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Difference in between KVM and OpenVZ Virtualization

Difference in between KVM and OpenVz Virtualization

Today I want to talk about virtualization in a more theoretical sense in order that you understand what type of virtualization to choose depending upon your needs. There are two major virtualization technologies KVM and OpenVZ. And due to equal popularity of both, there is a continuous debate between KVM vs OpenVZ.

Over the years, virtualization has evolved and adapted to the needs of users and/or the market. This evolution has resulted in different types of virtualization that go well beyond “classic” tools such as VMware or VirtualBox, giving us a wide range of possibilities to choose from. Among these types, there are two of them that have proven to be the most efficient of all and the most “innovative” in the field of virtualization. These types of virtualization are called level virtualization operating system and virtualization Kernel level, although they are best known for tools that make use of such technologies: OpenVZ and KVM (respectively).

Both virtualizations are very useful, but they have a number of differences that, although at first glance they cannot seem very significant, in practice they can be decisive in opting for one choice or another. To understand the difference between the two, the best would be to understand what each type of virtualization offers us.

What is Virtualization?

Virtualization: Virtualization is the practice of creating virtual instances or representations of computer resources, such as servers, operating systems, storage devices, or networks. It allows multiple virtual environments to run on a single physical system, enabling better utilization of resources, improved scalability, and increased flexibility in managing and deploying applications.

What is KVM?

KVM is an open-source virtualization solution for Linux. It is a virtualization infrastructure that turns the Linux kernel into a hypervisor, allowing it to host multiple virtual machines (VMs). KVM provides efficient and secure virtualization capabilities, enabling users to run a wide range of guest operating systems, including various Linux distributions, Windows, and more.

What is OpenVZ?

OpenVZ is an open-source container-based virtualization solution for Linux. It operates at the operating system level, providing lightweight and efficient virtualization by creating multiple isolated containers, also known as virtual private servers (VPS), on a single physical host. 

But what are the differences in between KVM and OpenVZ Virtualization? Let’s take a look!

First of all, the foremost basic difference between OpenVZ and KVM is that OpenVZ can solely host Linux operating systems, whereas KVM is a lot versatile and might host Linux, Windows, or can opt for custom OS.

Advantages and disadvantages of OpenVZ are that it permits the complete sharing of resources. OpenVZ uses a shared kernel with a layer of virtualization on top of the particular Linux Operating System. Since this kernel is shared by all the users over a specific node on VPS, the kernel isn’t customizable. Once you’ve hit your allotted RAM provided to you by the host, the remaining RAM becomes free for other server users. This is often not a problem if you run small software or applications, however, you may find yourself in a trouble if you’re running something that is resource-intensive.

With KVM, you can setup maximum and minimum values on your resources, allowing you to use only the resources that your applications will require. This is often true, real hardware virtualization, which means higher performance from lower needs on the hypervisor. 100 percent of the RAM and disk resources are dedicated to at least one individual user. KVM comes with an isolated environment and provides users their own kernel.

Key Differences Between KVM vs OpenVZ

Hardware Requirements:

Virtualization: Virtualization typically requires specialized hardware support, to enable hardware-level virtualization capabilities. This can impose certain limitations on the choice of hardware and may require CPUs with specific features.

OpenVZ: OpenVZ does not require specialized hardware support for virtualization. It leverages the host system’s kernel to create containers, allowing it to run on a wider range of hardware configurations.

OS Support:

Virtualization: Virtualization supports a wide range of operating systems, including various Linux distributions, Windows, macOS, and more. It provides the flexibility to run different OSs simultaneously on the same physical machine.

OpenVZ: OpenVZ is primarily designed for Linux environments and supports a limited number of Linux distributions as both the host and guest operating systems.

Kernel Version:

Virtualization: Virtualization, such as KVM, typically requires a specific kernel module to be installed. This module is closely tied to the kernel version and needs to match the host system’s kernel.

OpenVZ: OpenVZ requires a specific patched kernel, known as the OpenVZ kernel, to enable container-based virtualization. This kernel version may differ from the standard kernel used in other Linux distributions.

Memory Distribution:

Virtualization: In virtualization, memory is allocated to each virtual machine individually, allowing fine-grained control over resource allocation. Each virtual machine has a dedicated amount of memory assigned to it.

OpenVZ: OpenVZ uses a shared memory model, where the host system’s memory is divided among the containers. The memory allocation is dynamic and flexible, allowing containers to utilize unused memory resources on the host.


Virtualization: Virtualization solutions often come with licensing costs, especially for commercial offerings. The price can vary depending on the specific virtualization platform and additional features required.

OpenVZ: OpenVZ is an open-source project, meaning it is generally free to use and does not incur licensing costs. However, there may be costs associated with support, maintenance, or additional services depending on the specific implementation or provider.

Know the risk of overselling: Overselling is something where a web hosting provider overcommits the server resources to specific users considering that not each of the account uses up all those resources at a time. Whereas everything is oversold, Stay away from shady hosting firms that often oversells OpenVZ systems and host you on a system that has several containers. KVM also can be oversold, but it is highly isolated. Since OpenVZ hosts are usually oversold, OpenVZ servers are usually cheaper than KVM servers.

If you are looking for Speed, Scalability, and Affordable solution, OpenVZ is the platform that you should consider. KVM offers private virtualized hardware as well as a network card, disk and graphics adapter, and bonded resources for inflated reliableness and customizability. KVM packages are the best opt for serious resellers, game servers, small businesses, and medium-sized enterprises.

Which Virtualization You Should Choose?

OpenVZ vs KVM. The main difference between OpenVZ and KVM is that OpenVZ can only host Linux-based operating systems, while KVM can host Linux, Windows, and custom operating systems. The complete sharing of resources that OpenVZ is depended on the user whether to take it or not.


OpenVZ focuses on lightweight containerization, primarily for Linux environments, with broader hardware compatibility, shared memory distribution, a specific patched kernel, and open-source nature. The choice between these technologies depends on specific requirements, infrastructure preferences, and the desired balance between flexibility, performance, and cost.

I hope that with this small article you have understood the most important concepts of virtualization and know the advantages and disadvantages offered by each type of virtualization.


KVM vs OpenVZ; which virtualization is faster?

KVM, being a hardware-level virtualization technology, provides near-native performance as it runs guest operating systems on their own virtualized hardware.  OpenVZ, being a container-based virtualization technology, offers better efficiency and lower overhead since it shares the host system’s kernel and resources. 

What is the best choice for a VPS, KVM, or OpenVZ?

Ultimately, the best choice between KVM and OpenVZ for a VPS depends on the specific requirements, desired performance, isolation needs, OS flexibility, and budget constraints of the hosting environment.

The Author

A Journalist Specializing in Blogging, Social Networking and Community Management. As a constant learner, Pravin is always aiming towards new ideas and greater knowledge. When he is not doing research, reading, or writing for blogs, you can find him hanging around social media sites.

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