Are you looking to upgrade your Mac’s operating system or perform a clean install? One of the most convenient ways to do this is by installing macOS from an external hard drive. This method allows you to boot up your Mac from the external drive, giving you the flexibility to install a new version of macOS or troubleshoot issues with your current installation. In this article, we’ll take a closer look at the process of installing macOS from an external hard drive, including the requirements, preparation, and step-by-step instructions.
Requirements and Preparation
Before you begin, make sure you have the following:
- A Mac computer with a USB port (preferably USB 3.0 or later)
- An external hard drive with a capacity of at least 16 GB (32 GB or more recommended)
- A USB cable to connect the external hard drive to your Mac
- The macOS installation files (available from the Mac App Store or Apple’s website)
- A valid Apple ID and password
It’s also important to note that not all external hard drives are compatible with macOS. Make sure your external hard drive is:
- Formatted as Mac OS Extended (Journaled) or APFS
- Connected to your Mac via a USB port (not Thunderbolt or FireWire)
- Powered on and recognized by your Mac
Choosing the Right External Hard Drive
When selecting an external hard drive for installing macOS, consider the following factors:
- Speed: Look for an external hard drive with fast read and write speeds, such as a solid-state drive (SSD) or a hard disk drive (HDD) with a high RPM.
- Capacity: Choose an external hard drive with enough capacity to hold the macOS installation files and any additional data you want to transfer.
- Compatibility: Ensure the external hard drive is compatible with your Mac and the version of macOS you’re installing.
Some popular external hard drive options for installing macOS include:
- Western Digital My Passport
- Seagate Backup Plus
- LaCie Rugged
Creating a Bootable Installer
To install macOS from an external hard drive, you’ll need to create a bootable installer. This involves downloading the macOS installation files and creating a bootable disk image on your external hard drive. Here’s how:
Downloading the macOS Installation Files
- Go to the Mac App Store and download the macOS installation files.
- If you’re using a Mac with macOS High Sierra or later, you can also download the installation files from Apple’s website.
- Make sure you download the correct version of macOS for your Mac.
Creating a Bootable Disk Image
- Connect your external hard drive to your Mac.
- Open the Disk Utility app on your Mac.
- Select your external hard drive from the list of available disks.
- Click the “Erase” button to format the external hard drive.
- Select “Mac OS Extended (Journaled)” or “APFS” as the file system.
- Click the “Erase” button to confirm.
- Open the Terminal app on your Mac.
- Type the following command to create a bootable disk image:
sudo /Applications/Install\ macOS\ [version].app/Contents/Resources/createinstallmedia --volume /Volumes/[external hard drive name] --applicationpath /Applications/Install\ macOS\ [version].app - Press Enter to execute the command.
Installing macOS from the External Hard Drive
Now that you’ve created a bootable installer, you can install macOS from the external hard drive. Here’s how:
Booting from the External Hard Drive
- Connect the external hard drive to your Mac.
- Restart your Mac.
- Immediately hold down the Option (⌥) key.
- Select the external hard drive as the boot device.
- Click the “Continue” button to boot from the external hard drive.
Installing macOS
- Follow the on-screen instructions to select your language and country or region.
- Click the “Continue” button to proceed.
- Select the disk where you want to install macOS.
- Click the “Install” button to begin the installation process.
- Follow the on-screen instructions to complete the installation.
Troubleshooting Common Issues
If you encounter any issues during the installation process, try the following:
- Make sure the external hard drive is properly connected and recognized by your Mac.
- Ensure the external hard drive has enough free space to hold the macOS installation files.
- Try restarting your Mac and booting from the external hard drive again.
- If you’re using a Mac with a T2 chip, make sure the external hard drive is compatible with the T2 chip.
By following these steps and troubleshooting common issues, you should be able to successfully install macOS from an external hard drive. Remember to always back up your important data before attempting to install a new operating system.
What are the system requirements for installing macOS from an external hard drive?
To install macOS from an external hard drive, your Mac must meet certain system requirements. First, your Mac should be compatible with the version of macOS you want to install. You can check the compatibility of your Mac on the Apple website. Additionally, your external hard drive should have enough free space to accommodate the macOS installation files, which can range from 6 to 8 GB depending on the version.
