ASK A GROUP of Mac users for their favorite built–in app and you’d be hard pressed to find many that would say Disk Utility. Yet, it has dug many of us out of trouble, fixed problems that looked terminal, and enabled us to do all manner of things with drives and volumes that would otherwise require investing in third–party software.
Despite having a simple interface and being easy to use, Disk Utility’s use of some arcane terminology often puts people off using it. It shouldn’t. Whether you want to erase a drive, force an external drive to mount, create a partition (or container in APFS, more about that later), or fix a drive or volume that’s misbehaving, it’s straightforward to do in Disk Utility. Disk Utility is also a key component of macOS Utilities — the options that appear when you boot your Mac in Recovery mode. Sometimes, if your Mac won’t boot normally, booting in Recovery mode and repairing the disk using Disk Utility is all you need to do.
Here, we’ll take you through how to use it and explain that terminology; by the end, you won’t just know what you’re doing, but why.
How to use Disk First Aid
Having disk–related problems? Run First Aid to identify them
PERHAPS THE MOST frequently used tool in Disk Utility’s arsenal is Disk First Aid. It scans whichever drive you select for problems in the structure and integrity of the drive. If you select the whole drive, rather than a single volume, it checks the partition maps for the drive and directory, then checks each volume.
If you only select one volume, it just checks that. Volumes appear under the main drive in Disk Utility’s sidebar. For example, the internal drive on your Mac has a Macintosh HD volume which has volumes for data and for system information.
If Disk Utility finds problems on your startup disk, it will notify you but won’t attempt to fix them.