I have an obj mesh containing multiple disconnected component (island), when I create a null and connect to RBDSolver, it treats it as a single rigid body, sharing the translation and rotation DOFs. How can I ask RBD to treat each disconnected component a single rigid body, so they can have different motion?
Manually grouping them and create separate null node would certainly be an option, but there are just too many of components...

Group them with the name attribute using the connectivity node.
Check out some example files of the RBD Solver to see more specifics.