The diagram below illustrates a typical deployment architecture for a Subversion based backend. Similar deployment architecture applies to CVS or Subversion-HTTP. As you can see in the diagram below, each replica uses the WANdisco replication technology to ensure the primary and backups stay in sync with each other. WANdisco replication technology supports active-active replication. For the WANdisco HADR, only one replica node is allowed to be active at any given time by the license manager.
As show in the above diagram, the WANdisco HADR exchanges heartbeats with the replicas over a configurable control port (defaults to 6444). The heartbeats are used to test the liveness of a replica and mark a node as the active primary, it is not used for replication. The WANdisco Replicators communicate with each other on the DConeNet control port (defaults to 6444) for replication. The control ports are multi-protocol, in other words they can speak Http, DConeNet, DFTP etc protocols. This reduces the need for the administrator to open manage multiple ports for various protocols used by the WANdisco HADR or WANdisco Replicator.
Here is an explanation of various TCP ports used in the above deployment:
- Port 3690 (WANdisco Failover Agent)
- Used by Subversion clients for normal Subversion request processing
- Port 6444 (WANdisco Failover Agent)
- Multi-protocol port, used by administrator for Web management or for exchanging heartbeats with WANdisco Replicator
- Port 4690 (WANdisco Replicator)
- The WANdisco Failover Agent forwards Subversion client requests to WANdisco Replicator on this port
- Port 6444 (WANdisco Replicator)
- Multi-protocol port, used by WANdisco Replicators for replicating data as well as web administration
- Port 5690 (Subversion)
- Subversion server listens on this port for normal Subversion client requests. The Subversion server is configured to allow
only WANdisco Replicator to connect to this port. This ensure the WANdisco Replicators are not bypassed accidentally causing the Subversion
repository to evolve independently
