Virtual desktop infrastructure (VDI) technology often comes up when companies are discussing ways to bring down their desktop computing costs. What is it, and can it save you money? Read on to find out.
VDI virtualises desktop environments on the server, meaning that you don't run them on desktop hardware. Instead, you use lightweight terminal devices (or keep running older PCs) to access the server-based environments. Because you're running each desktop operating system as its own virtual machine on the server, you can store users' configurations separately so that they each keep their own settings.
The hidden costs
A well-run VDI system is convenient, but it also takes some investment if you're running an on-premise installation. The first cost to consider is the hardware. Not only do you need a server CPU beefy enough to support all your users (which means a larger number of CPU cores) but you'll also need sufficient server-side memory. Depending on what those users are doing, you'll want to budget 4Gb of memory at the bare minimum, and probably more like 8Gb each.
You may also need an upgrade to your networking architecture, especially if expanding from basic file and print server functions into virtual desktops. VDI access places a lot more strain on the network, so budget for faster networking components both in the server itself and in the links connecting access switches to the core network.
After buying the hardware, you must factor in the cost of the VDI software, which will administer the virtual desktops while also managing tasks like load balancing between users. Vendors typically provide this on a per-seat basis, often folding in support fees. And of course you'll need to license the desktop operating systems themselves.
Consider the cost of redundancy here. If a user's connection to the NAS box goes down, it's irritating. If their desktop is running on the server, then a network outage is a show-stopper, so redundant network links are important. For more resilience, you might want to build some redundancy into the server architecture too, with dual power supply units, hot-swappable storage, and so on.
Finally, don't expect this to be easy to set up. It takes some expertise to configure these systems properly so that you don't run into problems like network or compute congestion. Boot storms, where everyone logs on at once, bringing the system grinding to a halt, can be a particular
The potential savings
There are some financial upsides to VDI, too. If you implement it in the run-up to a client-side refresh you can cut the cost of expensive desktop PCs by installing bare-bones systems or simple thin client terminals. Alternatively, you could just turn your existing kit into terminals, pushing out the refresh by another year or two.
There are also implicit management and security advantages. Having full centralized control over your desktops makes it easier to fix software problems, while client-side hardware becomes virtually disposable. It also means better security by making it easier to stop people taking data out of the office on removable storage.
The client-side savings will offset some of the server-side costs, but the balance will depend on your specific use case. It's affected not just by factors like the number of users and how much you expect that to grow, but also by the applications they're using. Some apps support multi-threading, meaning that a single user might benefit from multiple cores, for example. Only a detailed ROI analysis will tell.
Consider the cloud
If on-premises VDI isn't for you, there are alternatives. In September 2019 Microsoft launched a VDI service in Azure cloud, which removes the capital expense in on-premise servers and networking, replacing it with a regular monthly payment. 100 virtual Windows desktops at 200 hours each per month with 128Gb of SSD each would cost just north of ₤1,400 a month (just over ₤14 per seat). You need an appropriate Microsoft 365, Windows 10, or per-user RDS CAL license licence to play, though. Eventually of course, you'll end up paying more for the service over time. When calculating the best option, you'll need to consider your project user growth and refresh rates for on-premises server hardware.
VDI isn't a cheap alternative to conventional desktop operating systems, but it does offer some valuable organizational benefits, and new cloud-based options can make the initial setup easier to bear financially. It's another option to throw into your end-user computing strategy.