Hyper-V takes a different approach to virtual machine file storage than Virtual Server 2005 R2. The default locations’re different, the storage approach is different, and the configuration files are different. What does this mean to the seasoned Virtual Server 2005 R2 administrator? It means that you’ll need to start with a fresh slate and learn how it all works. To allow all of the file storage and access changes, Hyper-V leverages a new type of SID added to Windows Server 2008 called a Service SID to control access to virtual machine files. A virtual machine gets a GUID when created and a corresponding unique Service SID is created for the virtual machine using a combination of the Service SID ""NT VIRTUAL MACHINE" and the VMGUID. Example: "NT VIRTUAL MACHINE\ C64FB013-6D92-4B9B-B106-690182B00FFA "
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