diff --git a/internal/datanode/collection.go b/internal/datanode/collection.go
index d489eef705..5932123352 100644
--- a/internal/datanode/collection.go
+++ b/internal/datanode/collection.go
@@ -1,6 +1,7 @@
 package datanode
 
 import (
+	"github.com/zilliztech/milvus-distributed/internal/errors"
 	"github.com/zilliztech/milvus-distributed/internal/proto/schemapb"
 )
 
@@ -9,22 +10,29 @@ type Collection struct {
 	id     UniqueID
 }
 
-func (c *Collection) Name() string {
+func (c *Collection) GetName() string {
+	if c.schema == nil {
+		return ""
+	}
 	return c.schema.Name
 }
 
-func (c *Collection) ID() UniqueID {
+func (c *Collection) GetID() UniqueID {
 	return c.id
 }
 
-func (c *Collection) Schema() *schemapb.CollectionSchema {
+func (c *Collection) GetSchema() *schemapb.CollectionSchema {
 	return c.schema
 }
 
-func newCollection(collectionID UniqueID, schema *schemapb.CollectionSchema) *Collection {
+func newCollection(collectionID UniqueID, schema *schemapb.CollectionSchema) (*Collection, error) {
+	if schema == nil {
+		return nil, errors.Errorf("Invalid schema")
+	}
+
 	var newCollection = &Collection{
 		schema: schema,
 		id:     collectionID,
 	}
-	return newCollection
+	return newCollection, nil
 }
diff --git a/internal/datanode/collection_replica.go b/internal/datanode/collection_replica.go
index 05869ecbaa..568295a09c 100644
--- a/internal/datanode/collection_replica.go
+++ b/internal/datanode/collection_replica.go
@@ -9,15 +9,13 @@ import (
 	"github.com/zilliztech/milvus-distributed/internal/proto/schemapb"
 )
 
-type collectionReplica interface {
+type Replica interface {
 
 	// collection
 	getCollectionNum() int
 	addCollection(collectionID UniqueID, schema *schemapb.CollectionSchema) error
 	removeCollection(collectionID UniqueID) error
 	getCollectionByID(collectionID UniqueID) (*Collection, error)
-	getCollectionByName(collectionName string) (*Collection, error)
-	getCollectionIDByName(collectionName string) (UniqueID, error)
 	hasCollection(collectionID UniqueID) bool
 
 	// segment
@@ -43,29 +41,30 @@ type (
 		endPosition   *internalpb2.MsgPosition // not using
 	}
 
-	collectionReplicaImpl struct {
+	ReplicaImpl struct {
 		mu          sync.RWMutex
-		collections []*Collection
 		segments    []*Segment
+		collections map[UniqueID]*Collection
 	}
 )
 
-func newReplica() collectionReplica {
-	collections := make([]*Collection, 0)
+func newReplica() Replica {
 	segments := make([]*Segment, 0)
+	collections := make(map[UniqueID]*Collection)
 
-	var replica collectionReplica = &collectionReplicaImpl{
-		collections: collections,
+	var replica Replica = &ReplicaImpl{
 		segments:    segments,
+		collections: collections,
 	}
 	return replica
 }
 
-func (colReplica *collectionReplicaImpl) getSegmentByID(segmentID UniqueID) (*Segment, error) {
-	colReplica.mu.RLock()
-	defer colReplica.mu.RUnlock()
+// --- segment ---
+func (replica *ReplicaImpl) getSegmentByID(segmentID UniqueID) (*Segment, error) {
+	replica.mu.RLock()
+	defer replica.mu.RUnlock()
 
-	for _, segment := range colReplica.segments {
+	for _, segment := range replica.segments {
 		if segment.segmentID == segmentID {
 			return segment, nil
 		}
@@ -73,14 +72,14 @@ func (colReplica *collectionReplicaImpl) getSegmentByID(segmentID UniqueID) (*Se
 	return nil, errors.Errorf("Cannot find segment, id = %v", segmentID)
 }
 
-func (colReplica *collectionReplicaImpl) addSegment(
+func (replica *ReplicaImpl) addSegment(
 	segmentID UniqueID,
 	collID UniqueID,
 	partitionID UniqueID,
 	channelName string) error {
 
