histogram: prometheus.NewHistogramVec(prometheus.HistogramOpts{
		Name:    "tier_ttlb_seconds",
		Help:    "Time taken by requests served by warm tier",
		Buckets: []float64{0.01, 0.1, 1, 2, 5, 10, 60, 5 * 60, 15 * 60, 30 * 60},
	}, []string{"tier"}),
}

func (t *tierMetrics) Observe(tier string, dur time.Duration) {
	t.histogram.With(prometheus.Labels{"tier": tier}).Observe(dur.Seconds())
}

package cmd

import (
	"testing"
	"time"
)

func TestTierMetrics(t *testing.T) {
	tier := "WARM-1"
	globalTierMetrics.Observe(tier, 200*time.Millisecond)
	expSuccess := 10
	expFailure := 5
	for i := 0; i < expSuccess; i++ {
		globalTierMetrics.logSuccess(tier)
	}
	for i := 0; i < expFailure; i++ {
		globalTierMetrics.logFailure(tier)
	}
	metrics := globalTierMetrics.Report()
	var succ, fail float64

)

var (
	// error returned when remote tier already exists
	errTierAlreadyExists = AdminError{
		Code:       "XMinioAdminTierAlreadyExists",
		Message:    "Specified remote tier already exists",
		StatusCode: http.StatusConflict,
	}
	// error returned when remote tier is not found
	errTierNotFound = AdminError{
		Code:       "XMinioAdminTierNotFound",
		Message:    "Specified remote tier was not found",
		StatusCode: http.StatusNotFound,

	os.TransitionTier = info.Tier
	os.TransitionStatus = info.Status
	os.RemoteObject = info.Name
	os.TransitionVersionID = info.VersionID
}

// shouldRemoveRemoteObject determines if a transitioned object should be
// removed from remote tier. If remote object is to be deleted, returns the
// corresponding tier deletion journal entry and true. Otherwise returns empty
// jentry value and false.

	VersionID string `msg:"vid"`
	TierName  string `msg:"tier"`
}

const (
	tierJournalVersion = 1
	tierJournalHdrLen  = 2 // 2 bytes
)

var errUnsupportedJournalVersion = errors.New("unsupported pending deletes journal version")

func newTierDiskJournal() *tierDiskJournal {
	return &tierDiskJournal{}
}

// NewTierJournal initializes tier deletion journal
func NewTierJournal() *TierJournal {

		merged.Bins[i] = cl.Bins[i].add(cm.Bins[i])
	}

	return merged
}

// DailyAllTierStats is used to aggregate last day tier stats across MinIO servers
type DailyAllTierStats map[string]lastDayTierStats

func (l DailyAllTierStats) merge(m DailyAllTierStats) {
	for tier, st := range m {
		l[tier] = l[tier].merge(st)
	}
}

func (l DailyAllTierStats) addToTierInfo(tierInfos []madmin.TierInfo) []madmin.TierInfo {

			wg.Wait()

			// Reset for the next interval
			timer.Reset(globalAPIConfig.getDeleteCleanupInterval())
		}
	}
}

func (s *erasureSets) cleanupStaleUploads(ctx context.Context) {
	timer := time.NewTimer(globalAPIConfig.getStaleUploadsCleanupInterval())
	defer timer.Stop()

	for {
		select {
		case <-ctx.Done():
			return
		case <-timer.C:
			var wg sync.WaitGroup
			for _, set := range s.sets {

### Timer changes

Go 1.23 makes two significant changes to the implementation of
[time.Timer] and [time.Ticker].

First, `Timer`s and `Ticker`s that are no longer referred to by the program
become eligible for garbage collection immediately, even if their
`Stop` methods have not been called.
Earlier versions of Go did not collect unstopped `Timer`s until after
they had fired and never collected unstopped `Ticker`s.

    Future<?> localTimer = timer;
    // Try to cancel the timer as an optimization.
    // timer may be null if this call to run was by the timer task since there is no happens-before
    // edge between the assignment to timer and an execution of the timer task.
    if (localTimer != null) {
      localTimer.cancel(false);
    }

    delegateRef = null;
    timer = null;
  }

	case madmin.Azure:
		d, err = newWarmBackendAzure(*tier.Azure, tier.Name)
	case madmin.GCS:
		d, err = newWarmBackendGCS(*tier.GCS, tier.Name)
	case madmin.MinIO:
		d, err = newWarmBackendMinIO(*tier.MinIO, tier.Name)
	default:
		return nil, errTierTypeUnsupported
	}
	if err != nil {
		return nil, errTierTypeUnsupported
	}

	if probe {
		if err = checkWarmBackend(ctx, d); err != nil {
			return nil, err