Virtualization - the technique of managing systems and resources functionally, regardless of their physical layout or location - represents a powerful breakthrough in IT efficiency, responsiveness and agility.
Since 2005, virtualization software was adopted faster than anyone imagined, including the experts. There are three areas of IT where virtualization is making headroads,.network virtualization, storage virtualization and server virtualization.
● Server virtualization
Server virtualization is the masking of server resources (including the number and identity of individual physical servers, processors, and operating systems) from server users. The intention is to spare the user from having to understand and manage complicated details of server resources while increasing resource sharing and utilization and maintaining the capacity to expand later. In general, server virtualization software runs between the operating system and the hardware. Server virtualization products are available from a number of vendors. VMware is the major software vendor providing server virtualization for Windows and Linux systems with Intel-powered servers. Microsoft offers its own Virtual Server product.
Vendors suggest that server virtualization allows a company to “scale-out”with multiple smaller computers as its processing needs grow rather than having to scale up to a more expensive multi-processor computer. Further advantages of server virtualization include: the ability to have all developers share the same machine while developing and testing new programs; the ability (in some cases) to support legacy applications (which run on an older version of an operating system) while newer applications run on the latest operating system level on the same server; and the ability to simulate distributed network applications on the same physical server.
Server virtualization is frequently used to mask the complexities of server consolidation and is closely related to the concept of the virtual machine, which uses a copy of an operating system to create the appearance of a full set of storage and other resources to each user.
● Network virtualization
Network virtualization is a method of combining the available resources in a network by splitting up the available bandwidth into channels, each of which is independent from the others, and each of which can be assigned (or reassigned) to a particular server or device in real time. Each channel is independently secured. Every subscriber has shared access to all the resources on the network from a single computer.
Network management can be a tedious and time-consuming business for a human administrator. Network virtualization is intended to improve productivity, efficiency, and job satisfaction of the administrator by performing many of these tasks automatically, thereby disguising the true complexity of the network. Files, images, programs, and folders can be centrally managed from a single physical site. Storage media such as hard drives and tape drives can be easily added or reassigned. Storage space can be shared or reallocated among the servers.
Network virtualization is intended to optimize network speed, reliability, flexibility, scalability, and security. Network virtualization is said to be especially effective in networks that experience sudden, large, and unforeseen surges in usage.
● Storage virtualization
Storage virtualization is the pooling of physical storage from multiple network storage devices into what appears to be a single storage device that is managed from a central console. Storage virtualization is commonly used in a storage area network (SAN). The management of storage devices can be tedious and time-consuming. Storage virtualization helps the storage administrator perform the tasks of backup, archiving, and recovery more easily, and in less time, by disguising the actual complexity of the SAN.
Users can implement virtualization with software applications or by using hardware and software hybrid appliances. The technology can be placed on different levels of a storage area network.
Virtualization can be viewed as part of an overall trend in enterprise IT that includes autonomic computing, a scenario in which the IT environment will be able to manage itself based on perceived activity, and utility computing, in which computer processing power is seen as a utility that clients can pay for only as needed. The usual goal of virtualization is to centralize administrative tasks while improving scalability and work loads.
虛擬化
虛擬化，一項從功能上管理系統和資源、而不管它們的物理布局或位置的技術，它代表了IT技術在效率、響應和敏捷方面的重大突破。
自2005年以來，采用虛擬化軟件的速度超過了包括專家在內的任何人的想象。虛擬化在IT的下列三個領域闊步前進：網絡虛擬化、存儲虛擬化和服務器虛擬化。
● 服務器虛擬化
服務器虛擬化是給服務器的用戶屏蔽掉服務器的資源（包括物理服務器、處理器和操作系統的數量和身份）。其目的是讓用戶不必了解和管理服務器資源復雜的細節、同時增強（資源的）共享和利用、以及保持今后擴展的能力。通常，服務器虛擬化軟件運行在操作系統和硬件之間。服務器虛擬化產品可從很多廠商那里獲得。其中，VMware公司是提供在基于英特爾微處理器的服務器上運行Windows和Linux系統的服務器虛擬化軟件的主要廠商。
廠商們認為，服務器虛擬化讓一家公司在處理需求增長時利用多臺較小的計算機進行“擴展”，而不必用較昂貴的多處理器計算機進行擴展。服務器虛擬化優點還包括：讓所有的開發人員共享同一臺機器開發和測試新的程序；（在有些情況下）在同一臺服務器上支持陳舊應用程序（運行在較老的操作系統版本上），同時讓更新的應用程序運行在最新的操作系統版本上；以及在同一臺物理服務器上模擬分布式網絡應用程序。
服務器虛擬化常常用來屏蔽服務器合并的復雜性，與虛擬機的概念密切相關，它是利用一份操作系統的拷貝給每個用戶生成存儲和其他資源的完整外觀。
● 網絡虛擬化
網絡虛擬化是一種方法，通過將可用帶寬分成多個通道，各個通道之間是互相獨立的，同時每個通道都實時地分配給某個特定的服務器或設備，從而將網絡上可資利用的資源結合在一起。每個通道獨自都是安全的。每位用戶都可從單臺計算機上分享網絡上的所有資源。
對于人類的網管員來說，網絡管理是一項費時、乏味的工作。網絡虛擬化是設想通過自動完成其中的很多任務，從而將網絡真正的復雜性隱藏起來，以提高網管員的工作效率和生產力以及工作滿意度。文件、圖像、程序和文件夾可以從單一地點加以集中管理。存儲介質，如硬盤和磁帶機，可以很容易地加進來或重新分配。在服務器之間可以共享或重新分配存儲空間。
網絡虛擬化旨在優化網絡的速度、可靠性、靈活性、可擴性和安全性。據說，網絡虛擬化在網絡突然遭受到無法預見的使用量劇增時非常有效。
● 存儲虛擬化
存儲虛擬化是將多個網絡存儲裝置的物理存儲組合成看上去由中央控制臺管理的單一存儲裝置。存儲虛擬化常常用于存儲區域網（SAN）。存儲裝置的管理是很乏味、很費時的。通過把SAN的實際復雜性隱蔽起來，存儲虛擬化有助于存儲管理員更容易和更快地執行備份、歸檔和恢復的任務。
用戶可以通過軟件應用或混合的軟硬件裝置實現虛擬化。此技術可以放在存儲區域網的不同等級上。
虛擬化可以看作是企業IT發展總趨勢的一部分，其中還包括自治計算（基于感知的活動自行管理自己的IT環境）和普遍計算（其中計算機的處理能力可以視作一種公用服務，客戶只需支付需要的那一部分）。虛擬化通常的目標是要使管理任務集中化，同時改進可擴性和網絡負荷。
文章來源于領測軟件測試網 http://www.kjueaiud.com/
