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.
