I have used for many years a 2Gen Drobo, firewire as my bootable backup created by Superduper. I was always able to boot from it if needed. This Drobo failed after many years of usage.
I have now a Drobo 5C, directly attached with USB and I can not boot from it anymore. I can select it in Preferences/Power+option but it ultimately boots from the HD. Bootable Backups are done by Superduper
I am on High Sierra, everything updated.
How can I fix this?