We do not provide any Magento MultiTier solution in AWS. If you want to deploy Magento in AWS and configure a separate database, you can follow this sample guide that explains how to create a RDS database
You can configure that other database with your requirements in mind.
Regarding our Magento Multi Tier solution (available in other clouds), it consists of 2 instances: The first one has the web server and the app's data and the second one includes the database. We do not configure any replication configuration in that database, it's simply a standalone configuration to store the information. If you want to replicate that server, you will need to modify the configuration to meet with your requirements.