Disk Utility can find and repair errors related to the formatting and directory structure of a Mac disk. Errors can lead to unexpected behavior when using your Mac, and significant errors might even prevent your Mac from starting up completely.
How to Repair a Mac Boot Disk with Disk Utility in Mac OS X Reboot the Mac and hold down Command+R to boot into Recovery, or hold down OPTION Select 'Recovery HD' at the boot menu At the Mac OS X Utilities screen, select 'Disk Utility'. Lightweight, yet reliable boot disk creator that packs additional tools All things considered, Bootdisk Utility is a handy portable application that can help you create bootable disks from your.
Before proceeding, make sure that you have a current backup of your Mac, in case you need to recover damaged files or Disk Utility finds errors that it can't repair.
Open Disk Utility
Start up from macOS Recovery, then select Disk Utility from the Utilities window. Click Continue.
If you're not repairing the disk your Mac started up from, you don't need to start up from macOS Recovery: just open Disk Utility from the Utilities folder of your Applications folder.
Locate your disk in Disk Utility
Choose View > Show All Devices (if available) from the menu bar or toolbar in Disk Utility.
The sidebar in Disk Utility should now show each available disk or other storage device, beginning with your startup disk. And beneath each disk you should see any containers and volumes on that disk. Don't see your disk?
In this example, the startup disk (APPLE HDD) has one container and two volumes (Macintosh HD, Macintosh HD - Data). Your disk might not have a container, and it might have a different number of volumes.
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Repair volumes, then containers, then disks
For each disk that you're repairing, start by selecting the last volume on that disk, then click the First Aid button or tab. Lfs 0.6b unlocker link. Macbook pro studio setup.
In this example, the last volume on the disk is Macintosh HD - Data.
Click Run to begin checking the selected volume for errors.
- If there is no Run button, click the Repair Disk button instead.
- If the button is dimmed and you can't click it, skip this step for the item you selected, and continue to the next item.
- If you're asked for a password to unlock the disk, enter your administrator password.
After Disk Utility is done checking the volume, select the next item above it in the sidebar, then run First Aid again. Keep moving up the list, running First Aid for each volume on the disk, then each container on the disk, then finally the disk itself.
In this example, the repair order is Macintosh HD - Data, then Macintosh HD, then Container disk2, then APPLE HDD.
If Disk Utility found errors that it can't repair
If Disk Utility found errors that it could not repair, use Disk Utility to erase (format) your disk.
If your disk doesn't appear in Disk Utility
If Disk Utility can't see your disk, it also can't see any containers or volumes on that disk. In that case, follow these steps:
- Shut down your Mac, then unplug all nonessential devices from your Mac.
- If you're repairing an external drive, make sure that it's connected directly to your Mac using a cable that you know is good. Then turn the drive off and back on.
- If your disk still doesn't appear in Disk Utility, your disk or Mac might need service. If you need help, please contact Apple Support.
Available only on Mac computers that have the Apple T2 Security Chip, Startup Security Utility offers three features to help secure your Mac against unauthorized access: Firmware password protection, Secure Boot, and External Boot.
To open Startup Security Utility:
- Turn on your Mac, then press and hold Command (⌘)-R immediately after you see the Apple logo. Your Mac starts up from macOS Recovery.
- When you see the macOS Utilities window, choose Utilities > Startup Security Utility from the menu bar.
- When you're asked to authenticate, click Enter macOS Password, then choose an administrator account and enter its password.
Firmware password protection
Use a firmware password to prevent anyone who doesn't have the password from starting up from a disk other than your designated startup disk. To set a firmware password, click Turn On Firmware Password, then follow the onscreen instructions. Learn more about firmware passwords.
You can also use External Boot to prevent even those who know the firmware password from starting up from external media.
Secure Boot
Use this feature to make sure that your Mac starts up only from a legitimate, trusted operating system. Learn more about Secure Boot.
External Boot
Use this feature to control whether your Mac can start up from an external hard drive, thumb drive, or other external media. The default and most secure setting is 'Disallow booting from external media.' When this setting is selected, your Mac can't be made to start up from any external media:
- Startup Disk preferences displays a message that your security settings do not allow this Mac to use an external startup disk.
- Startup Manager allows you to select an external startup disk, but doing so causes your Mac to restart to a message that your security settings do not allow this Mac to use an external startup disk. You'll then have the option to restart from your current startup disk or select another startup disk.
Open Disk Utility At Startup
To allow your Mac to use an external startup disk:
Apple Startup Disk Utility Software
- Open Startup Security Utility.
- Select 'Allow booting from external media.'
Your Mac doesn't support booting from network volumes, whether or not you allow booting from external media. - If you want to select an external startup disk before restarting your Mac, quit Startup Security Utility, then choose Apple menu > Startup Disk.
