'Calculate available space on the NFS share.
:param nfs_share: example 172.18.194.100:/var/nfs'

def _get_capacity_info(self, nfs_share):

    mount_point = self._get_mount_point_for_share(nfs_share)
    (df, _) = self._execute('stat', '-f', '-c', '%S    %b    %a', mount_point, run_as_root=self._execute_as_root)
    (block_size, blocks_total, blocks_avail) = map(float, df.split())
    total_available = (block_size * blocks_avail)
    total_size = (block_size * blocks_total)
    (du, _) = self._execute('du', '-sb', '--apparent-size', '--exclude', '*snapshot*', mount_point, run_as_root=self._execute_as_root)
    total_allocated = float(du.split()[0])
    return (total_size, total_available, total_allocated)
