====== Cluster Monitoring ======

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===== Introduction =====

Pandora FMS has a feature that allows you to monitor clusters, regardless of the system or application you are using.

The purpose of this system is to ensure fast, but above all, user-friendly cluster monitoring.

There are two types of clusters:

  * **Active - Active**: These are those in which the application or service provided is balanced among all the cluster nodes.
  * **Active - Passive**: Those clusters in which there is only one node operating simultaneously.
There are several types of elements in a cluster:

**Common elements**

These are the modules that must remain active in all cluster nodes, essential for clustering to work.

**Balanced elements**

These are the modules that will be executed only in the active node and that will balance from one node to another of the cluster, that is to say, they will report in one agent or another depending on the machine that executes the application.

<WRAP center round important 90%>

Balanced elements will only be necessary in the case of **Active - Passive**  clusters.

</WRAP>

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===== Planning monitoring =====

When monitoring a cluster, the following must be taken into account:

**If active cluster - active:**

The common modules to be monitored must be present in all the cluster agents. If not, it will not be possible to select them.

Identical monitors must then be created on all agents in the cluster to monitor the resources needed.

**If it is an active - passive cluster:**

The common modules will follow the same configuration as an //active - active//  and the monitoring of the balanced modules **only on the active node**  must be configured.

In order to monitor « the active node » you must use conditional monitoring, where the module will only report when a number of preconditions are met.

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===== Configure a new cluster =====

Menu <wrap :en>**Operation → Monitoring → Cluster view → Create cluster**</wrap>.

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==== Configure a new cluster Active Active ====

Click <wrap :en>**New cluster**</wrap> to start the creation wizard, selecting the "Active - Active" option in <wrap :en>**Cluster type**</wrap>.

Once a name, cluster type and target group have been selected, click <wrap :en>**Next**</wrap> to access the agent selection section.

Once the agents have been selected, click <wrap :en>**Update and continue**</wrap>. In this step, all the **critical modules for the service**  to be monitored are selected from the agents added to the cluster.

A threshold in node percentage (%) must be selected to define the cluster states based on common modules (OK and not OK).

After configuring the cluster you may add alerts on the different elements of the cluster so that a certain action is taken when changing the modules you select to a specific state.

After adding the alerts, click <wrap :en>**Finish**</wrap>. After module evaluation you will see the cluster map with the status information.

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==== Cluster view Active Active ====

<WRAP center round important 90%>

  * If the cluster is **Active - Active**, only the common elements will be visible.
  * The thresholds indicate the moduel percentage in a state **different from normal**.

</WRAP>

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==== Setting up a new Active Passive cluster ====

Click <wrap :en>**New cluster**</wrap> to start the cluster creation wizard and select the "Active - Passive" option in <wrap :en>**Cluster type**</wrap>.

Once a name, cluster type and target group have been selected, clicking <wrap :en>**Next**</wrap> takes you to the agent selection section. You may go back to the previous step at any point in the process with the <wrap :en>**Go back**</wrap> button.

Select in this step all the **critical modules for the service**  you need to monitor among the agents you added to the cluster and a threshold in node percentage (%) to define the cluster statuses based on common modules (OK and not OK status).

**In this step balanced modules are added**  (the ones that are reporting in the active agent). The list will show all the modules of all the agents that are part of the cluster. In this last section select which of the balanced modules are critical for the **Active - Passive**  cluster.

<WRAP center round info 90%>

Modules in the passive node are not created automatically, they must be configured manually and then added to the cluster.

</WRAP>

After the cluster has been configured, alerts may be added on the different elements of the cluster so that a specific action is taken when the selected modules change to a specific state.

After module evaluation, the cluster map with status information will be displayed.

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