What is Virtualization?

Virtualization is a technology that allows the creation of virtual versions of resources such as servers, operating systems, storage, or networks. It makes it possible to run multiple “virtual machines” (VMs) on a single physical server. Each VM operates as a fully independent computer with its own operating system and applications, while sharing the physical resources of the underlying hardware.

The key component of virtualization is the hypervisor. A hypervisor is software that creates and manages virtual machines, distributing the host machine’s physical resources (CPU time, RAM, disk space, and network interfaces) among them.

Virtualization can be divided into two main types:

• Kernel-level virtualization (Type 1 Hypervisor): The hypervisor runs directly on the server’s “bare metal” hardware (e.g., VMware ESXi, KVM, Xen). It acts as the primary operating system and provides maximum performance as there is no extra layer.
• OS-level virtualization (Type 2 Hypervisor): The hypervisor is installed as an application on top of an existing operating system (e.g., VirtualBox, VMware Workstation). This is convenient for testing but less efficient for production environments.

Why is Virtualization Needed? Key Benefits

Virtualization has long ceased to be an exotic technology and has become a standard in IT. Here are the main reasons why it’s so important and beneficial for developers, system administrators, and businesses as a whole:

• Resource optimization and cost reduction: Virtualization allows you to maximize the computing power of a physical server. Instead of having multiple servers each operating at 10–20% load, you can consolidate them on a single powerful server running dozens of VMs. This directly leads to savings:

  • Lower hardware costs: Fewer physical servers are needed.
  • Reduced power consumption: Fewer servers mean lower electricity usage.
  • Lower cooling costs: Less heat generated in the data center.

• Efficiency and time savings:

  • Rapid deployment: Creating a new VM takes minutes instead of the hours or days required to set up a physical server. Preconfigured VM templates allow instant deployment of new services.
  • Isolation and security: Each VM is fully isolated from others. If one VM fails, it doesn’t affect the others. This makes virtualization ideal for running different applications or services on one host without risk of conflicts.
  • Easy testing and development: Developers can easily create virtual environments for testing new applications or configurations without risking damage to the production environment. VMs can be cloned, snapshotted, and rolled back to previous states.

• Reliability and availability:

  • Live Migration: Most modern hypervisors allow you to move running VMs from one physical server to another without downtime. This is essential for maintenance and hardware upgrades.
  • High Availability: If one physical server fails, its VMs can be automatically restarted on another server in the cluster, minimizing downtime.
  • Backup: Virtual machines are easy to back up and restore since they are essentially a set of files.

Containerization vs. Virtualization

In recent years, containerization (e.g., using Docker) has gained popularity. It’s important to understand the difference:

• VM: Each virtual machine includes a full operating system, making it more isolated and heavier.
• Container: Containers share the host operating system kernel. They are lighter, start faster, and consume fewer resources, but provide less isolation.

Virtualization and containerization are not mutually exclusive technologies. On the contrary, containers are often run inside virtual machines. This allows you to leverage the benefits of both: the security and isolation of VMs combined with the efficiency and portability of containers.

Conclusion

Virtualization is a powerful foundation of modern IT infrastructure. It enables efficient resource management, improves service reliability, and significantly accelerates development and deployment processes. For a modern IT professional, understanding virtualization principles and knowing how to work with hypervisors is an essential skill.

In upcoming articles, we will take a closer look at the most popular and powerful hypervisors: Proxmox VE, VMware, KVM, QEMU, Xen, and Hyper-V. We will explore their features, pros, and cons to help you choose the right tool for your needs.