ora-16665 timeout waiting for the result from a database

 The ORA-16665: timeout waiting for the result from a database error indicates that the Oracle Data Guard broker timed out while trying to communicate with a remote member database. This is typically a network issue or a problem with the remote instance. 

Causes

The primary causes for this error are:

• The network call to the remote database did not complete in a timely manner (network latency or firewall issues).
• The remote database was unable to execute the command due to an instance failure or performance issues. 

Troubleshooting and Resolution

To resolve the ORA-16665 error, follow these steps:

1. Check Data Guard Broker Logs: Examine the Data Guard broker log files (drc*.log files in the trace directory) on both the primary and standby sites for detailed error messages that provide context on the specific failure.
2. Verify Network Connectivity:
   • Ensure proper network communication (e.g., ping) is working properly between all members of the Data Guard configuration.
   • Use tnsping to check the reachability of the TNS service names used in the configuration from both the primary and standby servers.
   • Confirm that required ports (typically 1521, the default listener port) are open and not blocked by firewalls in both directions.
3. Check Database Status: Ensure all database instances in the Data Guard configuration are running and healthy. A failed instance at the remote end can cause this timeout.
4. Increase the Communication Timeout: If the network is simply experiencing high latency rather than a complete failure, you can increase the timeout values using the DGMGRL command-line interface.
   • The relevant properties are CommunicationTimeout (default is 180 seconds or 3 minutes) and OperationTimeout (default is 30 seconds).
   • Connect to DGMGRL and use the following command to increase the timeout (e.g., to 600 seconds or 10 minutes):
   sql

   DGMGRL> EDIT CONFIGURATION SET PROPERTY CommunicationTimeout = 600;
   DGMGRL> EDIT CONFIGURATION SET PROPERTY OperationTimeout = 600;
   

5. Reissue the Command: After checking the logs, fixing network issues, or increasing the timeout, reissue the Data Guard broker command that initially failed.