No locking by hosts not accessing the lun. Would count against the lun count.
vVols came about to overcome challenges that RDMs present. Lun count is one of those. Management from vSphere is another challenge.
The ar architectural changes wouldn’t be significant, but there would be a migration process, and would have some (could be minimal) downtime.
That said, if the application is working fine with RDMs, that provides plenty of time to manage the migration to vVols if they are desirable.
Desirable benefits of vVols: fewer host connections required (only Protocol Endpoint mapped), easy to recover volume snapshots with our vSphere Plugin, can easily change snap/replication schedules from vSphere, and more.
I believe the latest version of vSphere + vVols even allows hot expansion of volumes where previously this was done only on the array side with RDMs.
