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1、英文文献翻译 专业班级： 学生姓名： 学 号： 二九年五月二十五日1 Scientific Literature Server virtualization is one of those rare technologies that sounds too good to be true, but its real. Its earliest use was to consolidate underutilized server hardware onto a smaller number of machines. Since those early days, it has grown in
2、to 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
3、 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 thats installed directly onto the server hardware. Above that, a virtualization layer handles the redirection and emulation that
4、 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 configurationsas you choose. As are physical serve
5、rs, 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 OSs installation CD. Its just like installing an OS on a PC, and in general, if you wonder
6、 how virtualization will behave, thats the answer: Just like a PC. In fact, in an all-Windows environment, its 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 applicati
7、ons 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 servers dont have direct control over resources such as memory, hard drives, and network ports. Instead, the VM that sits be
8、neath the OS and applications intercepts requests for interaction with hardware and handles them as it sees fit. The real mindblower that turns this technology into something close to magic is that a world- class virtualization solution such as VMware ESX Server can synthesize an entire hardware con
9、figuration that has little resemblance to the underlying hardware. For example, the host 2 might simulate the initialization process of a SCSI controller to the last detail, convincing the guest OS that this initialization is being performed even when no physical SCSI controller exists. It can make
10、IDE drives look like SCSI drives, convert network shares into locally attached storage, turn one Ethernet adapter into several, and create gateways between older operating systems and unsupported modern hardware such as Fibre Channel adapters. You build your own servers that precisely fit the needs
11、of your applications, but you use a mouse instead of a screwdriver. Installing the OS and software onto a physical PC server every time you need one can be tedious. Fortunately, with virtualization you dont have to. After youve tuned a virtualized hardware configuration precisely to your liking, you
12、 can save that servers disk image to a file and use it as a template for other guest systems. In practice, this is a delight. You can back up a virtual server by copying the file. You can create a new server by duplicating the file copying Windows requires reactivation and an appropriate licenseor m
13、ove an existing server to different physical hardware. Virtualized servers do all the good and bad things regular servers do. They boot up, power down, suspend, hang, and even crash. If a guest OS or a device driver it uses is buggy, the virtual PC will crater. But not the physical computer, and tha
14、ts key. If your OS crashes or an application hangs, or even if you install a software fix that requires a reboot, nothing happens to the hardware. One virtual machine can fail over to another in a purely virtual sense or in a way thats closer to the real thing. Even if certain hardware devices have
15、malfunctioned, so long as the fail-over target is configured to use a secondary network adapter and an alternate path to storage, the fail-over will work exactly as it would if the virtual PCs were physical PCs. In most cases, an enterprise management system will monitor and react to a virtual fail-
16、 over as if it were the real thing. Solutions such as HP Open View see and interact with virtual servers the same way they do with physical ones. The reported configurations of the servers will change after theyre virtualized, but its entirely likely that the day-to-day management of your shop will experience little change. Internet becomes the focal point that the business family fixes eyes on gradually, in development of
