyes to view at a later date.

Shredit X: The Commercial Option

A quick visit to a software update site like versiontracker.com turns up Shredit X the file and data shredding application for Mac OSX. Shredit X claims to ability to shred absolutely anything, or at least anything that it has read/write access to on your Mac. This includes the ability to wipe over free space, data, files, folders, volumes, devices and even external media. At the same time it also operates a SAFETY FIRST policy which is designed to avoid everything ending in tears when you accidentally shred something. Shredding isn’t the same as just emptying the trash, because, as I described in the article on secure deleting files, there os NO going back! To this end, Shredit offers a “Confirm before Shred” feature as well as a “Safe Place” feature. To get started with the process of shredding your files, simply install Shredit X in your /Applications folder and then open it up. Once the main window appears, select the drive you wish to wipe from the drop down on the right and click the “Shred Free Space” button. The progress bar on the left of the screen will whir into action and when finished you will be alerted accordingly. Shredit X is a shareware application that costs a princely sum of 34.95 USD, but if privacy and security are your top priority then this is a small sum to pay for the pleasure! Anyhow, Mireth, the developer, offer a free trial period in which to try out the product before you purchase.

Conclusion: No Going Back!

And so there you have it, a simple need-to-know on wiping data and erasing files that have already been deleted from your Mac’s hard drives and other storage devices. Disk Utility, as ever, is the FREE, but very effective tool from Apple, which completes a very simple task. Shredit X on the other hand is a simple app that saves time and brings a slew of available functions into one place. Whether you use Disk Utility or Shredit X for the task, you can consider the job DONE! Find out more about Shredit X by visiting the Merith Shredit X product page.