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What is a Failover Master and how does it behave?



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In my PRTG cluster setup, the Primary Master server failed, so one of the failover nodes took over the master role. It is the Failover Master now.

What does the crawl box mean? It is shown when I log into the failover master'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 [Paessler Support]

Last change on May 6, 2019 11:57:17 AM by  Maike Behnsen [Paessler Support]

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This article applies to PRTG Network Monitor 19 or later

Master Node and Failover Nodes

In a PRTG fail-safe 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. All settings can only be changed there.

Whenever the master node is not reachable, a failover node takes over the master role until the master is back online again. Such outages can occur when, for example, the server running the master node is rebooted for some reason. The failover node(s) keep monitoring while the master node is not reachable, so gapless monitoring data is available at all times.

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

A Failover Master Temporarily Acts as a Master Node

A failover node that has taken over the master role is called Failover Master. It controls the cluster until the master is reachable again. Usually, the original Primary Master node becomes available again after a certain time (for example, when a server reboot has been completed).

Do Not Change Settings on the Failover Master Node

During the absence of the primary master node, no changes should be made to the configuration on the failover master. This is because with the primary master node back in the cluster, the original settings stored on it will be restored and deployed to the cluster. So, all changes made on the failover master will be lost.

If a Master Node Fails Permanently

Sometimes a server crashes and a master node installation cannot be restored. If a master node cannot be recovered, there is a possibility to convert a failover master so that it becomes the new primary master of a cluster. This procedure is recommended only in cases where you cannot restore the master node. For more information, please see PRTG 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 [Paessler Support]

Last change on May 8, 2019 5:25:27 AM by  Maike Behnsen [Paessler Support]

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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.