Disk Utility First Aid
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.
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.
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.
Published: 7/18/2009
Updated: 5/26/2015
Disk Utility’s Repair Disk feature can work with any hard drive connected to your Mac, except the startup disk. If you select the startup disk, the ‘Repair Disk’ button will be grayed out. You will only be able to use the Verify Disk feature, which can examine the drive and determine whether anything is wrong.
Repairing a startup drive with Disk Utility is still possible. To do it, you must boot from another hard drive that has OS X installed, or boot from the OS X installation DVD.
Aside from the time required to restart from another hard drive an installation DVD or the Recovery HD, using Disk Utility’s Repair Disk feature otherwise works the same way and takes the same amount of time. If you need to boot from an OS X installation DVD, you’ll find instructions on how to do this on pages 2 and 3 of Installing OS X 10.5 Leopard: Upgrading to OS X 10.5 Leopard.
Published: 7/18/2009
Updated: 5/26/2015
Disk Utility’s Repair Permissions may be one of the most overused services included with OS X. Whenever something isn’t quite right with a Mac, someone will suggest running Repair Permissions. Luckily, Repair Permissions is pretty benign. Even if your Mac doesn’t need any permissions fixed, Repair Permissions is unlikely to cause any type of problem, so it remains one of those things to do “just in case.”
You should use Repair Permissions if you experience a problem with an application, such as an application not launching, starting up very 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 will verify and repair, 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 will only verify and repair files located on bootable volumes that contain OS X.
Disk Repair will list any files that don’t match the expected permission structure. It will also attempt to change the permissions for those files back to the expected state. Not all permissions can be changed, so you should expect some files to always show up as having different permissions than expected.
Published: 7/18/2009
Updated: 5/26/2015
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.
Published: 7/18/2009
Updated: 5/26/2015
Disk Utility’s Repair Disk feature can work with any hard drive connected to your Mac, except the startup disk. If you select the startup disk, the ‘Repair Disk’ button will be grayed out. You will only be able to use the Verify Disk feature, which can examine the drive and determine whether anything is wrong.
Repairing a startup drive with Disk Utility is still possible. To do it, you must boot from another hard drive that has OS X installed, or boot from the OS X installation DVD.
Aside from the time required to restart from another hard drive an installation DVD or the Recovery HD, using Disk Utility’s Repair Disk feature otherwise works the same way and takes the same amount of time. If you need to boot from an OS X installation DVD, you’ll find instructions on how to do this on pages 2 and 3 of Installing OS X 10.5 Leopard: Upgrading to OS X 10.5 Leopard.
Repair Disk
- 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 Repair Disk’s attempt to scan and repair it kicked the drive over the edge.
- Launch Disk Utility, located at /Applications/Utilities/.
- Select the ‘First Aid’ tab.
- In the left-hand pane, select the hard drive or volume you wish to run Repair Disk on.
- Place a check mark in the ‘Show details’ box.
- Click the ‘Repair Disk’ button.
- If Disk Utility notes any errors, repeat the Repair Disk process until Disk Utility reports ‘The volume xxx appears to be ok.’
Published: 7/18/2009
Updated: 5/26/2015
Disk Utility’s Repair Permissions may be one of the most overused services included with OS X. Whenever something isn’t quite right with a Mac, someone will suggest running Repair Permissions. Luckily, Repair Permissions is pretty benign. Even if your Mac doesn’t need any permissions fixed, Repair Permissions is unlikely to cause any type of problem, so it remains one of those things to do “just in case.”
When to Use Repair Permissions
You should use Repair Permissions if you experience a problem with an application, such as an application not launching, starting up very 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.
What Repair Permissions Actually Fixes
Disk Utility’s Repair Permissions only repairs files and applications that are installed using Apple’s installer package. Repair Permissions will verify and repair, 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 will only verify and repair files located on bootable volumes that contain OS X.
Repair Permissions
- Launch Disk Utility, located at /Applications/Utilities/.
- Select the ‘First Aid’ tab.
- In the left-hand pane, select a volume you wish to run Repair Permissions on. (Remember, the volume must contain a bootable copy of OS X.
- Click the ‘Repair Disk Permissions’ button.
Disk Repair will list any files that don’t match the expected permission structure. It will also attempt to change the permissions for those files back to the expected state. Not all permissions can be changed, so you should expect some files to always show up as having different permissions than expected.
Published: 7/18/2009
Updated: 5/26/2015
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