I've searched through the topics and I can't seem to find a simply answer to this issue. If someone knows a thread that answers it please direct me.
I have a Model 3b+ with a powered 1TB external HDD attached. I'd like to have the pi boot from that drive since my understanding is that it will give better performance
I used the SD Card Copier to copy my SD card over to the HDD, that seems to have worked fine. I see the exact same partitions with at 900+ GB "data" partition.
As far as I can tell the pi is still booting from the SD card, which makes sense given the boot order the pi generally operates from.
So my ultimate question is; what do I do to erase Raspbian from the SD card safely without also deleting the stuff (the bootloader I think) that still needs to be on the SD card.