Introduction

A cluster is a sum of multiple computer nodes connected together through networking. One of the many advantages of clustering is that it moves virtual machines to different nodes as the need arises while providing the maximum uptime. A cluster also allows centralized management of all member nodes and virtual machines within the nodes. Although nodes in a cluster work together, it does not provide HA out of the box. In order to have a fully automated HA, we will have to configure it first. More on HA configuration can be found in Chapter 4, Network Configurations. Proxmox clusters use a few specific ports for various functions. It is important to ensure that these ports are accessible and not blocked any firewalls. This table shows the ports and their functions:

Port	Function
TCP 8006	Proxmox WebGUI
TCP 5900-5999	VNC Console access
TCP 3128	SPICE Console access
TCP 22	SSH access
UDP 5404, 5405	CMAN multicast when using cluster configurations

The following diagram...