[Element name] MediaLink [Description] 
Optional. If the disk that is being added is already registered in the subscription or the VHD for the disk already exists in blob storage, this element is ignored. If a VHD file does not exist in blob storage, this element defines the location of the new VHD that is created when the new disk is added. Example: http://example.blob.core.windows.net/disks/mydatadisk.vhd