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"
)

	}
	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

     * Called when the service transitions to the {@linkplain State#TERMINATED TERMINATED} state.
     * The {@linkplain State#TERMINATED TERMINATED} state is a terminal state in the transition
     * diagram. Therefore, if this method is called, no other methods will be called on the {@link
     * Listener}.
     *
     * @param from The previous state that is being transitioned from. Failure can occur in any

        monitor.leave();
      }
    }

    /**
     * Marks the {@link State} as ready to receive transitions. Returns true if no transitions have
     * been observed yet.
     */
    void markReady() {
      monitor.enter();
      try {
        if (!transitioned) {
          // nothing has transitioned since construction, good.
          ready = true;
        } else {

        monitor.leave();
      }
    }

    /**
     * Marks the {@link State} as ready to receive transitions. Returns true if no transitions have
     * been observed yet.
     */
    void markReady() {
      monitor.enter();
      try {
        if (!transitioned) {
          // nothing has transitioned since construction, good.
          ready = true;
        } else {

     * Called when the service transitions to the {@linkplain State#TERMINATED TERMINATED} state.
     * The {@linkplain State#TERMINATED TERMINATED} state is a terminal state in the transition
     * diagram. Therefore, if this method is called, no other methods will be called on the {@link
     * Listener}.
     *
     * @param from The previous state that is being transitioned from. Failure can occur in any

		uses   bool
	}{
		{ // transitioned object version
			xlmeta: xlMetaV2Object{
				VersionID: vID,
				DataDir:   dataDir,
				MetaSys:   transitioned,
			},
			uses: false,
		},
		{ // to be restored (requires object version to be transitioned)
			xlmeta: xlMetaV2Object{
				VersionID: vID,
				DataDir:   dataDir,
				MetaSys:   transitioned,
				MetaUser:  toBeRestored,
			},

--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

sleep 10s

## Add warm tier
./mc ilm tier add minio sitea WARM-TIER --endpoint http://localhost:9004 --access-key minioadmin --secret-key minioadmin --bucket bucket

## Add ILM rules
./mc ilm add sitea/bucket --transition-days 0 --transition-tier WARM-TIER
./mc ilm rule list sitea/bucket

./mc cp README.md sitea/bucket/README.md

until $(./mc stat sitea/bucket/README.md --json | jq -r '.metadata."X-Amz-Storage-Class"' | grep -q WARM-TIER); do