> 1. Does anyone know if Firebird + DRBD is a thing or am I ploughing my
> own furrow?
I have it working flawlessly for 5+ years here. DRBD + XFS + Firebird
Databases on 2 Cluster nodes with Heartbeat / Pacemaker.

The more interesting question is how database corruption will be "distributed" in such configuration?
How such device will handle careful writes and work of Firebird and OS cache?

So, did you make experiments with sudden reboot of one of the nodes with simultaneous high load (inserting or updating a lot of records)?


Regards,
Alexey Kovyazin
IBSurgeon