Welcome to this Masterclass episode, on how to setup, install and run
macOS Big Sur, on an External Disk.
We call this a Masterclass episode, because we’re going to be showing, two methods, the entire steps,
from start to finish, to successfully setup and run macOS Big Sur,
on an external disk.
Furthermore, after we’ve done playing around with macOS Big Sur,
we’ll show the entire process, on how to re-format, the external disk,
the right way, to its original state.
Before we begin, a few notes and tips, that’s purely optional to follow.
1. First and foremost, as a cautionary note.
Make sure to make a backup of your current computer, using for example, Apple Time Machine
2. Make sure your current computer, is able to run macOS Big Sur.
Using a late 2014 Mac Mini,
was on the list of compatible computers.
Attempting to download macOS Big Sur, from the App Store,
on an un- compatible computer, you’ll get the following pop-up window.
3. Make sure that your computer is up-to- date, with the latest macOS,
that you’re currently using, on your computer.
In our case, we’re using the latestmacOS Catalina 10.15.7
4. Using a fast SSD, helps in the experience of running macOS Big Sur,
from an external disk, the faster the better.
5. Turn Wi-Fi Off or Disconnect Ethernet Cable if connected.
We noticed that adding Wi-Fi or Ethernet connected, made the install take longer, at least in our install.
made the install take longer, at least in our install.
Anyway, we’ve got lots to cover.
Soooooo, Let’s Get Started.
Therefore, with all the necessary notes and tips taken care of,
let’s begin with one of the two methods, to install and run macOS Big Sur on an external disk.
Both Methods, takes roughly the same amount of time to complete.
Therefore, let’s start with Method 1.
Which Involves using a macOS Big Sur USB Installer,
to install macOS Big Sur on an external disk.
We’ve already covered, on a previous episode, how to create a macOS Big Sur USB installer.
The link, can be found in the description below,
or on the card link, shown in the top right hand corner of the screen.
Next, prepare the blank external disk.
Launch Disk Utility, click on your external disk on the sidebar.
And then, rename and format the disk toMac OS Extended (Journaled).
We’ll just rename it to “Macintosh EXT HD”.
Therefore, assuming you’ve already created a Big Sur USB Installer,
as mentioned earlier,
with the USB Installer connected to the computer, turn off your computer.
Now, while holding down the Option Key, power on the computer,
and continue holding down the Option key, until the boot screen appears.
Click and select the macOS Big Sur Installer icon, shown here.
On the recovery window, click on macOS installer Tab and then click the Continue button, here.
After agreeing to the terms, connect the external disk, to the computer.
Click on the external disk icon, then the continue button.
Now, the installation of macOS Big Sur, will begin on the external disk.
I'll just speed up the process, from here.
The computer will boot twice, to your current macOS login screen window, as shown.
On both occasions, shut down the computer, by clicking on the Shut down icon here.
Just like before, while holding down the Option key,
turn the computer back on, till you see the boot screen options.
And again, on both occasions, select andclick the “Macintosh EXT HD” icon,
to continue the install process.
After about 45 Minutes or so.
You’ll finally be shown the screen to enter your user details, complete as shown.
Once complete, you will be brought to the macOS Big Sur desktop.
An additional step is needed to complete the the setup.
By default, after installing macOS Big Sur, on the external disk,
it’s selected as the default boot computer.
We need to change that.
In order for the boot order to be the main computer,
which in our case, is currently running macOS Catalina,
do the following.
Launch, System Preferences and click on the Startup disk icon,
and after entering your password,
select your main computer as the first boot disk, then restart your computer.
As you’ll notice, the computer booted into macOS Catalina, as required, by default.
Now, anytime you want to run macOS Big Sur, from the external disk, do the following.
Like before, while holding down the Option Key,
power on the computer and continue holding down the Option key until the boot screen appears.
Click and select the “Macintosh EXT HD” icon, to begin running Big Sur, from the external disk.
That takes care of METHOD 1
Moving right along,
Method 2 Involves, launching macOS Big Sur installer, directly from your computer.
Therefore, after downloading macOS Big Sur from the App Store,
lets prepare the external disk, as was shown in Method 1.
With the external disk connected to your computer, in our case, named, “Macintosh EXT HD”
Launch the macOS Big Sur installer.
Select the external disk icon, and after clicking the continue button, theinstallation of Big Sur will begin.
Unlike Method 1, the install process is seamless.
No human interactions, needed.
After about 40 Minutes, or so,
You’ll be brought to entering your details as was shown in method 1.
I'll just speed up the process from here.
Again, like before, choose your computer boot order.
That takes care of Method 2.
Don’t go away just yet, one more thing
or I should say, one more important thing.
To format or revert the external disk, to itsoriginal state,
after you’re done playing around with macOS Big Sur, you’ll need to do the following.
Using the usual erase or format process in Disk Utility,
we were unable to erase or format the external disk.
In order to do so, executing a Terminal command was necessary, as follows.
After logging on to your main computer, do the following.
Step 1: Eject the external disk.
Step 2: Launch Terminal and enter the following command: diskutil list
It’s very important that you pay special attention and note the Identifier of your computer.
As you’ll notice, in our case, these are the disk identifiers for our main internal disk computer.
Step 3: Connect your external disk to the computer and as was done before, issue the following command:
Take note of your external disk identifier, in our case, our disk identifier is, disk2s2
Step 4: Issue the following command, using your noted disk identifier,
to re- format the external disk.
All Terminal Commands, is included in thedescription below.
Since our External Disk Identifier is disk2s2,
we’ll add it to the end of the command, shown above:
After pressing return, the erase process for the external disk will begin.
Step 5: Launch Disk utility, and you’ll notice, and you’ll notice, you’re able to rename or format the external disk,
as usual.
You now have two methods to setup and run macOS Big Sur from an external disk.
Use the Method that you feel comfortable with,
the choice is entirely up to you, both Methods work.
And that’s all there is to it.
Thanks for watching
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Peace.