Which replication method offers immediate consistency across systems?

Synchronous Replication is the method that provides immediate consistency across systems because it involves real-time data transfer. When data is written to the primary system, it is simultaneously written to the secondary system before the operation is considered complete. This ensures that both systems have the exact same data at any point in time, effectively eliminating the risk of losing data in the event of a failure.

Immediate consistency is crucial in scenarios where data integrity and availability are paramount, such as in financial services or critical transaction environments. In these situations, any delay in replicating data could lead to inconsistencies and complications. Hence, synchronous replication is designed specifically to meet these demands by guaranteeing that all replicas are updated at the same moment, thereby achieving a consistent state across all systems involved.

Other replication methods, on the other hand, might introduce latencies or potential mismatches in data until the next synchronization occurs, which is why they do not provide the same level of consistency as synchronous replication.