一个虚拟机运行在一个单独的操作系统内。
这使您可以在使用已知状态的环境中，为该环境中的所有虚拟机运行测试。
This lets you run your tests on an environment that USES a known state for all the virtual machines in the environment.
需要注意的是虚拟机运行并不会像本地主机（就是运行在非虚拟的硬件上的系统）上的程序一样快。
Something to note is that a virtual machine will not be as fast as a native application (native = running on non-virtualized hardware).
如果不介意较慢的启动时间，在没有最近出现的共享内存时，服务器虚拟机运行一段时间会变快。
If you don't mind the slower startup time, without the newly available Shared memory, the server VM will run more quickly over time.
然而，当多个虚拟机运行在同样的服务器上，并且开始竞争硬件和网络资源时，系统开销就会大大增加。
However, when several virtual machines run on the same server and start competing for hardware and network resources, the overhead is substantially higher.
如果视窗系统漏洞剥削WindowsServer 2008，然而，这将危及所有的虚拟机运行在它在一杆。
If a Windows vulnerability exploited Windows Server 2008, however, that would jeopardize all the VMs that are running on it in one shot.
放在jre \lib \ext目录中的JAR归档文件会被添加到通过虚拟机运行的所有应用程序的类路径。
JAR archives placed in your jre \ lib \ ext directory are added to the classpath of all applications run with that virtual machine.
WindowsServer 2008就被设计成这样，因此它清楚何时作为虚拟机运行，何时在物理硬件上运行。
The Windows Server 2008 was designed enlightened so it would know when it is running as a virtual machine and it would know when it is running on physical hardware.
放在jre \lib \endorsed目录中的JAR文件也被添加到了通过虚拟机运行的所有应用程序的类路径。
JAR files in the jre \ lib \ endorsed directory are also added to the classpath of all applications run with that virtual machine.
不管虚拟机运行的是哪种操作系统，你要确保WindowsVirtualPC集成插件已经安装，并且集成功能被启用。
No matter which guest operating system you are running you will also need to ensure that the Windows Virtual PC integration Components have been installed, and that integration features are enabled.
虚拟化可能在利用这样的信息源上存在缺陷，或者说在同一台主机上容纳多个虚拟机运行环境可能会穷尽可用的信息源，导致薄弱的随机数生成机制。
Virtualization might have flawed mechanisms for tapping that entropy source, or hav-ing several VMEs on the same host might exhaust the available entropy, leading to weak random number generation.
虚拟化可能在利用这样的信息源上存在缺陷，或者说在同一台主机上容纳多个虚拟机运行环境可能会穷尽可用的信息源，导致薄弱的随机数生成机制。
Virtualization might have flawed mechanisms for tapping that entropy source, or hav-ing several VMEs on the same host might exhaust the available entropy, leading to weak random number generation.
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