By default, Mac starts from its built-in hard disk, but a startup disk can be any storage device that contains bootable contents that compatible with your Mac. For example, if you install macOS or Microsoft Windows on a USB drive, your Mac can recognize that drive as a startup disk. This guide provides 2 ways to boot a Mac from a USB flash drive.
- Today I am showing how to make a boot able USB drive for Mac Using a.dmg file, 8gb usb drive, and the Disk Utility that comes with Mac OS X. I hope this hel.
- Choose to verify the disk you are burning as well, then click 'Burn' 11. Depending on what OS built the.iso, the result may not be readable by your Mac, but the PC or hypervisor where you will install it will be able to read and boot it. Note: you can also do this from the command line using hdiutil. It will give you more.
It is a Mac cleaning tool that could clean files on Mac for digital devices. You may use the first Tool 1 Mac Disk Utility or WD Disk Utility as free alternative instead of this paid tool. Mac Disk Utility and WD Disk Utility is highly recommended for no matter formatting a device or erasing a device, or repairing device errors.
Requirement
Starting up your Mac from an external disk requires the following:
- Intel-based Mac.
- Bootable USB thumb drive formatted with a GUID partition type and containing an OS X installer or a usable operating system.
Let’s see how to boot a Mac from a bootable USB drive and what to do if your Mac doesn’t start up from it.
Way 1: Boot Mac from USB Drive using Startup Manager
Getting your Mac to load from a USB drive is fairly straightforward. Use the following steps, you can easily set Mac boot from an external drive in Startup Manager, so it’ll only boot from USB that one time.
Step 1: Insert the USB boot media into a USB slot.
Step 2: Turn on your Mac (or Restart your Mac if it’s already on).
Step 3: Press and hold the Option key immediately after you see the Apple logo. Holding that key gives you access to OS X’s Startup Manager. Once the Startup Manager screen appears, release the Option key. The utility will look for any available drives that include bootable content.
Step 4: Using either the pointer or arrow keys on the keyboard, select the USB drive you wish to boot from. Once selected, either hit the Return key or double-click your selection. The machine will start to boot from the USB drive.
Way 2: Set a Mac Boot from USB Drive using Startup Disk
When you use Startup Disk preferences to set Mac boot from an external drive, so it’ll boot from that disk until you choose a different one. Here is how:
Step 1: Go to Apple menu > System Preference, then click Startup Disk.
Step 2: Click the locked icon and then enter your administrator password.
Step 3: Select External drive as the startup disk, then restart your Mac.
What to do if your Mac does not boot from the selected drive
If you see a message prompts that your security settings do not allow this Mac to use an external startup disk, check the External Boot setting in Startup Security Utility, and then allow your Mac to use an external startup disk.
Step 1: 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 utility 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.
Step 2: Select “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.
Note: If you’re using Boot Camp in a dual-boot Windows/OS X environment, you may be unable to boot negatively into supported versions of Microsoft Windows XP, Windows Vista or Windows 10 operating systems installed on external USB hard drive.
Make sure disk has been formatted with a GUID partition type
Intel-based Macs support starting from an external USB storage device’s volume that has been formatted with a GUID partition type. If you wish to boot from the drive, it’s important to format the partition as “GUID Partition Table” rather than either of the other two ahead of time when you use that drive as a bootable drive.
![Bootable Bootable](/uploads/1/3/8/3/138359306/126238338.jpg)
Make sure your disk is bootable
Volumes that aren’t bootable and don’t contain a copy of a valid operating system aren’t listed in Startup Disk or Startup Manager. Make sure the external drive you’re trying to start from contains a usable operating system.
- Supported version: 0.6.5
While you don't need a fresh install of macOS to use OpenCore, some users prefer having a fresh slate with their boot manager upgrades.
![Mac Mac](https://bombich.com/images/Preparing-your-backup-disk-for-a-backup-of-OS-X/Erase-the-disk-10.11.jpg)
To start we'll want to grab ourselves a copy of macOS. You can skip this and head to formatting the USB if you're just making a bootable OpenCore stick and not an installer. For everyone else, you can either download macOS from the App Store or with gibMacOS.
