totalDisks := offlineDisks.Merge(onlineDisks)

	// Report total capacity
	ch <- prometheus.MustNewConstMetric(
		prometheus.NewDesc(
			prometheus.BuildFQName(minioNamespace, "capacity_raw", "total"),
			"Total capacity online in the cluster",
			nil, nil),
		prometheus.GaugeValue,
		float64(GetTotalCapacity(server.Disks)),
	)

	// Report total capacity free

	s3MetricNamespace        MetricNamespace = "minio_s3"
)

const (
	cacheSubsystem            MetricSubsystem = "cache"
	capacityRawSubsystem      MetricSubsystem = "capacity_raw"
	capacityUsableSubsystem   MetricSubsystem = "capacity_usable"
	driveSubsystem            MetricSubsystem = "drive"
	interfaceSubsystem        MetricSubsystem = "if"
	memSubsystem              MetricSubsystem = "mem"