January 25, 2021


Virtualization is not a new concept. The web hosting industry leveraged server virtualization to create virtual servers and launched a new type of efficient hosting services – VPS Hosting. This is done by using a virtualization program called a hypervisor. It helps the host divide the physical web server into several virtual servers, each with dedicated resources, account isolation, and complete root access. There are various ways in which the web host can create VPS Servers, including KVM, Virtuozzo, and OpenVZ. Today, we will talk about hypervisors and compare these three hypervisor applications.

What are KVM, Virtuozzo, and OpenVZ?

  • KVM or Kernel-based Virtual Machine is a technique to create virtual servers that run on the kernel of the Linux operating system. This technique converts the kernel into a hypervisor to create virtual servers.
  • Virtuozzo is a container-based virtualization solution allowing hardware sharing using an abstraction layer. It creates containers that simulate a server. It is not a hypervisor but operates in a mix of the kernel and userspace with the proprietary kernel.
  • OpenVZ is also a container-based virtualization application for Linux. It is the basis of Virtuozzo and helps create virtual servers.

Difference between KVM, Virtuozzo, and OpenVZ

Let’s look at the features of KVM, Virtuozzo, and OpenVZ to understand the differences better:

Operating System support

  • KVM – Linux, Windows, and customized operating systems
  • Virtuozzo – Linux and Windows operating systems
  • OpenVZ – Linux operating system only

Kernel Versions

  • KVM – The virtual machines created by KVM can each run a different kernel version than the hypervisor
  • Virtuozzo – It runs a single kernel as the core. This core is sent to multiple distributions, that help create stand-alone entities.
  • OpenVZ – The containers created by OpenVZ have the same architecture and kernel version as the hypervisor. Hence, it has a lower overhead on the hypervisor.

Memory Distribution

  • KVM – This has a hard memory limit. Therefore, it offers a stable distribution of resources.
  • Virtuozzo – If the server does not have adequate RAM, then Virtuozzo can fail since it depends on virtual RAM. If it runs out of RAM, then it kills the processes.
  • OpenVZ – In OpenVZ, the memory that is not used by one container can be used by the other containers.

While as a site owner, you need to focus more on the features offered by the VPS Hosting plan, understanding the architecture and techniques used for creating the virtual servers can help you understand what to expect from the virtual servers. Talk to the hosting company and try to understand these details to make an informed decision.

Summing Up

VPS Hosting offers a range of benefits to websites since it is based on a virtual server that has dedicated resources, account isolation, and complete root access. The way the host creates the virtual servers can impact the performance of the virtual server and the hosting service. Hence, if you have some technical know-how, try to understand the type of hypervisor used by your provider –  KVM, Virtuozzo, or OpenVZ, to buy the right hosting plan for your site. Good Luck!