This document shows you how to migrate a Microsoft SQL Server instance installed on Amazon Elastic Compute Cloud (Amazon EC2) to a Microsoft SQL Server instance on Compute Engine in Google Cloud. This migration is solely based on built-in database technology provided by Microsoft SQL Server. This method is effectively a zero downtime method that uses an Always On Availability Group. The Always On Availability Group spans AWS and Google Cloud over VPN, and it enables the replication of the Microsoft SQL Server database. This document assumes that you're familiar with network setup, Google Cloud, Compute Engine, AWS, and Microsoft SQL Server

https://cloud.google.com/architecture/migrating-microsoft-sql-server-from-aws-to-google-cloud