In the mid-1990s, terminal servers like WinFrame and Windows Terminal Server centralized computing but failed to provide true isolation, as users shared a single operating system. This led to stability issues when different applications or drivers conflicted within the shared environment.
Sun Microsystems introduced the Sun Ray thin client in 1999, which allowed users to access their sessions from any terminal. While it pioneered the concept of user-centric workspaces, its reliance on the Solaris ecosystem and the limited server performance of the time restricted its mass adoption.
VMware, founded by Mendel Rosenblum and Diane Greene, challenged the belief that x86 architecture could not be virtualized. Their VMware Workstation, released in May 1999, used binary translation to enable independent operating systems on a single PC. The 2001 launch of ESX Server further enabled server consolidation, reducing CPU idle time previously estimated at 5–15%.
The Xen project, launched by Cambridge University in 2003, introduced paravirtualization, requiring guest OS modifications. Eventually, Intel VT-x and AMD-V hardware extensions standardized x86 virtualization. Later, the development of KVM by Qumranet and its integration into the Linux kernel in 2007 shifted virtualization toward open-source infrastructure.
Red Hat acquired Qumranet in September 2008 for $107 million, gaining both the KVM hypervisor and the Solid ICE remote desktop technology. This acquisition lowered the barrier for new entrants to the virtual desktop market by providing an open-source foundation for building VDI platforms.
By 2005, customers began using VMware ESX to run Windows XP virtual machines for individual users, connecting via RDP. This practice, which predated formal VDI brokers, marked the transition from server virtualization to the deployment of virtualized user desktops.
