Backup data base in oracle 12C
Backing Up PDBs with RMAN


  To back up one or more PDBs while connected to the root:
  
  
  Start RMAN and connect to the root as a common user with the SYSBACKUP
  or SYSDBA privilege as described in Connecting as Target to the Root.
  Issue a BACKUP PLUGGABLE DATABASE command at the RMAN prompt.
  
  
  The following example backs up the PDBs sales and hr:
  
  BACKUP PLUGGABLE DATABASE sales, hr;
  
  To back up one PDB while connected to the PDB:
  
  
  Start RMAN and connect to the PDB as a local user with the SYSBACKUP
  or SYSDBA privilege as described in Connecting as Target to a PDB.
  Issue a BACKUP DATABASE command at the RMAN prompt.
  
  
  BACKUP DATABASE;