In this section, I will show you how a Proxmox cluster helps us in enhancing the system availability. Assume that we are building a cluster with two active member nodes, which means virtual machines are running on both the server nodes. Let's take a look at the following structure:

As we mentioned in the section on system requirements, we need at least two physical servers connected with a network switch, and we need SAN storage to save virtual disk images. This is the minimal requirement to build a cluster. With this set of hardware, we can successfully install Proxmox in cluster mode. However, is it built with high availability? Unfortunately, it is not; let's see what happens when we cannot connect our network switch due to misconfiguration or hardware problems:

Right now, both servers think that the other side is out of service, as SRV1 and SRV2 cannot contact each other. What will they do? They will try to migrate the virtual machines...