Which type of consistency only makes writes visible to clients after they have been confirmed as written successfully to all replicas?

Strong consistency ensures that any write operation is immediately visible to all clients after it has been successfully written to all replicas in the system. This means that once a write is confirmed, any subsequent read operation will reflect this write, providing confidence that the most recent updates are available across the distributed system. This consistency model is crucial in scenarios where accuracy and immediate data validation are necessary, such as in banking transactions or critical data updates.

In contrast, eventual consistency allows updates to propagate asynchronously, meaning that not all clients may see the most recent write at the same time. Bounded staleness offers a guarantee that reads will be at most a certain amount of time stale but does not require immediate visibility of the latest writes. Eventual visibility, while not a standard term in data consistency models, implies a delayed visibility of writes, which aligns with auto-synced or timely data rather than the assured and immediate visibility that strong consistency guarantees. Thus, selecting strong consistency aligns with the requirement of confirming writes across all replicas before they are visible to clients.