How to Use the Disk Utility First Aid Tool to Repair Corrupted Drives in macOS

Understanding Disk Errors on macOS

Even with the robust APFS (Apple File System) architecture, macOS storage drives can occasionally develop directory errors, corrupted file permissions, or catalog file fragmentation. These hidden logical errors often manifest as unexpected app crashes, agonizingly slow boot times, missing files, or an inability to empty the Trash.

Before assuming that your Mac’s internal SSD is failing, you should always run the First Aid tool within the built-in Disk Utility application. First Aid scans the disk architecture and automatically repairs damaged directory structures.

Step 1: How to Open Disk Utility

If your Mac is still booting normally and you are just experiencing minor glitches, you can run First Aid directly from your desktop.

1. Open Finder.
2. Navigate to Applications > Utilities.
3. Double-click on Disk Utility. (Alternatively, you can press Command + Space, type “Disk Utility”, and hit Enter).

When the application opens, click on View in the top menu bar and select Show All Devices. This ensures you can see the root hardware drive, the APFS containers, and the individual data volumes.

Step 2: How to Run First Aid Properly (The Bottom-Up Approach)

To thoroughly repair a drive, Apple recommends repairing volumes and containers in a specific hierarchical order—starting from the smallest individual volumes at the bottom of the list and working your way up to the main hardware disk.

1. In the left sidebar, locate your main drive (usually named “Macintosh HD”).
2. Select the very last indented volume under Macintosh HD (usually “Macintosh HD – Data”).
3. Click the First Aid button located at the top of the Disk Utility window.
4. Click Run (or Repair Disk) to confirm.
5. Once the repair is complete, click Done.
6. Move up the list to the next volume (e.g., “Macintosh HD”), select it, and run First Aid again.
7. Move up to the “Container” level, select it, and run First Aid.
8. Finally, select the root hardware disk at the very top of the hierarchy (e.g., “APPLE SSD”) and run First Aid one last time.

Note: While First Aid is running on the startup disk, your Mac may become unresponsive for a few minutes. This is normal.

How to Run First Aid from macOS Recovery

If your Mac is experiencing severe directory corruption, it might refuse to boot past the Apple logo, or Disk Utility may fail to repair the drive while macOS is currently running off it. In this scenario, you must run First Aid from macOS Recovery.

For Apple Silicon Macs (M1, M2, M3):

1. Shut down your Mac completely.
2. Press and hold the power button until you see “Loading startup options” on the screen.
3. Click on Options (the gear icon) and click Continue.
4. Select your admin user account and enter your password.
5. From the macOS Utilities window, select Disk Utility.

For Intel-based Macs:

1. Shut down your Mac completely.
2. Press the power button to turn it on, then immediately press and hold Command + R.
3. Keep holding the keys until you see the Apple logo or a spinning globe.
4. Log in if prompted, and select Disk Utility from the utilities window.

Once you are in Recovery Mode, follow the exact same “bottom-up” approach described in Step 2. Because the operating system is not actively running off the Macintosh HD volume, First Aid can unmount the drive and perform much deeper, more aggressive repairs.