# Downloading macOS: Modern OS
- This method allows you to download macOS 10.13 and newer, for 10.12 and older see Downloading macOS: Legacy OS
From a macOS machine that meets the requirements of the OS version you want to install, go directly to the App Store and download the desired OS release and continue to Setting up the installer.
For machines that need a specific OS release or can't download from the App Store, you can use the gibMacOS utility.
Now let's grab gibMacOS(opens new window), then unzip it into a local directory.
Next run the
gibMacOS.command
:As you can see, we get a nice list of macOS installers. If you need beta versions of macOS, you can select
C. Change Catalog
. For this example we'll choose 1:- macOS 11, Big Sur Note: As this OS is quite new, there's still some issues with certain systems to resolve. For more information, see here: OpenCore and macOS 11: Big Sur
- For first time users, we recommend macOS 10.15, Catalina
- Nvidia GPU Note: Reminder to verify whether your hardware support newer OSes, see Hardware Limitations
This is going to take a while as we're downloading the entire 8GB+ macOS installer, so it's highly recommended to read the rest of the guide while you wait.
Once finished, we have to either extract the installer or build it:
- Extracting the installer
- For macOS 11+
- Building the installer
- For 10.15 and older
# Extracting the installer
For macOS 11 and newer, Apple now packages up the installer into the InstallAssistant package. This will be located under
gibMacOS/macOS Downloads/
:Run the InstallAssistant.pkg and point this to whichever drive you're booting off of, this is where the Install.app will be dropped:
Once done, you should find it located in your Applications folder:
From here, jump to Setting up the installer to finish your work.
# Building the installer
For macOS 10.15 and older, the installer will be downloaded in pieces and will need to be built. Here we'll want to run the
BuildmacOSInstallApp.command
:You will be prompted for the macOS installer files which were downloaded to
macOS Downloads
folder in the gibMacOS directory.From the Finder, drill down to the folder containing the downloaded files and either drag it to the command line or 'Cmd+C' and paste it to the terminal.
Once the task is completed, exit the utility. You will find the Install file in the directory.
Move the newly created image to the Applications folder – this will simplify the next section.
From here, jump to Setting up the installer to finish your work.
# Downloading macOS: Legacy OS
- This method allows you to download much older versions of OS X, currently supporting all Intel versions of OS X(10.4 to current)
# Legacy macOS: Offline method
This method allows us to download full installers from Apple, however is limited to 10.10, Yosemite, so older OSes will need to be grabbed via the 'Online Method' mentioned below.
To start, go to the following link:
Download your desired version and a .pkg file should be provided.
Depending on what OS you're on, you can run this script and head to Setting up the installer however if you receive this error:
This means we'll need to manually extract the installer.
# Extracting the Installer
To start, grab the InstallMacOSX/InstallOS.dmg and mount it:
Next, let's open up terminal window and make a folder on our desktop to break things. Run one at a time:
Now we get to the fun part, extracting the installer(Note this may take a few minutes):
- For El Capitan(10.11) and older:
- For Sierra(10.12):
Next, run the following(one at a time):
- Yosemite:
- El Capitan:
- Sierra:
Bootable Disk Utility Mac
Once this is done, you can head to Setting up the installer!
# Legacy macOS: Online method
This method allows us to download legacy versions of macOS including 10.7 to current, however these are only recovery installers so require an internet connection inside the installer itself
SSScheduler.exe is an executable file that is part of the McAfee Security Scan Plus program developed by McAfee, Inc. The software is usually about 11.5 MB in size. The.exe extension of a file name displays an executable file. ![Ssscheduler tutorials Ssscheduler tutorials](/uploads/1/3/8/3/138359306/394567387.png)
![Ssscheduler tutorials Ssscheduler tutorials](/uploads/1/3/8/3/138359306/394567387.png)
To start, you'll want to use macrecovery.py instead. This tool is actually already bundled in OpenCorePkg:
Instructions for running are quite simple, choose from one of the below commands depending on which OS you want to download:
From here, run one of those commands in terminal and once finished you'll get an output similar to this:
Once this is done, format your USB as FAT32 with GUID Partition Scheme:
And finally, create folder on the root of this drive called
com.apple.recovery.boot
and place the newly downloaded BaseSystem/RecoveryImage files in:From here, you can skip to Setting up OpenCore's EFI environment
# Legacy macOS: Disk Images
This method instead relies on hosted images either from Apple or Acidanthera, and restoring onto your drive.
