Virtual desktop infrastructure (VDI) runs Windows or Linux desktop operating systems as virtual machines in a data center or cloud and delivers each desktop to the user’s device over a display protocol such as RDP, Citrix HDX, Omnissa Blast or Amazon DCV. A connection broker assigns each user a desktop, so applications and data stay on central hosts while screen updates and input cross the network. As of October 2026, the platforms compared here are Amazon WorkSpaces, Citrix, Microsoft Azure Virtual Desktop and Windows 365, Omnissa Horizon and Parallels RAS.
More virtualization coverage is listed in Enterprise Techie’s topic index.
In this guide
Key facts
| Item | What the documentation says |
|---|---|
| Definition | Users connect to “virtual images of standardized, non-simulated operating systems and desktops” (NIST SP 800-46 Rev. 2) |
| Desktop types | Personal (persistent, one user per VM) or pooled (non-persistent, any VM in the pool) |
| Session-based alternative | Many users share one Windows Server (RDSH) or Windows Enterprise multi-session host |
| DaaS | The vendor runs the broker and gateway; some services also run the desktops |
| Windows licensing | Windows VDA rights; Azure Virtual Desktop also accepts eligible Microsoft 365 licenses; RDS CALs for Windows Server sessions |
What is VDI?
NIST’s telework guide, SP 800-46 Rev. 2 (July 2016), says VDI “involves the user connecting to a system that contains virtual images of standardized, non-simulated operating systems and desktops.” Microsoft’s Remote Desktop Services overview describes the model as “centralizing processing in the datacenter and remoting only the UI.” In VDI, each desktop is a single-session VM: Citrix says such machines “allow one user to connect to a machine at a time.”
VDI components
- Hypervisor hosts or cloud capacity. Run the desktop VMs; Citrix DaaS, for example, connects to Azure, AWS, Google Cloud, XenServer, Hyper-V, Nutanix AHV and vSphere.
- Connection broker. Authenticates users, checks entitlements and assigns a desktop. Omnissa says its Horizon Connection Server “is not part of the ongoing protocol connection.”
- Display protocol. Microsoft uses RDP, which multiplexes channels for “remote graphics, input, device redirection, printing, and more.” Citrix uses HDX, Omnissa Blast, PCoIP or RDP, and WorkSpaces DCV or PCoIP.
- Gateway. RD Gateway, Citrix Gateway or Omnissa Unified Access Gateway brings external users in without exposing desktops. Azure Virtual Desktop’s Microsoft-run gateway uses reverse connections “so you don’t need to open any inbound ports.”
- Image management. One golden image becomes many VMs. Citrix MCS “creates copies of a master image” while Citrix Provisioning “streams the master image” to machines.
- Profile management. Pooled desktops need profiles to follow users. An FSLogix profile container is a VHD(x) file attached at sign-in, and “All FSLogix containers can be stored on file shares that support the SMB protocol.” See NAS vs SAN.
- Endpoint client. Windows App, Citrix Workspace app, Horizon Client or the WorkSpaces client; Azure Virtual Desktop, Citrix and WorkSpaces also document browser access.
Persistent vs non-persistent VDI
Persistent (personal) desktops give each user a dedicated VM that keeps apps and settings. Non-persistent (pooled) desktops hand out any VM in the pool and discard changes; WorkSpaces Pools users “access a new virtual desktop each time they sign in.” AWS says Pools “will no longer accept new customers beginning July 31, 2026” and points new customers to WorkSpaces Applications. Microsoft compares the models:
| Personal VDI | Pooled VDI | Session-based (RDSH) | |
|---|---|---|---|
| Users and state | One, always the same user; retains changes | One at a time, any VM; resettable | Many at once, each in an isolated session |
| User profile | On the VM’s OS disk | Profile container on a file share | Profile container on a file share |
| Microsoft’s typical users | Developers, power users, customization-heavy apps | Knowledge workers needing Windows client compatibility | Task workers, line-of-business apps, seasonal users |
| Density and cost per Microsoft | Lowest density | Medium density and cost | Highest density, lowest per-user cost |
Terms vary: in Azure Virtual Desktop, pooled host pools can also be multi-session.
VDI vs RDS and session-based desktops
Session-based desktops put many users on one Windows Server through the Remote Desktop Session Host (RDSH) role. VDI gives each user a client OS VM, which suits apps that need a Windows client OS rather than Windows Server. Remote Desktop Services covers both, with RD Virtualization Host for “Virtual Desktop Infrastructure collections (pooled or personal Windows client VMs).”
