'Define a new snapshot group for a volume
:param label: the label for the snapshot group
:param volume: an E-Series volume
:param percentage_capacity: an optional repository percentage
:return: a new snapshot group'

def _create_snapshot_group(self, label, volume, percentage_capacity=20.0):

    if (not self._client.features.REST_1_3_RELEASE):
        vol_size_gb = (int(volume['totalSizeInBytes']) / units.Gi)
        pools = self._get_sorted_available_storage_pools(vol_size_gb)
        volume_pool = next((pool for pool in pools if (volume['volumeGroupRef'] == pool['id'])))
        if (volume_pool.get('raidLevel') == 'raidDiskPool'):
            pool_id_to_use = volume_pool['volumeGroupRef']
        else:
            pool_id_to_use = pools[0]['volumeGroupRef']
        group = self._client.create_snapshot_group(label, volume['volumeRef'], pool_id_to_use, repo_percent=percentage_capacity)
    else:
        group = self._client.create_snapshot_group(label, volume['volumeRef'], repo_percent=percentage_capacity)
    return group
