Managing the tnsnames.ora File on a Network

As you know, managing the tnsnames.ora file is the single largest maintenance task in a Oracle Net Services environment. Large and dynamic shops are always adding new Oracle servers, moving databases to new servers, and changing server IP addresses. Since the tnsnames.ora file is read dynamically, the size of the tnsnames.ora file does not affect Oracle performance, and tnsnames.ora files may contain hundreds of remote database descriptions. When changes occur, the DBA must edit and test the tnsnames.ora files and arrange for the distribution of the software. Obviously, it is important to be able to do so as efficiently as possible.
One strategy is to create and maintain a master copy of the tnsnames.ora file on a shared server. Though not supported by Oracle, this eliminates the tedious and time-consuming task of distributing the tnsnames.ora file whenever it changes. To do this, change the default location for the tnsnames.ora file in the NT or Windows 98 Registry to point to the location on the networked (that is, shared) disk.

The downside to this approach is that you introduce a central point of failure. If the shared disk fails, nobody will be able to connect to any Oracle databases.
Most DBAs who choose to distribute their tnsnames.ora file use a "push" tool such as Tivoli Courier. This tool will push the new tnsnames.ora file to the PC whenever it changes. Some shops automatically re-propagate the tnsnames.ora file weekly via a scheduled task. In the next lesson you will learn about the tools for testing connectivity.

Before moving on to the next lesson, click the Exercise link below to test your mastery of installation and maintenance issues.
Managing tnsnames.ora - Exercise