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What is a failover master node and how does it behave?



In my cluster setup, the primary master node server failed, so one of the failover nodes took over the master role. It is the failover master node now.

What does the crawl box mean? It is shown when I log into the failover master node's web interface and says:

Cluster is in Failover Mode. This failover node is your current master node because your primary node is not connected to this cluster. You can modify the monitoring configuration, but as soon as the primary node reconnects to the cluster all your changes will be overwritten by the configuration of the primary node.

clustering failover-master help prtg

Created on Aug 11, 2010 1:16:12 PM by  Daniel Zobel [Product Manager]

Last change on Jan 4, 2023 2:55:41 PM by  Brandy Greger [Paessler Support]

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Accepted Answer



This article applies as of PRTG 22

Master node and failover nodes

In a failover cluster, there is one master node and at least one failover node (there can be up to 4 failover nodes). The master node controls the configuration of the cluster. You can only change cluster settings on the master node.

Whenever the master node is not reachable, a failover node takes over the master role until the master node is back online. Such outages can occur when, for example, the server that runs the master node is restarted. The failover node(s) continue to monitor while the master node is not reachable, so gapless monitoring data is available at all times.

Note: During the outage of one cluster node, the database of the affected cluster node shows gaps because it cannot collect data during that time. There is no mechanism to fill in data from other cluster nodes. However, during the outage of one cluster node, monitoring data is still available for all other cluster nodes.

A failover master node temporarily acts as a master node

A failover node that has taken over the master role is called a failover master node. It controls the cluster until the primary master node, which is the master node by configuration, is reachable again. Usually, the primary master node becomes available again after a certain time (for example, when a server has been restarted).

Do not change settings on the failover master node

During the absence of the primary master node, you should not make changes to the configuration on the failover master node. When the primary master node is back in the cluster, the original settings stored on it are restored and deployed to the cluster. So, all changes made on the failover master node are lost.

If a primary master node fails permanently

Sometimes a server crashes and a primary master node installation cannot be restored. In this case, there is a possibility to convert a failover master node so that it becomes the new primary master node of the cluster. We recommend this procedure only in cases where you cannot restore the primary master node. For more information, see Cluster: How do I convert a (temporary) failover master node to be the primary master node?


Created on Aug 23, 2010 11:36:27 AM by  Daniel Zobel [Product Manager]

Last change on Jun 15, 2022 10:13:09 AM by  Brandy Greger [Paessler Support]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.