@Jarek Kupisz​ :

It's possible that the Azure networking setup is causing the issue, as it could be blocking the ODBC traffic between the two clusters.

As for your second guess, the ODBC driver on a Databricks compute should be capable of receiving ODBC commands from other Databricks clusters, as long as the necessary network configurations and security permissions are in place. However, there may be specific configurations or limitations that are not documented publicly, so it would be best to check with the Databricks support team to confirm.

The solution you've settled on, which posts a Databricks job for cluster to cluster communication, is also a valid approach. It may not be the most efficient or optimal, but it can work reliably and securely.

If you do want to explore other options or try to get the ODBC connection working between the Databricks clusters, I recommend reaching out to Databricks support for assistance.