Event though H2 is a great database system I would still recommend a postgres or oracle system for production stack: I have much more (nice) experience with them. Note that bonita engine is aimed to performs lots of parallel transaction, hence you would need a DBMS that manage well transaction. Not sure how H2 will behave with large DB and lots of transcations.
Scalability, backups, speed, availability, restore, security, access from other systems, sharing of business data.
H2 is really only for small standalone system, not big databases. And after a few processes have been run you will need a bigger database which is far more capable.
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