Another "How to boot your Raspberry Pi from SSD"

This is another short one in the category: "I keep forgetting, so let's document it". This post contains the steps to make your Raspberry Pi boot from an external device like an SSD or HDD. It works on Raspbian (Debian) 12 (Bookworm). I haven't tested this on any other versions.

1. Update your pi and reboot:
   
   sudo apt update
sudo apt full-upgrade
sudo reboot
   
   
2. Check to see if there is an EEPROM available:
   
   sudo rpi-eeprom-update
   
   
3. Upgrade EEPROM to the latest EEPROM version and reboot:
   
   sudo rpi-eeprom-update -a
sudo reboot
   
   
4. After this, the greed LED will keep flashing periodically. To stop this annoyance, edit config.txt:
   
   sudo nano /boot/firmware/config.txt
   
   And add:
   
   dtparam=sd_poll_once
   
   
5. You can repurpose the (green) activity LED to show a heartbeat for example:
   
   sudo sh -c "echo heartbeat > /sys/class/leds/ACT/trigger"
   
   However, this change doesn't persist after reboot. You could add the command to a startup script.

Then, if you want to clone your SD-card to your new SSD/HDD, go checkout rpi-clone.

Sources: raspberrystreet.com / raspberrypi.stackexchange.com