S3 Replication

Amazon S3 feature for automatically replicating objects + metadata + tags from a source bucket to one or more destination buckets — either Cross-Region Replication (CRR) for geographic redundancy or Same-Region Replication (SRR) for compliance/account-isolation. Built on top of [S3 Versioning](/node/s3-versioning) (versioning must be enabled on both source and destination). The high-tier variant **S3 Replication Time Control (RTC)** adds an SLA-backed **15-minute replication window** for 99.99% of new objects, plus built-in **S3 Replication Metrics** for monitoring backlog size and replication latency.

Geographic redundancy and cross-account isolation are first-class requirements for production S3 workloads — disaster-recovery, regulated multi-region deployments, cross-account staging-to-prod promotion. Pre-replication, operators built custom cross-region copy pipelines via SQS + Lambda + boto3 (still common where filtering logic is non-trivial). S3 Replication is the AWS-native answer that handles ordering, retries, and metadata propagation, with RTC adding an SLA when the replication-lag tail matters.

Disaster recovery via cross-region geographic replication, compliance use cases requiring data in a specific jurisdiction, cross-account replication where source and destination are in separate AWS accounts, low-RPO scenarios via RTC's 15-minute SLA, and high-bandwidth event-driven pipelines where the destination bucket triggers downstream Lambda/SQS workflows.