Hardware virtualization allows creating virtual machines (VMs) on physical hardware while distributing resources as efficiently as possible. This article explains how it works, what types exist, and what advantages it provides for business.
The basic level of any virtualization is the server. Data processing occurs on physical hardware, regardless of the level of abstraction.
In hardware virtualization, a hypervisor is installed on the server. This is software that creates sets of virtual resources. There are two main types of hypervisors: Type 1 (bare-metal), which runs directly on the hardware, and Type 2 (hosted), which runs on top of a host operating system. Both create and manage virtual machines, but Type 1 generally offers higher performance. We have covered hypervisors in detail in a separate article.
The top layer of abstraction is the virtual machine. At first glance, it does not differ from a traditional server. Essentially, a VM consists of a single virtual disk and files describing its configuration.
The virtual machine is installed on the hardware hypervisor. Once the VM is prepared, operating systems and application software can be installed on it.
A helpful analogy is a book. Imagine a physical server with installed software as a book on a shelf. You can pick it up and move it physically, but creating a copy to give to someone else requires significant effort: retyping or scanning each page, assembling the pages, and binding the book.
A configured VM with allocated resources and installed applications is like a digital version of the book. You can make unlimited copies with minimal time and effort. You can create a backup, transfer a copy to another machine, or share it with another user. Virtualization of CPUs and other resources enables this simplicity in deployment and management.
For VMs to function efficiently, resource allocation must be supported at the processor level. Two major technologies exist from leading manufacturers: Intel VT and AMD-V.
Both technologies have multiple development directions. The primary one is CPU virtualization, which allows running multiple systems on a single processor, either in parallel or nested within each other.
Technologies for virtualized graphics and input/output are also advancing. They facilitate remote access and sharing of physical hardware, which is useful for remote workstations or online gaming.
These hardware extensions are particularly important for Type 1 hypervisors, allowing virtual machines to run at near-native performance without modifying the guest operating system.
The main types of virtualization are:
Full virtualization: hardware is fully emulated. This creates an environment that can run on different servers without lengthy configuration.
Paravirtualization: a special version of the operating system is created for the virtual machine. It can be modified or recompiled based on the server's hardware resources. This method was historically used to improve performance, but modern hardware virtualization extensions have largely reduced its advantage.
Hardware-assisted virtualization: a fully virtualized VM is created using the computer's physical hardware with support from processor extensions (Intel VT/AMD-V).
The choice of type depends on the tasks to be solved.
Hardware virtualization is not the only approach. Software virtualization relies on a host system and adds an extra layer of abstraction:
Adding this extra layer complicates the process and reduces hardware performance. Physical resources are consumed by both the host OS and the hypervisor. Other issues include:
Software virtualization is suitable for simple tasks, such as testing another operating system inside the main one, avoiding the need to install multiple OSes side by side.
For business purposes, hardware virtualization is preferred because it provides higher performance and security. The key is efficient resource usage.
Virtualization technology offers several benefits:
Cost efficiency: reduces expenses for purchasing, configuring, and maintaining physical hardware. Instead of multiple servers, a single powerful machine can be used, with the virtualization system dividing resources among VMs performing different tasks.
Flexibility: VM configurations can be saved as images and deployed across different hardware or moved between servers.
Scalability: when workload increases, additional VMs can be quickly launched to add resources and stabilize operations.
Fault tolerance: VM snapshots can be created at any time. Copies can be distributed geographically, so even if part of the hardware fails, the infrastructure continues to function. The load on active components can be managed by adding extra resources.
Security: VMs are isolated from each other. Compromising one VM does not affect others.
With hardware virtualization, external applications cannot distinguish virtual machines from physical servers. Guest operating systems run on the CPU without knowledge of other OSes sharing the same hardware. This isolation helps maintain high security.
Virtualization is used by large companies, small and medium businesses, and individual users. It enables building a flexible infrastructure of any size that can be easily scaled and protected against internal and external threats.