mg := &MetricsGroupV2{
		cacheInterval:    1 * time.Minute,
		metricsGroupOpts: opts,
	}
	mg.RegisterRead(func(_ context.Context) (metrics []MetricV2) {
		metrics = make([]MetricV2, 0, 16)
		nodesUp, nodesDown := globalNotificationSys.GetPeerOnlineCount()
		metrics = append(metrics, MetricV2{
			Description: getNodeOnlineTotalMD(),
			Value:       float64(nodesUp),
		})