Formatting a hard drive is conceptually the same as erasing it. The main difference is that you will select a hard drive, not a volume, from the list of devices. You will also select the type of drive format to use. If you use the formatting method that I recommend, the formatting process will take a little longer than the basic erase method described earlier.
Format a Hard Drive
- Select a drive from the list of drives and volumes. Each drive in the list will display its capacity, manufacturer, and product name, such as 232.9 GB WDC WD2500JS-40NGB2.
- Click the ‘Erase’ tab.
- Enter a name for the drive. The default name is Untitled. The drive's name will eventually appear on the desktop, so it's a good idea to choose something that's descriptive, or at least more interesting than "Untitled."
- Select a volume format to use. The Volume Format dropdown menu lists the available drive formats that the Mac supports. The format type that I recommend using is ‘Mac OS Extended (Journaled).'
- Click the ‘Security Options’ button. A Security Options sheet will display multiple secure erase options.
- Select ‘Zero Out Data’ from the list of options. This option will perform a test on the hard drive as it writes zeros to the drive's platters. During the test, Disk Utility will map out any bad sections it finds on the drive's platters so they can't be used. This helps ensure that you won't be able to store any important data on a questionable section of the hard drive. This erase process can take a fair amount of time, depending on the drive's capacity.
- Make your selection and click the ‘OK’ button. The Security Options sheet will disappear.
- Click the ‘Erase’ button. Disk Utility will unmount the volume from the desktop, erase it, and then remount it on the desktop.