Even better than a replica, is using a strongly-consistent metadata store to drive the S3 metadata--use the metadata store to acquire unique S3 keys, write to S

Even better than a replica, is using a strongly-consistent metadata store to drive the S3 metadata--use the metadata store to acquire unique S3 keys, write to S3, then transact the S3 manifest back to the metadata store. Then you do not have to deal with the problem of replication.