How to Install and Use macOS Sierra on an External Drive

Last Updated: Feb 23, 2024 by

If you’re a Mac user, you may have heard about the latest operating system, macOS Sierra. This new system offers a range of new features and improvements, making it a highly desirable upgrade for many users. However, some users may not want to upgrade their main system and would prefer to install and use macOS Sierra on an external drive. In this article, we will guide you through the process of installing and using macOS Sierra on an external drive.

Preparing for Installation

Before you begin the installation process, make sure you have an external drive with at least 16GB of free space. You will also need to download the macOS Sierra installer from the App Store. Once you have these requirements, follow these steps:

  1. Connect your external drive to your Mac.
  2. Open the “Applications” folder and find the “Install macOS Sierra” file.
  3. Right-click on the file and select “Show Package Contents.”
  4. Navigate to the “Contents” folder and then the “Resources” folder.
  5. Look for the “createinstallmedia” file and double-click on it to launch the Terminal.
  6. In the Terminal window, type in the following command: sudo /Applications/Install\ macOS\ –volume /Volumes/ExternalDriveName –applicationpath /Applications/Install\ macOS\
  7. Press “Enter” and enter your administrator password when prompted.
  8. The process will take some time to complete, and you will see a message saying “Done” when it is finished.

Installing macOS Sierra on the External Drive

Now that you have prepared the external drive, you can proceed with the installation process. Follow these steps:

  1. Restart your Mac and hold down the “Option” key while it is booting up.
  2. You will see a list of available drives to boot from. Select the external drive with the name “Install macOS Sierra.”
  3. The installation process will begin, and you will be prompted to select a language.
  4. Follow the on-screen instructions to complete the installation process.
  5. Once the installation is complete, your Mac will restart, and you will see the setup screen.
  6. Follow the setup process as you would for a new Mac.

Using macOS Sierra on the External Drive

To use macOS Sierra on the external drive, simply restart your Mac and hold down the “Option” key while it is booting up. Select the external drive with the name “macOS Sierra” to boot from it. You can now use macOS Sierra on your external drive without affecting your main system.


If you encounter an error message saying “An error occurred while preparing the installation” during the installation process, try the following solutions:

  • Make sure your external drive is formatted as “Mac OS Extended (Journaled).”
  • Try using a different external drive.
  • Restart your Mac and try the installation process again.

If the error persists, you may need to contact Apple Support for further assistance.


By following these steps, you can easily install and use macOS Sierra on an external drive. This allows you to experience the new features and improvements of the latest operating system without affecting your main system. Have you tried this method? Let us know in the comments.

Gulrukh Ch

About the Author: Gulrukh Ch

Gulrukh Chaudhary, an accomplished digital marketer and technology writer with a passion for exploring the frontiers of innovation. Armed with a Master's degree in Information Technology, Gulrukh seamlessly blends her technical prowess with her creative flair, resulting in captivating insights into the world of emerging technologies. Discover more about her on her LinkedIn profile.