Redo Log Propagation Delays in Oracle Data Guard Synchronous Replication

Abstract

Oracle Data Guard synchronous replication provides strong data durability guarantees by ensuring that
redo records generated on the primary database are transmitted, persisted, and acknowledged at the
standby system before transaction commit. While this eliminates the risk of data loss during failover, it
also introduces additional latency into the transaction execution path, making commit responsiveness
directly dependent on network round-trip time, standby disk write performance, and redo apply
efficiency. This study conducts a structured performance analysis of redo propagation behavior across
single-region, multi-availability-zone, and cross-region deployments under both steady OLTP traffic
and burst-oriented batch workloads. Results demonstrate that synchronous replication latency is highly
sensitive to transient network jitter, log buffer saturation, and asynchronous apply backlog accumulation
on the standby. Further, the findings show that commit latency correlates more strongly with variance in
network and storage responsiveness than with average throughput. These observations indicate that redo
propagation delay is a dynamic systems characteristic shaped by workload pacing, topology design, and
runtime environmental stability. Effective synchronous deployment therefore requires balanced I/O
capacity between primary and standby, low-latency interconnect provisioning, and proactive monitoring
of commit wait events to maintain both performance stability and zero-data-loss resilience.