GOAL
A newly created 12c database might have Unified Auditing disabled:
SQL> SELECT VALUE FROM V$OPTION WHERE PARAMETER = 'Unified Auditing';
VALUE
----------------------------------------------------------------
FALSE
How can one enable it ?
SOLUTION
1) Shutdown the database:
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
Note: In case of RAC DB, use srvctl command to start/stop Database
2) Relink with the uniaud_on option :
% cd $ORACLE_HOME/rdbms/lib
% make -f ins_rdbms.mk uniaud_on ioracle
For RAC and Dataguard environments,please refer to the following notes:
How To Enable Unified Audit binaries on RAC Nodes ? (Doc ID 2371837.1)
12c Unified Auditing used with Data Guard (Doc ID 2021747.1)
3) startup the database
SQL> startup
ORACLE instance started.
...
Database mounted.
Database opened.
SQL> SELECT VALUE FROM V$OPTION WHERE PARAMETER = 'Unified Auditing';
VALUE
----------------------------------------------------------------
TRUE
NOTE: With Oracle Database 12c, Unified Auditing is introduced. Prior to Oracle Database 12c, auditing is configured using the AUDIT_TRAIL database parameter, this is called traditional auditing.
REFERENCES
Master Note For Database Unified Auditing (Doc ID 2351084.1)