Why repair disk permissions

Repair Disk Permissions uses the. Disk Utility's Repair Disk feature can work with any drive connected to your Mac, except the startup disk. If you select the startup disk, the Repair Disk tab is grayed out. You are only able to use the Verify Disk feature, which examines the drive and determines whether anything is wrong. However, repairing a startup drive with Disk Utility is possible. Back up your drive first. Even though your drive is having some problems, it's a good idea to create a new backup of a suspect drive before running Repair Disk.

While Repair Disk usually doesn't cause any new problems, it's possible for the drive to become unusable after an attempt to repair it. This isn't Disk Repair's fault. It's just that the drive was in such bad shape to begin with that the Repair Disk's attempt to scan and repair it kicked the drive over the edge.

To repair a drive using Disk Utility:. Select the First Aid tab. In the left pane, select the hard drive or volume you want to run Repair Disk on. Place a check mark in the Show details box. Click the Repair Disk button. Whenever something isn't quite right with a Mac, someone suggests running Repair Permissions. Fortunately, Repair Permissions is benign. You should use Repair Permissions if you experience a problem with an application, such as an application not launching , starting up slowly, or having one of its plug-ins refuse to work.

Permission problems can also cause your Mac to take longer than usual to start up or shut down. Disk Utility's Repair Permissions only repairs files and applications that are installed using Apple's installer package. Repair Permissions verifies and repairs, if needed, all Apple applications and most third-party applications, but it won't check or repair files or applications you copy from another source or the files and folders in your home directories.

In addition, Repair Permissions only verifies and repairs files located on bootable volumes that contain OS X. You've decided to leave a comment. That's fantastic! Check out our comment policy here. Let's have a personal and meaningful conversation. Save my name, email, and website in this browser for the next time I comment. Notify me of follow-up comments by email.

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Users that migrated to macOS from Windows might find this whole thing a little baffling. Why are disk permissions so important? How do they become damaged? How can I repair disk permissions?

When is that a good idea? Heck, what are permissions? Permissions are attached to each and every file and folder, and describe what kinds of users or applications can interact with that file. Files can have a range of permissions, describing who and what can mess with them. The Repair Disk function Repair Disk verifies and, if problems are found, corrects issues with the directory on a disk or volume.

If you are running Mac OS X This is known as Live Verification. If Verify Disk finds errors on your startup disk, you must repair the disk as noted in point 1. Under Mac OS X Installations are tracked in the InstallHistory. This means that Repair Disk Permissions will not correct permissions problems on: Third-party software, even if that software was installed using the Mac OS X Installer and created a receipt.

This is because the software was not "Apple-originated. Mac OS X Repair Disk Power outages, hard restarts, and system crashes can lead to disk directory corruption, requiring the use Repair Disk to correct such. Periodically, as part of your regular maintenance routine, to identify any hidden directory corruption before it becomes a problem.

Before reinstalling Mac OS X. Resolving disk, permission, and cache corruption.