-	colReplica.mu.Lock()
-	defer colReplica.mu.Unlock()
+	replica.mu.Lock()
+	defer replica.mu.Unlock()
 	log.Println("Add Segment", segmentID)
 
 	position := &internalpb2.MsgPosition{
@@ -96,31 +95,31 @@ func (colReplica *collectionReplicaImpl) addSegment(
 		startPosition: position,
 		endPosition:   new(internalpb2.MsgPosition),
 	}
-	colReplica.segments = append(colReplica.segments, seg)
+	replica.segments = append(replica.segments, seg)
 	return nil
 }
 
-func (colReplica *collectionReplicaImpl) removeSegment(segmentID UniqueID) error {
-	colReplica.mu.Lock()
-	defer colReplica.mu.Unlock()
+func (replica *ReplicaImpl) removeSegment(segmentID UniqueID) error {
+	replica.mu.Lock()
+	defer replica.mu.Unlock()
 
-	for index, ele := range colReplica.segments {
+	for index, ele := range replica.segments {
 		if ele.segmentID == segmentID {
 			log.Println("Removing segment:", segmentID)
-			numOfSegs := len(colReplica.segments)
-			colReplica.segments[index] = colReplica.segments[numOfSegs-1]
-			colReplica.segments = colReplica.segments[:numOfSegs-1]
+			numOfSegs := len(replica.segments)
+			replica.segments[index] = replica.segments[numOfSegs-1]
+			replica.segments = replica.segments[:numOfSegs-1]
 			return nil
 		}
 	}
 	return errors.Errorf("Error, there's no segment %v", segmentID)
 }
 
-func (colReplica *collectionReplicaImpl) hasSegment(segmentID UniqueID) bool {
-	colReplica.mu.RLock()
-	defer colReplica.mu.RUnlock()
+func (replica *ReplicaImpl) hasSegment(segmentID UniqueID) bool {
+	replica.mu.RLock()
+	defer replica.mu.RUnlock()
 
-	for _, ele := range colReplica.segments {
+	for _, ele := range replica.segments {
 		if ele.segmentID == segmentID {
 			return true
 		}
@@ -128,11 +127,11 @@ func (colReplica *collectionReplicaImpl) hasSegment(segmentID UniqueID) bool {
 	return false
 }
 
-func (colReplica *collectionReplicaImpl) updateStatistics(segmentID UniqueID, numRows int64) error {
-	colReplica.mu.Lock()
-	defer colReplica.mu.Unlock()
+func (replica *ReplicaImpl) updateStatistics(segmentID UniqueID, numRows int64) error {
+	replica.mu.Lock()
+	defer replica.mu.Unlock()
 
-	for _, ele := range colReplica.segments {
+	for _, ele := range replica.segments {
 		if ele.segmentID == segmentID {
 			log.Printf("updating segment(%v) row nums: (%v)", segmentID, numRows)
 			ele.memorySize = 0
@@ -143,11 +142,11 @@ func (colReplica *collectionReplicaImpl) updateStatistics(segmentID UniqueID, nu
 	return errors.Errorf("Error, there's no segment %v", segmentID)
 }
 
-func (colReplica *collectionReplicaImpl) getSegmentStatisticsUpdates(segmentID UniqueID) (*internalpb2.SegmentStatisticsUpdates, error) {
-	colReplica.mu.Lock()
-	defer colReplica.mu.Unlock()
+func (replica *ReplicaImpl) getSegmentStatisticsUpdates(segmentID UniqueID) (*internalpb2.SegmentStatisticsUpdates, error) {
+	replica.mu.Lock()
+	defer replica.mu.Unlock()
 
-	for _, ele := range colReplica.segments {
+	for _, ele := range replica.segments {
 		if ele.segmentID == segmentID {
 			updates := &internalpb2.SegmentStatisticsUpdates{
 				SegmentID:    segmentID,
@@ -166,87 +165,58 @@ func (colReplica *collectionReplicaImpl) getSegmentStatisticsUpdates(segmentID U
 	return nil, errors.Errorf("Error, there's no segment %v", segmentID)
 }
 
-func (colReplica *collectionReplicaImpl) getCollectionNum() int {
-	colReplica.mu.RLock()
-	defer colReplica.mu.RUnlock()
+// --- collection ---
+func (replica *ReplicaImpl) getCollectionNum() int {
+	replica.mu.RLock()
+	defer replica.mu.RUnlock()
 
