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Showing posts with the label ORA-12537 TNS connection closed

How to Troubleshoot Connectivity Issue with 11gR2 SCAN

I installed the Oracle 11g RAC successfully, But when tried connecting from remote client via SCAN, it used to raise ORA-12537. This is the most common issues that the happens with SCAN listener. And there are few common mistakes that generally  cause this issue. . So, here is how we can troubleshoot the connectivity issues with SCAN, and cases out the possibilities. 1)  Check if Local_listener and remote_listener parameter are set properly on all nodes. 2)  The very common issue is with permissions. SCAN will always be created under grid user (Grid cluserware installation user). Oracle will also create one local listener “LISTENER” during grid infrastructure installation. But if that is not present then always make sure that you create a local listener with grid user. This is required to handover the connection between remote and local listener. 3)  Also “oracle” executable should have given to oracle and grid user i.e. 6751.  Under $ORACLE_HOME/bi...