https://community.cloudera.com/t5/Support-Questions/All-Nodes-are-disconnected-from-NiFI-Cluster/m-p/187398#M149499 <P><A rel="noopener noreferrer noopener noreferrer noopener noreferrer noopener noreferrer nofollow noopener noreferrer" href="http://@Malthe%20Borch" target="_blank"><EM>@Malthe Borch</EM></A></P><P><EM>Nifi cluster coordinator relays on the zookeeper for the election. NiFi employs a Zero-Master Clustering paradigm. Each node in the cluster performs the same tasks on the data, but each operates on a different set of data. One of the nodes is automatically elected (via Apache ZooKeeper) as the Cluster Coordinator. </EM></P><P><BR /></P><P><EM>All nodes in the cluster will then send heartbeat/status information to this node, and this node is responsible for disconnecting nodes that do not report any heartbeat status for some amount of time. Additionally, when a new node elects to join the cluster, the new node must first connect to the currently-elected Cluster Coordinator in order to obtain the most up-to-date flow. If the Cluster Coordinator determines that the node is allowed to join (based on its configured Firewall file), the current flow is provided to that node, and that node is able to join the cluster, assuming that the node’s copy of the flow matches the copy provided by the Cluster Coordinator. If the node’s version of the flow configuration differs from that of the Cluster Coordinator’s, the node will not join the cluster.</EM></P><P><STRONG><EM>Checklist</EM></STRONG></P><P><EM>Ensure you have 3 zookeepers (ensemble) to manage your Nifi cluster, and all should be up and running.</EM></P><P><EM><STRONG>Walkthrough</STRONG></EM></P><UL><LI><EM>Stop all the Nifi instances</EM></LI><LI><EM>Ensure the 3 zookeepers are up and running</EM></LI><LI><EM>Start the Nifi one at a time</EM></LI><LI><EM>Validate that one nifi has been elected coordinator as is PRIMARY </EM></LI></UL><P><BR /></P><P><STRONG>See screenshots</STRONG></P><P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="110406-nifi-cluster.png" style="width: 1586px;"><img src="https://community.cloudera.com/t5/image/serverpage/image-id/18725i06E96163516D0FBB/image-size/medium?v=v2&amp;px=400" role="button" title="110406-nifi-cluster.png" alt="110406-nifi-cluster.png" /></span></P><P><BR /></P><P><STRONG><EM>Coordinator elected</EM></STRONG></P><P><span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="110364-nifi-cluster-coordinator.png" style="width: 1544px;"><img src="https://community.cloudera.com/t5/image/serverpage/image-id/18726iFF623BC466E4B100/image-size/medium?v=v2&amp;px=400" role="button" title="110364-nifi-cluster-coordinator.png" alt="110364-nifi-cluster-coordinator.png" /></span></P><P><BR /></P><P><EM>HTH</EM></P><P><EM><BR /></EM></P> Sun, 18 Aug 2019 08:02:59 GMT Shelton 2019-08-18T08:02:59Z