Today I saw the next warnning into a listener log file constantly;
‘WARNING: Subscription for node down event still pending’
This error is related to the Oracle TNS Listener’s default subscription to the Oracle Notification Service (ONS). In non-RAC architecture it’s recommende switch off this functionality.
Modify the listener.ora file with the next parameters;
After that you need restart or reload the listener.
For more information about this parameter, please take a look at 372959.1 ML/MOS note.
HTH – Antonio NAVARRO