How to Create a High Sierra Bootable USB

Creating a bootable macOS High Sierra USB installer offers a convenient way to deploy the OS across multiple Macs without repeated downloads. This guide details the process, providing options for both startup and non-startup drive installations.

Prerequisites for a Bootable High Sierra USB Drive:

1. USB Flash Drive (16GB minimum): A blank USB drive with sufficient storage is essential.
2. Reliable Internet Connection: Downloading the High Sierra installer (approximately 5GB) requires a stable connection.
3. External Hard Drive (Recommended): Back up your data before proceeding to avoid data loss. The external drive should have at least the same capacity as your Mac's internal storage.
4. Time: Allocate about an hour or two for the entire process.

Preparing Your Mac:

Begin by optimizing your Mac's performance. Removing unnecessary files and applications using a utility like MacKeeper can improve efficiency before backing up.

Backing Up Your Data:

1. Connect your external hard drive.
2. Access System Preferences → Time Machine.
3. Enable Time Machine and select your external drive as the backup destination.
4. Time Machine will prompt you to reformat the external drive; confirm to proceed.

A detailed Time Machine backup guide is available elsewhere.

Downloading the macOS High Sierra Installer:

1. Open the App Store.
2. Search for "High Sierra" and download the installer. The installer ("Install macOS High Sierra") will be in your Applications folder. Quit the installer after download.
3. If you've already upgraded, locate the installer in the App Store's Purchased section.
4. Alternatively, use a direct download link (if available).

Prepare your chosen external drive (an SSD is ideal, but a 16GB USB drive suffices). Rename it "HighSierra." The system will reformat it for Mac compatibility.

Creating the Bootable Installer (Using Terminal):

1. Connect the "HighSierra" drive.
2. Open Terminal (Applications → Utilities → Terminal).
3. Execute this command: sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/HighSierra
4. Enter your login password.
5. Confirm the drive erasure (Y/N).
6. Choose "Don't use" when prompted about Time Machine backups.
7. Wait for the installer to copy to the drive.

Installation Options:

A. Installing on Your Startup Disk:

This method erases all data on your main drive. Back up your data first!

1. System Preferences → Startup Disk, select the installer.
2. Restart, holding Command (⌘) R for Recovery Mode.
3. Connect your bootable USB.
4. Select "Reinstall macOS" from macOS Utilities.
5. Follow the on-screen instructions.

B. Clean Install on a Non-Startup Drive:

This safer method requires a second drive or partitioned volume.

1. Use Disk Utility to erase the target volume.
2. Download the High Sierra installer.
3. Launch the installer, click "Show All Disks," and select your prepared drive.
4. Follow the installation instructions.

After installation, restore your data from your backup. For a more general guide on creating macOS bootable USBs, refer to other resources. Maintaining sufficient free disk space is crucial; use MacKeeper's Safe Cleanup to optimize storage.

The above is the detailed content of How to Create a High Sierra Bootable USB. For more information, please follow other related articles on the PHP Chinese website!