Show All Devices and Erase the Parent Drive. By default, Disk Utility only shows the Volumes on your. Open Disk Utility via one of the following methods: In Mac OS X 10.7, to partition your startup disk, restart your computer while holding down Command-r. When you see the gray Apple logo, release the keys. If you see a screen asking you to select your main language, choose it and then click the arrow. Click Disk Utility and then click Continue.
Repair a storage device in Disk Utility on Mac. Disk Utility can fix certain disk problems—for example, multiple apps quit unexpectedly, a file is corrupted, an external device doesn’t work properly, or your computer won’t start up. Disk Utility can’t detect or repair all problems that a disk may have.
Disk Utility is in the Utilities folder inside the main Applications folder. It is also available on Mac OS X software installation CDs and DVDs, and, in Mac OS X 10.7 (Lion) or later, on your Recovery HD volume. For more about using Disk Utility, from Disk Utility's Help menu, select Disk Utility Help.
Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
Apple silicon: Turn on your Mac and continue to press and hold the power button until you see the startup options window, which includes a gear icon labeled Options. Select Options, then click Continue.
Intel processor: Make sure that your Mac has a connection to the internet. Then turn on your Mac and immediately press and hold Command (⌘)-R until you see an Apple logo or other image.
If you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password.
Reinstall macOS
Select Reinstall macOS from the utilities window in macOS Recovery, then click Continue and follow the installer's instructions.
Follow these guidelines during installation:
Allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart and show a progress bar several times, and the screen might be empty for minutes at a time.
If the installer asks to unlock your disk, enter the password you use to log in to your Mac.
If the installer doesn't see your disk, or it says that it can't install on your computer or volume, you might need to erase your disk first.
If the installer is for a different version of macOS than you expected, learn about other installation options, below.
If the installer offers you the choice between installing on Macintosh HD or Macintosh HD - Data, choose Macintosh HD.
After installation is complete, your Mac might restart to a setup assistant. If you're selling, trading in, or giving away your Mac, press Command-Q to quit the assistant without completing setup. Then click Shut Down. When the new owner starts up the Mac, they can use their own information to complete setup.
Other macOS installation options
By default, macOS Recovery installs the latest macOS that was previously installed on your Mac.* You can get other macOS versions using one of these methods:
On an Intel-based Mac, you can use Option-Command-R at startup to upgrade to the latest macOS that is compatible with your Mac. Exceptions:
If macOS Sierra 10.12.4 or later was never previously installed, you will receive the macOS that came with your Mac, or the closest version still available.
If your Mac has the Apple T2 Security Chip and you never installed a macOS update, you will receive the latest macOS that was installed on your Mac.
On an Intel-based Mac that previously used macOS Sierra 10.12.4 or later, you can use Shift-Option-Command-R at startup to install the macOS that came with your Mac, or the closest version still available.
Reinstall macOS from the App Store instead of using macOS Recovery. If you can't install the latest macOS, you might be able to install an earlier macOS.
Create a bootable installer, then use it to install macOS on your Mac or another Mac.
* If you just had your Mac logic board replaced during a repair, macOS Recovery might offer only the latest macOS compatible with your Mac. If you erased your entire disk instead of just the startup volume on that disk, macOS Recovery might offer only the macOS that came with your Mac, or the closest version still available.
What are disk permissions and why do they need repairing?
Disk permissions on macOS are used to keep your files secure. They’re designed so that certain programs (or other users if you share your Mac) can’t just dip into a system file they have no business with and modify it. They’d need permission to do that.
Every file and folder on your Mac comes with an associated set of permissions. From the Apple Community:
“Many things you install in Mac OS X are installed from package files (whose filename extension is '.pkg'). Each time something is installed from a package file, a 'Bill of Materials' file (whose filename extension is '.bom') is stored in the package's receipt file, which is kept in /Library/Receipts/ in Mac OS X v10.5 and earlier. These files don't take up much disk space and you shouldn't put them in the Trash. Each of those '.bom' files contains a list of the files installed by that package, and the proper permissions for each file.”
Unfortunately, these permissions can easily become messed up unintentionally. It’s quite common for this to happen when installing and uninstalling apps on your system. And when it does, apps can find themselves with free reign to alter files and modify read-only files which can cause all kinds of permission errors and system issues such as lagging, freezing, or crashing.
If you notice anything out of the norm regarding system performance, the first thing you should do is troubleshoot those disk permissions.
Below we’ll show you two ways: the manual and the easy one. Choose the way that works best for you.
How to repair permissions on Mac: The manual way
If you’re running an older version of macOS, Disk Utility is the go-to tool for troubleshooting problems.
Why an older version?
Because as of macOS version 10.11 El Capitan, Disk Utility no longer comes with the option 'repair disk permissions'. Boooo!
Apple even removed the command line:
But there’s a method to the madness. macOS now comes with a feature called System Integrity Protection (SIP) which is designed to automatically repair file permissions during software updates and system changes. SIP works by restricting the root account so that it can’t do things like modify protected locations and processes such as /System and /usr. This should prevent malware from gaining root permissions and infecting your system files.
Anyway, back to using Disk Utility to repair disk permissions. If you’re running a pre-El Capitan version of macOS, follow these steps:
Press Command + Space to open Spotlight, type in “Disk Utility”, and hit Enter.
Select Macintosh HD from the left sidebar menu.
Click on the First Aid tab.
Click on Verify Disk Permissions. By taking this step, Disk Utility will work through your hard drive to detect broken or misbehaving permissions and list them for repair. This might take a few minutes but you can check the Show details box to keep an eye on its progress.
Click on Repair Disk Permissions and wait while Disk Utility runs through the identified permissions to fix them.
If disk permission issues have played such havoc that your Mac won’t boot correctly, it’s possible to access Disk Utility in Recovery Mode. Do this by holding Command + R during bootup.
Section 9 movie trailer. If you’re installing a newer (or older) version of macOS on top of your existing operating system, Mac will perform a disk permission repair as a part of the installation so that you start from a clean slate.
How to repair disk permissions on Mac: The easy way
Iphone testing simulator. For users of macOS versions El Capitan and newer, the removal of Repair Disk Permissions means you have no troubleshooting solution to turn to in if your Mac is ailing.
But worry not, CleanMyMac X is the hero you need.
CleanMyMac is like Disk Utility in that it does all of the heavy lifting for you to verify permissions and repair your Mac’s disk.
Even System Integrity Protection running quietly in the background doesn’t prevent certain issues from arising. If you’re suffering from any of the following problems, boot up CleanMyMac and have it take care of business:
Improper functioning of applications.
Inability to move or delete files.
Inability to access files.
If you Mac appears to be running fine, it’s still worth running repairs every so often to ensure it stays that way. Not all broken permissions affect performance but that doesn’t mean they shouldn’t be fixed.
Repairing Disk Permissions in a few clicks
First things first, you’ll need to download CleanMyMac X. You can do that here. It’s free so you won’t need your credit card. Once that’s done, follow these four steps:
Launch CleanMyMac.
Click on Maintenance from the left sidebar menu.
Check the box next to Repair Disk Permissions.
Click Run.
CleanMyMac will scan your system to verify disk permissions and automatically repair permissions that are found to be faulty. When the task is complete, you’ll be able to view a log of all the permissions that were repaired.
And that’s all there is to it. Your Mac should now be running as intended.
Disk Utility Download
Disk permissions are critical to your system’s security and performance but only when they’re working as they should. Use CleanMyMac to verify and repair disk permissions whenever you run into issues with apps or files for a healthy running Mac. Battlegrounds sign up.