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What is exactly Virtualization Technology means?


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I was reading about Vista Enterprise, and while reading I saw the new feature called "New virtualisation Technology" or something like that....

Then I begun asking people and some of them say that that the old programs that where running on Windows 98 and 95 will run on Vista Enterprise... some of them say that Virtualization technology means that you can run instances of Vista on couple VMs without the need to activate it for each VM...

Which is correct????????

thanx in advance....

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The virtualization in Vista is how some (typically legacy) applications are "dummied" into thinking they are creating & working with files in protected areas - such as %systemroot%.

Vista has a lot more granular security around services, processes, logon sessions and files on disk - some people don't like this "lack of control" or the fact that a system user account has exclusive access to some folders and change the permissions/owners (making it an unsupported scenario).

An application wants to create a config.ini file in %systemroot%, but is run by a regular user and not elevated - access would be denied, application would probably fall over or do something unexpected due to bad design.

By virtualizing the process, the application thinks it is writing to %systemroot% (C:\Windows) but is in fact having its I/O redirected silently by the kernel - so it gets "success" reported by creating the file, and similarly reading the data back works too.

So the first description you mentioned was the closest to the truth.

In Task Manager you can see which processes are virtualized and change the virtualization status of a running process.

Working example to prove the concept:

Open a cmd prompt (not elevated!) and enter the following commands:

cd \Windows

copy con testvirt.txt

Enter some random text and then press enter

Result: "Access is denied."

Start Task Manager and right-click the cmd.exe process on the Processes tab, click the Virtualization option then click Yes.

Now go back to your command prompt window and repeat the above actions - this time no "Access is denied" message appears, so press CTRL-Z and enter to create the file on disk.

Open an Explorer window and browse into your C:\Windows folder, look for testvirt.txt.... it doesn't exist (as explorer.exe is not being virtualized).

The file is really present in C:\Users\username\Appdata\Local\VirtualStore\Windows - a per-user virtual store for a protected folder.

Log on as a different user, repeat the above test using different random text - the file does not appear to exist as this user has not created one, they are distinct.

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