KVM (Kernel-based Virtual Machine) and OpenVZ are the two main virtualization technologies used by VPS providers worldwide, including the Russia market. Each has distinct advantages and limitations that affect what you can do with your VPS. This guide compares them on performance, flexibility, OS choice, kernel modules, and use cases to help you choose the right virtualization technology for your needs.
1. How KVM Works
KVM (Kernel-based Virtual Machine) is a full hardware virtualization technology built into the Linux kernel. Each KVM VPS is a complete virtual machine with its own kernel, dedicated hardware resources, and full isolation from other VPS on the same physical server. KVM uses hardware-assisted virtualization (Intel VT-x or AMD-V) to achieve near-native performance. Because each KVM VPS has its own kernel, you can run any operating system (Linux, Windows, BSD), load custom kernel modules, configure firewall rules with iptables/nftables, and run nested virtualization. KVM is the modern standard for VPS virtualization — all providers in our 2026 cohort use KVM.
2. How OpenVZ Works
OpenVZ is a container-based virtualization technology where each VPS (called a "container") shares the host's kernel. OpenVZ containers are isolated at the OS level (process isolation, file system isolation, network isolation) but all run on the same Linux kernel. Because there is only one kernel, OpenVZ containers can only run Linux (not Windows or BSD), cannot load custom kernel modules, and have limited firewall configuration (no iptables in some configurations, no network namespaces in older versions). OpenVZ is lighter weight than KVM — less memory overhead, faster startup, easier overselling — but is significantly less flexible. OpenVZ has been largely replaced by LXC and Docker in modern deployments, but some budget VPS providers still use it.
3. Performance Comparison
Performance between KVM and OpenVZ is similar for CPU and memory-intensive workloads — both achieve 95-99% of bare-metal performance with hardware-assisted virtualization. The differences appear in I/O and network. OpenVZ has slightly lower I/O overhead because containers share the host's file system cache, but the difference is small (5-10%). KVM has slightly higher network latency due to the virtual network interface, but again the difference is small (1-2ms). For most workloads, the performance difference is negligible — choose based on flexibility, not raw performance. If your workload is extremely I/O-intensive (database server, large file storage), OpenVZ may have a slight edge. For everything else, KVM is fine.
4. OS Choice and Kernel Flexibility
KVM allows you to run any operating system: any Linux distribution (Ubuntu, Debian, CentOS, Alpine, Arch), Windows Server, FreeBSD, OpenBSD, even custom OS images. You can also load custom kernel modules — critical for VPN software (WireGuard, OpenVPN with TUN/TAP), Docker (which requires specific kernel features), file system drivers (ZFS, Btrfs), and security modules (AppArmor, SELinux custom policies). OpenVZ restricts you to the host's kernel — you can run different Linux distributions but only those compatible with the host kernel version. You cannot load custom kernel modules. This makes OpenVZ unsuitable for VPN servers, Docker hosts, file system experiments, and any workload requiring kernel-level customization.
5. Resource Isolation and Fairness
KVM provides stronger resource isolation — each VPS has dedicated RAM and CPU allocation that cannot be exceeded (you can burst above guaranteed levels on some configurations, but the guaranteed minimum is yours). OpenVZ uses a "fair share" CPU scheduler and "beancounters" for memory — your VPS gets a guaranteed minimum plus the ability to burst into unused resources. The downside is that OpenVZ providers can oversell more aggressively — if all VPS on a server try to use 100% CPU simultaneously, performance degrades for everyone. KVM overselling is also possible but is more visible (CPU steal time is reported in /proc/stat). For predictable performance, KVM is preferable.
6. Network Configuration
KVM VPS have full network stack control — you can configure iptables/nftables rules, set up custom routing, use network namespaces, configure VPN tunnels (WireGuard, OpenVPN, IPsec), and run network monitoring tools. OpenVZ VPS have limited network configuration — iptables may be restricted (no NAT in some configurations), network namespaces are unavailable in older versions, and some VPN protocols (OpenVPN with TUN/TAP) require the host kernel to have specific modules loaded. For VPN servers, custom routing, or advanced network configurations, KVM is required. OpenVZ is fine for basic web hosting where you only need ports 80 and 443.
7. Use Case: Web Hosting
For basic web hosting (single site, LAMP/LEMP stack, no special requirements), either KVM or OpenVZ works fine. If you are running a simple WordPress site, a static site, or a small web application, OpenVZ is sufficient and may be slightly cheaper. However, if you plan to run Docker containers, set up a VPN, use Let's Encrypt with custom configurations, or run multiple isolated sites, KVM is required. Most modern web hosting uses Docker or similar container technology, which requires KVM. For new deployments in 2026, choose KVM even for basic web hosting — the flexibility is worth the small price premium.
