Disk Utility: Your formatting friend
When you format a hard drive, you’re setting up the drive so it can read and write data on your computer. It’s not a task you’d do on a frequent basis. When you buy a new hard drive, it’s usually pre-formatted, so all you have to do is connect it to your Mac.
But there may come a time when you need to format a hard drive. For example, if you bought a hard drive that wasn’t specifically geared towards Macs, it’s probably formatted for Windows. Re-formatting the drive can help improve performance and is required if you want to use the drive with Time Machine. Another example: You bought a new Mac, and you’re giving your old Mac away. Formatting the hard drive erases the data.
This article will show how to format a hard drive using Disk Utility, a helpful application that comes with every Mac. It’s easy, and takes a few minutes. The steps here are using Mac OS X 10.6.7 and should be similar for older OS versions.
Step 1: Meet Disk Utility
The Disk Utility application can be found in /Applications/Utilities. The left column lists the Mac’s storage devices. Listed under each drive are the partitions. (We’ll cover how to partition a hard drive in a separate tutorial.) For example, in the screenshot here, the first drive listed (320.07 Hitachi) is the internal drive of my MacBook Pro. Listed underneath that is the one partition that’s on the internal drive called Macintosh. The second drive listed (1.04 GB Generic Flash Disk) is an external flash thumb drive with a single partition called 1GB USB. The last device listed is the internal optical drive.
There is a set of tabs across the top right part of Disk Utility. To format a drive (or format a partition), the first step is to select it in the left column and click on the Erase tab—don’t click on the Erase button on the lower part of the interface just yet.
Disk Utility can’t format the hard drive that’s being used as the startup disk, which is usually the Mac’s internal drive. If you want to format the startup disk (which will wipe out all the data, including the system) you need to use a different drive as the startup disk or startup using the Mac OS X installation disc. You can run Disk Utility from the installation disc.