VDI and desktop virtualisation: how it works and when it makes sense for your business

VDI (Virtual Desktop Infrastructure) is desktop virtualisation: users' PCs no longer run on physical machines at their desks, but as virtual machines on a central server or in the cloud. Users connect from any device and find their full desktop waiting, while data and applications stay protected in the datacentre.

That's the simple definition — but behind it sit technical decisions that affect budget, security and productivity. Over more than 25 years as a B2B System Integrator, we at TN Solutions have designed VDI environments for professional firms, manufacturers and organisations with distributed sites. In this guide we explain how desktop virtualisation really works, when it makes commercial sense for an SMB, and when a lighter alternative is the better call.

What VDI is and how it works

With desktop virtualisation, the user's operating system — typically Windows 10 or 11 — runs as a virtual machine on a hypervisor (VMware Horizon, Citrix, Proxmox VE with VDI solutions, Azure Virtual Desktop). All that remains at the desk is an access device: a thin client, a repurposed older PC, or even a tablet.

A VDI infrastructure has four main components:

• Virtualisation hosts: one or more servers with multi-core CPUs, plenty of RAM and fast storage (NVMe or an all-flash SAN), running the virtual desktops.
• Connection broker: the software that authenticates each user and routes them to their desktop, managing pools, sessions and load balancing.
• Remoting protocol: RDP, PCoIP, Blast or HDX transmit only screen, keyboard and mouse to the client. The data never leaves the server.
• Endpoint: the user's device, which becomes little more than a "window" onto the remote desktop.

Persistent vs non-persistent desktops

One of the key design decisions is the desktop type:

• Persistent: each user has a dedicated VM that keeps settings, files and applications between sessions. It's the experience closest to a traditional PC — ideal for engineering teams and roles that rely on specialist software.
• Non-persistent: at every login the user gets a "clean" desktop generated from a master image, with the profile attached dynamically (FSLogix, roaming profiles). It cuts storage and maintenance, and suits task workers, call centres and shift-based workstations.

In practice, for SMBs we often design mixed environments: persistent desktops for people running line-of-business applications, non-persistent pools for standardised roles.

On-premises VDI, DaaS and remote desktops: the differences

Several distinct approaches shelter under the "desktop virtualisation" umbrella:

• On-premises VDI: the infrastructure runs on your own servers, in-house or in a managed datacentre. Maximum control over data and performance, higher upfront investment.
• DaaS (Desktop as a Service): virtual desktops delivered from the cloud on a monthly subscription, as with Azure Virtual Desktop or Windows 365. No hardware to buy, but recurring costs that scale with headcount.
• Session-based (RDS): multiple users share the same Windows Server through Remote Desktop Services. Cheaper than full VDI, but with less isolation and weaker application compatibility.

For many of the SMBs we support, the most balanced route is VDI on an existing virtualisation cluster: if you have already consolidated your servers, adding virtual desktops sweats the investment you've made. We cover this in our dedicated page on server virtualisation services.

The real-world benefits of desktop virtualisation for an SMB

Vendor marketing aside, these are the benefits our clients actually measure.

Security: data never leaves the datacentre

With VDI, a stolen or lost laptop contains no company data: the only thing travelling to the device is the video stream of the session. You can block copy/paste to the client, disable USB peripherals and enforce centralised policies. That's a major advantage for anyone handling sensitive data — law firms, HR and payroll, design offices — and for anyone who needs to demonstrate appropriate technical measures under the GDPR. VDI does not replace perimeter and endpoint defences, though: it should be combined with the protections we describe in our article on EDR.

Centralised management and fewer desk-side visits

Updating 50 physical PCs means 50 interventions, or a software distribution system to maintain. With non-persistent desktops you patch a single master image, and on the next restart every user has the same patches, applications and configuration. Provisioning a new workstation drops from half a day to a few minutes.

Remote working without taking data outside

Access to the virtual desktop works from home, from a client's site or from a branch office exactly as it does in the head office. Compared with classic remote access, the experience is identical to the corporate PC and files are never synchronised onto personal devices. External access still needs multi-factor authentication and an encrypted tunnel — see our guide to the business VPN for that.

