Setting up Mirrorred SQL Server

Hi ptmk25,

Microsoft does not explicitly mention a same region requirement for SQL Mirroring, which can be overlooked. In reality, Mirrored Databases rely on the Fabric gateway pipeline, and this pipeline requires that the gateway region, data source region, and Fabric capacity region all match. Because of this, a SQL connection might work for Dataflows but fail for Mirroring, showing the error Test connection failed. undefined. This happens when Fabric’s mirroring service cannot properly validate the backend connection. To help prevent this issue, make sure your gateway is updated and located in the same region as the Fabric capacity, that the login has full database permissions and CDC is enabled, and try restarting the gateway. The region alignment rule applies to Mirroring even though it is not specifically mentioned in the documentation.

Thankyou.

Hi ptmk25, as a general recommendation, I suggest to use different connections to your on-premise SQL server for data pipelines/dataflows and for mirroring. Setting up mirroring requires more permissions for the SQL server account you use in the connection credentials.

There may be some confusion about the data gateway as well. You need to use specifically an On-Premises Data Gateway for your on-prem SQL server (see here Install an on-premises data gateway)

There is a detailed instruction on setting up a mirrored SQL database in Fabric, see here Tutorial: Configure Microsoft Fabric Mirroring from SQL Server - Microsoft Fabric. Check that you are using an instruction compatible with your SQL Server version.

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