'Retrieve stats info from volume group.'

def _update_volume_stats(self):

    LOG.debug('Enter    _update_volume_stats.')
    gpfs_base = self.configuration.gpfs_mount_point_base
    data = {}
    backend_name = self.configuration.safe_get('volume_backend_name')
    data['volume_backend_name'] = (backend_name or 'GPFSNFS')
    data['vendor_name'] = 'IBM'
    data['driver_version'] = self.get_version()
    data['storage_protocol'] = 'file'
    self._ensure_shares_mounted()
    global_capacity = 0
    global_free = 0
    for share in self._mounted_shares:
        (capacity, free, _used) = self._get_capacity_info(share)
        global_capacity += capacity
        global_free += free
    data['total_capacity_gb'] = (global_capacity / float(units.Gi))
    data['free_capacity_gb'] = (global_free / float(units.Gi))
    data['reserved_percentage'] = 0
    data['QoS_support'] = False
    data['storage_pool'] = self._storage_pool
    data['location_info'] = ('GPFSNFSDriver:%(cluster_id)s:%(root_path)s' % {'cluster_id': self._cluster_id, 'root_path': gpfs_base})
    data['consistencygroup_support'] = 'True'
    data['consistent_group_snapshot_enabled'] = True
    self._stats = data
    LOG.debug('Exit    _update_volume_stats.')
