What is Server Virtualization?

In our modern society, where billions of people are connected through the internet, servers are an integral part of the network infrastructure. They provide the data and programs that countless users worldwide can access daily. However, many applications cannot be run together on a server, for example, when different operating systems or development environments are needed. Server virtualization makes it possible to implement various virtual server solutions on a single piece of physical hardware. The following article explains how this works:

What is Server Virtualization?

Server virtualization involves dividing a physical server into multiple virtual server environments (VPS hosting). This is typically achieved through three different methods:

• Virtual Machines
• Paravirtual Machines
• Operating System Virtualization

Virtual Machines

This method involves hosting various virtual hardware replicas on a single device. Each virtual machine (VM) operates independently with its own operating system, while sharing the resources of the physical server.

The coordination of the different VMs and the CPU is ensured by a hypervisor. This program monitors the hardware resources and harmonises their distribution to the virtual machines. Through the hypervisor, each VPS hosting receives the resources it needs for its current processes without overloading the CPU.

Paravirtual Machines

This method is very similar to the aforementioned one. Here too, virtual machines and a hypervisor are used. However, in this solution, the individual VPS hosting servers communicate with each other and know the specific requirements they place on the system.

As a result, the hypervisor is relieved, consuming less computing power. The saved capacities are then available to the applications of the virtual servers.

Operating System Virtualization

The third method of server virtualisation is operating system virtualisation. This method fundamentally differs from the previous two. The VPS hosting servers use the same operating system, as it takes on the role of the hypervisor.

Although the individual servers run independently and any security vulnerabilities do not affect each other, if the operating system itself is infected with malware such as viruses or trojans, this can have direct consequences on all connected virtual machines. In the worst case scenario, a virus-infected operating system can result in the failure of several or all servers.

Graphic: Schematic representations of server virtualisation

Advantages and Disadvantages of Server Virtualisation

Server virtualisation is widely used by many web hosting providers today. There are indeed good reasons that speak in favour of this solution. However, there are also some disadvantages to consider. It is therefore important to weigh up which server solution is best suited for which project.

Advantages of Virtualisation

Overall, server virtualisation offers significant advantages.

• Various VPS hosting can be hosted separately on one hardware. This saves both space and energy. Ultimately, this solution also reduces costs for larger hosts, as device capacities, especially storage volume, can be fully utilised.

• Furthermore, server virtualisation through virtual machines ensures the availability of applications. If they run simultaneously on different servers, one VM can take over in case of another's failure. This completely avoids downtime for web projects.

• By housing virtual servers in separate environments, troubleshooting is also not a problem. If a problem occurs on a VPS hosting, the entire system is not directly affected.

• In addition, test environments for new or updated applications can be deployed more quickly. Instead of using a complete physical server for this purpose, it is sufficient to test the software on a VPS hosting of the same device before going live.

Disadvantages of Virtualisation

Despite all the advantages that server virtualisation brings, there are also disadvantages.

• Since the VPS hosting is installed on shared hardware, a failure of this hardware also means the failure of multiple servers. A reliable backup solution is therefore essential.

• Furthermore, it must be considered that the hypervisor itself consumes computing power that is not available to the servers. Especially for more complex web projects, slightly more powerful hardware is needed than when using separate physical machines.

• Lastly, it is important to consider that the method of operating system virtualisation is more vulnerable to hacker attacks. If an attack penetrates the operating system via a VPS hosting, all other VMs are no longer secure. Data thieves could then easily steal data from various servers.

Server Virtualisation in Practice

Especially for web hosts offering customers web hosting packages or virtual servers, server virtualisation is an important tool to enable resource-efficient and cost-effective business operations. If all web packages were hosted on separate physical servers, the prices for web hosting would be much higher.

Virtual servers are offered with various virtualisation techniques including:

OpenVZ VPS hosting
Virtuozzo VPS hosting
KVM VPS hosting
Xen VPS hosting
VMWare VPS hosting
Proxmox VPS hosting
Hyper-V VPS hosting
 

More information on the differences between the various virtualisation solutions in the detailed comparison:

Xen or KVM
KVM or VMware
VMware or Xen
Virtuozzo or KVM
Xen or Virtuozzo
VMware or Virtuozzo
 

For businesses managing various web projects, server virtualisation is an option to significantly reduce costs. Alternatively, a cloud server could be used instead of a VPS hosting.

In the private sector, server virtualisation is particularly relevant for home networks. By using a virtual machine, the home network server can be hosted directly from the desktop PC. This saves on the purchase and space needed for additional devices. Both systems (desktop and server) can run in parallel on the same hardware without interference. Furthermore, different operating systems are possible, especially since a Linux server is generally more secure against hacking attacks.

Email servers can also be separated from web projects using a VPS hosting. With software such as Roundcube, setting up the email server is easy. This solution improves the overview of storage space for web and email servers and simplifies management.

Our article is based on our own experiences and research as well as information from external sources.

References & further links on the topic:
https://www.computerweekly.com/de/definition/Server-Virtualisierung (Article on server virtualization)
https://www.pcwelt.de/ratgeber/Zeit-fuer-eine-Bilanz-Die-10-groessten-Vorteile-von-Server-Virtualisierung-6197202.html (Article on server virtualization)
https://www.linux-kvm.org/page/Main_Page (Official KVM community wiki)
https://www.redhat.com/de/topics/virtualization/what-is-KVM (Information from the owner of the KVM developer)
https://xenproject.org/ (Official Xen Project website)
https://www.linux-magazin.de/ausgaben/2017/12/xen/ (Article on Xen in Linux Magazine)
https://www.vmware.com/de.html (VMware company website)
https://vmware-forum.de/ (Largest German VMware forum)
https://www.virtuozzo.com/ (Official Virtuozzo website)
http://download.parallels.com/doc/pvc/PVC_DataSheet_Ltr_EN.pdf (Information on Parallels Virtuozzo Containers)

Image credit:
Gerd Altmann on Pixabay