The Ceph Octopus release 15.2.5 introduces the new feature rbd mirroring based on snapshots.
The new method no longer uses the journal to synchronize the data. It synchronizes the data between two snapshots using the fast-diff and delta-export features.
This type of synchronization requires fewer IOP resources and does not directly affect the performance of the current system, as is the case with journal base mirroring.
The new implementation directly uses the kernel features of Ceph and not external libraries: librbd, rbd-nbd, ...