2 Replies Latest reply on Jan 14, 2020 12:04 PM by Heyward Drummond

    Adding MultiSubnetFailover=Yes to a Tableau Connection

    George DiNicola



      Looking to see if anyone knows how to add a parameter often used in SQL Server called "MultiSubnetFailover" to a Tableau workbook connection. The only relevant information I have found regarding this is found is this discussion: , TDC usage on Tableau Server 2018 - MultiSubnetFailover and ApplicationIntent ReadOnly. This involves creating a custom .tdc file for Tableau server, but Tableau emphasizes that they do not support or test .tdc files (reference: https://kb.tableau.com/articles/howto/using-a-tdc-file-with-tableau-server)


      Has anyone come across a solution to this? For instance, I work on a team with two server nodes (let's say nodes "A" and "B"), which can be failed over to one another in the case of disaster or power outage. For instance, if node A fails, the "always on availability group listener" then points to node B. This is accomplished through SQL Server connections by adding "MultiSubnetFailover=Yes" to the connection string.


      I've tried connection Tableau to SQL server in this manner, however Tableau ignores the parameter i.e I can type  "MultiSubnetFailover=hello",  "MultiSubnetFailover=No",  "MultiSubnetFailover=notARealValue" and am able to connect to the server without any issue (a clear indication that the parameter is ignored).


      Please let me know if you have any advice or experience using .tdc files in a company in which many developers deploy new Tableau workbooks every week. I have not found too many tips on using these types of files, and I'm looking for insight on how this solution can be scaled to support an entire team (for instance, I don't want each developer creating or modifying any files outside the workbook that will end up on the server). In addition, I am looking to prevent any intensive manual work if the connection for every .tdc needs to change due to a possible server migration.


      Thank you.

        • 1. Re: Adding MultiSubnetFailover=Yes to a Tableau Connection
          Toby Erkson

          A .TDC file needs to be on the Tableau Server as well as on the developer's computer.  The TDC file contains the necessary settings for the specific connection only and will only be invoked for that type of data source -- not the specific data source but the type e.g. MS SQL Server or GoogleAnalytics or Oracle or etc.  The location on the Tableau Server varies with the major version, however, for Tableau Desktop you save the TDC file in the DATASOURCES folder of your Tableau Repository location.  For example, here's where I have mine:

          As you can see, this TDC is only for MS SQL Server connections.


          Tableau doesn't support TDC files in the aspect like they do with their primary products.  Thus you could ask for help and suggestions but they are not obligated to find you a solution.  You will likely need to do experimentation yourself to figure out what works.

          • 2. Re: Adding MultiSubnetFailover=Yes to a Tableau Connection
            Heyward Drummond

            Toby, nice response. I just wanted to clarify that when using and fooling with .tdc files, you are pretty much on your own. Tableau provides the function to be able to control certain aspects of the data source connection, but you would not or should not expect to call into technical support and get help fooling with the tdc settings. That being said, there are times that a support engineer may ask you to open the tdc file and do something as part of a tech support case. Just be aware this is outside the normal Support position on tdc files.