Enterprise Mac Security: Mac OS X Snow Leopard

1.13. Securely Erasing Disks

When you delete a file from a hard drive, the file is marked for deletion, but is often kept by the file system until the system needs to free up space for new files. Quick formatting a hard drive does the same thing. To ensure that data isn't accessed by malicious users, always securely erase a disk before disposing of it or repurposing the drive.

To securely erase a disk, open Disk Utility, and click the drive in the left column. Next, click the Erase tab, and then click the Security Options button (see Figure 1-17).

Figure 1-17. Erase feature of Disk Utility

This will display a list of secure erase options (see ...