OS X Snow Leopard: Using Disk Utility to Repair a Disk
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General Information
This article explains how to use Disk Utility in Mac OS X to repair a disk. Disk Utility is included with OS X and can be used to repair system file permissions and minor errors in a disk's directory structure. It is located in the Utilities folder within the Applications folder on the hard drive. Disk Utility can also be run from a Mac OS X installation disc.
Repair Disk Permissions
1. Insert the Mac OS X Install disc. Restart the computer, and hold the C key when you hear the startup sound.

2. It is normal for your computer to take longer to startup from a CD or DVD. The disc will automatically start the OS X installer, but you do not need to reinstall OS X. Select English as your language and select the right arrow button to proceed.

3. Select Disk Utility from the Utilities menu at the top of the screen.

4. The Disk Utility window should look similar to the picture below. Select the name of the hard drive (e.g. Macintosh HD) on the left side of the window and click the First Aid tab if it is not already selected.

5. To check the directory of the disk and attempt repair of any problems found, click the Repair Disk button. If any problems are found, they will be listed. If no problems are discovered, it will say "The volume Macintosh HD appears to be OK."
6. If you need to repair Disk Permissions, open the Disk Utility window. Make sure the First Aid tab is selected.
7. Select the name of the Hard drive on the left and click Repair Disk Permissions button.

8. Once the Repair completes, you can close the Disk Utility window.
Referenced from: Apple.com
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1/6/2015 11:14:21 AM