OpenVZ
DevOps & AdminOpenVZ is an operating-system-level virtualization technology for Linux that creates multiple isolated containers on a single host kernel. Each container behaves like a separate server with its own processes, users, and file system, while sharing the host kernel for efficiency. It is often associated with lightweight VPS offerings, emphasizing high density and low overhead compared with full hardware virtualization.
How It Works
OpenVZ virtualizes at the OS level: one Linux kernel runs on the physical server, and that kernel is partitioned into containers (sometimes called virtual environments). Each container has isolated process trees, network interfaces, and file systems, so applications run as if they were on a dedicated server. Because containers share the same kernel, OpenVZ avoids the overhead of running separate guest operating systems, which can improve performance and allow more instances per node.
Resource management is enforced through kernel features such as cgroups and namespaces, with limits for CPU time, memory, disk space, and I/O. In practice, OpenVZ plans may be configured with either strict guarantees or shared (burstable) resources depending on how the host is tuned. Since the kernel is shared, you cannot run a different kernel inside the container, and supported operating systems are limited to Linux distributions compatible with the host kernel.
Why It Matters for Web Hosting
If a VPS plan uses OpenVZ, it affects what you can install, how predictable performance will be, and how much control you have. OpenVZ containers typically boot fast and offer good efficiency, but they do not provide true kernel-level isolation like KVM. When comparing hosting plans, ask whether resources are guaranteed or burstable, what limits apply to RAM and I/O, and whether you need custom kernel modules or nonstandard networking features that containers may restrict.
Common Use Cases
- Low-overhead Linux VPS instances for small websites and APIs
- High-density hosting nodes where many containers share one server
- Development and staging environments that need fast provisioning
- Running standard Linux services (web server, database, cache) without custom kernel requirements
- Multi-tenant setups where per-container quotas and isolation are sufficient
OpenVZ vs KVM
OpenVZ is container-based virtualization with a shared host kernel, while KVM is full virtualization where each VM runs its own kernel. OpenVZ often delivers lower overhead and faster startup, but it limits kernel customization and can be more sensitive to noisy neighbors if resources are not strictly allocated. KVM generally offers stronger isolation, broader OS compatibility, and more predictable behavior for workloads needing dedicated kernel features.