There are several reasons as to why you may want to replicate the data in S3 across regions. From a compliance perspective, you may want to store data hundreds of miles apart. From a latency perspective, you may want to distribute data to regional customers with very low latency; and from a security perspective, you may just want to create multiple replicas managed by separate AWS accounts.
You can either replicate an entire bucket or it can be just prefix based. Once cross-region replication is enabled, it only replicates new PUTs. This means new uploads into the source bucket will be replicated. Cross-region replication is a fast and reliable asynchronous replication and is set between any two regions on a 1:1 basis. Deletes and lifecycle actions are not replicated. You can also change the destination storage class for minimizing the cost.
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