I need to move a large production S3 bucket from us-east-1 to eu-west-1 for compliance and latency reasons. Since S3 bucket names are globally unique and tied to a specific region upon creation, I'm confused about the transition. Do I have to manually download and re-upload everything, or is there a way to automate this using Cross-Region Replication or the AWS CLI sync command? I'm worried about data integrity and potential downtime during the transfer.
3 answers
Since you cannot simply "move" a bucket because its name is locked to the original region, you must create a new destination bucket in your target region. For small to medium datasets, the fastest human way is using the AWS CLI. Run aws s3 sync s3://source-bucket s3://destination-bucket --source-region us-east-1 --region eu-west-1. This command is smart; it only copies new or changed files. For massive production buckets, I'd recommend enabling Cross-Region Replication (CRR). Note that CRR only replicates new objects by default, so you'll need to trigger an S3 Batch Operations job to sync the existing historical data.
When using the CLI sync method, are you concerned about the transfer costs and whether you need to maintain the original object metadata and versioning history during the move?
I always suggest using S3 Batch Operations for production moves. It gives you a completion report so you can verify every single object made it to the new region safely.
I agree with Barbara. The manifest-driven approach of Batch Operations is much more reliable for audit purposes than just running a CLI command and hoping there were no network hiccups.
That is a great point, Mark. If versioning is a priority, the standard CLI sync won't preserve the version IDs. You would actually need to use S3 Batch Replication or a custom script to ensure the entire version history is migrated. Regarding costs, AWS does charge for inter-region data transfer, so definitely calculate that before moving petabytes of data across the ocean!