It’s also essential to ensure that your external hard drive is formatted correctly. The drive should be formatted as a Mac OS Extended (Journaled) volume, and it should be set as the startup disk. If your external hard drive doesn’t meet these requirements, you may need to reformat it or use a different drive. You can check the format of your external hard drive by connecting it to your Mac and going to Disk Utility.
How do I prepare my external hard drive for installing macOS?
To prepare your external hard drive for installing macOS, you’ll need to erase and reformat it. Connect the external hard drive to your Mac and go to Disk Utility, which can be found in the Applications/Utilities folder. Select the external hard drive from the list of available disks and click the “Erase” button. Then, select the “Quick Erase” option and click “Erase” to confirm.
Once the erase process is complete, you’ll need to reformat the external hard drive as a Mac OS Extended (Journaled) volume. To do this, select the external hard drive in Disk Utility and click the “Erase” button again. This time, select the “Mac OS Extended (Journaled)” option from the format menu and click “Erase” to confirm. This will prepare your external hard drive for installing macOS.
How do I download the macOS installation files?
To download the macOS installation files, you’ll need to go to the Apple website and click on the “Support” tab. From there, select “Downloads” and then click on the “macOS” tab. You’ll see a list of available macOS versions, so select the one you want to install and click the “Download” button.
The download process may take some time, depending on the speed of your internet connection. Once the download is complete, you’ll see a “.dmg” file in your Downloads folder. This file contains the macOS installation files, which you’ll need to copy to your external hard drive. You can do this by connecting the external hard drive to your Mac and dragging the “.dmg” file to the drive.
How do I create a bootable installer for macOS?
To create a bootable installer for macOS, you’ll need to use the “createinstallmedia” command in the Terminal app. First, connect the external hard drive to your Mac and open the Terminal app, which can be found in the Applications/Utilities folder. Then, type the following command: “createinstallmedia –volume /Volumes/MyVolume –applicationpath /Applications/Install\ macOS\ High\ Sierra.app” (replace “MyVolume” with the name of your external hard drive and “High Sierra” with the version of macOS you’re installing).
Once you’ve entered the command, press Enter to execute it. The createinstallmedia command will erase the external hard drive and create a bootable installer for macOS. This process may take some time, depending on the speed of your Mac and the external hard drive. When it’s complete, you’ll see a bootable installer on the external hard drive, which you can use to install macOS on your Mac.
How do I boot my Mac from the external hard drive?
To boot your Mac from the external hard drive, you’ll need to restart your Mac and hold down the “Option” (⌥) key while it’s booting up. This will take you to the Startup Manager, where you can select the external hard drive as the startup disk. Use the arrow keys to select the external hard drive and press Enter to boot from it.
Alternatively, you can set the external hard drive as the startup disk in the Startup Disk preferences. To do this, go to System Preferences and click on “Startup Disk.” Select the external hard drive from the list of available disks and click “Restart” to boot from it. Your Mac will now boot from the external hard drive, where you can install macOS.
What are the common issues that may arise during the installation process?
During the installation process, you may encounter some common issues, such as the installation freezing or the external hard drive not being recognized. If the installation freezes, try restarting your Mac and booting from the external hard drive again. If the issue persists, you may need to re-create the bootable installer or try a different external hard drive.
Another common issue is the external hard drive not being recognized by your Mac. If this happens, try reconnecting the external hard drive and restarting your Mac. You can also try using a different USB port or a different external hard drive. If none of these solutions work, you may need to seek further assistance from Apple support or a professional Mac technician.
How do I troubleshoot issues with my Mac after installing macOS from an external hard drive?
If you encounter issues with your Mac after installing macOS from an external hard drive, there are several troubleshooting steps you can take. First, try restarting your Mac in Safe Mode by holding down the “Shift” (⇧) key while it’s booting up. This will disable any third-party kernel extensions that may be causing issues.
If Safe Mode doesn’t resolve the issue, try running the Disk Utility app to check for any disk errors. You can also try reinstalling macOS or seeking further assistance from Apple support or a professional Mac technician. Additionally, you can try resetting the System Management Controller (SMC) and the NVRAM to their default settings.