When using Oracle RAC additional considerations must be taken into account.
For a VMDK or pRDM to be shared between more than one guest OS, the multi-writer flag must be set. (See VMware KB 1034165). Doing so allows multiple guest OS systems to write to the same VMDK or RDM. However this modification also means that the VM can no longer be suspended, migrated with Storage vMotion, supported by VM HA or DRS, and snapshots are no longer possible.
Shared VMDKs must use a SCSI controller with the physical sharing flag enabled. Shared VMDKs must be set to Independent-Persistent.
VMDKs for use with Oracle RAC should be selected as Eager Zero Thick, as this is required when setting the multi-writer flag. Eager Zero Thick will negate the benefit of thin provisioning.