Windows Enterprise multi-session is a client edition that “allows multiple concurrent interactive sessions.” Microsoft does not allow it in production outside Azure Virtual Desktop, and “Only Microsoft or the Azure Virtual Desktop Approved Providers, Citrix and Omnissa, can provide access to the Azure Virtual Desktop service.” It reports the same ProductType as Windows Server, so “Some application installers can block installation” on it.
VDI vs DaaS
Desktop as a service (DaaS) moves the control plane (broker, gateway, portal, databases and console) to the vendor’s cloud. How much else the vendor runs differs:
- Azure Virtual Desktop: Microsoft provides “the virtual desktop infrastructure (VDI) components for core functionality as a service,” including the web, broker and gateway services. Customers remain “responsible for creating and managing session hosts,” including images, networking and backup.
- Citrix DaaS: Citrix runs Delivery Controllers, databases and Studio in Citrix Cloud; customers run the VDA machines on their own hypervisors or clouds. Citrix Managed Azure adds Citrix-run Azure hosting.
- Windows 365 and Amazon WorkSpaces: the provider runs the desktops too. Windows 365 Cloud PCs are billed per user per month, so customers avoid “the variability of compute and storage costs of a traditional hosted desktop model.”
Self-hosted VDI, such as Citrix Virtual Apps and Desktops or Horizon 8 in a customer data center, keeps every layer, including SQL databases for Citrix, with the customer.
VDI and DaaS platforms compared from their own documentation
Listed alphabetically, not ranked. Omnissa was “Formerly the End User Computing business of VMware”; Citrix is one of the brands of Cloud Software Group.
| Platform | Who runs the control plane | Where desktops run | Display protocol | Desktop types documented |
|---|---|---|---|---|
| Amazon WorkSpaces | AWS (fully managed) | AWS Regions | DCV or PCoIP | Personal (persistent); Pools (non-persistent, closed to new customers since July 31, 2026) |
| Citrix DaaS / Virtual Apps and Desktops | Citrix Cloud (DaaS) or customer Delivery Controllers | Azure, AWS, Google Cloud; XenServer, Hyper-V, Nutanix AHV, vSphere | HDX | Single-session, multi-session and Linux VDAs |
| Microsoft Azure Virtual Desktop | Microsoft | Azure; Azure Local; existing on-premises hypervisors (Azure Virtual Desktop Hybrid) | RDP | Personal or pooled host pools; Windows Enterprise multi-session |
| Microsoft Windows 365 | Microsoft (SaaS) | The Windows 365 service | RDP, via Azure Virtual Desktop connectivity | One Cloud PC per user; Flex shares one non-concurrently |
| Omnissa Horizon | Customer Connection Servers (Horizon 8) or cloud control plane (Horizon Cloud) | vSphere, Nutanix AHV, OpenStack, Red Hat OpenShift (limited availability expected in Horizon 8 2609); Azure, AWS, Google Cloud, Oracle Cloud, Alibaba Cloud | Blast, PCoIP or RDP | Virtual desktops, RDSH desktops and apps |
Parallels RAS delivers “remote PC, RDSH and VDI,” integrates with VMware ESX, Hyper-V, Scale, Nutanix, Azure, Azure Virtual Desktop and AWS EC2, and reaches Proxmox through its Custom Provider Framework. See also Citrix alternatives.
Where VDI fits and where it doesn’t
- Contractors and BYOD. NIST says VDI “is particularly helpful for safeguarding telework on BYOD and third-party-controlled devices.”
- Regulated data. Microsoft says RDS is common “in regulated sectors (finance, healthcare) where data residency and auditability matter,” and Azure Virtual Desktop on Azure Local keeps “app and user data on-premises.”
- Task workers and labs. AWS positions WorkSpaces Pools “for task workers, contact centers, training labs, and other shared-environment use cases.” New customers now go to WorkSpaces Applications instead.
- GPU workstations. Microsoft lists GPU acceleration for “graphic designers, video editors, 3D modelers” and similar roles.
- Weak fit: offline users. Every platform here streams the desktop over a network, so users who work offline need a local OS.
