Extra metadata maintained internally in `xl.meta` for a transitioned object

```
...
        "MetaSys": {
          "x-minio-internal-transition-status": "Y29tcGxldGU=",
          "x-minio-internal-transition-tier": "R0NTVElFUjE=",

	Disabled = "Disabled"
	// TransitionStatus status of transition
	TransitionStatus = "transition-status"
	// TransitionedObjectName name of transitioned object
	TransitionedObjectName = "transitioned-object"
	// TransitionedVersionID is version of remote object
	TransitionedVersionID = "transitioned-versionID"
	// TransitionTier name of transition storage class
	TransitionTier = "transition-tier"
)

}

func (dui DataUsageInfo) tierMetrics() (metrics []MetricV2) {
	if dui.TierStats == nil {
		return nil
	}
	// e.g minio_cluster_ilm_transitioned_bytes{tier="S3TIER-1"}=136314880
	//     minio_cluster_ilm_transitioned_objects{tier="S3TIER-1"}=1
	//     minio_cluster_ilm_transitioned_versions{tier="S3TIER-1"}=3
	for tier, st := range dui.TierStats.Tiers {
		metrics = append(metrics, MetricV2{

	}
	return opts
}

// SetTransitionState sets ILM transition related information from given info.
func (os *objSweeper) SetTransitionState(info TransitionedObject) {
	os.TransitionTier = info.Tier
	os.TransitionStatus = info.Status
	os.RemoteObject = info.Name
	os.TransitionVersionID = info.VersionID
}

// shouldRemoveRemoteObject determines if a transitioned object should be

--restore-request Days=3
```

### 4.1 Monitoring transition events

`s3:ObjectTransition:Complete` and `s3:ObjectTransition:Failed` events can be used to monitor transition events between the source cluster and transition tier. To watch lifecycle events, you can enable bucket notification on the source bucket with `mc event add`  and specify `--event ilm` flag.

Note that transition event notification is a MinIO extension.

## Explore Further

			break
		}
		err = fn(ctx, entry.ObjName, entry.VersionID, entry.TierName)
		if err != nil && !isErrObjectNotFound(err) {
			logger.LogIf(ctx, fmt.Errorf("tier-journal: failed to delete transitioned object %s from %s due to %s", entry.ObjName, entry.TierName, err))
			// We add the entry into the active journal to try again
			// later.
			jd.addEntry(entry)
		}
	}
	if done {

|:------------------------------------------|:-------------------------------------------------|
| `minio_cluster_ilm_transitioned_bytes`    | Total bytes transitioned to a tier.              |
| `minio_cluster_ilm_transitioned_objects`  | Total number of objects transitioned to a tier.  |
| `minio_cluster_ilm_transitioned_versions` | Total number of versions transitioned to a tier. |

## Cluster KMS Metrics

		return toObjectErr(errMethodNotAllowed, bucket, object)
	}
	// verify that the object queued for transition is identical to that on disk.
	if !opts.MTime.Equal(fi.ModTime) || !strings.EqualFold(opts.Transition.ETag, extractETag(fi.Metadata)) {
		return toObjectErr(errFileNotFound, bucket, object)
	}
	// if object already transitioned, return
	if fi.TransitionStatus == lifecycle.TransitionComplete {
		return nil
	}

	transitionPendingTasks       MetricName = "transition_pending_tasks"
	transitionActiveTasks        MetricName = "transition_active_tasks"
	transitionMissedTasks        MetricName = "transition_missed_immediate_tasks"

	transitionedBytes    MetricName = "transitioned_bytes"
	transitionedObjects  MetricName = "transitioned_objects"
	transitionedVersions MetricName = "transitioned_versions"

	})

	if !remoteCallRequired && !globalTierConfigMgr.Empty() {
		// Schedule object for immediate transition if eligible.
		objInfo.ETag = origETag
		enqueueTransitionImmediate(objInfo, lcEventSrc_s3CopyObject)
		// Remove the transitioned object whose object version is being overwritten.
		os.Sweep()
	}
}

// PutObjectHandler - PUT Object
// ----------