# Acidanthera Images
The below installers were pulled from genuine Mac restore disks with their SMBIOS lock removed, contents of OS X itself have not been modified in any way.
# Apple Images
Note that these images require you to have an Apple Developer account to access.
# Restoring the drive
Now comes the fun part, you'll first want to open the dmg you just downloaded and have it mounted. Now open Disk Utility and format your drive as macOS Extended(HFS+) with a GUID partition map:
Next we have 2 options to follow:
- ASR Restore(Apple Software Restore)
- Terminal based, works with SIP enabled
- Disk Utility Restore
- May require SIP disabled in newer OSes
# ASR
Here you'll simply want to open terminal and run the following:
Osx Usb Boot Disk Utility
- Note: This may not align with your setup, please change accordingly:
- Change
/Volumes/Mac OS X Install DVD
to what your mounted Disk Image is called - Change
/Volumes/MyVolume
to what your USB is called
- Change
This will take some time but once you're finished, you can skip to Setting up OpenCore's EFI environment
# Disk Utility
Due to some pesky issues with Disk Utility, many restores can fail if SIP is enabled. If you have issues we recommend either using the ASR Method or disable SIP.
To start, open Disk Utility and you should see both your USB drive and the Disk Image in the sidebar. From here, select restore
This will take some time but once you're finished, you can skip to Setting up OpenCore's EFI environment
If you get an error such as this one during restore:
This likely means SIP needs to be disabled, however we recommend using ASR Method instead.
# Setting up the installer
Now we'll be formatting the USB to prep for both the macOS installer and OpenCore. We'll want to use macOS Extended (HFS+) with a GUID partition map. This will create two partitions: the main
MyVolume
and a second called EFI
which is used as a boot partition where your firmware will check for boot files.- Note: By default, Disk Utility only shows partitions – press Cmd/Win+2 to show all devices (alternatively you can press the View button)
- Note 2: Users following 'Legacy macOS: Online method' section can skip to Setting up OpenCore's EFI environment
Next run the
createinstallmedia
command provided by Apple(opens new window). Note that the command is made for USB's formatted with the name MyVolume
:This will take some time so you may want to grab a coffee or continue reading the guide (to be fair you really shouldn't be following this guide step by step without reading the whole thing first).
You can also replace the
createinstallmedia
path with that of where your installer's located (same idea with the drive name).Pulled from Apple's own site: How to create a bootable installer for macOS(opens new window)
# Legacy Setup
For systems not supporting UEFI boot, see below:
To start, you need the following:
- BootInstall_IA32.tool or BootInstall_X64.tool
- This can be found in OpenCorePkg under
/Utilties/LegacyBoot/
- This can be found in OpenCorePkg under
- Install USB(Created above)
Within your OpenCore build folder, navigate to
Utilities/LegacyBoot
. Here you'll find a file called BootInstall_ARCH.tool
. What this does is install DuetPkg to your desired drive.Now run this tool in terminal with sudo(This tool will likely fail otherwise):
This will give you a list of available disks, choose yours and you will be prompted to write a new MBR. Choose yes
[y]
and you'll be finished.This will provide you with an EFI partition with either a bootia32 or bootx64 file
# Setting up OpenCore's EFI environment
Setting up OpenCore's EFI environment is simple – all you need to do is mount our EFI system partition. This is automatically made when we format with GUID but is unmounted by default, this is where our friend MountEFI(opens new window) comes in:
You'll notice that once we open the EFI partition, it's empty. This is where the fun begins.