This contains an example with a Yamcs server with three instances node1, node2 and node3 with the data replicating:
node1 -> node2
node1 -> node3
node2 -> node3 when the TM link to node1 goes down.

The node2 TM link and  node2->node3 replication are disabled by default. A script can be written to monitor the node1 TM link and start the node2 link when the node1 link goes down.

This setup corresponds to a node1 and node2 running in some sort of redundancy mode, pushing data to a node3.

The three instances can be separated on different Yamcs servers by copying the instance configuration file. 

Connecting via a web-browser, you can go to nodeX->Archive->Streams and observe the stream count.
