To better organize your hard drive or fix disk errors, Disk Utility is a tool to get things done. Built into MacOS, the disk utility is stuck in the Utilities folder, which is found in the Applications folder, but is easy to detect using Spotlight – which you trigger by pressing the Command + Space bar and then just typing the Disk Utility.
The tool displays a graph and details of your hard drive configuration, showing the overall capacity as well as used and free space and different volumes.
The disk utility has been overhauled several times over the years, so the options may vary slightly depending on the version of MacOS you’re using. For example, in Mac OS X the El Capitan Disk utility was redesigned and many features were developed or removed. Some changes have also been made to the MacOS High Sierra for the new file format introduced by Apple: APFS. And when Catalina came out with a new Macintosh HD – the data volume started to show along with the read only Macintosh HD system volume.
Why use Disk Utility
You can use the disk utility to do the following:
- Delete, configure, or manage internal disks and external storage devices. (Read: How to format a drive on a Mac)
- Diagnose and fix problems with a disk or damaged volumes. (See: How to check the health of your Mac drive using Disk Utility).
- To delete, format, or partition a disk or volume. (See: How to partition a Mac drive or create an APFS volume).
- Add a password to encrypt the storage device or secure a drive.
- To mount, unmount or remove a disk.
- To change the file system – for example enable or disable journaling.
- Working with RAID sets. Combining multiple disks into one RAID set that works as a single disk can increase performance, reliability, and storage.
- Create a disk image of the files you want to move, archive, or back up to a different computer.
- Disk utility permissions were used to verify and repair, but from El Capitan it is unnecessary.
If you feel the following, you may want to use the Disk Utility:
Below we will look at how to perform the most common disk utility tasks.
How to find out if your disk is faulty using Disk Utility
If you think there is a problem with the drive inside your Mac or an external storage device, you can use Disk Utility to test the First Aid feature.
The first aid feature in Disk Utility will run various tests and repair it if it detects a problem with your disk.
Keep in mind that you cannot use first aid to fix your start-up drive while operating system. How we will run through that next.
Here’s how to run First Aid on your Mac or an external drive to check for disk issues:
- Open Disk Utility.
- From the sidebar, select the device you’re having trouble with. Click Show All Devices (see dropdown above) if you don’t see it.
- Click on First Aid.
- Disk Utility will check the volume for errors and repair it if necessary. Click Run.
- You cannot use your Mac while checking disk utility volume – be aware that this can take a long time.
If it finds a problem with the disk, Disk Utility will try to repair it.
If the disk is unable to repair the utility drive, or it believes that the disk is going to fail it will alert you. In this case your data should be backed up before it is too late. Read this article to back up your Mac. You may also find it useful: a way to recover and delete data from a failed hard drive, SSD or external drive.
If the disk utility reports that the disk is OK it means there is no problem with the disk.
How to repair your boot disk / startup disk with Disk Utility
You can run First Aid on your startup drive by following the steps above, but if Disk Utility finds an error it will not attempt to fix it.
If you want to repair your Mac’s startup drive (boot volume) you will not be able to because disk utility cannot repair mounted volume (from which everything is running).
In this case you need to turn on your Mac in recovery mode and repair the disk from there. This way things can run from the Recovery HD volume created when installing MacOS.
How to access recovery depends on your Mac:
- If you have an M1-Series Mac, turn off the Mac, then press and hold the Power button as you boot.
- If you have an Intel Mac, restart your Mac and hold down Command-R on your keyboard.
We have a detailed tutorial on how to use recovery mode here.
To Repair Your Startup Disk:
- Get started with recovery by following the steps above.
- Once your Mac recovery is booted you will see a utility screen. Select Disk Utility.
- Select the disk you want to repair from the menu and click First Aid.
- Like the above, Disk Utility will run its check and try and repair if possible.
The repair process may take some time.
For more information, read how to check the health of your Mac drive using Disk Utility.
How to format a disk using Disk Utility
There are many reasons why you want to format a drive. You may want to delete your startup drive so that you can perform a new installation of OS X, or you may want to encrypt an external storage drive that you use for work, or you may want to create a partition or other version for Windows. Mac operating system.
There are several file formats you may want to use, including:
- Apple File System (APFS) – Apple’s filing system from MacOS 10.13.
- Mac OS Extended – Apple’s filing system before MacOS 10.13.
- And MS-DOS (FAT) and ExFAT – for compatibility with Windows.
Here are the step-by-step instructions for formatting a Mac drive.
You can also add encryption and other security features when you are formatting a drive.
How to use Disk Utility if a drive is not mounted
If you plug a hard drive or flash drive into your Mac and don’t see it and it doesn’t allow you to access data, read on: What to do if a hard drive is not mounted.
How to create a disk image using Disk Utility
The Disk Utility is capable of creating a disk image of the contents of a folder that you can then transfer to another Mac, an archive, or a location that does not accept the folder.
This is similar to compressing a folder in a zip archive, but the advantage is that you can not only use disk image compression to save space, but also take advantage of Apple’s encryption for disk images.
Follow these steps to create a disk image using the Disk Utility.
How to create a disk partition or a volume
You may want to partition a disk into separate containers or install multiple operating systems. How you do this will depend on the version of macOS you are running. You should create a volume on new Macs instead of creating a partition.
Read our guide on how to make a Mac partition.