SWITCHOVER VERIFY WARNING: switchover target's apply lag is more than 300 seconds

PROD Server and PROD Database 

oraclelab1.localdomain.com - DEVDB (PROD)

DR Server and DR Database 

oraclelab3.localdomain.com- DRDB (DR)

Issue:

Dataguard switch over failing with Error Message "SWITCHOVER VERIFY WARNING: switchover target's apply lag is more than 300 seconds. It takes time for the recovery to catch up. This may slow down switchover process."

Error Message:

SWITCHOVER VERIFY WARNING: switchover target's apply lag is more than 300 seconds. It takes time for the recovery to catch up. This may slow down switchover process.

Cause: 

PROD and Standby database are not on sync

Fix:

Make both PROD and DR database on sync and rerun the swicthover verify command 

Error Logs and commands output:

1. Switchover verify command failed at primary database or PROD database.

[oracle@oraclelab1 2025_05_07]$ sqlplus / as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Wed May 7 10:28:17 2025

Version 19.17.0.0.0

Copyright (c) 1982, 2022, Oracle.  All rights reserved.

Connected to:

Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production

Version 19.17.0.0.0

SQL> alter database switchover to DRDB verify;

alter database switchover to DRDB verify

*

ERROR at line 1:

ORA-16475: succeeded with warnings, check alert log for more details

SQL> archive log list

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     90

Next log sequence to archive   92

Current log sequence           92

SQL>

SQL> exit

Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production

Version 19.17.0.0.0

[oracle@oraclelab1 2025_05_07]$

2. Error Message reported on the PROD database alert log

[oracle@oraclelab1 2025_05_07]$ locate alert_DEVDB.log

/u01/app/oracle/diag/rdbms/devdb/DEVDB/trace/alert_DEVDB.log

[oracle@oraclelab1 2025_05_07]$ tail -100f /u01/app/oracle/diag/rdbms/devdb/DEVDB/trace/alert_DEVDB.log

2025-05-07T10:25:38.253130+05:30

SWITCHOVER VERIFY: Send VERIFY request to switchover target DRDB

SWITCHOVER VERIFY WARNING: switchover target's apply lag is more than 300 seconds. It takes time for the recovery to catch up. This may slow down switchover process.

ORA-16475 signalled during: alter database switchover to DRDB verify...

3. Standby Database is not in sync with PROD and there is 1 archive log or 1 sequence number is not yet applied on standby database

[oracle@oraclelab3 2025_05_07]$ sqlplus / as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Wed May 7 10:25:58 2025

Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle.  All rights reserved.

Connected to:

Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production

Version 19.3.0.0.0

SQL>  select sequence#,applied FROM v$archived_log where sequence#>=90;

 SEQUENCE# APPLIED

---------- ---------

        90 YES

        91 NO

SQL>

4. After few mins the pending archive log or sequence number got applied on the standby side 

SQL> select sequence#,applied FROM v$archived_log where sequence#>=90;

 SEQUENCE# APPLIED

---------- ---------

        90 YES

        91 YES

SQL> exit

Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production

Version 19.3.0.0.0

[oracle@oraclelab3 2025_05_07]$

5. Rerun the switchover verify command which is complete successfully

[oracle@oraclelab1 2025_05_07]$ sqlplus / as sysdba

SQL*Plus: Release 19.0.0.0.0 - Production on Wed May 7 10:29:00 2025

Version 19.17.0.0.0

Copyright (c) 1982, 2022, Oracle.  All rights reserved.

Connected to:

Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production

Version 19.17.0.0.0

SQL> alter database switchover to DRDB verify;

Database altered.

SQL> exit

Disconnected from Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production

Version 19.17.0.0.0

[oracle@oraclelab1 2025_05_07]$