Install Macos On External Hard Drive From Windows

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These advanced steps are primarily for system administrators and others who are familiar with the command line. You don't need a bootable installer to upgrade macOS or reinstall macOS, but it can be useful when you want to install on multiple computers without downloading the installer each time.


From Finder Window navigate to the location where we have to install our application in external HDD. Right click on the folder and click on 'Get Info'. Under 'Sharing and Permissions': Click on '+' while holding 'opt' key, which opens a popup window. Search 'system' and select 'System Administrator' here and click ok.

Apologies for the video not being the greatest quality, I just wanted to document and share this. Installing Windows 10 on the External Drive via VirtualBox If you start VirtualBox normally, you won't see the VM that you created when running under sudo If you attempt to run the VM and it fails to run, try unmounting/ejecting the drive and then starting the VM again. The best way to make a hackintosh is to install macOS on an external USB hard drive with your laptop or desktop to make sure everything works before installing it to the internal Hard Drive. This is how I configure and install an external USB hard drive for Catalina 15.5. One of the main goals of using the external drive for Windows installation is not to waste your storage on the macOS system. Thus, make sure to: remove the VM installation in the VirtualBox.

What you need to create a bootable installer

  • A USB flash drive or other secondary volume formatted as Mac OS Extended, with at least 14GB of available storage
  • A downloaded installer for macOS Big Sur, Catalina, Mojave, High Sierra, or El Capitan

Download macOS

  • Download: macOS Big Sur, macOS Catalina, macOS Mojave, or macOS High Sierra
    These download to your Applications folder as an app named Install macOS [version name]. If the installer opens after downloading, quit it without continuing installation. To get the correct installer, download from a Mac that is using macOS Sierra 10.12.5 or later, or El Capitan 10.11.6. Enterprise administrators, please download from Apple, not a locally hosted software-update server.
  • Download: OS X El Capitan
    This downloads as a disk image named InstallMacOSX.dmg. On a Mac that is compatible with El Capitan, open the disk image and run the installer within, named InstallMacOSX.pkg. It installs an app named Install OS X El Capitan into your Applications folder. You will create the bootable installer from this app, not from the disk image or .pkg installer.

Use the 'createinstallmedia' command in Terminal

  1. Connect the USB flash drive or other volume that you're using for the bootable installer.
  2. Open Terminal, which is in the Utilities folder of your Applications folder.
  3. Type or paste one of the following commands in Terminal. These assume that the installer is in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using. If it has a different name, replace MyVolume in these commands with the name of your volume.

Big Sur:*



High Sierra:*

El Capitan:

* If your Mac is using macOS Sierra or earlier, include the --applicationpath argument and installer path, similar to the way this is done in the command for El Capitan.

After typing the command:

  1. Press Return to enter the command.
  2. When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
  3. When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the volume is erased.
  4. After the volume is erased, you may see an alert that Terminal would like to access files on a removable volume. Click OK to allow the copy to proceed.
  5. When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Big Sur. You can now quit Terminal and eject the volume.

Use the bootable installer

Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:

Apple silicon

  1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
  2. Turn on your Mac and continue to hold the power button until you see the startup options window, which shows your bootable volumes.
  3. Select the volume containing the bootable installer, then click Continue.
  4. When the macOS installer opens, follow the onscreen instructions.

Intel processor

  1. Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing.
  2. Press and hold the Option (Alt) ⌥ key immediately after turning on or restarting your Mac.
  3. Release the Option key when you see a dark screen showing your bootable volumes.
  4. Select the volume containing the bootable installer. Then click the up arrow or press Return.
    If you can't start up from the bootable installer, make sure that the External Boot setting in Startup Security Utility is set to allow booting from external media.
  5. Choose your language, if prompted.
  6. Select Install macOS (or Install OS X) from the Utilities window, then click Continue and follow the onscreen instructions.

Learn more

A bootable installer doesn't download macOS from the internet, but it does require an internet connection to get firmware and other information specific to the Mac model.

For information about the createinstallmedia command and the arguments you can use with it, make sure that the macOS installer is in your Applications folder, then enter the appropriate path in Terminal:

macOS Big Sur is still in pulic beta and not stable according to user feedback. We heard dozens of popular apps like Dropbox and Parallels Desktops not working properly in Big Sur. So it is not the perfect time to upgrade to Big Sur. Instead, you can test it out by installing the OS on an external hard drive or SSD.

Before moving ahead, you must be familiar with the task that you need to perform in the operation. In a glimpse, you will need an external hard drive and format it Disk Utility. Next, you need to download the installer (.dmg file) and then create a bootable USB drive and at last, you will learn the ways to install macOS Big Sur on an external hard drive. Now, you will have to go through each section one by one, and here, you will get the detailed instructions of each method.

Portable Hard Drive or SSD?

The first question comes to the selection of portable external drive, which is the final storage media to keep OS files. It could be a traditional Hard Disk Drive (HDD) or Solid State Drive (SSD). In simple terms, hard drive should be the your choice only if you had tight budget or looked for large volume disk (over 1TB). For rest of the cases, SSD is always the best chocie because of faster writing and reading speed. No one want to run macOS Big Sur on external drive but with weak performance, right?

Please note! No matter what kind of external drive you decided to buy, make sure the ports are compatible with your Mac. On modern Macs, it is usually shipped with USB 3.0 port and Thunderbolt 2/3.

Part 1: Format External Hard Drive or SSD

The default file system on portable hard drive or SSD is exFAT or FAT, which is used for Windows or Linux OS. macOS uses totally different file system so you have to format the external drive first in order to install Big Sur on it. Formatting the external drive (SSD) will wipe all the data associated to it. So, if you had important files, then make sure to take a backup first.

