Boot from specified partition (or FS) UUID without knowing Device ID

[Tom Hale]

I want to have a fallback boot situation where boot is first tried from 
one partition, and then from another partition (on a different device) 
if the first partition isn't available (eg, if the first device fails).

Can I boot from a specific FS UUID or a partition UUID without knowing a 
particular device ID?  (I'm not sure if my devices will always be 
detected in a repeatable order).

Can fatload be used with only a partition UUID?  Or can I somehow get 
the dev number from the UUID?

Thanks in advance,

Tom