xenserver

Citrix XenServer is the complete server virtualization platform from Citrix.
citrix xenserver是来自citrix的完全服务器虚拟化平台。
The XenServer package contains all you need to create and manage a deployment of virtual x86 computers running on Xen®, the open-source paravirtualizing hypervisor with near-native performance.
xenserver包包含所有你需要用来创建和管理一个运行在xen（一个近乎原生性能的开源半虚拟化hypervisor）之上的虚拟x86计算机部署。
XenServer is optimized for both Windows and Linux virtual servers.
xenserver是为windows和linux虚拟服务器而优化的。

XenServer runs directly on server hardware without requiring an underlying operating system, which results in an efficient and scalable system.
xenserver直接运行在服务器硬件之上，不需要一个底层操作系统，
XenServer works by abstracting elements from the physical machine (such as hard drives, resources and ports) and allocating them to the virtual machines running on it.
xenserver通过提取来自物理机的元素（例如硬盘，资源与端口）并且分配它们给运行在xenserver之上的虚拟机。

A virtual machine (VM) is a computer composed entirely of software that can run its own operating system and applications as if it were a physical computer.
一个虚拟机就是一个完全由软件组成的计算机，这台计算机运行它自己的操作系统和应用程序就好像它是一个物理计算机一样。
A VM behaves exactly like a physical computer and contains its own virtual (software-based) CPU, RAM, hard disk and network interface card (NIC).
虚拟机行为完全像一个物理计算机，并且包含它自己的虚拟（基于软件的）cpu,ram,硬盘和网络接口卡（NIC）。

http://xenserver.org/overview-xenserver-open-source-virtualization/project-roadmap.html