KVM VPS vs OpenVZ: What You Are Actually Buying
KVM VPS vs OpenVZ: what full virtualization gives you that a container cannot, from your own kernel to a real console, and how to tell which you bought.
KVM VPS vs OpenVZ is the difference between renting a whole machine and renting a room inside someone else's. Both get sold as a "VPS" at similar prices, and on a spec sheet they look identical: same RAM number, same core count, same disk. The gap only shows up later, on the day you need to run Windows, load a kernel module, or get back into a server that will not boot. Here is what full virtualization actually buys you, and how to check which one you are about to pay for.
What KVM and OpenVZ actually are#
KVM stands for Kernel-based Virtual Machine, a virtualization layer that has shipped inside Linux since kernel 2.6.20 in 2007. It emulates a whole computer: your server boots its own kernel (the core of an operating system, the part that talks to the hardware), sees its own virtual disks and network cards, and has no idea what else runs on the physical host.
OpenVZ, LXC, and Virtuozzo are container platforms. They do not emulate a machine; they carve one running Linux kernel into isolated slices, each with its own filesystem, processes, and IP address. That is efficient engineering, and a container starts in about a second. The catch is that every tenant on the node shares one kernel, and it is not yours.
KVM VPS vs OpenVZ: the differences that decide it#
| KVM (full virtualization) | OpenVZ or LXC (containers) | |
|---|---|---|
| What boots | Your own kernel, your choice of distribution | The host's kernel, whatever version it happens to run |
| Operating systems | Any Linux, plus Windows Server | Linux only, from the host's template list |
| Kernel modules | Yours to load | Only what the host already loaded |
| Swap | A real swap file you create | An accounting trick, or nothing |
| What monitoring sees | The resources you bought | Often the host's totals, so tools misread the numbers |
| When it will not boot | Browser console and rescue mode, on your own | A support ticket, then waiting |
| Cost to the provider | Higher | Lower, which is the whole point |
What a container VPS cannot do for you#
These four come up in support tickets constantly, and they are the practical reason we run KVM on every plan we sell.
- Run Windows. A Linux container can only ever hold Linux. Our reinstall menu offers Windows Server 2019, 2022, and 2025 evaluation images, which is only possible because there is a real virtual machine underneath.
- Load a kernel module. WireGuard, custom netfilter rules, ZFS, and some Docker storage drivers all need to touch the kernel. On a container you get whatever the host loaded and no vote. On KVM you have full root and can install your own kernel.
- Give you real swap. Swap is disk space the kernel uses as overflow when memory runs out, and it is the difference between a slow hour and a dead process. Here you create a swap file yourself in about two minutes.
- Hand you a console when the network dies. Every server here includes a browser VNC console and a rescue ISO: a virtual keyboard and monitor wired straight to the machine, so a firewall rule that locked out SSH is a five-minute fix at 2am instead of a ticket. Containers have no screen to attach.
How to tell which one you bought#
Three commands, thirty seconds, and they work on any provider's box:
systemd-detect-virtprintskvmon a real virtual machine, andlxc,openvz, orlxc-libvirton a container.uname -rshows the running kernel. On KVM it matches the distribution you installed. On a container it is often an old or unfamiliar build, because it belongs to the host.lsblklists block devices. A KVM guest shows its virtual disk, usually/dev/vda. A container often shows nothing useful, having never had a disk of its own.
If the order page will not say which it is, that is the answer.
Full virtualization is necessary, not sufficient#
Here is the part most comparison articles skip. KVM stops a neighbor from reading your files. It does not stop them from eating your CPU. A KVM node packed to twice its honest capacity feels worse than a lightly loaded container host, and plenty of budget providers run exactly that. The hypervisor is the floor, not the finish.
What fixes it is density policy, and the honest version of that has two numbers in it rather than one. A shared vCPU plan allocates more virtual cores than the host has physical ones. That is how a shared core gets sold at a shared price, and it costs you nothing right up until the machine is genuinely busy. What keeps it from getting there is a ceiling on measured use, not on allocation: we limit every node to 60 percent average CPU load, published live, and we sell from a fixed stock of slots per host instead of filling one until somebody complains. That is the argument we made at length in why we use stock control.
The Performance line runs AMD EPYC 4000-series hosts on NVMe RAID, the Foundational line runs enterprise Intel hosts on hardware RAID-10 SSD, and both are KVM under SolusVM. Results are published quarterly on VPSBenchmarks rather than asserted, and you can run the same benchmark yourself the hour your server is delivered.
That is the test to apply to any host. Full virtualization, stated plainly. A density policy they will describe. Numbers you can reproduce.
Frequently asked questions#
Is KVM faster than OpenVZ?#
Not inherently. Containers carry less overhead because there is no second kernel to run, so on identical, honestly loaded hardware a container can edge out a virtual machine on some workloads. Speed is not the reason to choose KVM. Control, isolation, and being able to fix your own server are.
Can I run Docker on an OpenVZ VPS?#
Sometimes, and it is fragile. Docker leans on kernel features the host may not expose to a container, and a host kernel update can break your stack without warning. On KVM it is an ordinary install, which is why our Docker guide is the same on every plan.
Is LXC the same as OpenVZ?#
Different projects, same consequences for a buyer. LXC is the container implementation in the mainline Linux kernel and OpenVZ was the older out-of-tree one, but either way you share a kernel you do not control.
Does a VDS change any of this?#
A virtual dedicated server is still KVM. What changes is the ratio: VDS cores are sold one to one against physical cores, with no shared-core allocation layered on top, so sustained load stays predictable. The same 60 percent load ceiling applies. The plan chooser lays out where each line wins.