Virtualisation can ease desktop application deployment in a variety of ways.
It separates the application not just from the underlying hardware but also from the operating system. It means, for example, that you can run applications – or several copies of the same application – side by side in separate virtualised spaces without fear of clashes between them or with the operating system.
Seen primarily as a desktop technology, virtualisation offers the key advantage that because applications are independent of the client architecture you can deliver them in different ways, depending on the user's needs.
Just an illusion
They can be installed within their own virtualised space on the client, or they can be streamed so that the user sees only an image of the application, with almost no code downloaded. Applications can be deployed quickly and managed centrally so users stay abreast of security patches and other updates.
This can be a big win for users. Sometimes the applications they need to do their job are supported on the device they want, but all too often they are not. What if the user could select a device and know that pretty much any application will run on it? It could be a big selling point.
Perhaps the biggest time saver is that regression testing almost disappears, speeding up deployment. You test once in the virtual environment and the application is ready to go. Dependencies on or conflicts with operating system levels, hardware drivers or other applications can almost disappear.
Application virtualisation also helps with licence management. You know where all the applications are deployed at any time and how many users are accessing each one, and you can gather and analyse historical data.
For example, you can look up the maximum number of concurrent users and incorporate that intelligence into your licence purchasing plans; you may be surprised to discover just how many unused licences the company has bought.
And when it is time for an application to be retired, you just delete it from the server: no more uncertainty about whether there are unlicensed copies still being used out there.
You can see how this kind of fine-grained access to application usage could help to apply chargeback mechanisms. Effectively, it is a step in the direction of a private cloud.
Remote desktop server applications can now be virtualised too, with similar advantages. The technology reduces the complexity of application and operating system updates and deployment, resulting in fewer application images to maintain and so a reduction in management costs.
This is especially useful because server applications are usually much more complex to install and configure than desktop ones. Additionally, server applications are tightly coupled into virtual machine images, making it difficult to update either without disruption. Once the application is virtualised, the problem largely disappears.
Of course, no technology is without disadvantages. Application virtualisation adds complexity, which as we all know is the bugbear of any IT deployment. The more choices that need to be made during installation, the more likely it is that things will go wrong. And when they do, the problems will be harder to locate.
Once it is all installed and running, it will need time to maintain and to manage, which is a cost item. Virtualising applications may also increase back-end costs: those applications that are no longer running on client machines still need CPU time and memory, no matter where they are running, so they will need to be factored into server capacity planning.
And on the desktop side, users won't take kindly to having their applications messed about with. Get it wrong and the helpdesk lines will glow. Getting buy-in for a similar project in future will be much harder – although that is true of any initiative.
All that said, however, virtualisation can help you deliver applications on demand, reduce testing times massively and improve the speed and ease with which applications can be deployed.
And on a strategic level, they may be a key element of what the IT director is promising the board right now.
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