AWS S3 Support
AWS S3 cross-Region replication setup.
Cross-Region Replication copies new objects to a bucket in another Region for disaster recovery, latency or compliance. It is easy to enable and easy to get subtly wrong: existing objects are not copied, deletes behave in specific ways and encrypted objects need extra permissions. We set it up and prove it works.
When You Need This
The situations where this work pays for itself.
Signs it is time
- You need a copy of critical data in a second Region
- A compliance rule requires geographic separation of backups
- Users in another Region need lower-latency reads
- You must replicate between accounts for a log archive or a security vault
- Replication is on but some objects never arrive
What you get
- Replication configuration and IAM roles in infrastructure as code
- Batch Replication run for existing data with a completion report
- CloudWatch alarms on replication lag and failures
- A written and tested Regional failover runbook
How we do it
A clear, safe process you can follow along with.
1. Define the goal
We confirm whether you need disaster recovery, compliance copies or latency, because it changes the destination storage class, retention and whether you also need Multi-Region Access Points.
2. Prepare both buckets
Versioning must be enabled on source and destination. We also set destination encryption, Object Lock if required and Block Public Access, and decide on a lifecycle policy for the replica.
3. Create the replication role and rule
S3 assumes an IAM role to replicate. We grant read on the source, replicate permissions on the destination and KMS permissions if objects are encrypted. We scope the rule by prefix or tag and choose storage class and ownership override for cross-account targets.
4. Handle SSE-KMS objects
Replicating SSE-KMS objects must be explicitly enabled in the rule, with a destination KMS key in the destination Region and permissions on both keys.
5. Backfill existing objects
A new rule only replicates new objects. We use S3 Batch Replication to copy existing objects and retry failed ones.
6. Decide on deletes and monitoring
Delete marker replication is configurable and permanent version deletes are not replicated. We enable replication metrics and event notifications and alarm on failed or pending replication.
7. Test the failover plan
We upload test objects, verify ReplicationStatus reaches COMPLETED, and rehearse how applications read from the replica bucket in a Regional outage.
Mistakes we help you avoid
Common ways this goes wrong, and what we do instead.
Assuming existing objects replicate
Only objects written after the rule is active are copied until you run Batch Replication.
Ignoring KMS
Encrypted objects silently fail to replicate without the right key permissions and rule settings.
Treating replication as a backup
Replication copies mistakes and deletes too. Pair it with versioning, Object Lock or AWS Backup for recovery from errors.
Never testing failover
A replica nobody has read from is a hope, not a plan.
Frequently Asked Questions
Does S3 replication copy objects that already exist?
Not automatically. A replication rule applies to new objects. Use S3 Batch Replication to copy existing objects and to retry ones that failed.
How long does S3 replication take?
Most objects replicate within minutes but there is no default time guarantee. S3 Replication Time Control adds a monitored target and metrics, at extra cost.
Can I replicate between AWS accounts?
Yes. The destination bucket policy must allow the replication role, and you can change object ownership to the destination account in the rule.
Want Help With AWS S3 cross-Region replication setup?
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