'Get volume stats.
:param refresh: if it is True, update the stats first.
:returns: dictionary with the stats from HNAS
.. code:: python
_stats[\'pools\'] = {
\'total_capacity_gb\': total size of the pool,
\'free_capacity_gb\': the available size,
\'QoS_support\': bool to indicate if QoS is supported,
\'reserved_percentage\': percentage of size reserved,
\'max_over_subscription_ratio\': oversubscription rate,
\'thin_provisioning_support\': thin support (True),'

def get_volume_stats(self, refresh=False):

    LOG.info('Getting    volume    stats')
    _stats = super(HNASNFSDriver, self).get_volume_stats(refresh)
    _stats['vendor_name'] = 'Hitachi'
    _stats['driver_version'] = HNAS_NFS_VERSION
    _stats['storage_protocol'] = 'NFS'
    max_osr = self.max_over_subscription_ratio
    for pool in self.pools:
        (capacity, free, provisioned) = self._get_capacity_info(pool['fs'])
        pool['total_capacity_gb'] = (capacity / float(units.Gi))
        pool['free_capacity_gb'] = (free / float(units.Gi))
        pool['provisioned_capacity_gb'] = (provisioned / float(units.Gi))
        pool['QoS_support'] = 'False'
        pool['reserved_percentage'] = self.reserved_percentage
        pool['max_over_subscription_ratio'] = max_osr
        pool['thin_provisioning_support'] = True
    _stats['pools'] = self.pools
    LOG.debug('Driver    stats:    %(stat)s', {'stat': _stats})
    return _stats
