v.Online, v.Offline = globalNotificationSys.GetPeerOnlineCount()
		return v, err
	}
	return cachevalue.NewFromFunc(1*time.Minute,
		cachevalue.Opts{ReturnLastGood: true},
		loadNodesUpDown)
}

type driveIOStatMetrics struct {
	readsPerSec    float64
	readsKBPerSec  float64
	readsAwait     float64
	writesPerSec   float64
	writesKBPerSec float64

)

// Opts contains options for the cache.
type Opts struct {
	// When set to true, return the last cached value
	// even if updating the value errors out.
	// Returns the last good value AND the error.
	ReturnLastGood bool

	// If NoWait is set, Get() will return the last good value,
	// if TTL has expired but 2x TTL has not yet passed,
	// but will fetch a new value in the background.
	NoWait bool
}

}

var bucketStorageCache = cachevalue.New[DataUsageInfo]()

// Init initialize bucket quota.
func (sys *BucketQuotaSys) Init(objAPI ObjectLayer) {
	bucketStorageCache.InitOnce(10*time.Second,
		cachevalue.Opts{ReturnLastGood: true, NoWait: true},
		func(ctx context.Context) (DataUsageInfo, error) {
			if objAPI == nil {
				return DataUsageInfo{}, errServerNotInitialized
			}
			ctx, done := context.WithTimeout(ctx, 2*time.Second)

func (z *erasureServerPools) ListBuckets(ctx context.Context, opts BucketOptions) (buckets []BucketInfo, err error) {
	if opts.Cached {
		listBucketsCache.InitOnce(time.Second,
			cachevalue.Opts{ReturnLastGood: true, NoWait: true},
			func(ctx context.Context) ([]BucketInfo, error) {
				ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
				defer cancel()

				buckets, err = z.s3Peer.ListBuckets(ctx, opts)

// to populate new values upon cache invalidation.
func (g *MetricsGroupV2) RegisterRead(read func(context.Context) []MetricV2) {
	g.metricsCache = cachevalue.NewFromFunc(g.cacheInterval,
		cachevalue.Opts{ReturnLastGood: true},
		func(ctx context.Context) ([]MetricV2, error) {
			if g.metricsGroupOpts.dependGlobalObjectAPI {
				objLayer := newObjectLayerFn()
				// Service not initialized yet
				if objLayer == nil {