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What is a Kernel-Based Virtual Machine? (KVM)?

VPS rental is becoming an increasingly popular service both for small sites and for highly loaded information systems. VPS is superior to inexpensive shared hosting in all respects, but at the same time, it is cheaper than a dedicated server. 

When choosing a provider and service plan user has to take into account a huge number of different characteristics of VPS. One of them is the software used by the hoster to emulate a separate server – the hypervisor. Today we will take a look at one of the most popular virtualization systems, KVM (Kernel Based Virtual Machine), but first, let’s see what kinds of hypervisors there are. 

OpenVZ Web Panel

This virtualization system runs on Linux operating system, uses a shared kernel with the OS, and allows the creation of virtual environment containers. The main advantage of this hypervisor is its relative flexibility:

  • Possibility to reinstall the OS and change settings online, without rebooting the server;
  • Ease of administration and management;
  • Speed of operation at the level of the physical server (in some cases it may even be higher);
  • All modules are shared and loaded into the underlying operating system, which allows VPS to use almost no resources for its operation;
  • Is the cheapest virtualization option.

As a Linux-based development, OpenVZ does not support Windows and requires a good knowledge of programming and administration. Also, this platform allows for over-selling by the ISP.

LXC containers managed by Proxmox VE

A more optimized virtualization system than OpenVZ. Also works at the Linux OS level and does not interact with Windows. It doesn’t use containers, allows to change time and date. A bit more expensive than the platform described above.

Microsoft Hyper-V Virtualization System

As the name suggests, it is used for administering Windows-based servers. In this platform, IT professionals, appreciate such qualities as sufficiently high reliability, scalability, and support for clustering to create cloud services. The hypervisor can be downloaded for free from the Microsoft website. All other costs will be associated with configuring and purchasing additional software for administration.

On the downside, Hyper-V users point out the limitations of configuring work with storage. It is difficult to migrate VMs within the cluster, which is only allowed between servers with processors of the same family. Like all products of the Microsoft family, it requires additional software installation for protection due to high vulnerability to external threats.

VMware vSphere Web Client

One of the most expensive systems for creating virtual environments. Works independently of the operating system. Able to create virtual devices, add memory, CPU, and disks to them without VM reboot. It supports all known operating systems and allows the management of multiple network devices simultaneously.

While VMware vSphere has a number of significant advantages, it does have some disadvantages as well:

  • It requires the purchase of a licensed version (VMware vCloud Suite Enterprise) to get the deployed functionality;
  • potential hardware conflicts – hardware compatibility with ESXi must be verified prior to installation;
  • each CPU will require a separate vSphere license;
  • you need to purchase an annual maintenance package for each license.

KVM-Based virtualization

KVM is quite a young development based on Linux, gaining in popularity due to the wide functionality with a very reasonable cost of implementation and administration. This solution is distributed free of charge, and for corporate customers, there is a commercial version, RHEL distribution (Red Hat Enterprise Linux), which provides official technical support (for 10 years) and advanced management capabilities. 

Pros and Cons of KVM

Kernel-based Virtual Machine Hypervisor is hardware virtualization, thanks to which it is impossible to understand whether it is a virtual server or a physical one. For users, each server is in fact a full virtual machine. Additional advantages, in contrast to the other OpenVZ virtualization platform, include:

  • the ability to install your own Linux kernel;
  • fast access to all modules of the system iptables\tun\tap;
  • the ability to install any operating system;
  • providing root access rights to manage the server;
  • organization of GRE tunnels, IPIP, and others;
  • using virtual eth network with its own parameters.

With all the obvious advantages, the KVM hypervisor also has a number of disadvantages:

  • changing resources is not possible without rebooting the system, the expansion of disk space is done manually;
  • the administration of KVM is more complicated, most settings must be done manually;
  • adding IP-addresses is also done manually.

Compared to VMware virtualization, KVM is the system of choice for implementing cloud solutions based on the IaaS model. At the same time, the Kernel platform is convenient for developers specializing in the creation and implementation of “Linux” software.

With its high functionality, low resource consumption, and affordability, the KVM hypervisor is continually upgraded with support from the global OpenSource developer community. This allows to quickly eliminate bugs and weaknesses, constantly improving the program taking into account the practical use in difficult situations.


Choosing the right virtualization system is primarily important for hosting providers. The wrong decision can have both tactical and strategic consequences. The most obvious ones are the time and money losses associated with implementing, configuring, and managing data center servers.

The usability of a particular hypervisor by end-users is an even more important criterion that determines a company’s competitiveness, returns on investment, and viability. 

Both should consider not only the current state of the business but also the prospects for its development. The option of implementing a virtualization system based on KVM technology looks optimal in all respects, has the necessary flexibility and potential, including in the promising direction of cloud technology development.

If you are interested in choosing KVM for your project, check out our KVM VPS hosting offer.

About the author


Shelly is an avid reader, and the love of reading takes her to content writing eventually. She loves writing on various topics.

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