KVM Overview

KVM is the #3 ranked solution in our list of best Server Virtualization Software. It is most often compared to Oracle VM VirtualBox: KVM vs Oracle VM VirtualBox

What is KVM?
KVM (for Kernel-based Virtual Machine) is a full virtualization solution for Linux on x86 hardware containing virtualization extensions (Intel VT or AMD-V). It consists of a loadable kernel module, kvm.ko, that provides the core virtualization infrastructure and a processor specific module, kvm-intel.ko or kvm-amd.ko.
KVM Buyer's Guide

Download the KVM Buyer's Guide including reviews and more. Updated: May 2021

KVM Customers
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AM
Software Architect with 501-1,000 employees
Real User
I find the density of the product most valuable.

What is our primary use case?

My primary use case for KVM is running multiple VMs and containers on the one node.

What is most valuable?

I find the density of the product most valuable. It is because of kernel same page merging technology (KSM) that is integrated into Linux kernel. That high density makes KVM one of the important players of the virtualization market.

What needs improvement?

In the future release of KVM, I would like to have improved support for Windows guests.

For how long have I used the solution?

More than five years.

What do I think about the stability of the solution?

The stability of this solution is less than other products in the same category. But, it is OK. 

What do I think about the scalability of the solution?

The scalability of the product…
AR
IT-Leiter (IP) at IN-telegence GmbH
Real User
Top 20
I like the ability to execute live migrations

What is our primary use case?

Running virtualization clusters with more than 300 VMs.

How has it helped my organization?

The platform changes from hardware to virtualized whenever possible.

What is most valuable?

Open source The ability to execute live migrations Linux, a base OS.

What needs improvement?

Management of underlying volumes.

For how long have I used the solution?

Three to five years.
Learn what your peers think about KVM. Get advice and tips from experienced pros sharing their opinions. Updated: May 2021.
479,894 professionals have used our research since 2012.
System Architect at a aerospace/defense firm with 10,001+ employees
Real User
Provides a freedom that you do not have with other solutions on the market

What is our primary use case?

Our primary use for this product is server virtualization.

Pros and Cons

  • "It is an open ecosystem, and we see there is a benefit in open-source solutions."
  • "We would like to have a software lifecycle solution included in this solution. We can handle the software needed for KVM, but also the software that we provide. A lifecycle component would be very beneficial."
System Architect at a aerospace/defense firm with 10,001+ employees
Real User
This solution integrates nicely with other soft-open-software components.

What is our primary use case?

The main use case is, of course, to run virtual machines. The specific use case is to run virtual network functions (VNFs) and the performance is very good on KVM.

Pros and Cons

  • "I think nine out of the ten supercomputers in the world use Linux KVM, so I think that attests to the fact that it is a scalable product."
  • "Technical support is not top-notch."
DB
System Architect at a tech services company with 11-50 employees
Real User
A very reliable solution which can be used for x86 architecture virtualization with reasonable overhead

What is our primary use case?

Great support for many types of hardware, disks, memory, RAID controllers, etc.

Pros and Cons

  • "KVM has a rich options set which can be directly used or via wrappers, such as libvirt."
  • "If you are a Linux desktop user, KVM is the solution to go with if you have to start virtual machines with Linux or other operating systems with almost zero extra configuration needed."
  • "A very reliable solution which can be used for x86 architecture virtualization with reasonable overhead."
  • "The only negative aspect of needing hardware support is a fully functional KVM can be dropped. It would be nice if the support for other platforms, like ARM or Risk, were as good as the x86 one. However, with the democratization of Chromebooks based on these chips and mobile devices, it will not take long for that to happen."
Student at Universidade de Brasília at a tech services company
Consultant
The performance, scalability, and security are valuable.

What is most valuable?

Low cost, if not lowest. Great performance and scalability. Security is top-notch. Free.

What needs improvement?

Networking configuration might be annoying depending on how you want to set it up; usually works fine, though.

For how long have I used the solution?

I have used it for one year.

What was my experience with deployment of the solution?

We have not encountered any deployment issues.

What do I think about the stability of the solution?

We have not encountered any stability issues.

What do I think about the scalability of the solution?

We have not encountered any scalability issues.

How are customer service and technical support?

Customer Service: Well, none. Technical Support: Unless you can count open forums?

Which solution did

Senior Consultant IT Infrastructure at a tech consulting company with 51-200 employees
Consultant
KVM allows me to run virtualized environments for my customer projects and to modify the code as it's open-source, although there were stability issues when running I/O intensive tasks.

What other advice do I have?

Make sure to gain a lot of knowledge about virtualization and the way KVM works. Then implement it with libvirt and virt-manager because this makes running KVM guests a lot easier.
IT Manager at a tech vendor with 51-200 employees
Real User
Top 5
Review about KVM

Valuable Features:

It gives us live VM migrations.

Improvements to My Organization:

It allows us to virtualize our entire IT Infrastructure without any software cost. We only need to spend money on support and deployment.

Use of Solution:

Used since 2009 from version 0.8, so 6 years now.

Deployment Issues:

No.

Stability Issues:

No.

Scalability Issues:

It's scaled for us since version 0.8.
Business process Advisor for RTP at a energy/utilities company with 10,001+ employees
Vendor
I had lots of issue with it.
I have used KVM with centos 7. Unfortunately, I had lots of issue with it. First of all, I wanted all the VMs to share the same network. I had to modify the centos network interface files myself. I had to do it with every single VM.  At some point it created lots of issue in the module firewalld which also act as the nat to connect the VM with the physical interface. I could read "command failed" for rules of a VM that was already deleted in KVM.  Then, I had issues with virsh the command line of KVM. Among other things, it exports and imports VM. I wanted to move a Virtual Machines from kvm on centos bare metal server to kvm on debian bare metal server and I discovered that in order to do so, I had to modify the XML configuration inside the VM file.  I have also been unable to clone VMs…
Tech Support Staff with 51-200 employees
Vendor
Possibility of using KVM Virtualization in Hosting
Virtualization has made a lot of progress during the last decade, primarily due to the development of myriad open source virtual machine hypervisors. This progress has almost diminished the barriers between operating systems. There are mainly two types of virtualizations; Software Virtualiztion and Hardware Virtualization. Up until recently, the focus always has been on software­emulated virtualization. KVM KVM is short for Kernel­based Virtual Machine and makes use of hardware virtualization, i.e., you need a CPU that supports hardware virtualization, e.g. Intel VT or AMD­V. Connsidering the time line of virtualization techniques, KVM is a relative newcomer. Several incumbent open source methods exist today, such as Xen, Bochs, UML, Linux VServer, and coLinux, but KVM is…