- Weak fit unless optimized: calls and video. Teams on Azure Virtual Desktop uses media optimizations that redirect calls and meetings “to the local device” on supported clients. AWS says DCV “performance is degraded” at round-trip latency between 250ms and 400ms.
VDI cost drivers
- Hosts, storage and network. Microsoft’s Azure Virtual Desktop pricing page lists virtual machines, storage “for operating system images, data disks, and user profiles” and networking as required Azure infrastructure.
- GPUs. GPU frame encoding “may consume more network bandwidth and both session host and client resources.”
- Windows licensing. Windows VDA is “a device or user-based licensing mechanism for managing access to virtual desktops.” For Azure Virtual Desktop, eligible licenses include Microsoft 365 E3 or E5 and Windows VDA per user; Windows Server session hosts need RDS CALs. BYOL WorkSpaces run “on hardware that is dedicated to you.”
- Platform licenses. WorkSpaces bills monthly or hourly, Windows 365 a fixed monthly fee per user, Parallels RAS by concurrent users, and Omnissa sells Horizon 8 as SaaS or term subscriptions.
- Bandwidth. Available bandwidth “dramatically impacts the quality of your experience,” per Microsoft, and Windows 365 notes “Additional costs may apply based on network usage.”
Security considerations
Data location is the main control. Microsoft says centralized execution “keeps data resident in the datacenter so only the UI stream leaves,” and NIST, which groups VDI with portals, notes the software and data “are on the portal server.” That holds only with redirection locked down: NIST warns portals “can be configured to allow clients to download content,” and Horizon documents policies “for clipboard usage, device redirection, printing, and session actions.”
The endpoint still matters: NIST advises that “Organizations should assume that client devices will become infected with malware and plan their security controls accordingly,” and names strong authentication, preferably multi-factor, as the primary option against device reuse threats.
VDI evaluation checklist
- Desktop model per user group: personal, pooled or session-based, and which apps fail on multi-session.
- Control plane: self-hosted or DaaS, and what stays yours (session hosts, images, backups).
- Hypervisor and cloud support: match the broker to your planned hosts. See Hyper-V vs VMware and Proxmox vs VMware.
- Protocol: pilot from the worst-connected sites and confirm Teams redirection on your clients.
- Image pipeline: clone method, patch cadence and rollback.
- Profiles: FSLogix shares not upgraded to AES-SHA1 Kerberos “might have access issues” after the April 2026 Windows Server update.
- Storage: desktop I/O is write-heavy. The Nutanix Cloud Bible calls its erasure coding “Not suitable for workloads that are write or overwrite intensive, such as VDI.” See What is HCI?
- Licensing: Windows access rights, RDS CALs, multi-session limits and BYOL hardware rules.
Bottom line
VDI centralizes desktops so data and patching stay on central hosts, in exchange for network dependence and a stack of brokers, images, profiles and licenses. Match the desktop model to each user group, decide who runs the control plane, then pilot real users on real networks. For hypervisor options, see the VMware alternatives shortlist.
Frequently asked questions
What is VDI?
Virtual desktop infrastructure runs desktop operating systems as VMs on central servers or cloud capacity and streams them to users over a display protocol. A broker assigns desktops, and data stays on the hosts.
What is the difference between VDI and DaaS?
Who runs the infrastructure. With self-hosted VDI the organization runs everything; with DaaS the vendor runs the control plane. Windows 365 and Amazon WorkSpaces also run the desktops; Azure Virtual Desktop and Citrix DaaS leave session hosts to the customer.
What is the difference between persistent and non-persistent VDI?
A persistent desktop belongs to one user and keeps changes. A non-persistent desktop comes from a shared pool and resets, so profiles live separately, such as in FSLogix containers on an SMB share.
VDI vs RDS: what is the difference?
RDS session hosts put many users on one Windows Server, which Microsoft says gives the highest density and lowest per-user cost. VDI gives each user a client OS VM for compatibility and isolation.
Sources
- NIST SP 800-46 Rev. 2
- Microsoft Learn: Remote Desktop Services overview, Azure Virtual Desktop terminology, Azure Virtual Desktop architecture, licensing, Windows 365, FSLogix
- Amazon WorkSpaces guide
- Citrix: DaaS overview, Virtual Apps and Desktops overview
- Omnissa: Horizon 8, Horizon 8 architecture
- Parallels RAS
Last checked: October 2026. Guidance and product features change; check each source before you rely on it.
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