What is VDI – What is Virtual Desktop Infrastructure

To explain what is Virtual Desktop Infrastructure (VDI), it would be useful to start by explaining what “Virtual” means in this context.

What is virtualisation?

Those of us who have been bought up with traditional computers will recognise programs like Microsoft Windows as “Operating Systems” (OS), their main function is to control and manage the hardware that everything runs on. Initially this was mainly managing the disk drives, hence Disk Operating System MS-DOS. This has grown to managing everything from all the PC hardware, anything that plugs into it, the security of the whole system, and connections to the wider world. But we still see the OS and the hardware as being intrinsically linked, two sides of the same coin.

Of course, the operating system and everything that runs on it is just software, 1s and 0s. So, into the mix comes “virtualisation” which separates the OS from the hardware, letting the OS live in its own virtual world and not being tied to a specific “physical” computer. It becomes a “Virtual Machine” (VM).

Virtualisation brings two useful traits, firstly the operating system can now reside on any physical computer, and be moved from one computer to another. The second trait is that multiple virtual machines “guests” can now run along side each other on the same physical host; making much better use of the resources on that host, which may be far greater than an individual computer needs.

What is VDI?

A VDI setup will include extensive collections of virtual machines including the desktops OS that end users can access their applications on, but also the rest of the infrastructure to support and manage the whole thing. The term virtualisation can be applied to other aspects of computer infrastructure including networks, storage, application and servers. The Virtual Desktop Infrastructure VDI technology is a combination of the hardware and virtual systems that run on it to provide virtual desktop environments to end users. Virtual desktops can be accessed by the end user over a network, including the Internet.

Two types of VDI – Persistent VDI and non-persistent VDI

Persistent VDI VMs behave much like normal PCs. Users can configure different settings on them, save favourites, history, passwords and so on. In fact, persistent VMs can function as a user’s entire PC with almost nothing running on the local, physical computer. Persistent VMs require a greater element of storage and management than their non-persistent cousins.

Non-persistent VDI VMs do not save any settings. Once a user logs off they revert to the exact same state they were in before they logged on. These are useful in places such as public libraries, hotels, and other “kiosk” situations where the saving of data and settings may be unwelcome. They are also frequently used in task-based roles such as call centres to present a consistent user experience so reducing support and training costs.

How does VDI work?

VDI works by using software called a “Hypervisor” running on a central server, which separates the operating system from the physical hardware. The hypervisor allows multiple VMs to be run from a physical host, and for VM guests to move from one host to another.

VDI technology also uses a “Connection Broker” which provides an initial authentication step. As well as connecting an end user with the relevant VM.

What is VDI used for?

There are a lot of industry types that make use of VDI deployments but there are some specific areas where VDI can be successfully utilised:

• Remote working – a VDI desktop is connected to over a network. This can be a local network on a company premises, but as the network requirements are fairly lightweight it is very easy to connect to a VDI desktop over the internet. Making remote access straightforward.

• Task Based Work – non-persistent VDI is particularly suited to task-based work such as workers in call centres where very specific virtual apps and standardised desktops are used and there is no requirement for personalisation or customisation of the desktop environments.

• Shift Workers – Where multiple sets of people may use the same physical desktop during their shifts, users can access their own individual virtual desktops which will present the applications and data specific to them.

• High Security Environments – standardised desktops in a VDI setup can be strictly controlled and managed, making it much easier to enforce organisational security policies. Data within a VDI is not saved on the physical desktop or laptop so if these are stolen there is less risk of data being lost.

• Bring Your Own Device – As all sorts of devices can be used to connect to VDI virtual machines it makes is easier to adopt a BYOD policy allowing users to use any device they choose without increasing support issues or risking information security.

What are the benefits of Virtual Desktop Infrastructure VDI?

VDI is ideal for remote access. This isn’t just Working from Home, but may be different branches of the same organisation spread across the country (or further afield). The databases, documents and virtual desktop infrastructure may be held on a central server with end users spread across different sites all connecting remotely to run applications connecting to this data.
VDI is “endpoint device” agnostic making it easier to run the same virtual apps and desktops regardless of whether people use PCs, Macs, tablets or phones. IT departments can also roll out “Thin Client” terminals which are cheaper and less costly to manage and support.

VDI deployments can provide cost savings as they are a better use of hardware resources. High end servers can run dozens of virtual desktops. The end user endpoint device can be lower spec cheaper models.

VDI will provide a consistent user experience, with the same desktop images deployed to multiple users. Those desktop images created from standard templates so reducing deployment effort (and therefore saving costs).

What are the drawbacks of VDI?

An on-premise VDI solution requires an investment in new skills for IT departments or new IT professionals joining the team.

It is a long-term solution that will require significant upfront investment, but give cost savings over the long term for large organisations.

What is the difference between VDI and other remote solutions like Remote Desktop, Hosted Desktops and Desktop as a Service?

VDI has traditionally, although not exclusively, been implemented as an on-premise solution. Large corporations setting up VDI, either on premise or in a 3rd party data centre, to reduce costs and improve flexibility whilst maintaining security.
With Desktop as a Service (DaaS) applications are hosted by third party providers in their data centre. DaaS may be a VDI solution or a hosted remote desktop solution. See this article to see the differences between DaaS and VDI.

VDI works in a slightly different way then Remote Desktop Services (RDS). With VDI each user has their own OS all to themselves. With RDS lots of users share one operating system, but can all connect at the same time. RDS solutions usually require less space than VDI and have a less complex infrastructure, so generally a lower overall cost.

Where the remote desktops service is provided by a third party provider this is known as hosted remote desktops service, or Hosted Desktops. This is also a form of DaaS. See this article for the difference between VDI and Hosted Desktops.