The Ceph way of doing asynchronous replication would be to run separate clusters and ship incremental snapshots between them. I don't know if anyone's programmed the automation for that, but it's definitely doable. For S3 only, radosgw has it's own async replication thing.

https://ceph.io/en/news/blog/2025/stretch-cluuuuuuuuusters-p...

Disclaimer: ex-Ceph-developer.