Failover Cluster; Prerequisites - CheckMK rack1 Mark III Manual

Check_MK rack1 Mark III - Manual

13. Failover cluster

You can combine two Check_MK appliances to form a failover cluster. In doing so, all configurations and
data will be synchronised between the two devices. The devices connected as a cluster are also referred
to as nodes. One of the nodes in the cluster assumes the active role, executing the tasks of the cluster.
There is a constant exchange of information between both nodes regarding their state. As soon as the
inactive node detects that the active node can no longer complete its tasks (due to failure for example),
the inactive node assumes the tasks and becomes the active node.
The failover cluster is there to increase the availability of your monitoring installation by protecting a
device or individual components against hardware failures. The clustering is not a replacement for data
backup.
The cluster ensures a shorter downtime in the following situations:
• If the RAID in a Check_MK rack1 or the SD card in a Check_MK rail2 is no longer accessible, the
inactive node takes control of the resources.
• If the device that has been active until now can no longer be accessed (has failed), the inactive node
takes control of the resources.
• If the active device can no longer access the "external" network and, unlike the inactive node, has a
connection to this network, the inactive node takes control of the resources.
• If you carry out a firmware update, you can update the nodes individually. While one node is being
updated, the other node will continue performing the monitoring.

13.1 Prerequisites

In order to build a cluster, you first need two compatible Check_MK appliances. The following models
can be clustered with one another:
• 2x Check_MK rack1
• 2x Check_MK rail2
• 2x Check_MK virt1
• 1x Check_MK rack1 and 1x Check_MK virt1
In addition, the two devices must use a
The devices must be wired with at least two mutually independent network connections. It is recom-
mended to use as direct a connection as possible between the devices and to make a further connection
over your LAN.
To increase the availability of network connections, you should, instead of using two connections via
individual network connectors, create a bonding configuration that uses all four network connectors of
Check_MK rack1. Use the
LAN3 and LAN4 for the direct connection between the devices.
©Copyright Mathias Kettner GmbH 2018
compatible
interfaces LAN1 and LAN2 for the connection to your network and the interfaces
firmware, and at least version 1.1.0.
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