What should be created to ensure data remains accessible following a single data center failure in an Amazon Aurora deployment?

Creating a replica in another Availability Zone of the same AWS Region is a sound strategy for ensuring data accessibility following a single data center failure in an Amazon Aurora deployment. This approach leverages Amazon Aurora's ability to automatically manage and replicate data across different Availability Zones within a region.

When a replica is set up in a different Availability Zone, it helps to provide high availability and resilience against localized issues such as hardware failures or natural disasters that might affect one Availability Zone. Aurora’s fault-tolerant architecture allows for quick failover to the replica in case of failure of the primary instance, ensuring minimal downtime and continuous access to the database.

In contrast, while having a primary instance or a replica in another AWS Region can enhance disaster recovery capabilities and protect against region-wide outages, it introduces more latency and complexity in failover processes. A primary instance in the same region is not a fail-safe solution, as failure within that Availability Zone would still compromise access. Therefore, the setup of a replica in another Availability Zone within the same region is the most effective solution for maintaining data accessibility following a localized failure.