Enable ARCHIVELOG and FLASHBACK mode on ASM

To enable ARCHIVELOG on ASM and configure FLASHBACK (without enabling it) you need to set up the appropriate initialization parameters (db_recovery_file_dest_size, db_recovery_file_dest, db_flashback_retention_target).

SQL>alter system set db_recovery_file_dest_size = '400G' scope=both sid='*';
SQL>alter system set db_recovery_file_dest = '+DATA_RAC3' scope=both sid='*';
SQL> alter system set db_flashback_retention_target = 60 scope=both sid='*';


Then you need to put the database in MOUNT mode; ARCHIVELOG and FLASHBACK mode can be changed only when the database is in the MOUNT state.
srvctl stop database -d RAC3 -o immediate
srvctl start database -d RAC3 -o mount


To enable ARCHIVELOG and FLASHBACK mode you should issue the following command
sql> ALTER DATABASE ARCHIVELOG;
sql> ALTER DATABASE FLASHBACK ON; (I didn't issue for my installation)

Then you can open your database and check its status.
sql> SELECT LOG_MODE,FLASHBACK_ON FROM V$DATABASE;
LOG_MODE FLASHBACK_ON
------------ ------------------
ARCHIVELOG NO (You should see YES)