Longer hardware life and predictable costs

Because the processing happens on the server, clients can be thin clients costing €200-300 or repurposed PCs that are 7-8 years old. The endpoint replacement cycle stretches considerably, and spending shifts to a small number of properly sized servers — far easier to plan for and to protect.

When VDI pays off (and when it doesn't)

Desktop virtualisation isn't the right answer for everyone. These are the criteria we use during the analysis phase.

VDI makes sense when:

• you have 15-20 or more workstations with similar requirements: below that threshold the infrastructure rarely pays for itself;
• you handle sensitive data or intellectual property and want it kept off the endpoints;
• your workforce is distributed: multiple sites, structured remote working, external consultants, seasonal staff;
• you run client-server ERP or line-of-business applications that benefit from sitting close to the database;
• you want to standardise a currently heterogeneous desktop estate and cut the support workload.

Look at alternatives when:

• you have fewer than 10-15 users: centralised management policies and a solid support contract are often enough;
• your users run heavy 3D graphics applications (advanced CAD, rendering): GPU-enabled VDI exists, but the costs climb steeply;
• connectivity at your sites is weak: VDI depends on the network, and without stable bandwidth and low latency the user experience degrades;
• your application estate is already entirely SaaS: in that case VDI's added value shrinks.

Infrastructure requirements not to underestimate

A serious VDI project needs fast storage (the morning "boot storm", when everyone powers up their desktop at once, brings slow disks to their knees), generous RAM (4-8 GB per office desktop, more for power users), host redundancy — if the VDI server stops, every desk stops with it — and a tested continuity plan. On that last point, the same rules apply as for any critical infrastructure: you'll find them in our guide to backup and disaster recovery for SMBs.

Watch out for Microsoft licensing too: virtualised Windows desktops require specific licences (VDA, or eligible Microsoft 365 subscriptions) — a cost line that belongs in the budget from day one.

How much a VDI project costs for an SMB

The numbers vary with sizing, but as a rough guide:

• On-premises VDI: for 25-50 users, the investment across servers, storage, licences and implementation starts at roughly €25,000-60,000, amortised over 5 years. The cost per seat falls as the user count grows.
• DaaS/cloud: from around €30 to €80 per user per month depending on the profile and allocated resources. No upfront investment, but over 5 years the total can exceed on-premises.
• Frequently forgotten items: VDA/RDS licences, thin clients, network upgrades, user training and ongoing operational management.

The right way to compare the options is a 5-year TCO set against a traditional PC refresh, factoring in the IT management time saved. That's the analysis we run during the assessment phase, before proposing any architecture.

How we run a VDI project at TN Solutions

Our method — refined over 25 years of virtualisation projects and certified to ISO 9001 and ISO 27001 — follows four phases:

1. Assessment: an inventory of applications, user profiles, usage peaks and network constraints. This produces real-world sizing, not price-list sizing.
2. Pilot: a small pool of virtual desktops for a representative group of users, to validate performance and user experience before you commit.
3. Phased rollout: migration in waves, department by department, keeping the physical workstations as a fallback until sign-off.
4. Ongoing management: monitoring, master image patching, resource tuning and user support under the support contract.

We work on both commercial platforms and open-source stacks, choosing on the merits of each case rather than a vendor's price list — the same pragmatic approach we take when helping clients choose between a physical server and a virtual server.

Let's talk about your desktop virtualisation project

If you're considering VDI for your business — to lock down your data, simplify workstation management or put remote working on a proper footing — the right first step is an assessment of your existing infrastructure. TN Solutions has been designing and managing virtualisation environments for SMBs for over 25 years, based in Melzo (Milan) and certified to ISO 9001 and ISO 27001.

Get in touch for a no-obligation conversation, or call us on 02 9517550: we'll analyse your scenario and tell you — with the numbers on the table — whether desktop virtualisation is the right choice for you.