A company has had an S3 bucket in production for two years, containing millions of objects, and today configures Same-Region Replication (SRR) from that bucket to a new backup bucket for the first time. A week later, an engineer notices the backup bucket only contains objects uploaded since the replication rule was created, none of the two years of pre-existing objects. What is the correct explanation and fix?
- This is a temporary delay; S3 will eventually replicate all pre-existing objects automatically given enough time
- SRR never replicates more than 30 days of historical objects under any configuration
- By default, replication only applies to objects created after the replication configuration was added; replicating the pre-existing backlog requires an S3 Batch Replication job
- The engineer must delete and re-upload every pre-existing object for it to be picked up by replication
Why C? And why not the others?
Correct answer: C. By default, replication only applies to objects created after the replication configuration was added; replicating the pre-existing backlog requires an S3 Batch Replication job
AWS documentation on what S3 replicates states plainly that, by default, Amazon S3 replicates objects created after a replication configuration is added to the bucket; objects that already existed beforehand are not automatically picked up by live, rule-based replication (whether Same-Region or Cross-Region). To replicate that pre-existing backlog, AWS provides S3 Batch Replication, a separate, explicitly initiated job that takes a manifest of the existing objects and replicates them to the destination bucket on demand. This is exactly the gap the engineer observed and exactly the fix required. The idea that S3 will eventually replicate the backlog automatically given more time is incorrect: standard replication configurations never retroactively sweep up pre-existing objects, no matter how long the rule has been active, which is precisely why a distinct Batch Replication feature exists to solve this problem. There is no 30-day historical cutoff rule governing which pre-existing objects can ever be replicated; the constraint is about the object's creation time relative to when the rule was added, not a fixed lookback window, and Batch Replication has no such 30-day limitation. Deleting and re-uploading every object would technically make each object new relative to the replication rule and trigger replication, but this is a wasteful, disruptive, and unnecessary workaround (it destroys version history and metadata timestamps) when S3 Batch Replication is the documented, purpose-built solution for replicating an existing dataset without touching the source objects.
Source: AWS S3 documentation: What does Amazon S3 replicate? — objects created before a replication configuration are not replicated by default; use S3 Batch Replication for existing objects