What should the solutions architect do to meet these requirements with minimum application change?
Migrate the database to Amazon RDS for PostgreSQL in us-east-1. Set up a read replica in us-west-2. Set the managed RPO for the RDS database to 30 seconds.
Migrate the database to Amazon RDS for PostgreSQL in us-east-1. Set up a standby replica in an Availability Zone in us-west-2. Set the managed RPO for the RDS database to 30 seconds.
Migrate the database to an Amazon Aurora PostgreSQL global database with the primary Region as us-east-1 and the secondary Region as us-west-2. Set the managed RPO for the Aurora database to 30 seconds.
Migrate the database to Amazon DynamoDB in us-east-1. Set up global tables with replica tables that are created in us-west-2.
Explanations:
While Amazon RDS for PostgreSQL can be set up in us-east-1 with a read replica in us-west-2, read replicas in RDS do not support cross-region replication with a guaranteed RPO of 30 seconds. They typically have higher lag and do not meet the stringent RPO requirement.
Similar to option A, a standby replica in an Availability Zone does not address cross-region failover. RDS standby replicas are designed for multi-AZ deployments and do not provide cross-region capabilities with a 30-second RPO.
Migrating to an Amazon Aurora PostgreSQL global database allows for low-latency cross-region replication with an RPO as low as 30 seconds. This solution meets the requirements for disaster recovery with a primary database in us-east-1 and a failover database in us-west-2 while minimizing application changes.
Migrating to Amazon DynamoDB does not fulfill the requirement of using PostgreSQL, as it is a different database technology. Although DynamoDB global tables allow for cross-region replication, this option would require significant application changes and does not align with the existing database technology.
I assess that the answer is:
Migrate the database to an Amazon Aurora PostgreSQL global database with the primary Region as us-east-1 and the secondary Region as us-west-2. Set the managed RPO for the Aurora database to 30 seconds.