I just followed James' tutorial on how to run a Pi 4 off an SSD. jamesachambers.com
I don't know enough about OS so the question for me is how is the SD card used after these modifications?
From his post:
In this guide I’ll show you a workaround to use USB devices as your rootfs device and use a Micro SD card as bootloader only which gives us full SSD performance after boot!
Am I correct in assuming that the SD card is just being read very briefly and points to the SSD immediately after powering up? Or is the SD card still being read from/written to during subsequent operations and thus at risk of breaking? Which begs the question what will happen when the SD card breaks. Should I make a backup of the SD card or the SSD or both?