Virtualisation Technology: An Overview

Virtualisation is creating a virtual version of something i.e. converting physical IT resources into virtual IT resources. IT resources like servers, storage, network, power can be virtualised. Virtualisation process starts with the allocation of IT resources followed by the installation of an operating system. Virtualisation software operates on a physical server called a host or physical host.

Virtualisation software sometimes called a Virtual Machine Monitor/Manager (VMM) or commonly as a Hypervisor and its functionality encompasses system services that are strictly related to virtual machine management that does not find on standard operating systems. This technology also enables different virtual servers to share one physical server to increase hardware utilisation, load balancing, and optimisation of available IT resources under server consolidation.  

Virtualisation contributes to manage workloads by transforming traditional computing to provide it more scalability. Virtualisation also provides hardware independence, server consolidation, and resource replication, and further supports resource pooling and elastic scalability.

Major timeline of virtualisation development

1960 – IBM develops Cp-40 – the first version of CP/CMS in the mid-1960s proposing to implement full virtualisation.

1970 – In 1970 IBM introduces the System/370 announcing several virtual storage operating system including VM/370 available on all S/370 model.

1999 – In 1999, VMware introduces its first X86 virtualisation product enabling VMware virtual platform based on software emulation with Guest/Host OS design.

2008 – In 2008, VMware releases VMware Workstation 6.5 beta for windows and Linux to authorise DirectX 9 accelerated graphics on Windows XP guests.

During the 1960s and 1970s, IBM has invested a lot of time in developing robust time-sharing solutions working for sharing usage of computer resources among a large group of users. These solutions has aimed to increase the efficiency of both the user and the computer resources they share.

Types of virtualisation

Operating system-based virtualisation – In operating system-based virtualisation, the virtualisation software is installed in a pre-existing operating system i.e. host operating system, and hence guest operating system is of no use to this. The host operating system utilises CPU, memory, and other hardware IT resources. This is one of the best ways of virtualisation and is carried out directly in the kernel, the central task manager of the operating system.

The VM is first installed into a full host operating system in the different logical layers of operating system-based virtualisation and is used to generate virtual machines.

This is a great solution for running a parallel Linux and Windows-based environments which helps in reducing cost and time spent updating software on multiple machines.

Hardware-based virtualisation – This virtualisation allows the installation of virtual software directly on the physical host hardware which gets engaged with operating system-based virtualisation. The interaction of the virtual servers with hardware without requiring intermediary action from the host operating system makes hardware-based virtualisation more efficient.

The different logical layers of hardware-based virtualisation do not require another host operating system.

Virtualisation software is typically referred to as hypervisor for this type of processing which mainly functions for controlling and monitoring the processor, memory, and other hardware resources. Since controlling virtual machine is much easier than the physical machine so this virtualisation is done for server platforms.

Virtual servers are realised through either operating system-based or hardware-based virtualisation.

Server virtualisation – Virtualisation software is directly installed on the server system. Server virtualisation provides space for many virtual machines to run on one physical server.

key benefits of server virtualisation are –

  • greater IT efficiency
  • reduced operating costs
  • higher server availability
  • faster workload deployment
  • increased application performance

Network virtualisation – Network virtualisation creates a vision of the network using software where an administrator can use to manage the network from a single console. It enables full replication of a physical network within the software with the same logical devices and services which help to reduce the number of physical components such as switches, routers, etc.

The types of network virtualisation are Software-Defined Networking – which virtualises hardware to control network traffic and Network Function Virtualisation – which virtualises one or more hardware appliances to provide a specific network function.

Desktop Virtualisation – Desktop Virtualisation allows to run multiple desktop operating systems in its Virtual Machine on the same computer. This virtualisation enables one-time mass replication and terminates the need for installation, configure, and updating of the desktop on each machine.

Application virtualisation – Application Virtualisation is a ‘single executable and everywhere operable’ type of application. It runs application software without installing it directly on the user’s operating System i.e. only applications run virtually and the operating system remains as usual.

This virtualisation reduces system integration and administration costs with a common software environment across multiple computers which protects the application and operating system from bugs and malicious codes. This also enables operating system migration where applications can be transported to removable media making it a portable software.

Storage virtualisation – Storage virtualisation is sharing of the physical resources into multiple storage devices making them appear as a single storage device. This virtualisation is, sometimes, referred to as a group of available storage devices managing from a central system. This provides easy backup, recovery and achieving of the data. It also eases the actual complexities of the Storage Area Network and applies to all levels of SAN.

Benefits of virtualisation

  • IT flexibility, scalability, and agility
  • Fault isolation and hardware-level security
  • Minimal downtime
  • Simplified data centre management
  • Quicker backup
  • Operating cost and capital reduction and improved productivity
  • Greater business continuity and disaster recovery

Drawbacks of virtualisation

  • High initial investment
  • Quick scalability can be a challenge
  • Unintended server sprawl
  • Data security
  • Not all hardware and software can be virtualised

The Last Corner

Virtualisation has re-emerged as an effective route for IT departments of organisations to provide a dynamic operation and enable them to quickly respond to business needs and demands.

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