Can I access an Azure SQL database in another tenant/subscription when creating a mirrored Azure SQL database?

Yep, Microsoft Fabric supports mirroring Azure SQL databases, even if the source database resides in a different Entra ID tenant — as long as:

• The customer has appropriate delegated or service principal-based access to your Azure SQL database.
• Cross-tenant data access and authentication are correctly configured.
• Private endpoints, firewall, and networking configurations allow the communication.
• The Mirroring feature in Microsoft Fabric supports cross-tenant sources.

For this to work, you'd need to set up:

1. Cross-tenant access configuration

• Your Entra ID tenant must allow external identities (from the customer's tenant) to access the Azure SQL DB.
• This usually involves:
  • Adding the customer’s Microsoft Entra ID tenant as a guest.
  • Granting appropriate RBAC roles to the service principal or user they will use.
  • Or giving the customer a dedicated user/service principal in your tenant for least privilege access.

2. Authentication support

Microsoft Fabric currently supports:

• Entra ID interactive authentication
• Service principal authentication

Your customer can configure a service principal in their own tenant and have it granted access to your Azure SQL DB.

Note that fabric mirroring requires OAuth-based authentication. SQL authentication (user/password) is not supported.

3. Networking

• Your Azure SQL Server must allow Azure services or the customer's specific IP ranges.
• If private endpoints are used, extra configuration is needed, such as:
  • Private DNS zone peering
  • Allowing traffic from the customer’s tenant via VNet peering or VPN.

4. Mirroring in Fabric

Once access is configured:

• In Fabric, the customer would configure Data Factory mirroring, and select Azure SQL Database as the source.
• Provide the connection information and authentication details.
• Initiate the mirroring setup and ingestion process.

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hth

Marcin