A client hypervisor is a software layer between the operating system and the PC hardware that allows hardware resources (CPU, RAM, Disk, etc.) to be shared between multiple execution environments. A client PC has very different requirements then a server and therefore the client-focused hypervisor must have specific functions to ensure a high quality user experience. Some of these functions include sleep/power management, device pass-through and more.
How Do Client Hosted Virtual Desktops (CHVD) differ from other forms of client virtualization?
Within the client virtualization arena the nuances of how solutions are implemented are diverse. There are four key types of solutions: application virtualization, workspace virtualization (also referred to as type-2 hypervisors), client hosted virtual desktops (CHVD), and server hosted virtual desktops (SHVD) also referred to as VDI. Each method has its own benefits and drawbacks.
- Application Virtualization: Application virtualization isolates an application and its dependencies so they execute in a separate ‘containers’, eliminating application conflicts and accelerating deployment. This type of virtualization is specific to application and works above the WIndows kernel and requires a fully functional operating system
- Type-1 based hypervisors (CHVD): Type 1 (or native, bare-metal) hypervisors are software systems that run directly on the PC’s hardware and can provide control over device hardware and manage the guest operating systems. Type-1 hypervisors essentially create an abstraction between the HW and the operating system
- Type-2 based hypervisors (aka workspace virtualization): Type-2 hypervisor products or operating system hosted solutions (Microsoft virtual PC, VMWare Workstation or Fusion, Parallels, etc.) requires a host operating system to run. This is used commonly in lab, test, QA, and development environments, or more recently as a way to solve application compatibility problems by running applications that require Windows XP under Windows 7 (XP mode). However since the secondary OS runs on top of a host OS, the performance is significantly degraded in video, network, disk, etc. Performance as well as the overhead of a second operating system still require IT management
- Server Hosted Virtual Desktops (SHVD) Also referred to as VDI or desktop virtualization: Desktop virtualization as personified by VMWare’s Virtual Desktop Infrastructure (VDI), VMWare View or Citrix XenDesktop, provides the PC image to a shared server resource in the data center, the mouse and keyboard re remotely sent across the wire to the server and the results are sent to the client for rendering. Since little to no processing is occurring at the client the PC can be a machine with minimal resources (thin client). This also means that a system can be more flexible and a user can connect to the same desktop over a multitude of devices from a wide range of locations.
Client-hosted vs. Server-hosted virtual desktops
Client-hosted virtualization (CHVD) differs from server-hosted virtualization (SHVD) in some critical ways. Where SHVD is remotely executing the OS image on a server and sending screenshots across the network, CHDV is executing te OS image locally on the client itself, taking advantage of the PCs powerful hardware. CHVD can be taken offline from the network, whereas SHVD requires a network connection. Client hosted virtual desktops fit into the trend of today’s move towards distributed computing environments with lots of mobile computing devices spread throughout the world. The scalability of a SHVD server is limited to 20-30 concurrent sessions and require a lot of backend infrastructure. CHVD relies on the PC hardware that is in place today and requires no additional infrastructure in the data center.