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Disk Utility: Using Disk Utility to Repair Hard Drives and Disk Permissions

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Disk Utility First Aid
Disk Utility First Aid

The First Aid tab is where you will find Disk Utility's repair tools.

Disk Utility, one of the many applications included with OS X, allows you to work with your hard drives. You can use Disk Utility not only to erase, format, and partition a drive, but also to repair problems that may crop up from time to time.

Disk Utility’s First Aid feature provides two unique functions. One can help you repair a hard drive; the other lets you repair file and folder permissions.

Repair Disk

Disk Utility can repair common disk issues, ranging from corrupt directory entries to files left in unknown states, usually from power outages, forced restarts, or forced application quits. Disk Utility’s Repair Disk feature is excellent at making minor disk repairs to a hard drive’s file system, and it can make most repairs to a hard drive’s directory structure, but it’s no substitute for a good backup strategy. The Repair Disk feature is not as robust as some third-party applications that do a better job of repairing hard drives as well as recovering files, something Repair Disk is not designed to do.

Repair Disk Permissions

Disk Utility’s Repair Disk Permissions feature is designed to restore file or folder permissions to the state the OS and applications expect them to be in. Permissions are flags set for each item in the file system. They define whether an item can be read, written to, or executed. Permissions are initially set when an application or group of files are installed. The installation includes a .bom (Bill of Materials) file that lists all the files that were installed, and what their permissions should be set to. Repair Disk Permissions uses the .bom file to verify and repair permission issues.

What You Need

  • Disk Utility, located at /Applications/Utilities/.

  • Ten minutes to an hour of your time, depending on which First Aid tools you will be using.
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