If you are using DBConnect, it has extensive logging options, which can be configured in Settings. Before contacting Splunk support, you might want to enable debug logging, in case you need to provide Splunk support with DB Connect debug logs. Splunk DB Connect activity is logged to files in $SPLUNK_HOME/var/log/splunk and automatically indexed to _internal. The relevant log files for DB Connect are
splunk_app_db_connect_server.log
splunk_app_db_connect_job_metrics.log
splunk_app_db_connect_dbx.log
splunk_app_db_connect_audit_server.log
To view DB Connect logging activity, use a search command such as the following:
index=_internal sourcetype=dbx
Full details are here:
http://docs.splunk.com/Documentation/DBX/2.0.5/DeployDBX/Troubleshooting
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