Xen vs. KVM: What Are They and How Do They Differ?

Both Xen and KVM are well-known, powerful virtualizers that are used by many. You can use them to turn a physical machine into a virtual one, which will then act as a separate, independent computer. Many web hosting companies use this technology to provide VPS (Virtual Private Server) services to users. However, virtualizers like Xen and KVM can be used for many other purposes, and both come with their fair share of advantages and disadvantages, which we will go through in this KVM vs. Xen comparison.

However, before we dig into the main part, first, let’s learn more about virtualization. 

What Is Virtualization? 

Virtualization is a process that involves creating a virtual version of certain resources or devices. For example, it’s used to create virtual computers out of physical ones, virtual storage devices, and other computer resources. 

Many companies and individuals use virtualization because it allows them to get the most out of their machines. For instance, they pay for one computer, and with virtualization, they create multiple virtual computers out of it and get more value for their money. 

Virtualization uses software that allows hardware elements, like processors, storage, memory, and more, to be separated into multiple virtual machines. Every virtual machine runs its own operating system and acts as a separate computer. This allows every virtual machine to be independent of one another, even though they’re all running on a portion of the same computer hardware. 

What Is Xen?

Xen is a type 1 hypervisor that allows you to execute multiple OS’ on the same hardware simultaneously. It can be used for many different purposes, such as server virtualization, desktop virtualization, security applications, IaaS, and more. 

Companies like Amazon, Alibaba, Oracle Cloud, and IBM Softlayer use it in their day-to-day operations as it offers great flexibility and security.

What Is KVM?

KVM stands for Kernel-based Virtual Machine and is an open-source virtualization module in the Linux kernel. It allows Linux to act as a hypervisor and host multiple virtual machines on one physical host. So, KVM is a part of Linux.

Many developers and companies prefer KVM over Xen due to its excellent hardware support, performance, storage security, flexibility, and other similar features. 

Xen vs. KVM: Key Differences

The main differences between Xen and KVM include the following:

• Xen vs. KVM Performance – in the KVM vs. Xen performance battle, Xen has a slight upper hand as it has better processing performance than its opponent. 
• Xen vs. KVM Function – Xen functions seamlessly on a computer’s hardware and can replace the operating system. KVM has a kernel module – kvm.ko, which uses the CPU’s virtualization ability and Linux memory. 
• KVM vs. Xen Build – Xen is a hypervisor that comes under Linux. On the other hand, KVM is a superficial hypervisor module based on the Linux kernel.
• KVM vs. Xen OS Support – Xen is supported on GNU/Linux, FreeBSD, NetBSD, OpenBSD, MINIX, and Windows, while KVM is supported on Linux, BSD, Solaris, Windows, Haiku, ReactOS, Plan 9, AROS Research, macOS, Android 2.2, GNU/Hurd (Debian K16), Minix 3.1. 2a, Darwin 8.0, and Solaris 10 U3.

Lastly, another critical difference between the two is that Xen needs to be patched to the kernel while KVM is built into it.

Last Words

Both Xen and KVM are two efficient and powerful virtualizers. The main difference between the two is that Xen is a type 1 hypervisor that allows multiple operating systems to run on the same hardware simultaneously. On the other hand, KVM is a virtualization module in the Linux kernel that works similarly to a hypervisor. 

Xen and KVM come with different benefits, so choosing between the two often depends on your infrastructure, what kind of resources you have, and what you want to do with your virtualizer.