Creating a Bootable Installer: A Step-by-Step Guide

Posted: October 24, 2023

a laptop computer sitting on top of a wooden desk

Introduction

The versatility and performance of macOS make it a go-to choice for many users. Despite its excellent functionalities, like any other machine, a Mac could encounter issues occasionally. One such common issue is when the MacBook Pro won't boot from the internal hard drive, leaving you in a state of panic. This is where a bootable macOS installer comes in handy. This article aims to provide insight into the purpose of a bootable installer and why you might need one for your Mac.

Purpose of a Bootable Installer

A bootable macOS installer allows users to boot their Mac from a USB drive, bringing the non-responsive machine back to life. It is an indispensable tool for troubleshooting hardware and software issues on your Mac. Creating a bootable installer for macOS allows you to:

Reinstall an older version of the macOS on your computer.
Download the newest macOS onto multiple Macs without re-downloading the installer on each computer.
Create an emergency backup disk for unforeseen system malfunctions.
Mount macOS on a newly installed SSD.

The Need for a Bootable Installer

Keeping a bootable installer on hand provides an array of benefits. It allows you to clean install Catalina or any other version of macOS, which implies a complete wipe of your startup disk, necessitating booting from an external drive. It also serves as a protective measure against potential catastrophes that may hit your Mac's startup disk.

Normally, you would boot from the recovery partition to reinstall macOS, which involves re-downloading the installer. However, a bootable installer becomes a valuable alternative if you don't have a stable internet connection. Specifically, users with multiple Mac machines can bypass the time-consuming task of downloading the macOS installer for each device by creating a bootable macOS installer.

Requirements for Creating a Bootable Installer

Creating a bootable installer for macOS requires some preparations. Here are what you need to guarantee success in making a bootable macOS installer for your Mac.

External Drive Considerations

You first need a healthy, operational Mac to create a bootable USB installer. Like a flash drive with at least 15GB of free space, a clean external drive is also a must. Although theoretically, an external hard drive such as SSD and HDD can also serve the purpose, a USB flash drive is always recommended due to its relative speed advantage over standard hard drives.

Furthermore, compatibility plays a critical role. Hence, you should confirm that the USB suits your Mac's ports to ensure successful detection. Remember, different USB ports might affect the speed. Backing up the USB or transferring critical files and then formatting the USB on the Mac will help you acquire a clean flash drive.

Obtaining macOS Installation Files

The next step involves getting a macOS installer compatible with your Mac. This is fundamental as the bootable installer needs to work with your Mac. You should identify your Mac model and check the macOS/OS X versions that it can run. This way, you ensure the macOS installer is appropriate for your Mac.

Direct Links for Specific macOS Versions

Finally, each macOS version requires a specific installer. Be sure to download the installation file corresponding to the macOS version you want to create a bootable USB. This is a crucial part of the process, as the wrong installer won't work with your system.

Procedure for Creating a Bootable Installer

Once you have your Mac and USB drive ready and have obtained the correct macOS installation file, it's time to create a bootable macOS installer. Here is a straightforward process to do so.

Inserting and Setting Up Your USB Drive

First, insert your USB flash drive into one of the USB ports on your Mac, creating a macOS bootable USB installer. Afterward, you must set up your drive. Ensure the USB drive is empty; this process will erase all data. You can do this by moving any important files from your USB to your Mac or another safe location.

Using Terminal to Create a Bootable Drive

While creating a bootable drive can be done effectively via a third-party app, Terminal allows you to opt out of installing extra software. This method might seem technical due to the requirement of entering 'createinstallmedia' commands, but following accurate instructions can make it comparatively straightforward.

To start, open your Terminal. In most cases, you can find it in the Utilities folder within Applications on your Mac. After that, use the 'createinstallmedia' command along with the right installer path and destination to start creating your installer.

Completing the Process

Once the Terminal successfully does its job, you'll have a macOS bootable USB installer ready. You can use this bootable drive whenever your Mac encounters a system failure, or you wish to install the macOS on a new machine. Remember to safely eject the bootable installer after use to avoid any potential damage to the installer or the computer's USB port.

Usage of a Bootable Installer

Once you have created a bootable installer for macOS, using it is fairly straightforward. The process can be slightly different based on your Mac type, but the instructions outlined below will guide you through executing this task smoothly.

Instructions for Apple Silicon Macs

If you're operating an Apple Silicon Mac, insert the bootable installer into your Mac and make sure your Mac is both online and compatible with the macOS version you intend to install. While the bootable installer doesn't download macOS from the web, it necessitates an internet connection to retrieve firmware and other Mac model-specific information.

Power up your Mac and press and hold the power button until the startup options window appears, revealing your bootable volume choices. Choose the volume that holds the bootable installer and then click 'Continue.' After the macOS installer launches, just adhere to the step-by-step onscreen installation instructions.

Instructions for Intel Macs

For Macs with an Intel processor, the process is slightly different. Connect the bootable installer to your Mac, ensuring that you're online and the macOS version on the installer is compatible with your machine. Like in Apple Silicon Macs, an internet connection is needed to grab some specifics of your Mac model.

Switch on your Mac, and instantly press and hold down the Option (Alt) key. Once the dark screen displaying your bootable volumes appears, release the key. Now choose the volume with the bootable installer, and click the onscreen arrow or press the 'Return' key. If you cannot boot from the installer, verify that your Startup Security Utility allows booting from external or removable media.

Importance of an Internet Connection

An internet connection is crucial when using a bootable installer, even though the macOS doesn't download from the web. The connection is required for fetching firmware and prior information specific to the Mac model you are installing the macOS on. So, you must ensure a stable internet connection before executing the bootable installer installation process.