How to Use Disk Utility to Erase a Macintosh Hard Drive

zhengl

This article comes from the following address - http://www.udel.edu/pnpi/tools/erase/mac/erasedisk.html
You must reboot your computer using the OS X system CD that came with your Macintosh. To do so, follow these steps:

• Insert the CD into the CD drive.
  
• Hold down the C key during the startup process.
  

• Select your preferred language. You will then see the Welcome to the Mac OS X Installer window.
  
• From the Installer Menu Bar, click Open Disk Utility. You will then see the Disk Utility window.
  
• In the left pane of the Disk Utility window, click the drive you want to erase.
  
• In the right pane of the Disk Utility window, click the Erase tab.
  
• From the Volume Format drop-down menu, select Mac OS Extended (Journaled).
  
• In the Name field, highlight the existing text and type the name the hard drive is to be called after it's formatted.
  
• NOTE: If you ever plan to connect another computer running OS 9 to this hard drive, you'll want to install the Mac OS 9 disk driver, so that this disk will be visible from an OS 9-booted computer. If you don't know if you will do this in the future, it's best to install these drivers.　　
  
• The following are the available security options:
  

• Don't Erase Data—This option only rewrites the headers on the disk. Files can be recovered by forensics, disk utilities, and other advanced recovery software.
  
• Zero Out Data—There are forensics utilities that, albeit expensive and time consuming, can retrieve zeroed-out data.
  
• 7-Pass Erase—This is considered sufficient by government standards to erase data from a disk. It writes random data over the disk seven times. It may take several hours or more to complete this process.
  
• 35-Pass Erase—This makes it absolutely impossible to regain any data off the drive. This option takes an extremely long time, possibly more than one day.
  

• Click the radio button in front of 7-Pass Erase (recommended by UD).
  
• Click OK.
  
• Click Erase.
  
• Confirm you want to erase. The program will unmount the volume, partition the drive, and rename the volume to the name you typed in step #7 above.