虚拟化系统网络科技文摘.doc

英文文献翻译 专业班级： 学生姓名： 学 号： 二〇〇九年五月二十五日 Scientific Literature Server virtualization is one of those rare technologies that sounds too good to be true, but it’s real. Its earliest use was to consolidate underutilized server hardware onto a smaller number of machines. Since those early days, it has grown into a multipurpose solution that enables greater reliability, improved management, and other benefits that make it an all-but-indispensable tool for enterprise datacenter administrators. To use an oversimplified definition, a virtual server mimics, using software alone, the behavior and capabilities of a stand-alone computer. The nomenclature of virtualization is simple. The bottom of the software stack is occupied by a single instance of an ordinary operating system that’s installed directly onto the server hardware. Above that, a virtualization layer handles the redirection and emulation that make up the virtual computer. The combination of these two lower layers is referred to as the host. The host provides the full workings of a familiar PC right down to its BIOS ROM, and it can spawn as many independent PCs— using varying user-defined configurations—as you choose. As are physical servers, a virtual PC is useless until you install an operating system on it. The operating systems that you install on your virtual hosts are called guests. Installing a guest OS can be as easy as booting from the OS’s installation CD. It’s just like installing an OS on a PC, and in general, if you wonder how virtualization will behave, that’s the answer: Just like a PC. In fact, in an all-Windows environment, it’s easy to lose your place: Are you looking at your Windows host OS or at one of the four Windows guest OSes you just installed? You might get confused, but your guest OSes and their applications never do. Each guest OS believes it has the whole machine to itself. And, in a sense, it does Software-based hardware Operating systems and applications running on virtual s