Empirical Evaluation of Replication Strategies and Failover Behavior in AWS Storage Services

Replication is fundamental to achieving availability and durability in cloud storage systems, yet the operational characteristics of failover under controlled disruptions remain insufficiently quantified in reproducible settings. This paper presents an empirical evaluation of replication and failover behavior in Amazon Web Services (AWS) using systematic synthetic failure injection. We measure Recovery Time Objective (RTO), Recovery Point Objective (RPO), tail recovery latency (P95/P99), replication lag distributions, latency amplification, and throughput degradation under zone-level and region-level failure scenarios. Results demonstrate that synchronous multi-availability-zone replication achieves low and stable RTO with negligible RPO, whereas asynchronous cross-region replication introduces measurable lag and significantly amplified tail recovery. By decomposing failover into detection, control-plane redirection, and client stabilization phases, the study provides a structured methodology for analyzing recovery dynamics and offers evidence-based guidance for replication strategy selection in stateful cloud workloads.