Ask Max: What's the best way to erase my Mac hard drive?
Just bought a new iMac and will be trading in my G4 Mirror Door Power Mac. Please recommend the most efficient and trust-worthy way to wipe/erase my Power Mac hard disk, before sending it up to Powermax.
And...when I do that, does it also erase the operating system at the same time?
Apple's Disk Utility securely erases data from hard drives, and it's built right in to OS X. If you're running OS X 10.7 or higher, you do this through Internet Recovery. Restart your Mac and hold down Command + R during the start up process. Don't let up on those keys until the Apple logo appears. A menu will appear giving you a few choices: Disk Utility, Reinstall OS X, and Restore from Time Machine.
Choose Disk Utility. Choose the HD you want to erase, then click erase. You can choose quick erase or secure erase, depending on your needs. Read this Apple Support article on Internet Recovery if you have any troubles.
If you're running 10.6.8 or earlier, you must do this with your OS Install media. Boot up your iMac computer off the disc and open Disk Utility from the Utilities menu. Under the Erase tab will be a Security button. Click on it and set it to write zeros over your data. This will take a good amount of time, and be sure to check out Apple's article on Disk Utility's secure erase options.
After you erase the drive, you can install the Mac OS on it, but it is not necessary for our Mac trade-in program. We format the drives when they come in, but please do erase your drive to the security level that you would like.