During installation, if you select a multitenant container database (CDB), and configure pluggable databases (PDBs), then Oracle recommends that you add services to the PDBs after installation.
MOUNTED
state.
PDBs are opened in Read Write mode after failover or relocation only after you have configured the PDBs to have associated services. If you have not associated services to PDBs, then the PDBs remains in MOUNTED
state when the CDB instance restarts.
After you add services to your PDBs, if you relocate the CDB with which the PDBs are associated, or the CDB fails over, then the PDBs associated with that CDB automatically open in Read Write
state.