With Appleʼs 2011 MacBook Pro refresh, many Mac users are contemplating an upgrade. Given the impressive features and specs on the new lineup, it is understandable why this is such an appealing time to upgrade. For those who may not be looking for a MacBook Pro, Appleʼs future upgrades to the other hardware lines will no doubt be equally compelling.
At the same time, however, just because you may be ready to upgrade (or looking forward to upgrading in the future), that does not mean that your current machine no longer has any value. In fact, depending on when you purchased it, your current machine may have lost relatively little in resell value. Therefore, you may decide to sell your current machine, helping to offset the cost of your new Mac.
If you do decide to sell you current machine, you will need to ensure that your data is safely removed. Some users simply empty the contents of their Documents, Music, Movies and Pictures folders, empty the Trash and sell their machine. However, that process does not actually erase the deleted files. Dragging files to the Trash, and emptying it, does not erase the data that makes up those files…it simply deletes the operating systemʼs reference to them. This ensures that the OS does not “see” the files, even though they are technically still there. Unless the data is erased, or overwritten, data recovery software can be used to recover the files.
To ensure that your files are safely erased before selling your current machine, follow these steps:
- Back up your data. Using Time Machine, or another backup option, make sure your backup is current. Once you complete these steps, there will be no way of retrieving anything.
- Boot off of your OS X disk. To do this, insert the OS X disk that came with your machine, reboot your computer, and hold down the C key while the machine is booting up.
- Open Disk Utility. Once your machine has booted off of the disk, and you have selected your preferred language, go to the Utilities menu and select Disk Utility. Once Disk Utility is open, proceed to the Erase tab.
- Enter a name for the formatted drive. On the Erase tab, enter a name that will be used once the drive is erased. By default, a Macʼs hard drive is named “Macintosh HD.” Since you are preparing to sell the machine, this is a good choice.
- Select the security level. Below the name field, you will see a button that says: “Security Options.” Once selected, you will be presented with a number of different options. These include: “Do Not Erase Data,” “Zero Out Data,” “7-Pass Erase,” and “35-Pass Erase.” The first option is essentially the same as dragging a file to (and then emptying) the Trash…except that it does it for every single file on the hard drive. Ultimately, however, the data still remains. The other three options erase the data and write zeros over the entire hard drive once, 7 times, or 35 times depending on the option you choose. For most people, the single “Zero Out Data” will be more than sufficient. If your machine has particularly sensitive information on it, such as company financials, trade secrets, or the next great novel, you may want to go with the “7-Pass Erase.” This option is considered secure enough to be the standard procedure for erasing US Department of Defense computers. You can rest easy using this option, while the “35-Pass Erase” is essentially overkill for all but the most extreme cases. Once you have selected the appropriate option, click the Erase button.
- Install OS X and reboot. Once the format is completed (this could take anywhere from one to 12 hours, depending on the option you chose) quit Disk Utility and follow the instructions to install OS X. Once OS X is installed, the machine should automatically reboot and present you with the standard user setup. At this point, using the computerʼs Eject button on the keyboard, eject the disk. Once the disk is ejected, use the Power button to turn the machine off, without entering any setup information. This ensure that, once the new owner receives the machine, they will be able to setup the machine as they see fit.
By following these steps, you can ensure that your data is safely, and securely, erased. In addition, whoever purchases your machine will have the satisfaction of starting with a clean slate.
Obsessed with tech since the early arrival of A/UX on Apple, Sudz (SK) is responsible for the original editorial direction of AppleToolBox. He is based out of Los Angeles, CA.
Sudz specializes in covering all things macOS, having reviewed dozens of OS X and macOS developments over the years.
In a former life, Sudz worked helping Fortune 100 companies with their technology and business transformation aspirations.