'Get size of an existing ISE volume.'

def manage_existing_get_size(self, volume, ise_volume_ref):

    LOG.debug('X-IO    manage_existing_get_size    called')
    if ('source-name' not in ise_volume_ref):
        LOG.error('manage_existing_get_size:    No    source-name    in    ref!')
        RaiseXIODriverException()
    ref_name = ise_volume_ref['source-name']
    vol_info = self._get_volume_info(ref_name)
    if (vol_info['location'] == ''):
        LOG.error('manage_existing_get_size:    %s    does    not    exist!', ref_name)
        RaiseXIODriverException()
    return int(vol_info['size'])
