High availability and the compute cluster

Management node high availability (HA) and the compute cluster are tightly coupled, so changing nodes in one usually affects the other. Take note of the following:

• Each node in the HA configuration must meet the requirements for the management node listed in the Server requirements. If the compute cluster is to be created, its hardware requirements must be added as well.
• If the HA configuration has been created before the compute cluster, all nodes in it will be added to the compute cluster. This applies to both three-node and five-node HA configurations.
• If the compute cluster has been created before the HA configuration, only nodes in the compute cluster can be added to the three-node configuration. Additionally, such nodes must be connected to all networks with the VM public traffic type. To be able to create the HA configuration with a particular node, add this node to the compute cluster first. However, once the HA configuration is created, it can be expanded with two more nodes, with or without the compute role.
• If the HA configuration and compute cluster include exactly the same nodes, single nodes cannot be removed from the compute cluster. In such a case, the compute cluster can be destroyed completely, but the HA configuration will remain. This is also true vice versa, the HA configuration can be destroyed, but the compute cluster will continue working.
• With the five-node HA configuration, up to two nodes can be removed from the management node HA without destroying it. After this, these two nodes can be removed from the compute cluster.