I need to migrate one database from one RDS to another without any downtime. I can perform a simple point in time restore, but that still needs to be followed by updating new RDS with delta updates from old RDS, hence RDS master-slave replication seems to me an option
I have gone though AWS Read Replicas and Multi-Az feature, but it does not allows to reduce the instance storage space(which is the second requirement here). Current RDS consists of multiple databases and too big in size. Hving a same size RDS for a small database is not worth.