A quorum disk is a small shared storage in a cluster design, and it is necessary for a two-node Proxmox cluster to work properly. As we only have two member nodes in a cluster, it will cause racing problems when one of the nodes is down. In our example, we would like to use a disk-based quorum daemon—qdisk—to solve this problem. The functionalities of a qdisk are listed as follows:
Heartbeat and liveliness determination: Node updates the status blocks on a quorum disk and alters the timestamp, which is used to decide whether a node has hung or not. If there are certain misses during the heuristics testing, a node is declared as offline.
Scoring and heuristics: As mentioned in the previous point, up to 10 heuristics (minimum 1 heuristic) can be configured by the administrator. There is a score for each heuristic. Normally, there are multiple heuristics defined in a cluster configuration. A node is defined as healthy only if it has scored half of the total maximum...