As mentioned previously, working backups are a key strategy in ensuring that a failure does not result in the loss of data. Starting with the Jewel release, Ceph introduced RBD mirroring, which allows you to asynchronously mirror an RBD from one cluster to another. Note the difference between Cephs native replication, which is synchronous, and RBD mirroring. With synchronous replication, low latency between peers is essential, and asynchronous replication allows the two Ceph clusters to be geographically remote, as latency is no longer a factor.
By having a replicated copy of your RBD images on a separate cluster, you can dramatically reduce both your Recovery Time Objective (RTO) and Recovery Point Objective (RPO). The RTO is a measure of how long it takes from initiating recovery to when the data is usable. It is the worst case measurement of time between each data point and describes the expected...