SQL Server Migration using Distributed Availability Groups

Distributed Availability Groups (DAGs) in SQL Server facilitate cross-region, cross-cloud, and cross-datacenter disaster recovery and migration for large-scale databases, with minimal downtime. This guide details the process of migrating SQL Server databases from on-premises or cloud environments like Azure and AWS to Tessell SQL Server High Availability using a DAG. The architecture involves configuring source and target availability groups, ensuring network connectivity, and setting up necessary ports. Migration involves three main steps: provisioning the Tessell SQL Server for DAG, creating the Distributed Availability Group and initiating automatic seeding of databases, and finally, failing over the DAG to the Tessell primary replica. The process is designed to ensure the synchronization of databases across environments, with automatic seeding suitable for database sizes under 1TB, while manual methods are recommended for larger sizes. Once migration is completed, the distributed availability group can be dropped, finalizing the transfer to Tessell SQL Server.