What is the difference between hosted virtualization and hypervisor-based virtualization?

Answer 1

Both VMware's ESX Server 3.5 and Microsoft's Hyper-V are built using a hypervisorbased architecture. This architecture gives both platforms bare-metal performance that significantly outperforms older hosted virtualization products such as Microsoft Virtual Server 2005 and VMware's Virtual Server 2.0. Hosted virtualization products run the virtualization software on top of the host OS, which introduces additional overhead and a longer code execution path for the virtual machines (VMs) that run in the hosted virtualization environment. In contrast, hypervisor-based products such as ESX Server and Hyper-V are designed to run the hypervisor directly on the system hardware. Although ESX Server and Hyper-V both share a similar hypervisor-based architecture, there are significant differences in the way the products are designed.

In both cases, the hypervisor runs directly on the system hardware. However, with ESX Server the hardware drivers are all part of the hypervisor, which significantly increases the size of the hypervisor. In addition, the device drivers are created by the hardware vendors, which introduces third-party code into the hypervisor and limits the hardware that ESX Server supports. Even so, ESX Server is supported on most of the server systems made by all the tier-one vendors, such as HP, Dell, and IBM. Many of these vendors also sell systems configurations with VMware ESX Server preloaded.