Virtual Private Servers (VPS), the term virtualization has created a lot of buzzes. However, at the same time, it is still not very clear what it really is and what it entails. In this blog post, I’ll be covering the basics of What Server Virtualization is, its types and the Pros and Cons for the same, to help you leverage the best of it.

Before we move on to Server Virtualization, let’s have a look at what Virtualization in general means.

Virtualization refers to the act of creating a virtual version of something, including virtual computer hardware platforms, storage devices, and computer network resources. In simple words, it refers to running more than one Operating System on a single physical hardware. An easy example to understand this is, partitioning a single hard drive into two hard drives. This way there are ‘virtually’ two hard drives but in reality, there is only one.

What is Server Virtualization

Server Virtualization as the name suggests involves ‘servers’. In this a physical server is partitioned into several smaller virtual servers, enabling the server to utilize its resources to the maximum. Here, the server resources are isolated (hidden) from other users in the virtual environment. These virtual environments are known as Virtual Private Servers/Virtual Machines, that in turn act as exclusive physical devices. The software used to partition the server is known as a Hypervisor.

Why use Server Virtualization

Virtualization is an ideal solution for small to mid resource usage applications. Some of the reasons to use server virtualization are:

  1. Virtualization helps in preserving space, as several resources share the same physical space owing to the partition. This also helps in effective resource management.
  2. Virtual Servers offer users the privilege of the dedicated server but at a less price. This is helpful in case of small and medium-sized businesses that do not require the whole dedicated infrastructure and resources.
  3. Backing up of data is simple thereby preventing data loss.

Although there are several reasons to choose Server Virtualization, choosing the right technology too is equally important. There are two widely used types namely, KVM (Kernel-based Virtual Machine) and Virtuozzo.

KVM stands for Kernel-based Virtual Machine, it is a Virtual Private Server primarily for Linux OS though it does support Windows, BSD and Solaris OS’s as guests. KVM is virtualization in the true sense as VPS operates as its own server, not dependent on the host node. It is open source and hardware-based virtualization.

Virtuozzo, on the other hand, is not a free and open source software program. Virtuozzo is container-based and comes with a proprietary Kernel Service Abstraction Layer (KSAL) that manages access to the kernel and prevents any single VPS from bringing the entire physical server down. Also, it addresses virtualization by running a single OS kernel as its core.

Pros and Cons of KVM and Virtuozzo

Even though both KVM and Virtuozzo are popular virtualization software, each has its set of Pros and Cons that end up being the deciding factor. Here is a list of the Pros and Cons of each:

Pros of KVM:

  1. Being open source, KVM is priced relatively lower.
  2. As the base of KVM is Linux, the security is enhanced.

Cons of KVM:

  1. One of the major disadvantages of using KVM is the complexity of the setup and it requires adequate networking knowledge.
  2. KVM virtualization is available only to certain limited processes and lacks manageability features.

Pros of Virtuozzo:

  1. Server resources are utilized efficiently.
  2. Has a web-based GUI Panel. Also, it is an independent platform and, can be used with both Linux and Windows.

Cons of Virtuozzo:

  1. As RAM is shared, there is always a shortage of RAM. This may lead to the killing of a process to compensate the lack of RAM.
  2. Sharing of resources isn’t that great.


Server Virtualization is growing and will continue to grow with the advances in technology. If you want full control over your server, then KVM should be your choice. On the other hand, if you have no major requirements, then Virtuozzo is far more affordable than KVM. Eventually what you as a user choose to invest on is personally your choice depending on your usage.

If you have any more points based on your experience, we would love to hear them in the comments below.

Since the addition of VPS on our platform, we’ve only been providing a specific type of virtualization, Virtuozzo. A month ago, we introduced KVM virtual private servers on our platform. That must have got you thinking, “What’s the difference between the two?” This blog post covers the distinguishable features of KVM and Virtuozzo.  Virtualization has changed the way we compute. We utilize lesser hardware, save energy and costs as well as run various applications and operating systems on that very server.

Why do we need virtualization?

