The Datacenter-to-Datacenter Replication setup in ArangoDB has a few limitations. Some of these limitations may be removed in later versions of ArangoDB:
All the machines where the ArangoDB Server processes run must run the Linux operating system using the AMD64 architecture. Clients can run from any platform.
All the machines where the ArangoSync Server processes run must run the Linux operating system using the AMD64 architecture. The ArangoSync command line tool is available for Linux, Windows & macOS.
The entire cluster is replicated. It is not possible to exclude specific databases or collections from replication.
In any DC2DC setup, the minor version of the target cluster must be equal to or greater than the minor version of the source cluster. Replication from a higher to a lower minor version (i.e., from 3.9.x to 3.8.x) is not supported. Syncing between different patch versions of the same minor version is possible, however. For example, you cannot sync from a 3.9.1 cluster to a 3.8.7 cluster, but you can sync from a 3.9.1 cluster to a 3.9.0 cluster.