ReFs, which stands for Resilient File System, is a new File Systems that will make an appearance in Windows 8 Server (and possibly into the client OS at a later date). This is the first major update to the FS after the FAT to NTFS move and the first attempt from Microsoft after the WinFS fiasco.
You can read about the implementation of ReFs in this post
ReFs along with StorageSpaces seems to be a very interesting proposition and can ease recovery and stability of the FS.


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