Apart from saving time, money and energy, it:

  • Helps you to manage your resources efficiently
  • Provides a secure remote access and thus increases productivity
  • Helps against data loss prevention

What makes virtualization possible is a software known as a hypervisor or a virtualization manager. The VM sits between the hardware and operating system and basically allocates the amount of access that applications and operating systems have with the processor and other hardware resources.

Choosing the right technology for virtualization is essential. The two main choices when it comes to virtualization are Virtuozzo and KVM. Depending on your needs, either of these could suit your requirements. Here are the pros and cons of both Virtuozzo and KVM.

Virtuozzo at a glance

With Virtuozzo, the resources of your server are efficiently split. However, it’s not free and it’s not an open source program (unlike OpenVZ). It doesn’t use the normal hardware abstraction layer construction. Instead, Virtuozzo comes with a proprietary Kernel Service Abstraction Layer (KSAL) that manages access to the kernel and basically prevents any single VPS from bringing the entire physical server down. It approaches virtualization by running a single OS kernel as its core. The core is then exported to various partitions on the host and each partition becomes an independent entity better known as a virtual private server (VPS).

KVM at a glance

Kernel-based Virtual Machine (KVM) is a virtualization infrastructure for the Linux kernel that turns it into a hypervisor. It only works with the Linux OS but does support Windows, BSD and Solaris as guests.

Virtuozzo is container-based while KVM is a hardware-based virtualization. KVM runs on x86 and x86-64 systems with support for virtualization extensions. It’s an open source choice and consists of a loadable kernel module. This module provides the virtualization infrastructure core and it also provides a processor specific module.

Pros and Cons of Using Virtuozzo

The Pros

  • Independent Platform – You can use Virtuozzo with Windows or Linux without any hassle
  • Web-based GUI panel – The Virtuozzo Power Panel is a GUI based web powered panel, which enables you to handle servers on their own over the web
  • Easy Restoration – Restoring is easy and comes with full root access. You’re also able to restore an individual file or the entire VPS

The Cons

  • RAM is shared – If the server doesn’t have enough RAM, Virtuozzo struggles and usually will fail since the system depends on virtual RAM. Ultimately, it will kill processes when it runs out of RAM
  • Lack of device support – In some cases, Virtuozzo won’t allow custom devices. For example, VPNs
  • Resource sharing isn’t great – The resource sharing of Virtuozzo isn’t that great. If one user is using resources heavily, it can slow things down.

Pros and Cons of Using KVM

I’m sure you already know that KVM is one of the top open source choices for virtualization. Then again,

Pros of using KVM

  • Excellent Security – Since the base of KVM is made up of Linux, it uses the SE Linux advanced security system. This helps to ensure security of the virtual machines meets a very high level. KVM has also received awards for meeting the security standards of the government.
  • Available for Anybody to Use – The open environment of KVM means anybody can use it and customize the system to fit specific requirements.

Cons of Using KVM

  • Complex Setup – One of the main disadvantages of using KVM is the complex setup process. It’s actually more complex than other systems
  • Limited Processors – Keep in mind that the system doesn’t work with all processors
  • May Require Built-in CPU Virtualization Support – In some cases, KVM may require built-in CPU virtualization support to ensure the best possible performance

Overall, using KVM can be beneficial, it could outweigh the disadvantages for some users. But then again, the use case depends on the user. Here are a few highlights that you can have a look at

Virtuozzo KVM
Can only host Linux operating systems Can host Linux, Windows and custom OS options
Most Virtuozzo hosts are oversold Is better isolated even though it can be oversold
More affordable, provides users with speed and scalability Offers private virtualized hardware and is more customizable
Easier to set up Requires more networking knowledge

If you’re looking for full control over your server, KVM is your go-to. On the other hand, Virtuozzo is a great choice if you don’t have any special requirements and is more affordable than KVM. Then again, it’s vital to crosscheck and look at the benefits and how they apply to your situation. If your choice of virtualization boils down to the two of these, make sure you weigh your options before making a decision. What do you prefer using for your customers? Do let us know any other parameters of comparison that you found useful to evaluate.

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