What Is Virtualization?

Whether on servers or as an additional software level on the iMac at home: Virtualization is an integral part of modern IT.

Basically, virtualization describes the separation of hardware and software. This means the virtualized system can be run on (almost) any hardware, which greatly simplifies the procurement of spare parts. For example, problems such as driver incompatibilities when changing hardware are a thing of the past.

In particular, the resources of a physical server can be used much more efficiently by distributing (delegating) them to the guest systems and thus making better use of them overall.

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Native and hosted virtualization systems

Basically, virtualization systems are divided into hypervisor and desktop virtualization. A classic hypervisor provides its own operating system. Which is used exclusively for virtualization and is specially designed for this (a so-called native or type 1 hypervisor).

Desktop virtualization, on the other hand, denotes an application that can be installed on an independent host operating system (e.g. Microsoft Windows). This can also virtualize entire operating systems but requires a Windows installation as the basic system (so-called hosted or type 2 hypervisor).

Overview of virtualization types (Image: Wikipedia/Public Domain)

In the following, we take a closer look at the most well-known systems of both categories.

VMware ESXi

The hypervisor vSphere ESXi distributed by VMware (a former subsidiary of Dell) is a type 1 hypervisor from the enterprise range. It is offered in various (also free) versions and is therefore interesting for both end-users and data centers.

VMware can virtualize most operating systems and offers very good stability as well as mature and complex functions. The operation – and especially the troubleshooting – requires a lot of experience. Furthermore, the licenses are very expensive.

Microsoft Hyper-V

Hyper-V is entering the race as a hybrid. Microsoft offers the system both as a native hypervisor (Hyper-V server) and in the form of a Windows application as a hosted hypervisor. The latter is not technically correct. As the Windows host, OS is also running as a guest, in this case, effectively creating a Type 1 hypervisor.

Since Hyper-V is based on Windows Server, it can be installed in a few minutes and can be operated in the familiar Windows Server environment. Which simplifies administration. However, the more complex functions (e.g. high availability) are not as mature as, for example, with an ESXi. Furthermore, Windows servers have to be supplied with updates much more frequently than pure hypervisor systems.

Citrix

With Citrix Hypervisor, Citrix Systems, Inc. provides its own virtualization technology. This became known mainly with the virtualization of terminal servers.

The specialization in VDI provision offers the advantage of a lean and very robust provision of remote desktop services. This advantage becomes a disadvantage in file server applications. For example, because the system is automatically less suitable there than the other, less specialized systems.

But there are also many smaller, specialized, and partly free virtualization products.

Virtual containers with Docker

Docker pursues the targeted virtualization of individual applications and not, as in the other examples, entire operating systems. A so-called container is built modularly on a base image so that each additional instance uses only minimal resources.

However, Docker is not always a complete replacement for virtual machines – sharing the kernel creates security problems, and setting up and managing it is complicated and requires experience.

Parallels Desktop

Virtualizing a Windows system on Mac OS is the main task of Parallels Desktop. Of course, other systems (Linux, BSD, OS/2, Mac OS X, etc.) can also be virtualized. The software (formerly Parallels Workstation) thus represents a type 2 hypervisor.

virtual box

The software offered by Oracle can be used under various host operating systems. Such as Linux, Mac, and Windows in order to provide x86 or x64 guest systems.

VMware Player

As the name already suggests, the VMware Player is primarily intended for playing ready-made virtual machines. This means that finished images, e.g. for test purposes, can be easily started and executed. The new setup (installation) of virtual machines has also been supported since version 13.

Where is virtualization used?

The functions of the systems are tailored entirely to the target market and, for type 1 virtualizers. Very extensive, depending on the license purchased. For example, while backups are not possible with a free VMware ESXi due to the deactivated API, the highest license allows highly redundant data center operation.

In such an environment, topics such as backup, snapshots (snapshots of the status of the VM), replication (copy of the VM on another host system), and dynamic hardware allocation are particularly important. All of these points are met in particular by the professional systems. Although these are in association with high license costs.

According to the market research institute Statista, VMware is the market leader with a market share of almost 12 percent, followed by Hyper-V (approx. 10.7 percent) and Citrix (approx. 8.3 percent). In general, however, the market is very diverse – with a market share of 54 percent for other providers.

However, since companies usually do not just rely on a single virtualization solution, these figures can only be the same as relatively imprecise.

Conclusion

Hyper-V is an ideal way for a company to start virtualization because of the free license that comes with a server operating system.

If it needs to be more professional or systems like macOS should also be virtual, there is no way around VMware – at the latest when high availability and server clusters become an issue.

For private use, everything is conceivable, from VMware Player for simple gimmicks to Virtualbox to a fully-fledged ESXi (e.g. the free version). However, VMware, in particular, requires at least an Essentials license for a backup via third-party software, and is therefore companies primarily use it.

In any case, it remains an individual consideration as to which system can best fulfill the exact application purpose.

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