CDB and PDB sharing the same Undo

Hello Team,

We are on oracle 12c R2  RAC with 2 nodes on Redhat 7.4 as the OS.

We noticed that CDB and PDB on instance 1 are sharing the same tablespace. however on Instance 2 CDB and PDB are sharing separate UNDO.

The parameter Local_undo_enabled is set to true on both instances.

SQL>SQL> select * from database_properties where property_name='LOCAL_UNDO_ENABLED';PROPERTY_NAME             PROPERTY_VALUE            DESCRIPTION------------------------- ------------------------- -----------------------------------LOCAL_UNDO_ENABLED        TRUE                      true if local undo is enabledSQL>

Node 1

SQL>  alter session set container=cdb$root;Session altered.SQL> select inst_id,con_id,name,value from gv$parameter where name='undo_tablespace' order by 1;   INST_ID     CON_ID NAME                                                                             VALUE---------- ---------- -------------------------------------------------------------------------------- ------------------------------         1          1 undo_tablespace                                                                  UNDOTBS1         2          1 undo_tablespace                                                                  UNDOTBS2SQL>SQL> alter session set container=PDB1;Session altered.SQL> select inst_id,con_id,name,value from gv$parameter where name='undo_tablespace' order by 1;   INST_ID     CON_ID NAME                                                                             VALUE---------- ---------- -------------------------------------------------------------------------------- ------------------------------         1          3 undo_tablespace                                                                  UNDOTBS1         2          3 undo_tablespace                                                                  UNDO_2SQL>