If you want to use real-time apply Oracle Data Guard, you have to add standby logfile to standby database.
Show Logfiles Before Add
SQL> select * from gv$logfile;
INST_ID GROUP# STATUS TYPE MEMBER IS_RECOVERY_DEST_FILE
1 3 ONLINE +DATA/testdb/onlinelog/group_3.14134123 NO
1 1 ONLINE +DATA/testdb/onlinelog/group_1.35116731 NO
1 2 ONLINE +DATA/testdb/onlinelog/group_2.32513245 NO
1 4 ONLINE +DATA/testdb/onlinelog/group_4.12255335 NO
1 2 ONLINE +FRA/testdb/onlinelog/group_2.13423425 YES
1 1 ONLINE +FRA/testdb/onlinelog/group_1.53242411 YES
1 3 ONLINE +FRA/testdb/onlinelog/group_3.34634123 YES
1 4 ONLINE +FRA/testdb/onlinelog/group_4.32525244 YES
Add Standby Logfile ASM
SQL> alter database add standby logfile ‘+DATA’ size 52428800;
Add Standby Logfile FileSystem
SQL> alter database add standby logfile ‘/oracle/db/datafile/standby_redo01.rdo’ size 52428800;
Show Logfiles After Add
SQL> select * from gv$logfile;
INST_ID GROUP# STATUS TYPE MEMBER IS_RECOVERY_DEST_FILE
1 3 ONLINE +DATA/testdb/onlinelog/group_3.14134123 NO
1 1 ONLINE +DATA/testdb/onlinelog/group_1.35116731 NO
1 2 ONLINE +DATA/testdb/onlinelog/group_2.32513245 NO
1 4 ONLINE +DATA/testdb/onlinelog/group_4.12255335 NO
1 2 ONLINE +FRA/testdb/onlinelog/group_2.13423425 YES
1 1 ONLINE +FRA/testdb/onlinelog/group_1.53242411 YES
1 3 ONLINE +FRA/testdb/onlinelog/group_3.34634123 YES
1 4 ONLINE +FRA/testdb/onlinelog/group_4.32525244 YES
1 5 STANDBY +DATA/testdb/onlinelog/group_5.42344234 NO
1 6 STANDBY +DATA/testdb/onlinelog/group_6.90895675 NO
1 8 STANDBY +DATA/testdb/onlinelog/group_8.45674886 NO
1 7 STANDBY +DATA/testdb/onlinelog/group_7.87456844 NO
Alter Data Guard To Real-Time Apply
SQL> alter database recover managed standby database using current logfile disconnect;
You can drop log file with below operation. Logfile status has to be ‘INACTIVE’ when you drop logfile. You can look status at v$log dictionary view.
Drop Logfile
SQL> alter database drop logfile group 8;