I haven't used NetApp so my first question ... what are the steps you perform to get NetApp to take a database dump/snapshot of a PDB?
Which method do you use to resync the RDB? [Have you seen the new(ish) 'resync' capabilities that came with RS 15.6? If not, take a look at the New Features manual for RS 15.6 for some detailed examples of using the new resync capabilities.]
I'm thinking one of the resync scenarios may be feasible ... but would need details on how the NetApp snapshot is obtained (especially with regards to how it handles ongoing/active transactions in the PDB).