Step 1: Connect the external drive to Mac using the cable.

Step 2: Open Disk Utility and click on the view icon to select Show All Devices.

Step 3: Now, select your connected external drive and further click on the Erase button.

Step 4: You will have to fill the available boxes with the Big Sur or another name in the Name section. Select APFS from the drop-down menu in the format box and finally, select GUID Partition Map for the Scheme section.

Step 5: After completing the above task, click on the Erase button. Now wait for a few seconds as the format process is started and once it is completed, click on the Done button.

Your first task is done as you have formatted the drive to Mac supported format and now you need to download the macOS DMG file for creating macOS USB bootable drive.

Part 2: Download macOS Big Sur DMG File

DMG is the default file type on Mac for compressing files and macOS Big Sur installation file ends with .dmg. If you already got this file, then move to Part 3. If not, please download .dmg file of macOS Big Sur from here (Link 1 & Link 2). The installation file is 10GB so it could take some time to complete the download process. This is largely dependent on how fast your Internet connection is.

Your second task is done and you have successfully download the dmg file of macOS Big Sur. Now, you need software to burn macOS Big Sur dmg file to external drive. This part can be done with the help of UUByte DMG Editor.

Part 3: Create Bootable macOS Big Sur Installer for External Drive

To make a macOS Big Sur bootable drive, you have to burn .dmg file to it. However, this must be done with the right software. A single copy-paste won't work in this way. In here, we will use DMG Editor as example, which can directly write .dmg file to external drive like hard drive, SSD and USB stick. Moreover, DMG Editor allows the users to open and extract the DMG files on both Windows and Mac operating systems.


Step 1: Run UUByte DMG Editor and Connect External Drive

Download and Install UUByte DMG Editor on your Mac and make sure to perform the task from its official site. Plug your external drive to Mac and launch UUByte DMG Editor on your Mac. On the main interface, you will get Burn and Extract options. Click the Burn section, and then click on the Next button.

Step 2: Import .dmg File

Now, import the downloaded file of macOS Big Sur into DMG Editor by clicking on the Browse button. Also ensure that the external drive is detected by this application, if not, then reconnect the drive to Mac.

Step 3: Burn macOS Big Sur .dmg to External Drive

After uploading the OS files, you need to click on the Burn button and within a short time, the burning process will be completed. Once it is done, you will get a successful message on your Mac screen.

The burning process is completed and a bootable drive is ready to use. Now, you need to boot this drive to install macOS Big Sur. The comprehensive steps are provided below.

Part 4: Install macOS Big Sur on an External Hard Drive or SSD

Step 1: Connect the external drive to your Mac.

Install windows 7 on mac external hard drive

Install Macos On External Hard Drive From Windows

Step 2: Shut down your Mac and then turn it on. Make sure to press the Option key at booting. Now, select the bootable external drive and then press the Return key.

Step 3: Your Mac will restart few times, and then it will direct you to Recovery Mode; click on the Utilities, and further click on Reinstall macOS.

Step 4: Now, provide the installation path, i.e. your external hard drive, and then click on the Install button. Wait for a while as the installation process will take some time.


Step 5: Once the installation of macOS Big Sur on an external drive is completed, you will be directed to the setup page, and here you need to click on the Continue button.

Step 6: Next, you need to Sign-in with your Apple credentials to sync the files on the iCloud. Now, click on the Get Started button and configure the Big Sur as per your convenience.

Install Macos On External Hard Drive From Windows

Once the setup is completed, you can always boot into macOS Big Sur by pressing Option key at booting stage. This is much more safe and convenient to install macOS on internal drive of your Mac.

Part 5: Troubleshooting Guide

We have tested the whole process throughly on an MacBook Pro and iMac. However, you might experience some error before or after installation process. We have gathered a few common issues according to user feedback and provide useful suggestions to fix it. Please read more and check it out!

Note: macOS Big Sur can be only installed on supported Macs according to Apple Official document. You have to make addition adjustment if you want to install it on unsupported Mac. And you will receive error message more frequently than supported Mac. Please keep this in mind.

Install Macos On External Hard Drive From Windows To Mac

Q: External drive is not bootable

A: All Macs with T2 chip will have this issue if Startup Security Utility is enabled on your Mac. This mostly happens on MacBook Pro with Touchbar. Please follow this guide to turn on the options to allow Mac booting from external media.

Q: The Operation couldn't be completed. (BIErrorDomain error 8)

A: Make sure your Mac is connected to Internet. If the error still exists, erase the external drive to HFS+ instead of APFS as we suggested in Part 1. After that, download the latest Big Sur beta and create the bootable installer once more time.

Q: A software update is required to use this startup disk.

A: This error means you just try to install an out-dated version of Big Sur. Please download the latest version and follow the instructions to make a bootable installer.

Install Windows 7 On Mac External Hard Drive

Q: Installation completed successfully but frozen.

A: Wipe clean the external drive in Disk Utility and create a fresh bootable installer. And repeat the above process. If this does not work and you really want to use macOS Big Sur, please backup your internal drive and install Big Sur on it with a new partition (if the volume is big enough).

Install Macos On External Hard Drive From Windows 10


Install Windows On External Hard Drive From Mac

So, these were all about the way to install macOS Big Sur on an eternal drive. The method is pretty simple and all you need a bootable USB drive and an external hard drive to accomplish the task. You can simply create a bootable USB drive using DMG Editor because it takes less time and gives the desired output.