運行在虛擬服務器上的操作係統和應用程序不直接控製內存、硬盤和網絡端口等資源,而是由位於 OS和應用程序之間的VM(虛擬機)截取與硬件交互的請求並在認為合適時對它們進行處理。 真正將此技術變成接近於魔術的是 VMware公司的ESX Server等世界級的虛擬化解决方案,這類解决方案能合成整個硬件的配置,而它與基礎的硬件幾乎沒有關係。例如,宿主機可以最詳細地模擬SCSI控製器的初始化過程,讓客OS相信即使不存在物理的SCSI控製器時初始化也在被執行。它能使IDE磁盤機看上像SCSI磁盤機,能將網絡共享的磁盤機轉換成裝在本機內的存儲設備,將一個以太網卡變成幾個網卡,並能在較老式的操作係統和它不支持的新式硬件(如光通道卡)之間生成網關。你可以建立完全適合應用程序需要的屬於你自己的服務器,這時你用的是鼠標而不是用改錐。 在每次需要時把 OS 和軟件裝到物理的 PC 服務器是很煩人的。幸虧有了虛擬化你就不必這麽做。在完全按你的喜好調好虛擬硬件的配置後,你就能把服務器磁盤映像保存到文件中,對其他的客係統而言它可以當做樣板用。在實際中,它是一件賞心悅目的好事。你能通過拷貝該文件將虛擬服務器備份。復製該文件就能創建新的服務器 —— 而拷貝 Windows 需要重新激活和相應的許可證,或者把已有的服務器移到不同的物理硬件上。
Virtual Server
Server Virtualization is one of several rare, they sounded very good and it seems untrue, but in fact is true. Its early use is to reduce under-utilization of server hardware, (to deal with mission) into fewer machines. Since these early applications, it has developed into a multi-purpose solution to achieve higher reliability, better management, as well as enterprise data centers has become an indispensable tool for administrators. In accordance with a very simplified definition, the virtual server is the only use of an independent computer software to simulate the behavior and capabilities. The term virtualization is very simple. (Server Virtualization) software set at the bottom of the stack is directly installed on the server hardware, operating system, the ordinary. Is deal with their re-orientation and simulation of virtual layer, and re-orientation and constitute a virtual computer simulation. This is at the bottom two layers together are called the host. Host to provide everyone familiar with PC-BIOS ROM of the entire work, in accordance with the user's choice, use change user-defined a lot of preparation and give birth to an independent PC. As a physical server, virtual PC machine, only installed the operating system be useful. Installed in the virtual host's operating system, said a guest OS. Off the operating system installed (OS) is very simple, just from the OS installation from CD-ROM guide. This PC-installed OS is no different. Generally, if you do not know is how virtualization works, this is the answer: Just like a PC. In fact, in the whole Windows environment, you can easily find the North: in the look Windows host OS, or just watch the installation of the four Windows off an OS? May confuse you, but your customer OS and its applications are never made no mistake of. Each passenger OS think it has the whole machine. In a sense, it is to have the entire machine.
Software-based hardware
Running in a virtual server operating system and applications do not directly control the memory, hard drives and network resources such as ports, but by the OS and applications is located between the VM (virtual machine) that interacts with hardware interception of the request and when deemed appropriate, deal with them. Become closer to the real magic of this technology is that VMware's ESX Server, such as world-class virtualization solutions, such solutions can be synthesized throughout the hardware configuration, and it is based on the hardware and almost does not matter. For example, the host can be the most detailed simulation of SCSI controller initialization process so that customers believe that the OS does not exist even if the physical initialization of the SCSI controller also be executed. It can look like IDE disk drive SCSI disk drive, network share can be converted into the disk drive is installed in the local storage device, an Ethernet network adapter card into a few, and can operate in the more old-fashioned system and it does not support new hardware (such as the optical channel card) generated between the gateway. You can create complete applications for the needs of your own server, then you are using a mouse rather than using screwdriver. When necessary to each OS and software loaded into the PC physical server is very annoying. Thanks to virtualization you do not have to do so. Completely according to your preferences tuned virtual hardware configuration, you will be able to server disk image saved to the document, on the other passenger and systems it can use as a template. In practice, it is a pleasant thing. You can copy the file to virtual server backup. Copy of the document will be able to create a new server - and need to re-activate copies of Windows and the corresponding permit, or the server has been moved to different physical hardware.