A Proxmox VE cluster combines multiple servers for centralized management and HA. Minimum 3 nodes required for HA quorum.
pvecm create my-cluster --link0 192.168.1.100
pvecm add 192.168.1.100 --link0 192.168.1.101
ha-manager add vm:100 --group ha-group --state started
Configure fencing (IPMI/iDRAC/PDU) for reliable HA. Without fencing, a split-brain scenario can corrupt data when a node becomes unreachable.