How to create a bootable macOS Big Sur USB installation drive

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There are all kinds of reasons why you might want to create a bootable macOS Big Sur USB installation drive. For example, if you often have to perform updates or a clean install of macOS on multiple Macs, having a bootable installation drive can make your task fairly straightforward. Not to mention, it can also help if you ever want to downgrade from macOS 12 Monterey beta and go back to the stable version of macOS Big Sur. With that said, let me show you how to create a macOS bootable install drive.

How to create a bootable macOS Big Sur USB installation drive (2021)

First things first, make sure you have a USB flash drive with at least 16GB of storage space. A USB drive with a USB-C connector should be the preferred option considering that all modern Macs come with USB-C. In terms of both speed and efficiency, SanDisk flash drives are top-notch. You can choose the Sandisk 64GB Ultra Flair for $ 11 and the Sandisk 64GB Ultra Dual Drive Luxe for $ 13.89 at Amazon.

Note that you will need to erase your disk and format it to Mac OS Extended (Journaled). You can do this in the Disk Utility application located in the Applications -> Utilities folder. Use the following table to learn how to create a bootable macOS Big Sur USB installation drive.

Download the macOS Big Sur setup software

Another essential requirement is the Installation of macOS Big Sur software that you can download from the Mac App Store.

  1. Launch the Mac App Store and search for macOS Big
  2. Now, click on the ” Get” button.
  3. Then the Software Updatesystem preference will open. Click the ” Download” button to begin downloading the macOS Big Sur installation software.

Once the download is complete and the installer starts, make sure you don’t click the Continue button. You can exit the installer by pressing the Command + Q shortcut. Next, head over to the Applications folder to check the “Install macOS Big Sur” application, which you can use to create the boot drive.

Use terminal to create a bootable macOS Big Sur drive

Terminal makes it easy to turn an external drive into a bootable macOS installer. So even if you are not very familiar with it, you can get the job done with ease.

  1. To get started, connect the US drive to your Mac. It is important to note that in this guide, I have used “Drive” as the name of the external drive. You can change “Unit” to the name of your unit for ease of use. Then, launch Terminal(Applications -> Utilities -> Terminal) application. You can use Spotlight to get started quickly.
  2. Now, select and copythe following command:

sudo / Applications / Install macOS Big Sur.app/Contents/Resources/createinstallmedia –volume / Volumes / Drive – / Applications / Install macOS Big Sur.app

  1. Next, paste the copied codeinto Terminal on your Mac. Make sure to change “Handle”to the name of your USB drive. Then, press the Return key.
  2. If prompted, enter the system password and press Return. Terminal may warn you that your external USB drive will be erased. You have to type “Y”and press Return to continue.
  3. Now, an alert may appear saying: “Terminal wants to access files on removable volume”. Click ” okey” in the pop-up window.

Terminal will purge your USB drive and then copy the Big Sur installation file to your drive. The whole process may take several minutes. At the end, you will see a message that your drive is ready for use in Terminal. You can also use Terminal to create the macOS Big Sur ISO file if you want.

How to start macOS Big Sur from the USB installation drive

Once you’ve created the macOS Big Sur bootable installation drive, you can start your Mac from it with ease. We are now very close to moving from macOS 12 beta to macOS 11 Big Sur. Follow the steps below:

  1. Make sure the external drive is connected to your Mac. Then, restart your Mac and hold down the Alt / OptionYou must press the key when the Apple logo first appears on the screen and until the Startup Manager opens.
  2. When the Startup Manager appears, select your external drive. Now, your Mac will boot into Recovery Mode, and a window with four options will appear.
  3. To install Big Sur and keep your data intact, select Install macOS Big Sur.However, if you want to start over and erase the data, go to ” Disk Utility” and then install macOS Big Sur.

If you enter Disk Utility, format your hard drive and then exit the application. It will take you back to the recovery mode window, where you can perform the operating system installation.

Update the macOS installation drive

Sometimes you may need to update the installation drive to use it to do a clean install of macOS Big Sur on your Mac machine.

  1. Plug in your external driveand then restart your Mac and hold down the Option key while Mac starts up (when you see the Apple logo on the screen).
  2. Your Mac will then display the Startup Managerwith the available boot drives. Now, click on the external drive and hit Return. Then a pop-up window will appear saying: “A software update is required to use this startup disk. You can upgrade now or select another startup disk. ” Click the Updatebutton.

When the update starts running, your macOS device will reboot. Please note that the update will take several minutes to complete.

Change Mac security settings to use an external startup disk

macOS comes with a security setting to disallow the external startup disk. If enabled, you will need to change the security settings to allow booting from external USB or removable media drives.

  1. To get started, restart your Mac. After that, press and hold Command + Rduring the boot process to put your Mac into recovery mode.
  2. Now your Mac will start up with a macOS Utilities Window. Click on the ” Utilities” menu and choose ” Launch Security Utility “.
  3. Next, an alert will appear saying: “Authentication required. You will need to authenticate as an administrator to change the boot security settings “. Then, click on ” Enter macOS password“, and enter username and password.
  4. In the Allowed bootable media section, check the “Allow booting from external or removable media” button. Then restart your Mac and follow the steps above to boot from the USB drive.

Create and use a bootable macOS USB installation drive

Well that’s it! So here’s how you can create and use a bootable macOS Big Sur USB installation drive. The same process also works for older generation versions of macOS. With a bootable USB installation drive at your disposal, it’s easy to do a clean install of macOS on your Mac machine. If you have to update or clean the operating system most of the time, this should be the preferred way to go.

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by Abdullah Sam
I’m a teacher, researcher and writer. I write about study subjects to improve the learning of college and university students. I write top Quality study notes Mostly, Tech, Games, Education, And Solutions/Tips and Tricks. I am a person who helps students to acquire knowledge, competence or virtue.

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