US Patent 9996429 Mountable container backups for files

A file stored in a volume on a client is backed up in a mountable format by creating on the client a template virtual volume that corresponds to the volume in which the file is stored. A set of file extents occupied by the file is identified. A file extent in a backup stream is identified. If the file extent is not within the set of file extents, the template virtual volume is accessed to backup a data block associated with the virtual volume. If the file extent is within the set of file extents, the file is accessed to backup a data block of the file.