A PRTG Cluster consists of two or more installations of PRTG that work together to form a high availability monitoring system. The objective is to reach true 100% uptime for the monitoring tool. Using clustering, the uptime will no longer be degraded by failing connections because of an internet outage at a PRTG server's location, failing hardware, or because of downtime due to a software update for the operating system or PRTG itself.
How a PRTG Cluster Works
A PRTG cluster consists of one Primary Master Node and one or more Failover Nodes . Each node is simply a full installation of PRTG which could perform the whole monitoring and alerting on its own. Nodes are connected to each other using two TCP/IP connections. They communicate in both directions and a single node only needs to connect to one other node to integrate into the cluster.
During normal operation the Primary Master is used to configure devices and sensors (using the web interface or Enterprise Console). The master automatically distributes the configuration to all other nodes in real time. All nodes are permanently monitoring the network according to this common configuration and each node stores its results into its own database. This way, the storage of monitoring results also is distributed among the cluster (the downside of this concept is that monitoring traffic and load on the network is multiplied by the number of cluster nodes, but this will not be a problem for most usage scenarios). The user can review the monitoring results by logging into the web interface of any of the cluster nodes in read only mode. Because the monitoring configuration is centrally managed, it can only be changed on the master node, though.
By default, all devices created on the Cluster Probe are monitored by all nodes in the cluster, so data from different perspective is available and monitoring for these devices always continues, even if one of the nodes fails. In case the Primary Master fails, one of the Failover Nodes takes over the master role and controls the cluster until the master node is back. This ensures a fail-safe monitoring with gapless data.
Note: During the outage of a node, it will not be able to collect monitoring data. The data of this single node will show gaps. However, monitoring data for this time span is still available on the other node(s). There is no functionality to actually fill in other nodes' data into those gaps.
If downtimes or threshold breaches are discovered by one or more nodes, only one installation, either the Primary Master or the Failover Master, will send out notifications (via email, SMS text message, etc.). Thus, the administrator will not be flooded with notifications from all cluster nodes in case of failures.
Note: For clusters we recommend you to stay below 10,000 sensors per cluster.
PRTG offers single failover clustering in all licenses—even using the freeware edition. A single failover cluster consists of two servers ("Current Master" Node and "Failover Node"), each of them running one installation of PRTG. They are connected to each other and exchange configuration and monitoring data.
Illustration of a Single Failover Cluster
For setting up a cluster you need two or more servers and there is one core installation necessary on each of them—with different settings configured for each type of node. In return, you benefit from seamless high-available monitoring with automatic failover and/or multi-location monitoring.
In a cluster, you can run:
- 1 Master Node
On the master node, you set up your devices and configuration. Also notifications, reporting, and many other things are handled by the master node. - Up to 4 Failover Nodes
You can install one, two, three, or four additional nodes for fail-safe, gapless monitoring. Each of these nodes can monitor the devices in your network independently, collecting their own monitoring data. The data can be reviewed in a summarized way, enabling you to compare monitoring data from different nodes.
Note: During an outage of one node, you will see data gaps for the time of the outage on that node. However, data for that time span will still be available on all other cluster nodes.
Before Getting Started
Configuring a cluster with one failover node is the most common way to set up a seamless network monitoring with PRTG. You will need two servers running any Windows version (Vista or later); your servers can be real hardware (recommended! ) or virtual machines.
Please make sure the following:
- Your servers must be up and running.
- Your servers must be similar in regard to the system performance and speed (CPU, RAM memory, etc.).
- In a cluster setup, each of the cluster nodes will individually monitor the devices added to the Cluster Probe . This means that monitoring load will increase with every cluster node. Please make sure your devices and network can handle these additional requests. Often, a larger scanning interval for your entire monitoring is a good idea. For example, you could set a scanning interval of 5 minutes in the Root Group Settings .
- We recommend installing PRTG on dedicated real-hardware systems for best performance.
- Please bear in mind that a server running a cluster node may in rare cases be rebooted automatically without notice (e.g. for special software updates).
- Both servers must be visible for each other through the network.
- Communication between the two servers must be possible in both directions . Please make sure that no software- or hardware firewall is blocking communication. All communication between nodes in the cluster is directed through one specific TCP port. You will define it during cluster setup (by default, it is TCP port 23570 ).
- A Failover Master will send notifications in case the Primary Master is not connected to the cluster. In order for mails to be delivered in this case, please make sure you configure the Notification Delivery settings in a way they can be used to deliver emails from your Failover Node as well (for example, using the option to set up a secondary Simple Mail Transfer Protocol (SMTP) server).
- Make your servers safe! From every cluster node, there is full access to all stored credentials as well as other configuration data and the monitoring results of the cluster. Also, PRTG software updates can be deployed through every node. So, please make sure you take security precautions to avoid security attacks (hackers, Trojans, etc.) You should secure every node server the same careful way as the master node server.
- Run the nodes in your cluster either on 32-bit or 64-bit Windows versions only. Avoid using both 32-bit and 64-bit versions in the same cluster, as this configuration is not supported and may result in an unstable system. Also, ZIP compression for the cluster communication will be disabled and you may encounter higher network traffic between your cluster nodes.
- If you run cluster nodes on Windows systems with different timezone settings and use Schedules to pause monitoring of defined sensors, schedules will apply at the local time of each node . Because of this, the overall status of a particular sensor will be shown as Paused every time the schedule matches a node's local system time. Please use the same timezone setting on each Windows with a cluster node in order to avoid this behavior.
- We recommend you to stay below 10,000 sensors per cluster for performance reasons.
The following sensor types cannot be used in cluster mode but only on a local or remote probe:
