'Reboot all instances and reconfigure the cluster'

@print_timing('Restarting    cluster')
def restart_cluster(self, reboot_only=False):

    nodes = self.nodes
    if (not nodes):
        raise exception.ClusterValidationError('No    running    nodes    found')
    self.run_plugins(method_name='on_restart', reverse=True)
    log.info('Rebooting    cluster...')
    for node in nodes:
        node.reboot()
    if reboot_only:
        return
    sleep = 20
    log.info(('Sleeping    for    %d    seconds...' % sleep))
    time.sleep(sleep)
    self.setup_cluster()
