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Windows Vista – Virtualized Files

For the past few weeks, I’ve been playing around with Windows Vista. I have to admit, I was a bit skeptical at first, but after a while of working with Vista, I have been quite impressed. One area I like is the virtualization of several sections of the OS and of key files.

When an application requires the ability to write to the Program Files directory, Vista places those files into a virtual location in the user’s profile without the application ever knowing that this has happened. For example, let’s say there’s an application that needs to write to C:\Program Files\My Application\configuration.ini. In previous versions of Windows, unless the user explicitly has write access to that file or has administrative rights, the application may fail. In Vista, the OS will place the configuration.ini file in C:\Users\username\AppData\VirtualStore\Program Files\My Application\configuration.ini so that the application can write to the file without failing. The application won’t even know this has happened as Vista takes care of this all behind the scenes. This new feature makes an administrator’s life easier by being able to keep the Program Files directory secure.

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2 Responses to “Windows Vista – Virtualized Files”

  1. jpaecorr on March 19th, 2007 5:30 pm

    Thank you. I knew it was virtualized I just havent taken the time to dig where.

    The obvious queston this leaves is “If the program file directory is virtualized for modification, how does the system know whether or not the modification is due to an install or running a program that just needs to modify files located in Program Files”? In other words, if I install a program to program files, how does Vista know whether to create the folder actually in Program Files or to virtulize it? I have seen instances of program where even running “as administrator” it still virtualizes the data, that is why I ask.

  2. dave on March 19th, 2007 5:50 pm

    What I am given to understand about Vista is that the only time files are written to the Program Files directory is when an application is being installed. Even administrator accounts run at a lower level of privileges. When an application installer is called, Vista prompts the user for administrative credentials. If you are logged in with a normal account, you will be asked to enter in the username and password of an administrator. If you are already logged in as an administrator, you will still be asked to elevate your privileges by clicking Continue on a user prompt.

    Once your privileges have been elevated, the installation of the application will proceed by writing directly to the Program Files directory. Upon completion of the install, the your privileges return to their lower state and any future writes to Program Files will go to the VirtualStore.

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