How to Securely Erase Data From a Mac Hard Drive

When you move an item to the Trash and click "Empty Trash," your data is still recoverable. Even when you reformat a hard drive the right person can still dig up some of those personal files. The best way to securely erase data is to write over that data on your hard drive with new information. Since you can't quite do this on your own, and just "trashing" the files won't do much, Apple's Disk Utility has several aptly named "Secure Erase" options to completely erase your data so that it's not retrievable.



This article explores the options.

Things You'll Need

• Apple Macintosh Computer running Mac OS X
• Disk Utility
• Hard Drive or other removable storage device (optional)

Instructions

1. 

   Launch Disk Utility. This is in the Applications folder under "Utilities."

2. 

   Select the drive you want to erase.

   Mac OS X will not allow you to completely erase your main hard drive.

3. 

   Select the "Erase" tab.

4. 

   Enter a name for your drive under "Name." Leave the "Volume Format" as is unless you're familiar with the differences.

5. 

   Click the "Security Options..." button.

6. 

   Click the radio button next to the "Secure Erase Option" you want.

   "Don't Erase Data" is the least secure. The data still remains on your drive so it's still potentially recoverable.

   "Zero Out Data" writes over your data with zeroes. This is a quick way to erase data and offers decent security.

   "7-Pass Erase" writes over your data seven times. This is a highly secure method of erasing data, but it takes about seven times longer than the "Zero Out Data" method.

   "35-Pass Erase" is the most secure option, but it takes a long time. If you do this, be prepared for Disk Utility to run overnight or all day depending on the drive size.

7. Click "OK" once you've selected your "Secure Erase Option."

8. 

   Click the "Erase" button. This can take a long time, depending on the size of the drive you're erasing.

Tips & Warnings

• It's a good idea to use the "Secure Erase" option when you're giving away, selling or otherwise passing on an older Macintosh computer. This is also useful for thumb drives and other removable storage.

• Don't erase unless you absolutely have to. If you just want to erase the free space to get rid of all the data you've deleted before, use the "Erase Free Space" option.

Resources

• Description of Secure Erase Options