 class DiffSyncFile_server extends diffsync.DiffSync
     constructor:(@cm_session, cb)  ->
         @path = @cm_session.path
-        @_backup_file = misc.meta_file(@path, 'backup')
-        # check for need to save a backup every this many milliseconds
-        @_autosave = setInterval(@write_backup, 10000)
-
-        # We prefer the backup file only if it both (1) exists, and
-        # (2) is *newer* than the master file.  This is because some
-        # other editing program could have edited the master, not
-        # knowing about the backup, in which case it makes more sense
-        # to just go with the master.
 
         no_master    = undefined
         stats_path   = undefined
-        no_backup    = undefined
-        stats_backup = undefined
         stats        = undefined
         file         = undefined
 

                                    cb(err)
                                else
                                    fs.close fd, cb
                else if no_backup # no backup file -- always use master
                    file = @path
                    stats = stats_path
                    cb()
                else if no_master # no master file but there is a backup file -- use backup
                    file = @_backup_file
                    stats = stats_backup
                    cb()
                else
                    # both master and backup exist
                    if stats_path.mtime.getTime() >= stats_backup.mtime.getTime()
                        # master is newer
                        file = @path
                        stats = stats_path
                    else
                        # backup is newer
                        file = @_backup_file
                        stats = stats_backup
                    cb()
            (cb) =>
                e = check_file_size(stats?.size)

                    stats_path = _stats_path
                    cb()
            (cb) =>
                if no_master
                    # create
                    file = @path
                    misc_node.ensure_containing_directory_exists @path, (err) =>
                        if err
