In this guide, you will learn how to modify your Raspberry Pi 4 bootloader to boot via USB storage media, such as an external SSD (solid-state drive), which is way faster, more reliable, and offers more storage than a microSD card. You will also learn how to enable network boot on your Raspberry Pi 4 to boot via an Ethernet (internet) connection.
Why Boot Raspberry Pi 4 via SSD or Network?
There are certain situations where you would want to boot your Raspberry Pi via an SSD instead of a microSD card.
For instance, when you enable USB boot, the Pi checks for connected bootable USB devices first. If no bootable USB device is detected, the Pi checks for the SD card and boots the OS. Thus, you can use Raspberry Pi to boot, run, or test other OS releases without needing to format or delete the main OS from the SD card that you use every day.
Also, if you don’t have an SD card, or have a smaller-size SD card but require more storage for your purpose, USB boot via a flash drive (such as a thumb drive or SSD) makes sense. However, if the Raspberry Pi 4 stops booting, look for these causes for a Raspberry Pi that won’t boot and fix them.
Flash USB Bootloader Firmware
To enable the USB boot, you need to flash the USB bootloader firmware to your Raspberry Pi 4. For this, you will require a microSD card of any size (as small as 256MB will work). Then follow these steps to flash the USB bootloader to your Raspberry Pi 4.
- Download, install, and launch the latest version of the Raspberry Pi Imager tool. Also, connect the microSD card to your computer system.
- Click Choose OS and select Misc Utility Images > Bootloader > USB Boot.
- Click Choose Storage and select the microSD card.
- Click Write. Wait for it to complete. Once completed, dismount/eject and then disconnect the microSD card from the system.
- Turn off the Raspberry Pi 4 and insert the USB boot microSD card.
- Connect the power supply to the Raspberry Pi 4. The Pi will turn on and the USB bootloader will flash automatically. This will take only a few seconds. The green LED light on the Raspberry Pi will blink steadily once the bootloader is flashed successfully. If you have connected the HDMI port to a display, you will see a green screen once the firmware is flashed.
- You can now turn off the Raspberry Pi and remove the microSD card.
Create and Boot Raspberry Pi 4 using Bootable USB Media
Your Raspberry Pi 4 is ready to boot from external USB storage media, such as a thumb drive or portable SSD or hard drive. However, you need to flash the USB boot media with the desired OS you want to boot via Raspberry Pi 4. The steps are as follows:
- Launch the Raspberry Pi Imager tool and click Choose OS to select the OS from the list. If you want to flash an OS image you have downloaded on your local machine, select the Custom option and then select the .img OS file from your system.
- Click Choose Storage to select the connected USB storage media and click Write.
- After the OS is flashed on the USB boot media, such as an external SSD or thumb drive, dismount/eject it and then disconnect the drive from the system.
- Connect the USB drive to one of the USB 3.0 ports on your Raspberry Pi 4.
- Connect the power supply to turn on the Raspberry Pi 4. The Pi will check for the bootable USB media first and if found, it will start booting the operating system from the connected USB storage drive.
- You can now use the Raspberry Pi with the OS running via the USB storage drive. This will enable you to try various operating systems and projects