The Xen ® hypervisor is the fastest and most secure infrastructure virtualization solution available today. Xen provides an abstraction layer that allows a physical server to run one or more "virtual servers", effectively decoupling the operating system and its applications from the underlying physical server.

• Xen ® Hypervisor
• Paravirtualization
• Hardware-assisted virtualization
• Command line management tools
• GNU General Public License (GPLv2)

Parallels ® Virtuozzo Containers is the industry-leading operating system virtualization solution. Parallels ® Virtuozzo Containers creates multiple, independent containers on a single physical server and OS instance. Each container holds an independent virtual environment complete with its own operating system.

• Intelligent partitioning
• Complete isolation
• Dynamic resource allocation
• Live migration
• Mass management

Hyper-V is the hypervisor-based virtualization feature of Windows Server 2008. It operates directly on top of a physical server hardware and enables multiple virtual machines (VMs) to run an independent Windows or Linux based operating system.

• Large memory support
• Support for up to 8 Processors
• Cluster Shared Volume support
• Improved server utilization
• Small footprint