What is a cluster?
A cluster is a group of computers working together as one system so that if one fails the others keep the service running.
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A cluster is several machines (nodes) joined so they behave like a single, more reliable or more powerful system. Think of a relay team rather than a single runner: if one member drops out, another takes the baton and the race goes on. Nodes talk constantly to agree who is healthy and who should run which workload.
Proxmox clusters let you move virtual machines between hosts and restart them elsewhere when a host dies. Kubernetes clusters do the same for containers. Database clusters (PostgreSQL with replication, MongoDB replica sets) keep copies of the data on several nodes. Many clusters need an odd number of nodes, or a small extra voter, so that a split can still agree on a majority.
pvecm status
kubectl get nodesSee also: What is Kubernetes? and What is a virtual machine?
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See also
- 0104 Build a Proxmox VE cluster with pvecm and live-migrate VMs Join Proxmox VE nodes into a cluster with pvecm create and pvecm add, check quorum with pvecm status, then move running VMs… Advanced · Step by step · Linux Article Clusters & high availability · VMs & containers 15 Oct 2026
- 0105 High availability in Proxmox VE: HA resources, fencing and affinity rules Proxmox VE HA restarts VMs and containers on another node when a node fails. Learn the requirements, how watchdog fencing protects your… Advanced · Explains an idea · Linux Article Clusters & high availability 15 Oct 2026
- 0107 Proxmox VE command line cheat sheet: qm, pct, pvecm, pvesm and more The Proxmox VE commands you use most: qm for VMs, pct for containers, pvesm for storage, pvecm for the cluster, vzdump for… Intermediate · Cheat sheet · Linux Article Clusters & high availability · VMs & containers 15 Oct 2026
- 0112 Fix: TASK ERROR: cluster not ready – no quorum? The node is not part of a quorate cluster, so /etc/pve is read-only and guests cannot be started or changed. Restore the… Advanced · Fixes an error · Linux Article Clusters & high availability 15 Oct 2026
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