Oracle 12c Database Gateway configuration

Question

I have an Oracle 12c installation and want to open a 12c Gateway to a SQL Server.

I have read and re-read the documentation. Installed and re-installed the gateway. Many days later and I still do not have a working connection.

I have the Gateway installed under its own path but on the same server as the Oracle DB.

Here are some of my questions: 1) Should there be two ORALCE_HOMEs, one for the DB and one for the gateway? If yes, how is that configured. Do I put both paths in the Oracle_Home environment variable?

2) Should the Gateway listener, with it's own name 'listener_GTW' be in the "listener.ora" file of the db? Or in it's own "listener.ora" file in it's own path. If it is in it's own path, how does lsnrctl know about it. Looks like lsnrctl gets the "listener.ora" path from the TNS_ADMIN environment variable. Can I but the DB and Gateway home paths in the TNS_AMDIN variable??

With luck maybe just answers to these questions will help everything to fall into place.... I hope.

Answer 1

1. Yes, there should be two Oracle Homes. One for the DB and one for the gateway. The software is different, keep it separate.
2. Put the gateway software in a separate directory structure. Treat it as a completely independent component. It will have it's own ORACLE_HOME and it's own TNS_ADMIN.
3. The gateway listener should be in it's own listener.ora file. Most people place it in the $GW_HOME/msql/dg4msql/admin dir along with all the other config files.
4. lsnrctl will start the GW listener(s) once you've set TNS_ADMIN to the config directory (like the one mentioned in point 3). Before doing this, set the ORACLE_HOME and the PATH to use the gateway binaries as well.
5. No, you can't put both the DB and Gateway home paths in the TNS_ADMIN variable. You do not use the DB path for anything while setting up the GW listener as they are separate SW installations. Just focus on the GW at this point. Set TNS_ADMIN to the location where you've placed the configuration files and listener.ora.
6. When it comes to creating the DB link and connecting from the Oracle DB to the MSQL DB then you set the TNS_ADMIN for the DB to point to the directory where you have the tnsnames.ora file that connects to the GW listener you configured in the previous steps. Run a tnsping before you attempt this to make sure the DB can connect to the GW listener.