Github user jtstorck commented on a diff in the pull request:
https://github.com/apache/nifi/pull/3056#discussion_r223855961
--- Diff: nifi-docs/src/main/asciidoc/administration-guide.adoc ---
@@ -2393,19 +2395,53 @@ When the DFM makes changes to the dataflow, the
node that receives the request t
nodes and waits for each node to respond, indicating that it has made the
change on its local flow.
-*Dealing with Disconnected Nodes* +
+=== Managing Nodes
+
+==== Disconnect Nodes
+
+A DFM may manually disconnect a node from the cluster. A node may also
become disconnected for other reasons, such as due to a lack of heartbeat. The
Cluster Coordinator will show a bulletin on the User Interface when a node is
disconnected. The DFM will not be able to make any changes to the dataflow
until the issue of the disconnected node is resolved. The DFM or the
Administrator will need to troubleshoot the issue with the node and resolve it
before any new changes can be made to the dataflow. However, it is worth noting
that just because a node is disconnected does not mean that it is not working.
This may happen for a few reasons, for example when the node is unable to
communicate with the Cluster Coordinator due to network problems.
+
+To manually disconnect a node, select the "Disconnect" icon
(image:iconDisconnect.png["Disconnect Icon"]) from the node's row.
+
+image::disconnected-node-cluster-mgt.png["Disconnected Node in Cluster
Management UI"]
+
+A disconnected node can be connected (image:iconConnect.png["Connect
Icon"]), offloaded (image:iconOffload.png["Offload Icon"]) or deleted
(image:iconDelete.png["Delete Icon"]).
--- End diff --
For a node thatâs disconnected due to lack of heartbeat, it can't offload
in all disconnected scenarios. If it gets disconnected because the node died,
obviously it wonât be able to be offloaded, but if the operation canât
reach the node to start the offloading, it wonât be able to start it and the
UI should reflect that error. If it is disconnected due to firewall issues,
that might effect offloading as well, if the load balancing port is also
blocked by the firewall.
---
