Disk First Aid was not a full-featured disk repair tool.
It concentrated on just the basics: Disk First Aid was truly the first line of defense, able to correct minor problems. When Disk First Aid was unable to make a repair, which was quite common, third-party disk utility tools could often do the trick. With the advent of OS X , Apple vastly improved on the supplied ability to repair a hard drive and folded the functionality of Disk First Aid into the Disk Utility application.
Disk Utility is an all-around workhorse, providing nearly all the tools and features most users need to work with hard drives or disk images. Within the First Aid, the tab could be found options for verifying a disk without actually performing any type of repair, as well as for actually repairing a selected disk.
Because repairing a disk could occasionally lead to a volume no longer working, as was the case when a disk was in such bad shape that the repair process could result in unrecoverable errors, many people would first use the Verify Disk option by itself to see what kind of shape the disk was in. The new First Aid tab performed both the verify and repair in a one-step process.
While this may seem a step backward, it's actually a faster repair process, and with the quality of drives improving substantially since the early days of OS X, it's no longer the case that the repair process will often lead to disk errors. Now it happens only rarely, though you still should back up your data before ever performing a disk repair. System file and folder permissions could become compromised over time because the file permissions were set improperly by an app, app installer, or the end user.
Standard drives may show information about catalog files, catalog hierarchy, and multi-linked files, while Fusion drives will have additional items that are checked, such as segment headers and checkpoints.
If there are no errors found, you'll see a green check mark appear at the top of the drop-down sheet. However, you're limited to only performing a verification of the drive while the operating system is actively being run from the same disk. If an error is found, First Aid will display an error, but make no attempt to repair the drive.
Please note: If you're checking a Fusion drive, you must start up with OS X I recommend using the same version of OS X that is installed on your current startup drive. You'll find complete step-by-step instructions for how to boot from the Recovery HD volume and start Disk Utility in our guide: Once you have successfully restarted from the Recovery HD, and have launched Disk Utility, you can use the method above for using First Aid on a non-startup drive to verify and repair the drive.
Share Pin Email.
Tom Nelson has written hundreds of articles, tutorials, and reviews for Other World Computing and About. He is the president of Coyote Moon, Inc. Updated September 30, If errors are found, the repair process will begin.
Some notes on what to expect when using First Aid to repair a drive: In some previous versions of First Aid, it was necessary to run the repair process multiple times to ensure the repairs were complete; that is no longer required. The overlapped error indicates that two or possibly more files occupied the same location on the drive being repaired.
More than likely both files have become corrupt, but there's a small chance you can recover one or both of them. You can examine the files in the DamagedFiles folder. If you must have the file, then check your backup for a usable copy. If repairs aren't successful, and you have a backup of all the data stored on the affected drive, then I recommend reformatting the drive and performing a clean install of OS X.