How to Fix System Errors with Mac OS X Snow Leopard’s First Aid
Mac OS X Snow Leopard offers a First Aid pane. This feature of Disk Utility lets you check almost any disk for errors, as well as repair any errors that it finds. Here are the two exceptions when the buttons are disabled:
The start-up disk: Disk Utility can’t repair the start-up disk, which makes sense if you think about it, because that drive is currently being used.
If you have multiple operating systems on multiple disks, you can boot from another Mac OS X installation on another drive to check your current start-up disk. Or you can boot your system from the original Mac OS X installation DVD and run Disk Utility from the Installation menu.
Write-protected disks: Although you can use the Disk Utility to verify CDs and DVDs, Disk Utility can’t repair them.
You usually can’t repair a disk that has open files that are currently being used. If you’re running an application from a drive or you’ve opened a document that’s stored on that drive, you probably can’t repair that drive.
In order to verify or repair, you must be logged in as an admin-level user.
You can also select to verify and repair permissions (or privileges) on a disk. If you can’t save or move a file that you should be able to access, try checking that drive for permissions problems. Although you can’t fix disk errors on a boot drive, you can verify and repair permissions on any volume that contains a Mac OS X installation (whether it was used to boot your Mac or not).
To verify or repair a drive, follow these steps:
Access the Applications folder, and then open the Utilities folder.Find First Aid in the Utilities folder.
Open the First Aid pane.The First Aid pane displays a list of volumes on your Mac.
Select the target volume/partition in the list at the left.
Click the Verify Disk button
Snow Leopard checks the contents of the drive and displays any errors.Resize the window to display more messages.
Click the Repair Disk button.
Snow Leopard verifies the contents of the drive and fixes any problems.
It’s a good idea to check your disks once every two or three days. If your Mac is caught by a power failure or Mac OS X locks up, check disks after you restart your Mac.
A number of very good commercial disk repair utilities are on the market. However, Disk Utility does a good job on its own, and it’s free.