8. Use Case: VPN Server
For VPN servers (WireGuard, OpenVPN, IPsec), KVM is required. OpenVZ cannot run WireGuard (requires custom kernel module), cannot run OpenVPN with TUN/TAP (requires the host kernel to have tun module loaded, which most providers do not enable), and has limited support for IPsec. If you want to set up a personal or team VPN on your Russia VPS, you must use KVM. All providers in our 2026 cohort use KVM, so this is rarely an issue, but verify before signing up if you see suspiciously cheap plans — they may be OpenVZ.
9. Use Case: Docker Host
For Docker hosts (running containers on your VPS), KVM is required. Docker requires specific kernel features (cgroups, namespaces, overlay file systems) that OpenVZ containers cannot provide (they share the host's kernel, which may not have these features enabled for containers). If you want to run Docker on your Russia VPS, choose KVM. All providers in our 2026 cohort support Docker on KVM VPS. For Kubernetes nodes, KVM is also required — Kubernetes has the same kernel requirements as Docker.
10. Use Case: Database Server
For database servers (MySQL, PostgreSQL, MongoDB), both KVM and OpenVZ work, but KVM is preferable for production. Database servers benefit from kernel-level tuning (transparent huge pages, swappiness, I/O scheduler) that is only configurable on KVM. OpenVZ containers share the host's kernel settings, so you cannot tune for database workloads. For dev/test database servers, OpenVZ is fine. For production database servers, choose KVM for the ability to tune the kernel and the stronger resource isolation.
11. Use Case: Game Server
For game servers (Minecraft, CS:GO, Rust, Ark), both KVM and OpenVZ work, but KVM is preferable. Game servers often require custom kernel modules (some mods require specific kernel features), and benefit from kernel-level tuning for network performance (TCP buffer sizes, conntrack table size). OpenVZ game servers work but may have higher latency and cannot be tuned as aggressively. All modern game server management tools (Pterodactyl, LinuxGSM) recommend KVM. For best game server performance, choose KVM with at least 4 vCores and 4GB RAM.
12. Detecting OpenVZ VPS
If you are unsure whether your VPS is KVM or OpenVZ, several commands reveal the virtualization type. Run `systemd-detect-virt` — outputs "kvm" for KVM, "openvz" for OpenVZ, "lxc" for LXC. Run `cat /proc/1/environ | tr '\0' '\n' | grep -i virt` — OpenVZ containers have environment variables like `VZ_VE_STATE`. Check `/proc/user_beancounters` — if it exists, you are on OpenVZ. Check the kernel version with `uname -r` — OpenVZ containers often have "openvz" or "stab" in the kernel version string. If you discover your VPS is OpenVZ and you need KVM features, request migration from your provider or switch providers.
13. Why OpenVZ Is Rare in 2026
OpenVZ has been largely replaced by LXC (Linux Containers) and Docker in modern deployments. LXC provides similar OS-level isolation but with full kernel feature support (cgroups v2, namespaces, overlayfs). Docker provides application-level containerization without the VPS abstraction. Most VPS providers in 2026 have migrated from OpenVZ to KVM because customers demand the flexibility (custom kernels, Docker, VPN, Windows). The few providers still using OpenVZ are typically budget providers competing on price — the overhead savings allow them to oversell more aggressively. For any non-budget use case, KVM is the right choice.
14. The LXC Alternative
LXC (Linux Containers) is a modern alternative to OpenVZ that provides OS-level isolation with full kernel feature support. LXC containers can run Docker, load kernel modules (with appropriate permissions), and use modern Linux features. However, LXC is rarely offered by VPS providers — it is more common in private cloud deployments (Proxmox, LXD). If you encounter a VPS provider offering LXC, it is a good choice — you get the lightweight isolation of OpenVZ with the flexibility of KVM. But for most users, KVM remains the standard because it is universally supported and well-understood.
Conclusion
For nearly all Russia VPS use cases in 2026, KVM is the right choice. It offers full OS flexibility (Linux, Windows, BSD), custom kernel modules (required for VPN, Docker, file system drivers), stronger resource isolation, and full network configuration. OpenVZ is sufficient for basic web hosting without special requirements, but the small price premium of KVM is worth the flexibility. All providers in our 2026 cohort use KVM, so this choice is rarely an issue — but verify before signing up if you see suspiciously cheap plans. For VPN servers, Docker hosts, and any workload requiring kernel customization, KVM is required. Choose KVM unless you have a specific reason to choose OpenVZ.