You can boot Raspberry Pis that are older than the Pi 4 directly off of USB attached Drive. When you’re done with the process, you won’t even need to have a microSD card in the Pi’s slot.
1. Create your external boot drive. There are two main ways to do this.
- Use Etcher to “burn” the Raspbian OS to your external drive, a process we cover in our article on how to get started with Raspberry Pi. This works great, but doesn’t copy over any data from an existing build.
- Clone your current microSD card to the external drive using Raspbian’s built-in SD Card Copier, which is locked under the Accessories menu.
2. Create or find a bootable microSD card. If you already have a bootable microSD card, you can use it.
3. Connect both drives to your Raspberry Pi and boot it.
4. Open the the /boot/config.txt file for editing
sudo nano /boot/config.txt
5. Add program_usb_boot_mode=1 to the bottom of the file and save it.
6. Reboot the Raspberry Pi with the microSD card inside and external drive connected. When it boots, the Pi will write a bit to the firmware, informing it to boot off the USB drive. You only need to do this once and you can remove program_usb_boot_mode=1 to from the config.txt file, because the change is now permanently part of the Pi’s firmware.
7. Reboot the Pi again with the microSD card removed. It should now boot off of the external drive.
From now on, your Pi will boot from the attached USB Thumbdrive, without the need for the usual microSD card.