How to Boot from USB on a Mac Computer
Boot from a USB drive on your Mac computer is a useful method for upgrading your operating system, repairing issues with your current OS, or even installing a completely new system. This guide will walk you through the process of creating a bootable USB drive using the latest version of Mac OS X.
Steps to Create a Bootable USB Drive on a Mac
1. Download the Installer from the App Store
The latest versions of the Mac operating system, such as Mac OS X Lion, are only available through the App Store. Start by downloading the installer from there. The process may take some time depending on your internet connection. Keep a backup of the installer file and save it to your desktop. It's critical to work with a copy, not the original installer file, to avoid any risks of corruption.
2. Prepare the USB Drive
Use the backup file to prepare a USB drive that can boot from the installer. Here are the detailed steps to follow:
Insert your USB drive into the Mac computer. Open the Finder and select the USB drive from the sidebar. Right-click on it and select Get Info. Ensure the USB drive is not in use and remove any files if necessary. Open Disk Utility (found in the Utilities folder within your Applications folder). Select the USB drive from the left pane in Disk Utility. Click on the Erase tab to erase the USB drive. Make sure it is partitioned as HFS (Mac OS Extended). Enter a name for the USB drive, typically Macintosh HD. Click on the Erase button in the bottom right corner to begin the erasure process. Wait for the USB drive to be erased and restored to a clean and usable partition.3. Copy the Installer to the USB Drive
Now, you will copy the installer file to the USB drive:
Navigate to the Contents SharedSupport folder within the downloaded installer. Find the disk image file called This is the file you need to copy to the USB drive. Click on the magnifying glass icon in the menu bar and type InstallESD. Drag the file to the Finder window. Return to Disk Utility, and in the left pane, click on the Copy To Disk Utility menu. In the bottom-left corner of the Disk Utility window, drag the file from the source list to the USB drive. Click on the Restore tab in the center-top part of Disk Utility and hit Restore to begin the process. This can take some time, so be patient. Once the restore process is complete, close Disk Utility.4. Boot from the USB Drive
To boot from the USB drive, follow these steps:
Restart your Mac computer. While restarting, hold down the Option key. A list of available boot volumes will appear. Select the Installer app and click on it. You will then be able to proceed with your chosen action, such as verifying/diagnosing disk issues, repairing the current OS, upgrading to a new version, or performing a clean install of the macOS.Conclusion
By following these steps, you can create a bootable USB drive on your Mac computer to aid in various system operations. This method is particularly useful for users who do not have access to a physical installation disc or need to troubleshoot issues with their system.