KVM vs OpenVZ vs LXC — Why the Virtualisation Type Matters

What separates KVM from container VPS: own kernel, swap, custom modules, Windows images, fair isolation. Why NovaVPS sells KVM only.

Полный текст статьи на английском. Шапка, каталог и оплата переведены.

Containers vs virtual machines

OpenVZ/LXC are containers: every VPS shares the host’s kernel, and “RAM” is a pool with burst accounting that evaporates under load. KVM is a true virtual machine: a real kernel of your choice, real swap, dedicated memory the host cannot reclaim. The price difference is a few dollars; the difference in behaviour shows up exactly when your workload matters.

What KVM gives that containers cannot

• Any kernel: custom builds, BPF tooling, kernel modules ( WireGuard, DKMS drivers).
• Windows and BSD images — containers are Linux-only by design.
• Real swap — memory spikes degrade gracefully instead of hard-failing.
• Docker-in-VPS without restrictions, nested virtualisation on request, RAW sockets for packet tools.
• Honest RAM — 4 GB is 4 GB, not 4 GB shared with forty neighbours.

The failure modes of oversold containers

Classic OpenVZ symptoms: the host hits memory pressure and your process gets the OOM kill despite “your” usage being small; a kernel feature you need simply does not exist; iptables modules are missing. These are not provider bugs — they are the architecture. KVM removes the class of problem.