If you own a Mac that uses a traditional hard disk drive, chances are your data is very prone to loss and corruption due to normal hard disk wear and tear, plus some other factors.

It's very important to check the health of your Mac hard disk drive once in a while to see if there are potential problems that could lead to data loss. One easy and fuss-free way to check your Mac hard disk drive health is by using Disk Utility, a built-in application in macOS that features diagnostic tools to find out more about your disk drive. Disk Utility not only measures your disk drive's overall status and integrity, but also lets you customize your disk partitions, manage external drives, create disk images, repair disk drives, and so much more.

In this article we will be discussing how you can repair your Mac hard disk drive using Disk Utility. Although there are other third-party applications that boast of more capabilities and advanced features for disk management on Mac computers, Disk Utility is powerful enough for everyday computer users who don't need very technical or advanced software to diagnose and repair disk drives in macOS. If your Mac has issues in starting up (blinking question mark in folder), apps quitting unexpectedly and without warning, or fails to read and/or write files properly, using Disk Utility may solve these issues.

Verify Your Disk Using Disk Utility Within macOS

For minor disk issues, it's best to verify your Mac hard disk health first within Disk Utility before making any major troubleshooting steps or changes. Verifying your disk serves as a "first aid" method to check if the issue is rooted within the operating system. Issues caused by hardware problems must be diagnosed further using Disk Utility in Recovery Mode (more on this later). To verify your disk using Disk Utility in macOS, do the following steps:

Step 1: Open Disk Utility by going to Finder > Applications > Utilities > Disk Utility.

Step 2: In the Disk Utility app, click View > Show All Devices.

Step 3: Select a disk or volume in the sidebar, click the First Aid button (the one that looks like a stethoscope), then click Run. Take note that if you run First Aid on a disk, Disk Utility checks the partition maps and performs additional disk checks on every volume. On the other hand, running First Aid on a volume will check the contents of that volume only.

Step 4: After running First Aid, Disk Utility will tell you if your disk performs normally, needs to be repaired, or is about to fail. Failing drives cannot be repaired and must be replaced with a new one.

Repair Your Disk Using Disk Utility in Recovery Mode

Recovery Mode in macOS lets you run Disk Utility with administrator privileges, meaning you can do disk repairs without getting interfered by system permissions in macOS. While this is a fairly advanced procedure, it usually results in successful disk repairs for repairable drives. If First Aid tells you that your drive is about to fail, skip this step and take your Mac to a repair center that specializes in Mac repairs. To proceed with Disk Utility in Recovery Mode, follow these steps:

Step 1: Restart your Mac by clicking the Apple menu from the desktop, then choose Restart.

Step 2: While your Mac reboots, press and hold the Command and R keys until the Apple logo shows up.

Step 3: Click Disk Utility, then click Continue.

Step 4: Choose View > Show All Devices. In the sidebar, select the disk you want to repair.

Step 5: Click the First Aid button. If Disk Utility tells you the disk is about to fail, back up your data and replace the disk because you can’t repair it. Otherwise, click Run.

Step 6: If Disk Utility reports that the disk appears to be OK or has been repaired, you’re done. You can click Show Details to see more information about the repairs. Otherwise, you may need to do one of the following optional steps.

Step 7 (optional): If Disk Utility reports “overlapped extent allocation” errors, two or more files occupy the same space on your disk, and at least one of them is likely to be corrupted. You need to check each file in the list of affected files. Most of the files in the list have aliases in a DamagedFiles folder at the top level of your disk. If you can replace a file or re-create it, delete it. If it contains information you need, open it and examine its data to make sure it hasn’t been corrupted.

Step 8 (optional): If Disk Utility can’t repair your disk or it reports “The underlying task reported failure,” try to repair the disk or partition again. If that doesn’t work, back up as much of your data as possible, reformat the disk, reinstall macOS, then restore your backed-up data.


Repairing your Mac hard disk drive using Disk Utility is pretty straightforward. Disk Utility may look simple, but its advanced core features lets you diagnose disk problems on your Mac computer. The next time your Mac acts up by not booting up properly, apps quit all of a sudden, or your files can't be read or written properly, refer to this guide and open Disk Utility to find out what's going on with your Mac hard disk drive and what you can do about it.


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