What Is KVM? Features of VPS With KVM

KVM (Kernel-based Virtual Machine) is a virtualization technology for Linux that allows multiple independent operating systems to run on a single physical server. At the solution's core is a module included in the Linux kernel, which transforms it into a full-fledged hypervisor. In simple terms, the KVM system enables the creation of several virtual machines (VMs) on physical hardware, each of which behaves like a separate computer with its resources and settings.

KVM was initially developed by employees of the company Qumranet and later adopted by the Linux community, becoming part of the official kernel. The appeal of this approach lies in the fact that KVM does not require significant modifications in the user space, as KVM virtualization is implemented directly through mechanisms built into the kernel itself.

How KVM Works?

The heart of this virtualization is the built-in module in the Linux kernel, which enables the launch of guest machines by distributing computing resources between them. When KVM is enabled, each virtual environment receives its own emulated hardware components: processor, RAM, network interfaces, and storage units. Thus, each guest OS (Windows, Linux, or other supported systems) sees its environment, unaware that it is only a part of a larger server.

Thanks to hardware acceleration (Intel VT-x or AMD-V), virtual machines operate with high performance. The KVM hypervisor is responsible for isolation, allowing multiple operating systems to run simultaneously without interfering with each other. This provides more efficient use of physical resources: CPU, memory, network (considering bandwidth in Gbps or Mbps) and ensures flexibility in scaling.

Advantages and Disadvantages of KVM

Pros:

• High performance due to direct access to hardware capabilities;
• Complete isolation of each machine, increasing reliability and security;
• Broad support for modern OS: Linux, Windows, and other versions;
• Flexible resource management and automatic load distribution;
• Integration with major cloud platforms and hosting, simplifying VPS deployment.

Cons:

• Hardware requirements, since virtualization needs hardware instructions (VT-x, AMD-V);
• More complex initial setup compared to some container-based solutions;
• Some functions are tied to the Linux kernel, which may complicate KVM use in specific scenarios.

Comparison of KVM with Other Virtualization Technologies

Several types of virtualization solutions are on the market, including well-known ones like OpenVZ, VMware, and Hyper-V. The difference with KVM is that it uses the Linux kernel level as a hypervisor, whereas OpenVZ is a container-based technology, and Hyper-V and VMware ESXi are typically standalone systems with their interfaces on a different level.

Container solutions (e.g., LXC or Docker) work differently — they share a common kernel, so there is no full isolation. On the one hand, this ensures increased speed, but on the other, it risks a failure in the system that can affect all containers.

Features of VPS with KVM

When ordering virtual servers (VPS) based on KVM, the hosting provider allocates a specific amount of RAM and CPU cores and guarantees network bandwidth. This VPS infrastructure allows installing almost any operating system, whether various Linux distributions or Windows Server. Due to hardware virtualization, resources are reserved specifically for the virtual machine, which prevents scenarios where one user consumes too much power, leaving others with insufficient CPU or RAM.

Fine-tuning capability is especially important. Administrators can manage network interfaces, enable additional kernel modules, change security settings, and use any tools to ensure stable website operation. At the same time, stability remains close to a dedicated (physical) server without significantly added complexity.

Combined with specialized software, KVM offers more flexibility than container-based alternatives. For example, if different versions of PHP or full support for Windows applications are needed, KVM is an ideal foundational platform. Additionally, many cloud providers create comprehensive solutions based on KVM for dynamic scaling, allowing rapid resource expansion without downtime.

Conclusion

KVM is a modern virtualization technology that turned the Linux kernel into a powerful hypervisor. It provides near-complete isolation of virtual machines, high performance, and versatility in choosing operating systems. While the KVM setup may seem more complex than that of container solutions, in return, the user gets a reliable platform that closely resembles a physical server in terms of stability.

FAQ

What is a hypervisor in KVM?

The hypervisor in KVM is a component of the Linux kernel that enables the creation and running of virtual machines. It provides hardware virtualization, allowing each virtual machine to operate independently.

What operating systems can be installed on a KVM VPS?

You can install virtually any operating system that supports the x86 architecture on a KVM VPS, including Linux, Windows, and BSD.

How does KVM VPS affect the ability to install custom OS kernels?

KVM VPS provides full control over the virtual machine, allowing installation and use of custom OS kernels. This is especially important for those who require specific kernel configurations.

What is VNC access, and how is it used on KVM VPS?

VNC access is graphical access to the console of the virtual machine. It is used to manage the VPS through a graphical interface.

How do you back up a KVM VPS?

KVM VPS backups can be made using snapshots of virtual machines or by copying virtual disk files. This allows you to restore the VPS in case of failures or data loss.