Contrary to popular belief, virtualisation has been around almost since the beginning of IT. Early mainframes used virtualisation to separate different applications into their own silo’s to make management of scare and expensive memory easier.
Nowadays, virtualisation has come to mean the creation of something simulated or virtual, rather than the actual thing itself. In particular, Desktop Virtualisation is used to separate the user’s desktop environment from the device that is hosting it. More recently, with the advent of cloud computing, a Hosted Desktop is possible, where the user operates a desktop environment held on a private or hosted cloud platform.
The Hosted Desktop implementation of a Desktop Virtualisation environment allows for far greater control over the user desktop and lower maintenance costs, since all instances of the desktop environment can be managed from the Data Centre.
Other benefits include easier backup and restore, device flexibility as the user’s work environment is held on the host, and a significantly reduced potential for data loss since information is held on the host, not on an individual device.
Nowadays with the increasing use of BYOD, virtualisation can be the way to provide access to applications on a variety of non-compatible devices such as tablets and smartphones.
For IT administrators, desktop virtualisation supports a centralised client environment that makes better financial sense, and provides better user service levels, especially in distributed environments where on-site support is not readily available or economically feasible, for example retail sites or head office/branch office environments.
Given these benefits, how does one go about implementing Desktop Virtualisation in a Hosted Desktop environment?
The first step is to decide what systems architecture goes best with your existing and desired environment. A hosted virtual desktop comes in several different flavours, depending on whether the host is local or remote. Oher considerations include whether the desktop is to be persistent between sessions, the likely network response profile and information security.
Persistence is like the “sleep” or ‘Hibernate” function on a Windows laptop, where the user can terminate their current work session, and resume it at the exact same point at a later stage. Some users for example travelling sales staff like to just hang-up and go, picking things up later at the same point, perhaps on a different device at a different location.
Most users expect the virtual desktop to have similar response characteristics to a real desktop on a local device, and the designer needs to give careful consideration to their virtualisation design in high-latency or slow networks. This will also include remote access to the host over slow links, for example public WiFi connections.
In some cases, local emulation software is needed where reliable network access cannot be guaranteed or where local resources can provide a better service to the user.
A final consideration is the need for information security. In a high security environment, applications and data remain at the data centre, with only information pertaining to the mouse, keyboard and displayed image transmitted between the host and remote client.
Having worked all that out, the next step is to consider the software needed to deliver the hosted environment. That often depends on whether the virtualisation scenario supports single or multiple operating systems. If you intend to outsource virtualisation to a hosted service provider, then you can provide them with your operational needs and leave the architecture questions to them.
In a single OS environment, Remote Desktop Services (formerly called Terminal Services) provides a Windows-based means to access applications and data on a remote or networked server. Other platforms, for example VMWare allow for multiple OS implementations.
There are also emulators, called Hypervisors or Virtual Machine Managers, either software or embedded in firmware which create a virtual computer on the host. For example, a Windows server could, using this technique, host a Linux and an Apple Mac environment as separate virtual machines.
More recently, the virtualisation scenario has come to include cloud-based services in the “as-a-service” environment. Yes, you’ve guessed, Desktop-as-a-Service (“DaaS”) is now available, based around the Software-as-a-Service model, and it is being increasingly adopted in the cloud computing world. VMWare, however, hold the patent to the “Desktop-as-a-Service” and “Daas” names.
To summarise, Desktop Virtualisation can provide management and financial benefits in many environments, particularly the private and hosted cloud environments.