Repair Disk Problems – Mac Kung Fu, 2nd Edition

Tip 348Repair Disk Problems

Unlike Windows computers, OS X generally takes care of its disk invisibly and requires little user intervention. You’ll never need to defragment an OS X hard disk, for example. However, there are two things you might choose to do periodically in order to ensure the smooth running of your computer. The first is to repair permissions, and the second is to repair the directory and file structure. Some people habitually do both after a major update has been applied to the system.

Repairing Disk Permissions

To repair disk permissions, start Disk Utility, which can be found in the Utilities folder within the Applications list of Finder. In the Disk Utility program window, select the partition on which OS X is installed—usually it’s the indented second entry in the list of disks at the top left of the Disk Utility window. Then make sure the First Aid tab is selected. Now click the Repair Disk Permissions button. The process usually takes about five to ten minutes to complete. See Figure 51, Repairing permissions for a smooth-running computer for an example.


Figure 51. Repairing permissions for a smooth-running computer

Repairing the Disk

Although you might see the Repair Disk button in the same program window, don’t click it. In fact, it’s impossible to repair the disk while OS X is up and running. Instead, you must boot to the recovery system—reboot the computer, and then press and hold Command+R just before the boot-time Apple logo appears. Release it when the recovery screen appears, and select the Disk Utility option. As for repairing the disk, select the OS X partition and click the First Aid tab, but this time click the Repair Disk button. Again, the repair will take a few minutes to complete. Once done, click the Restart option from the main menu.