So what is shadow copy?
This is a feature within Server 2012 that can be used to restore previous versions of files and folders. It is a lot faster than restoring it from traditional backup methods. You should however not rely on this as being the primary backup solution.It takes a snapshot of the file or folders and then keeps track of any changes made to those files or folders. You can allocate a certain size of diskspace towards it and when that space is reached it rewrites over previous snapshots. For this builtin window feature to work you need to have a NTFS file system.