Past a certain data size, migrations are always a nightmare. For a much longer time than what you initially estimated, you are managing two systems with all th

Past a certain data size, migrations are always a nightmare. For a much longer time than what you initially estimated, you are managing two systems with all the related operational costs and complexity, as well as all of the IOPs and bandwidth migrating the data. I imagine scaling out RDS instead mitigated a lot of those costs.