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KVM Vs OpenVZ vs Xen – Virtualization Explained

by John Doe

There are a variety of virtualization technologies on the market, such as OpenVZ, Kernel-based Virtual Machine (KVM) and Xen. Perhaps you have been aware of them while trying to purchase a Virtual Private Server (VPS). If so, consider the following guide as you compare KVM, OpenVZ and Xen to decide which option would best suit your requirements.

This article will compare and contrast OpenVZ, Xen, and KVM virtualization technologies. Check out different ways of implementing each of them.

What is KVM (Kernel-based Virtual Machine)?

KVM (Kernel-based Virtual Machine) is a type of virtualization software that allows you to create and run multiple isolated virtual machines on a single physical server. Each virtual machine runs its own copy of an operating system and applications. KVM is free and open source software released under the GNU General Public License (GPL).

KVM is fully hardware virtualization, you can run virtually any operating system as a guest, BSD, Windows and Linux, as well as the virtio driver, which will put you on par with native performance, some open source projects have demonstrated not more than three times their drop in capacity between native and hardware virtual settings.

It allows for installation via three kinds of installation: From ISO, by template, and manually. It supports proper privacy partitioning. It can have noticeable IO lag under heavy burden that leads to guest OS and host OS issues. Each guest (VM) runs as its own process on the host node. This is a handy option in identifying which guest is causing issues when necessary.

Due to being an inherent feature of most modern kernels, KVM provides speed advantages over other virtual kernel technology and in some cases and is young and under active development. KVM is the leading choice for a lot of users due to its great performance and versatility, although not quite as stable as its competitor Xen.

What is Xen hypervisor?

Xen is a type of virtualization software that allows for the creation of multiple virtual machines on a single physical server. These virtual machines can run their own independent operating systems and applications, making Xen an ideal tool for consolidating servers and improving server utilization. Xen is open source software released under the GNU General Public License, and is supported by a wide variety of vendors including Citrix, Red Hat, and Oracle. The Xen software comes in two flavors: PV (paravirtualisation) and HVM (full hardware virtualisation).

In comparison with virtualisation through KVM, Xen HVM offers what appears to be a better Linux-based decompilation for Linux since the PV drivers have been available by default since around 2006, so you only need to install the virtio drivers for a performance boost. It’s not possible to overcome this on Windows with Xen PV drivers, even when some of the shortcomings are overcome to some extent.

Xen is quite old and quite mature, so it garners a high degree of trust among its users. Xen servers normally have pre-divided Ram and CPU cores along with the xen hypervisor so that it has distinct elements that guests can’t see to impact stability.

What is OpenVZ?

OpenVZ is an open source virtualization platform that enables users to create and run multiple isolated Linux containers (vz) on a single physical server. Containers are similar to virtual machines, but they use a shared kernel and are more lightweight, which makes them ideal for hosting multiple applications on a single server. OpenVZ can also help reduce hardware costs, as it allows users to consolidate multiple servers into one.

OpenVZ is highly revered in the hosting industry due to its fast and high deployment density, as the kernel is shared with the guests along with bandwidth, ram, disk, and cpu, with almost no partitioning between the guest and host. This is because almost no data transfer between guest and host occurs.

OpenVZ is not a virtualization program, but rather, a containerization technique. OpenVZ utilizes a kernel that is stable Linux and operates only one kernel. The downside of this approach, however, is the single kernel. OpenVZ’s shared kernel will not allow the user to configure or add additional modules to it.


KVM offers solid privacy, since data tends to be shielded from other users. In addition, it permits running whatever type of kernel you want, subject to its limitations. Thus, KVM is not only limited to the Linux kernel that’s installed on the system’s root. KVM is also able to run other x86 operating systems (for example, Windows and BSD). It also plays an important role.

What virtualization technology is set up on WebCare360’s Offshore VPS?

WebCare360 virtual private server (Offshore VPS) hosting servers rely on a KVM virtualization engine, which is KVM-capable and supported through QEMU, and allows users to access the various hardware virtualization features of the processor through the guest operating system. When this feature is the same as on the target system, QEMU can access KVM-specific features, such as speedups.


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