Which solution will meet these requirements?
Defer the maintenance update until the sales event is over.
Create a read replica with the latest update. Initiate a failover before the sales event.
Create a read replica with the latest update. Transfer all read-only traffic to the read replica during the sales event.
Convert the DB instance into a Multi-AZ deployment. Apply the maintenance update.
Explanations:
Deferring the maintenance update does not address the need for high availability and could lead to unexpected downtime or issues during the sales event due to the existing vulnerabilities or bugs in the current version.
Creating a read replica and initiating a failover before the sales event could potentially introduce downtime during the failover process. Additionally, read replicas are typically used for scaling read traffic and not for immediate failover in a single-node instance scenario.
While creating a read replica could help with read traffic, it does not ensure high availability for write operations. If the primary DB instance goes down during the sales event, there would be downtime, as the read replica cannot take over as a primary DB instance without the necessary failover capability.
Converting the DB instance into a Multi-AZ deployment enhances availability by creating a standby instance in another Availability Zone. This setup allows automatic failover, minimizing downtime during the maintenance update. The maintenance update can then be applied without impacting the availability of the database during the sales event.
I design that the answer is:
Convert the DB instance into a Multi-AZ deployment. Apply the maintenance update.