Many owners of Apple computers sometimes have to run the Windows operating system for work, games or other tasks. The built-in macOS mechanism for quick and easy installation of a third-party OS is not always suitable for this.
If you try to install Windows via Boot Camp on computers with a 128 GB drive, the utility will politely ask you to free at least 42 GB! Following this logic, to install the second OS, you need to remove all applications and data from the first.
You can try installing the system on an external drive, but this is not possible in recent versions of macOS.
BootCamp on macOS Catalina will not even start if an external drive is connected to the Mac.
There is not the easiest, but working way to install Windows 10 on an external drive, for this we need another Windows (in a virtual machine).
📍 Thank you re: Store for the helpful information. 👌
All manipulations will require a minimum of 30 GB of free space. A little more than 20 GB will be required for temporary installation of the virtual machine, and another 5-6 GB will take a Windows image and related files.
Topic: how to install macOS on an external drive
The installation process is not the most intuitive and some steps that were not required before will have to be done. This is how the general installation algorithm looks:
1. Prepare your Mac to boot from an external drive.
2. Prepare a removable drive for installing Windows.
3. Download all the necessary data.
4. Install Windows 10 on an external drive.
All this will take no more than an hour.
How to prepare a Mac with a T2 chip
New Apple computer models are equipped with a special T2 chip, one of the features of which is to prevent the computer from loading from an external drive. These Mac models are equipped with a similar thing:
▪️ iMac Pro
▪️ Mac mini (2018)
▪️ MacBook Air (2018 and later)
▪️ MacBook Pro (2018 and later)
▪️ Mac Pro (2019)
There is a solution, it will just reboot in recovery mode and allow booting from external drives.
We already wrote about this in detail in this article.
How to prepare a removable drive
Any drive with a capacity of 16GB is suitable. Depending on the tasks, you can install Windows even on a USB flash drive. USB 3.0 speed will be enough to work in simple applications.
The disk on which the system will be installed must first be formatted in exFAT format. This is necessary so that both operating systems can interact with it before recording Windows.
Attention! All data on the removable disk will be deleted. Take care of backups if necessary.
▸ Launch the Disk Utility application
▸ In the side menu, select the drive
▸ Click the Erase button and specify the desired file system
After the procedure, the drive is ready to install Windows.
What you need to download before installation
As mentioned above, the installation will not occur in the most familiar way. Here’s what you need to download in advance:
▸ We take the installation image of Windows 10 from the Microsoft website
▸ Download the free trial version of Parallels Desktop
▸ Download the WinToUSB program from the developer’s site
▸ Do not forget to download drivers and additional files for the operation of all Mac components on Windows. You can do this using the standard Boot Camp Assistant utility. In the menu bar, select Action – Download Windows Support Software.
When all the data is loaded, we can proceed.
How to install Windows 10 on an external drive
1. On MacOS, install the Parallels Desktop application.
2. In the program, create a new virtual machine using the downloaded Windows 10 image.
3. We carry out the initial setup process and wait for the end of the Windows boot to the virtual machine.
4. When Windows starts, transfer the downloaded data to the virtual machine (WinToUSB application and files from Boot Camp Assistant).
5. In the Windows environment, install the WinToUSB program.
6. Connect the external drive to the computer and redirect it to Windows in the Parallels Desktop dialog box.
7. In the WinToUSB menu, specify the Windows 10 image (this is the same image from which we created the virtual machine, it can be copied to Parallels Desktop or opened through a shared folder).
8. As the target disk, indicate the connected drive.
9. We wait about 15-20 minutes before the installation of Windows to an external drive is completed.
10. After installation, copy the files from Boot Camp Assistant to the root folder of the external drive with Windows 10 installed.
11. End the Parallels Desktop application and restart the Mac.
12. While the computer is booting, hold down the Option (Alt) key to enter the drive selection menu.
13. Specify the external drive and start Windows 10.
14. During startup, perform the initial installation of the system. Depending on your Mac model, you may need a wired USB keyboard and mouse.
15. After the first start, we install the drivers and related software from the copied Boot Camp Assistant files.
Congratulations! You received the installed Windows 10 operating system on an external drive. The drive can easily be connected to another Mac and boot from it (do not forget to disable protection on models with a T2 chip).
MacOS now allows you to uninstall the virtual machine and Parallels Desktop application.
This is how you have to get out of the situation that developers from Cupertino are driving users into.