Good questions. I don't want to get off-topic, but are you sure you'll be using PDB's at this point? I work in engineering on a variety of architecture projects and I still don't know what to think of PDB's. The main issue is there's still just one set of redo logs, controlfiles, and archive logs. That complicates managing them as truly independent databases. I know one cusotmer who host multi-tenant environments where they're using PDB's for isolation. They have something like 10 major end-customers running a very complicated and CPU-intensive product. Each end customer has their own app environment pointing at a PDB. They don't really do anything special beyond that. They just wanted the isolation.
Then there's the license costs for the multitenant option to consider. They're not horrible, but they aren't zero either. I'm still looking for a good use case on how that's proven to save money, not just something that looks good on paper.
The good news is that the PDB architecture has almost no impact on how snapshots are used. I tested the SnapCreator plugins with PDB's and I didn't have to make any changes at all. That makes sense, as the actual commands like "alter database begin backup" are unchanged. I wouldn't be surprised if Oracle eventually delivered a PDB tech with full data separation, meaning a PDB had dedicated logs, but for the moment a PDB is really more like a set of datafiles with better security. It's not quite a "database".
My best bet on how PDB's would be deployed would be separate flexvols for each PDB so they can be backed up and restored on an individual basis. The app layer, I think, will still end up being on a different server, probably running under a VM. I don't see a reason not to just treat backups the same as always. Put the whole DB in hot backup mode and take a snapshot. If you want to restore an individual PDB, you just restore those datafiles. I don't see a reason to backup a PDB on an individual basis, though. Why not just back up the whole thing with a single command and assume you've now captured the hot backup snapshots for all of them? What would the value be in doing them individually? The efficiencies of a snapshot make that of minimal value.
Got further thoughts? This is all new territory right now because there isn't significant adoption of the PDB option. I'm looking for someone to provide a different point of view.
