When messages are being sent round the cluster over NATs do offline DMAs in hot redundant pairs participate in the NATs network or not?
A NATS server instance is installed on each agent in the DMS cluster, including the offline Failover agents.
These instances are capable of actively brokering messages to clients within the cluster. However, under normal circumstances, very few clients are connected to an offline failover agent NATS server instance, so it typically remains idle.
The instance stays in a “ready” state, prepared to take over message handling when a failover switch is triggered.
DataMiner communicates via two possible communication channels.
One being the SLNet communication channel. These are connections point-to-point between all online dataminer agents. This excludes offline failover agents.
The other is NATS communication. Here, messages are broadcasted on the entire NATS bus. This means that a client connected to the local DMA, will broadcast the message to all DMAs (=nats-servers). This broadcast action is point-to-point. Only the interested DMA will reply on this broadcast message, sending it point-to-point back.
If the cluster is geographically dispersed, a NATS super-cluster can be used to limit broadcasting only withing nodes in the same area. unless
For both SLNet and NATS communication, no offline DMAs are used to route a request. for NATS the broadcasted message could be sent there and dropped immediately.
An exception to this might be if you configured your networking to route all network communication in a ring. But for DataMiner, that is transparent.
Hi Pieter,
we have a rather large cluster that when modeled to visualize it is in a ring, so if a client is connected to an online DMA on one side of the ring to get information from an element on the other side of the ring, one does that use NATs and 2 if so does the route use offline DMAs?