Virtualisation: Definition, Explanation & Examples

Definition and basics

Virtualisation describes a process by which physical IT components such as servers, storage or networks are converted into abstracted, virtual instances. At the centre is the software layer of the hypervisor, which makes it possible to divide up the hardware of a server in such a way that several independent operating systems - so-called virtual machines (VMs) - can run in parallel on the same physical infrastructure. This decoupling of physical and logical resources significantly increases the utilisation of existing devices, while at the same time increasing flexibility in the management and operation of the IT environment

Types and functionality

Virtualisation is implemented in various forms, each tailored to specific requirements and purposes

• Server virtualisation: with this method, several virtual servers including individual operating systems run on a single piece of physical hardware. Typical solutions in this area come from providers such as VMware (ESXi), Microsoft (Hyper-V) and KVM
• Desktop virtualisation: Here, complete workstation environments are hosted centrally in the data centre and made available to users via remote access. Platforms such as Citrix Virtual Apps and Desktops or VMware Horizon are frequently used for this
• Storage virtualisation: Different physical storage resources are combined in a shared storage pool and dynamically allocated as required
• Network virtualisation: Network functions are provided under software control, for example through Software Defined Networking (SDN) or VLANs, in order to create flexible, scalable structures

At the centre is the hypervisor as an intermediary between hardware and operating systems. For example, if you use a server with a hypervisor, you can operate several independent virtual machines on it: One system hosts four virtual servers, one of which runs on Linux and the others on different versions of Windows - each operating system without direct access to the others

Areas of application in practice

Companies from different sectors and of different sizes use virtualisation specifically to increase the efficiency and agility of their IT infrastructure. Typical practical examples can be observed in the following scenarios

• Test and development environments: Developers can quickly set up new virtual machines to test software under a wide range of conditions - no additional physical hardware is required
• Consolidation of servers: Various services that used to run on separate, often underutilised servers are combined on more powerful systems. This significantly reduces space requirements, energy consumption and maintenance costs
• Disaster recovery and backup: Virtual machines can be easily backed up, duplicated or restored on other hardware. In the event of a failure, critical services can be kept running on an alternative infrastructure within a short space of time
• Cloud environments: The provision of private or public cloud services is often based on virtualisation - especially when flexible resource pools and rapid scalability are required

Advantages of virtualisation

The strategic use of virtualisation brings numerous operational advantages and technical simplifications

• Better utilisation: multiple virtual machines run efficiently on a single hardware platform, making optimal use of resources
• Flexibility and scalability: New servers or applications are often set up as VMs within minutes or moved to other locations
• Cost savings: Less physical hardware in operation means a reduction in energy consumption, investment and maintenance costs
• Simple administration: Many administrative tasks such as updates or data backups are centralised and can be largely automated
• Business continuity: In the event of hardware faults or planned maintenance measures, the migration or recovery of VMs enables operations to be resumed quickly

Possible disadvantages and challenges

Despite its many strengths, virtualisation also brings challenges and risks

• Complexity: reliable operation of virtualised environments requires specialist expertise and targeted training for administrators
• Licence costs: High-performance hypervisors and comprehensive management tools often incur not inconsiderable licence fees
• Security aspects: If a virtualised environment is configured incorrectly, security vulnerabilities can arise - especially if different virtual systems are running on the same hardware

Virtualisation is always recommended when several independent server services are operated or when fast and flexible provisioning is required - for example in lab and test systems, when resource requirements fluctuate greatly or as part of high-availability and emergency strategies. Virtualisation has established itself as the standard in these scenarios and enables sustainable and future-proof IT operations