Installing macOS on an external drive can be a useful solution for those who want to have a portable version of their operating system that can be used on multiple computers or as a backup. In this guide, we will explain the steps required to properly install macOS on an external drive.

Preparing for Installation

Before embarking on the installation process, ensure that you have an external drive that is larger than 12GB, a stable internet connection, and a copy of the macOS installation file. Additionally, ensure that you have backed up all your data on the external drive as the installation process will erase all data on the drive.

Check Your External Drive

To ensure that your external drive is compatible with your Mac, plug it into your computer and go to “About This Mac >> System Report >> Hardware >> USB.” If the drive is listed, then it is compatible with your Mac.

Download the macOS Installation File

To download the macOS installation file, go to the App Store, search for “macOS,” and click “Get.” Once the download is complete, you will be prompted to install the file. Do not install the file as it is; instead, copy it to a folder on your desktop.

Creating a Bootable External Drive

To create a bootable external drive, you will need the following:

  • A Mac with an available USB port
  • A USB drive that is at least 12GB in size
  • A copy of the macOS installation file
  • An app called “DiskMaker X”

A key takeaway from this text is that in order to install macOS on an external drive, you need to ensure that the external drive is larger than 12GB, have a stable internet connection, and have a copy of the macOS installation file. You will also need to create a bootable external drive using an app called “DiskMaker X”. Additionally, if you encounter errors during the installation process, you can troubleshoot by restarting your Mac, checking that your external drive is formatted correctly, and downloading the installation file again from the App Store.

Download DiskMaker X

To download DiskMaker X, go to the developer’s website and download the latest version of the app.

Create the Bootable External Drive

Insert your USB drive into your Mac and launch DiskMaker X. Follow the prompts to select the macOS installation file and the USB drive. Once the process is complete, you will have a bootable external drive.

Installing macOS on the External Drive

With the bootable external drive ready, you can now proceed to install macOS on the drive. Follow the steps below:

Key takeaway: Before installing macOS on an external drive, ensure that the drive is larger than 12GB, backed up, and compatible with your Mac. Download the macOS installation file from the App Store and use an app like DiskMaker X to create a bootable external drive. During the installation process, select the external drive as the destination, and troubleshoot errors by restarting your Mac, checking that the drive is formatted correctly and compatible with your Mac, and deleting and re-downloading the installation file.

Connect the External Drive to Your Mac

Plug the bootable external drive into your Mac and restart your computer. As your computer restarts, hold down the “Option” key until the startup manager appears.

Select the External Drive

Use the arrow keys to select the external drive and press enter. The installation process will begin, and you will be prompted to select your language and agree to the terms and conditions.

Select the External Drive as the Destination

When prompted to select a destination for the installation, select the external drive that you created earlier. Follow the prompts to complete the installation process.

Troubleshooting the Installation Process

Sometimes the installation process may encounter errors. Below are some common errors and how to troubleshoot them.

“The macOS Installation Couldn’t Be Completed” Error

This error occurs when the installation process cannot complete the installation successfully. To troubleshoot the error, try the following:

  • Restart your Mac and try the installation process again.
  • Check that your external drive is formatted correctly.
  • Delete the installation file and download it again from the App Store.

“The Selected Disk Is Not a Valid Target” Error

This error occurs when the installation process cannot recognize your external drive. To troubleshoot the error, try the following:

  • Check that your external drive is formatted correctly and that it is compatible with your Mac.

FAQs for How to Install Mac OS on External Drive:

What are the benefits of installing Mac OS on an external drive?

Installing Mac OS on an external drive can offer various benefits, including more storage space, the ability to carry your operating system and files with you on the go, and the freedom to experiment with a new OS version without affecting your primary system. Additionally, if your primary drive fails, you can still access your files and data from the external drive.

What do I need before I start the installation process?

Before you start the installation process, you will need an external drive with enough space to accommodate the Mac OS installation (at least 16GB). You will also need a Mac device with at least one USB port or Thunderbolt port, a reliable internet connection, and a copy of the Mac OS installation file.

How do I create a bootable USB or installer for Mac OS?

To create a bootable USB or installer for Mac OS, you can use the Disk Utility application provided with your Mac device. Open Disk Utility, select your external drive, choose the Erase tab, and choose “Mac OS Extended” as the format. Then, open the Terminal app, type the command “sudo /Applications/Install\ macOS\ [OS name].app/Contents/Resources/createinstallmedia –volume /Volumes/[volume name]” and press enter. This will create the installer on the external drive.

How do I boot up my Mac from the external drive?

To boot up your Mac from the external drive, connect the drive to your Mac, restart your device while holding down the Option key, and select the external drive as the boot device. The Mac will automatically boot up from the external drive.

Can I install Mac OS on an external hard drive that already contains data?

Yes, you can install Mac OS on an external hard drive that already contains data. However, before proceeding with the installation, you need to back up all the important data and files from the drive, as the installation process will erase the drive.

What should I do if the installation process fails or encounters errors?

If the installation process fails or encounters errors, try restarting your Mac and re-attempting the installation process. If the issue persists, check if the external drive is formatted correctly and make sure that you have a reliable internet connection. You can also try resetting the System Management Controller (SMC) and the Non-Volatile Random Access Memory (NVRAM) on your Mac device. If you still cannot install Mac OS on your external drive, contact Apple support for further assistance.

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