'changes the vpool type.'

@retry_wrapper
def retype(self, ctxt, volume, new_type, diff, host):

    self.authenticate_user()
    volume_name = self._get_coprhd_volume_name(volume)
    vpool_name = new_type['extra_specs']['CoprHD:VPOOL']
    try:
        full_project_name = ('%s/%s' % (self.configuration.coprhd_tenant, self.configuration.coprhd_project))
        task = self.volume_obj.update(full_project_name, volume_name, vpool_name)
        self.volume_obj.check_for_sync(task['task'][0], True)
        return True
    except coprhd_utils.CoprHdError as e:
        coprhd_err_msg = (_('Volume    %(volume_name)s:    update    failed\n%(err)s') % {'volume_name': volume_name, 'err': six.text_type(e.msg)})
        log_err_msg = ('Volume    :    %s    type    update    failed' % volume_name)
        self._raise_or_log_exception(e.err_code, coprhd_err_msg, log_err_msg)
