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,

	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 {

	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.

				err = msgp.WrapError(err, "ObjName")
				return
			}
		case "vid":
			z.VersionID, err = dc.ReadString()
			if err != nil {
				err = msgp.WrapError(err, "VersionID")
				return
			}
		case "tier":
			z.TierName, err = dc.ReadString()
			if err != nil {
				err = msgp.WrapError(err, "TierName")
				return
			}
		default:
			err = dc.Skip()
			if err != nil {
				err = msgp.WrapError(err)
				return

		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 {

		}
	}
}

func (j *tierMemJournal) AddEntry(je jentry) error {
	select {
	case j.entries <- je:
	default:
		return fmt.Errorf("failed to remove tiered content at %s with version %s from tier %s, will be retried later.",
			je.ObjName, je.VersionID, je.TierName)
	}
	return nil

Aditya Manthramurthy <******@****.***> 1687222388 -0700

Transition tiers can be added to MinIO using `mc admin tier add` command to associate a `gcs`, `s3` or `azure` bucket or prefix path on a bucket to the tier name.
Lifecycle transition rules can be applied to buckets (both versioned and un-versioned) by specifying the tier name defined above as the transition storage class for the lifecycle rule.

## Implementation