Can You Install Mac Os On An External Hard Drive

Sep 08, 2021 • Filed to: Solve Mac Problems • Proven solutions

The macOS Sierra is a wonderful operating system - and easily the best for all Apple computers and laptops. If you have a Mac, then you probably cannot wait to get your hands on the Sierra - provided your system supports it. However, even if your Mac does support Sierra, there may be a few reasons as to why you may not be able to install it on your hard disk.

Macs are already expensive, and many people (including myself) simply don't have the budget to upgrade the storage! SSD upgrades from Apple are quite expensi. To get started you’ll need the Install macOS Monterey beta application and an external storage drive of 16GB or larger. A USB stick is usually best for this, but you could also use an SD card (if your Mac has an SD card slot), a partition on a larger external hard drive, or another kind of external storage drive. First, either download (from macOS App Store) or copy the file to the desktop (from external media) a copy of macOS Next, connect the external drive you wish to install macOS on, then mount the DMG file containing the installer Open the mounted dr.

  • The next time you restart that Mac, it will boot to main, internal hard drive as normal. (Or you can hold Option and boot to the external drive again, if needed.) Now, you can install iTunes and M4VGear on your external hard drive and then smoothly convert iTunes videos as before.
  • Disk Utility can be used to format external drives as well. It’s easy to reformat your hard drive using Disk Utility in macOS or OS X. If your Mac doesn’t work, you can do this using a second Mac and an external hard drive caddy. Otherwise, you can skip this step and do it from the Utilities page during the macOS or OS X installation.

For starters, it takes around 8GB of storage space. While that is the minimum recommended by Apple, you will probably need a bit more to make use of it. In addition to that, if you are using an older Mac, then you will still face a few issues while running Sierra. You also have to back up the entire system before installing macOS Sierra, which is a must-do step in any update. For those who have a lot of data on their Macs, this can be a very lengthy procedure.

However, there is a solution to all of that. You can simply go ahead and install the macOS Sierra on an external hard drive, and then boot your Mac from that!

The Prerequisites

There is no doubt about the fact that you will save a lot of trouble and hassle if you install the macOS Sierra on an external drive. It will even let you use the same hard drive with multiple Macs, without updating to Sierra on each of those. However, to begin with, this, you will need an external hard drive. Since Apple only requires you to have a little over 8 GB of free space, any hard drive, even one with 128 GB, will do just fine. For better performance, it is recommended that it be an SSD.

It must be better if you can format the external hard drive beforehand to make it compatible with your Mac.

You will also have to download macOS Sierra from the Mac App Store. To do that, just open the App Store on your Mac, and search for macOS Sierra. You can also download macOS Sierra by directly clicking on the link from your Mac. If your Mac is compatible, then the download option will appear. Click on it, and the download will begin.

The download size is around 5GB, and the total time may vary depending on your internet connection as well as Apple’s servers.

Once you have a hard drive, you can go ahead and follow the simple steps to install and use macOS Sierra from your external drive.

Part 1. Installing macOS Sierra on the external drive

1. Preparing the hard drive for the installation

Before you install macOS Sierra on the hard drive, you will need to clean the external device. Ensure that there is no important data on your hard drive. Then plug it into your Mac, go to Finder, and select Applications.

From Applications, go to Utilities and from there, find and double click on Disk Utility. In the Disk Utility tab, select the external hard drive that is connected to the Mac, and then click on Erase at the top.

Now rename it to something like sierra that you will remember, choose 'Mac OS Extended (Journaled)' in the format, and then click on Erase. Once the process completes, click on Done, and you are ready to begin the installation.

2. Creating the bootable drive

New hard drive os install

Once your hard drive is formatted, you will need to turn it into a bootable drive. Before you begin this, you will require the Administrator access on your Mac.

Related: Wanna access Mac data without reinstalling it? Go there and boot Mac up to recover data easily.

Step 1 Go to Finder to open the window, and from the left side, select Applications.

Step 2 From the application's Window, find and click Utilities, and from there, go to Terminal.

Step 3 Now, remember the name that you set for formatting your external drive (i.e. sierra). In case you named it something other than sierra, then make the appropriate changes in the following text. Once you are in the terminal, enter the following text, ensuring to use your drive’s name wherever Volumes/Sierra is written.

sudo /Applications/Install macOS --volume /Volumes/sierra --applicationpath /Applications/Install macOS –nointeraction

Step 4 When you tap enter, you will be asked the password for the administrator account. As you type the password, no text will be there in the terminal window. Depending on the drive, this process could take a while. Once the window reports ‘Done’, you can close the drive.

Part 2. Using macOS Sierra with the Bootable Hard Drive

Once the above step completes, your external hard drive will be ready to run macOS Sierra on any compatible Mac. First, you have to turn off the Mac on which you want to run Sierra from the bootable drive. Then, before switching it on, connect the drive through the Mac’s USB Port.

Then turn on your Mac, and as soon as you hear the startup sound, press the Option key and keep it pressed. Within a few seconds, you will get a screen that asks you to select the appropriate hard drive for booting. On this screen, select the one on which you have installed macOS Sierra, and you will soon have your Mac running Sierra!

Thus, as you follow these simple steps, you will have configured the macOS Sierra to run from an external hard drive. You do not have to worry about how much free space there is in your Mac or anything else of the sort. Through this approach, you can run macOS Sierra on any compatible Mac without having to separately download and install it on either one. In addition to that, since there are no backups of the mac’s hard disk required, the process will involve comparatively less hassle.

Any changes or files that you make can be stored on your Mac as well, so you do not have to worry about where your data is. This can be a great way to have the same OS on your personal as well as work Macs. Thus, now, you do not have to bother about freeing up your Mac’s drives or separately downloading it for every PC in the house- just configure it once on an external hard drive, and everything else is taken care of!

Whenever and however you lost your data, keep it in mind that you're able to retrieve data back from Mac by the means of data recovery software like Recoverit. It is the data recovery tool to help you retrieve all kinds of data from various devices.

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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.

Can i install macos on external drive

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.

Can you install mac os on an external hard drive download

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.

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.

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.


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.

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).

Can You Install Mac Os On An External Hard Drive Program


Can You Install Mac Os On An External Hard Drive Free

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.