What should a solutions architect do to meet this new requirement?
Add a new AWS Region to the DB cluster for multiple writes.
Add a new reader in the same Availability Zone as the writer.
Migrate the database tier to an Aurora multi-master cluster.
Migrate the database tier to an Aurora DB cluster with parallel query enabled.
Explanations:
Adding a new AWS Region does not provide continuous write availability. Aurora’s architecture supports regional failover but does not allow for multiple writes across regions due to eventual consistency. This option would not address the requirement for write availability during instance failover.
Adding a new reader in the same Availability Zone as the writer does not increase write availability. Readers are for read scaling and do not help with failover for the write instance. The requirement specifically mentions continuous write availability, which this option does not achieve.
Migrating to an Aurora multi-master cluster allows multiple write instances across different Availability Zones. This setup provides continuous write availability, as if one writer fails, others can continue to handle write requests. This directly addresses the requirement for instance failover and continuous writes.
Migrating to an Aurora DB cluster with parallel query enabled improves query performance but does not provide continuous write availability. This feature is more focused on read optimization and does not address the need for write availability during failover scenarios.
I systematize that the answer is:
Migrate the database tier to an Aurora multi-master cluster.