How to Run First Aid on Mac and Repair Disks?

By Vivian | Posted to Howto on July 1st, 2020 |

Summary: This content is about First Aid on Mac. It includes how to use First Aid, how to run First Aid from macOS Recovery mode, and what to do if First Aid fails or is not working on Mac.

First Aid is a built-in disk repair software in macOS . Its main task is to verify and check the health of the disks and volumes on your Mac, such as Macintosh HD, SSD, external hard drives, USB drives, flash drives, and SD cards.

If necessary, First Aid is able to repair minor errors in disk file system and partition structure, which cuts the loss before the disk gets more serious corruption.

How to run First Aid to repair the disk?

When your Macintosh HD and external drives are not working, unreadable, corrupted, or unmountable, or your Mac won't turn on, you can use First Aid to check if there is a problem inside the disk.

Step 1: Open Finder, go to the Applications folder, Utilities folder, find Disk Utility and open it.

If the problematical disk is Macintosh HD, you need to repair it in macOS recovery mode. Please hold Command + R and start your Mac into macOS Recovery mode. Then you can select Disk Utility from macOS Utilities window and click Continue.

Disk Utilities in macOS Recovery mode

Step 2: Click on View and choose Show All Devices to list all detected disks and volumes.

Step 3: Select the drive or volume that you want to repair in the left sidebar.

Step 4: Click First Aid on the top menu of Disk Utility.

Step 5: Click Run to check and repair errors in this drive.

If Disk Utility reports that the operation successful or has been repaired, you're done. Check if you can access that disk.

First Aid succeeded

If Disk Utility can't repair the disk, or First Aid process has failed, and it's asking if possible back up the data on this volume.

First Aid failed to repair the disk

First Aid failed to repair the disk, what to do?

If you receive a report that First Aid process has failed or First Aid can't repair the found errors, you'd better back up your data as much as possible. There are several solutions you can have a try to back up the data:

1. Back up the data with macOS built-in Time Machine.

2. Recover data with iBoysoft Data Recovery for Mac.

3. A local data recovery specialist.

After backing up the data, you can erase this drive with Disk Utility and make the external drive working again, or reinstall macOS on the Macintosh HD.