-	return len(colReplica.collections)
+	return len(replica.collections)
 }
 
-func (colReplica *collectionReplicaImpl) addCollection(collectionID UniqueID, schema *schemapb.CollectionSchema) error {
-	colReplica.mu.Lock()
-	defer colReplica.mu.Unlock()
+func (replica *ReplicaImpl) addCollection(collectionID UniqueID, schema *schemapb.CollectionSchema) error {
+	replica.mu.Lock()
+	defer replica.mu.Unlock()
 
-	var newCollection = newCollection(collectionID, schema)
-	colReplica.collections = append(colReplica.collections, newCollection)
-	log.Println("Create collection:", newCollection.Name())
+	if _, ok := replica.collections[collectionID]; ok {
+		return errors.Errorf("Create an existing collection=%s", schema.GetName())
+	}
+
+	newCollection, err := newCollection(collectionID, schema)
+	if err != nil {
+		return err
+	}
+
+	replica.collections[collectionID] = newCollection
+	log.Println("Create collection:", newCollection.GetName())
 
 	return nil
 }
 
-func (colReplica *collectionReplicaImpl) getCollectionIDByName(collName string) (UniqueID, error) {
-	colReplica.mu.RLock()
-	defer colReplica.mu.RUnlock()
+func (replica *ReplicaImpl) removeCollection(collectionID UniqueID) error {
+	replica.mu.Lock()
+	defer replica.mu.Unlock()
 
-	for _, collection := range colReplica.collections {
-		if collection.Name() == collName {
-			return collection.ID(), nil
-		}
-	}
-	return 0, errors.Errorf("Cannot get collection ID by name %s: not exist", collName)
+	delete(replica.collections, collectionID)
 
+	return nil
 }
 
-func (colReplica *collectionReplicaImpl) removeCollection(collectionID UniqueID) error {
-	colReplica.mu.Lock()
-	defer colReplica.mu.Unlock()
+func (replica *ReplicaImpl) getCollectionByID(collectionID UniqueID) (*Collection, error) {
+	replica.mu.RLock()
+	defer replica.mu.RUnlock()
 
-	length := len(colReplica.collections)
-	for index, col := range colReplica.collections {
-		if col.ID() == collectionID {
-			log.Println("Drop collection: ", col.Name())
-			colReplica.collections[index] = colReplica.collections[length-1]
-			colReplica.collections = colReplica.collections[:length-1]
-			return nil
-		}
+	coll, ok := replica.collections[collectionID]
+	if !ok {
+		return nil, errors.Errorf("Cannot get collection %d by ID: not exist", collectionID)
 	}
 
-	return errors.Errorf("Cannot remove collection %d: not exist", collectionID)
+	return coll, nil
 }
 
-func (colReplica *collectionReplicaImpl) getCollectionByID(collectionID UniqueID) (*Collection, error) {
-	colReplica.mu.RLock()
-	defer colReplica.mu.RUnlock()
+func (replica *ReplicaImpl) hasCollection(collectionID UniqueID) bool {
+	replica.mu.RLock()
+	defer replica.mu.RUnlock()
 
