What version of SnapCenter are you runnning? If you wish to backup virtualized SQL servers on VMFS datastores you will need to make sure the vSphere plugin is registered within SnapCenter. You can backup SQL servers attached to VMFS datastores but you should seperate your database and log files on different VMFS datastores. If you want different schedules or snapshot retentions for each database you will need to have multiple VMFS datastores. It doesn't matter if you use VMFS or RDM's you should be able to get granular recovery of those databases with SnapCenter.