'Check if file does not exist.
:param nfs_mount: string path of the nfs share
:param volume_name: string volume name
:returns: boolean (true for file not present and false otherwise)'

def _file_not_present(self, nfs_mount, volume_name):

    try:
        self._execute('ls', self._get_file_path(nfs_mount, volume_name))
    except processutils.ProcessExecutionError as e:
        if ('No    such    file    or    directory' in e.stderr):
            return True
        else:
            raise
    return False
