Kvm on Backend Engineering Strategy Tools

Proxmox VE

Thu, 14 May 2026 00:00:00 +0000

Proxmox VE (Virtual Environment) is an open-source Type 1 hypervisor built on Debian. It runs KVM for full virtual machines and LXC for lightweight containers, managed through a web UI or API. The subscription model is optional — the community edition is fully functional without a paid license; the subscription gives access to the enterprise update repository and support.

Comparison

Platform	License	VMs (KVM)	Containers	Clustering	Web UI
Proxmox VE	Open-source (optional sub)	Yes	Yes (LXC)	Yes	Yes
VMware ESXi	Commercial	Yes	No	Yes (vCenter)	Yes
Standalone KVM	Open-source	Yes	No	Manual	No
oVirt	Open-source	Yes	No	Yes	Yes

Proxmox is the practical choice when you want VMware-style management without the licensing cost, or when you want to run both VMs and containers on the same node.

Core concepts

Node — a physical host running Proxmox VE. Managed independently or as part of a cluster.

Cluster — multiple nodes joined together. Share a unified management view and allow live migration of VMs between nodes. Uses Corosync for distributed consensus.

Quorum — clusters require a majority of nodes to be reachable to avoid split-brain. Minimum useful cluster size is 3 nodes (loss of one node still leaves a majority). Two-node clusters need a quorum device (qdevice) to function safely.

VM — full virtual machine backed by QEMU/KVM. Hardware-level isolation. Arbitrary OS.

Container (CT) — LXC container. Shares the host kernel; lower overhead than a VM. Linux-only. Useful for services where you want process-level isolation without a full OS.

Storage pool — where disks and images live. Supported backends: local directory, LVM, LVM-thin, ZFS, NFS, CIFS, and Ceph (via rbd). ZFS and Ceph are the most capable options for a cluster — ZFS for local redundancy, Ceph for shared storage across nodes.

Proxmox VE documentation
Proxmox community forum
Corosync documentation
Ceph — distributed storage backend for Proxmox clusters
OpenStack — the next tier up the scale spectrum
Proxmox cluster in the homelab

KubeVirt

Mon, 01 Jan 2024 00:00:00 +0000

See Virtualization — KVM and KubeVirt for full coverage of both KVM and KubeVirt.

Virtualization — KVM and KubeVirt

Mon, 01 Jan 2024 00:00:00 +0000

KVM is the Linux kernel’s native hypervisor. KubeVirt extends Kubernetes to run virtual machines using KVM under the hood. They are the same virtualization layer at different levels of abstraction — KVM on bare metal, KubeVirt in a Kubernetes cluster.

KVM

Kernel-based Virtual Machine. KVM turns the Linux kernel into a hypervisor using hardware virtualization extensions (Intel VT-x, AMD-V). Virtual machines run as regular Linux processes backed by QEMU for device emulation. Managed via libvirt and its CLI tools (virsh, virt-install) or the virt-manager GUI.

# Create a VM from an ISO
virt-install \
 --name ubuntu-vm \
 --ram 4096 \
 --vcpus 2 \
 --disk path=/var/lib/libvirt/images/ubuntu.qcow2,size=40 \
 --cdrom /tmp/ubuntu.iso \
 --os-variant ubuntu22.04

# List running VMs
virsh list

# Start/stop
virsh start ubuntu-vm
virsh shutdown ubuntu-vm

# Connect to console
virsh console ubuntu-vm

KVM gives near-native performance for CPU-bound workloads. Network and disk I/O use virtio drivers for efficient paravirtualised I/O. Live migration moves a running VM between hosts without downtime if shared storage is available.

KubeVirt

KubeVirt adds VirtualMachine and VirtualMachineInstance CRDs to Kubernetes. VMs are defined as Kubernetes resources, scheduled by the Kubernetes scheduler, and managed alongside containers. Under the hood, each VM runs as a pod containing a QEMU-KVM process.

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
 name: ubuntu-vm
spec:
 running: true
 template:
 spec:
 domain:
 devices:
 disks:
 - name: rootdisk
 disk:
 bus: virtio
 resources:
 requests:
 memory: 4Gi
 cpu: "2"
 volumes:
 - name: rootdisk
 containerDisk:
 image: kubevirt/fedora-cloud-container-disk-demo

The virtctl CLI complements kubectl for VM-specific operations:

virtctl start ubuntu-vm
virtctl stop ubuntu-vm
virtctl console ubuntu-vm # serial console
virtctl ssh ubuntu-vm # SSH via the Kubernetes API
virtctl migrate ubuntu-vm # live migrate to another node

CDI — Containerized Data Importer

KubeVirt is typically paired with CDI, which imports VM disk images from URLs, container registries, or PVCs into DataVolume resources that VMs can boot from. CDI handles the data flow; the VM definition just references the DataVolume.

Why VMs in Kubernetes

Some workloads can’t be containerised — legacy applications expecting a full OS, Windows workloads, software with kernel module requirements. KubeVirt lets those workloads live in the same cluster as containers, managed with the same tooling, subject to the same scheduling and networking policies.

Kvm on Backend Engineering Strategy Tools

Proxmox VE

Comparison

Core concepts

Related

KubeVirt

Virtualization — KVM and KubeVirt

KVM

KubeVirt

CDI — Containerized Data Importer

Why VMs in Kubernetes

Resources