-	for _, collection := range colReplica.collections {
-		if collection.ID() == collectionID {
-			return collection, nil
-		}
-	}
-	return nil, errors.Errorf("Cannot get collection %d by ID: not exist", collectionID)
-}
-
-func (colReplica *collectionReplicaImpl) getCollectionByName(collectionName string) (*Collection, error) {
-	colReplica.mu.RLock()
-	defer colReplica.mu.RUnlock()
-
-	for _, collection := range colReplica.collections {
-		if collection.Name() == collectionName {
-			return collection, nil
-		}
-	}
-
-	return nil, errors.Errorf("Cannot found collection: %v", collectionName)
-}
-
-func (colReplica *collectionReplicaImpl) hasCollection(collectionID UniqueID) bool {
-	colReplica.mu.RLock()
-	defer colReplica.mu.RUnlock()
-
-	for _, col := range colReplica.collections {
-		if col.ID() == collectionID {
-			return true
-		}
-	}
-	return false
+	_, ok := replica.collections[collectionID]
+	return ok
 }
diff --git a/internal/datanode/collection_replica_test.go b/internal/datanode/collection_replica_test.go
index 8686e30520..2cb20b96c9 100644
--- a/internal/datanode/collection_replica_test.go
+++ b/internal/datanode/collection_replica_test.go
@@ -7,103 +7,95 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
-func initTestReplicaMeta(t *testing.T, replica collectionReplica, collectionName string, collectionID UniqueID, segmentID UniqueID) {
-	// GOOSE TODO remove
-	Factory := &MetaFactory{}
-	collectionMeta := Factory.CollectionMetaFactory(collectionID, collectionName)
-
-	var err = replica.addCollection(collectionMeta.ID, collectionMeta.Schema)
-	require.NoError(t, err)
-
-	collection, err := replica.getCollectionByName(collectionName)
-	require.NoError(t, err)
-	assert.Equal(t, collection.Name(), collectionName)
-	assert.Equal(t, collection.ID(), collectionID)
-	assert.Equal(t, replica.getCollectionNum(), 1)
-
-}
-
 func TestReplica_Collection(t *testing.T) {
 	Factory := &MetaFactory{}
-	collMetaMock := Factory.CollectionMetaFactory(0, "collection0")
-
-	t.Run("Test add collection", func(t *testing.T) {
+	collID := UniqueID(100)
+	collMetaMock := Factory.CollectionMetaFactory(collID, "test-coll-name-0")
 
+	t.Run("get_collection_num", func(t *testing.T) {
 		replica := newReplica()
-		assert.False(t, replica.hasCollection(0))
-		num := replica.getCollectionNum()
-		assert.Equal(t, 0, num)
+		assert.Zero(t, replica.getCollectionNum())
 
-		err := replica.addCollection(0, collMetaMock.GetSchema())
+		replica = new(ReplicaImpl)
+		assert.Zero(t, replica.getCollectionNum())
+
+		replica = &ReplicaImpl{
+			collections: map[UniqueID]*Collection{
+				0: {id: 0},
+				1: {id: 1},
+				2: {id: 2},
+			},
+		}
+		assert.Equal(t, 3, replica.getCollectionNum())
+	})
+
+	t.Run("add_collection", func(t *testing.T) {
+		replica := newReplica()
+		require.Zero(t, replica.getCollectionNum())
+
+		err := replica.addCollection(collID, nil)
+		assert.Error(t, err)
+		assert.Zero(t, replica.getCollectionNum())
+
+		err = replica.addCollection(collID, collMetaMock.Schema)
 		assert.NoError(t, err)
-
-		assert.True(t, replica.hasCollection(0))
-		num = replica.getCollectionNum()
-		assert.Equal(t, 1, num)
-
-		coll, err := replica.getCollectionByID(0)
+		assert.Equal(t, 1, replica.getCollectionNum())
+		assert.True(t, replica.hasCollection(collID))
+		coll, err := replica.getCollectionByID(collID)
 		assert.NoError(t, err)
 		assert.NotNil(t, coll)
-		assert.Equal(t, UniqueID(0), coll.ID())
-		assert.Equal(t, "collection0", coll.Name())
-		assert.Equal(t, collMetaMock.GetSchema(), coll.Schema())
+		assert.Equal(t, collID, coll.GetID())
+		assert.Equal(t, collMetaMock.Schema.GetName(), coll.GetName())
+		assert.Equal(t, collMetaMock.Schema, coll.GetSchema())
 
-		coll, err = replica.getCollectionByName("collection0")
+		sameID := collID
+		otherSchema := Factory.CollectionMetaFactory(sameID, "test-coll-name-1").GetSchema()
+		err = replica.addCollection(sameID, otherSchema)
+		assert.Error(t, err)
+
+	})
+
+	t.Run("remove_collection", func(t *testing.T) {
+		replica := newReplica()
+		require.False(t, replica.hasCollection(collID))
+		require.Zero(t, replica.getCollectionNum())
+
+		err := replica.removeCollection(collID)
+		assert.NoError(t, err)
+
+		err = replica.addCollection(collID, collMetaMock.Schema)
+		require.NoError(t, err)
+		require.True(t, replica.hasCollection(collID))
+		require.Equal(t, 1, replica.getCollectionNum())
+
+		err = replica.removeCollection(collID)
+		assert.NoError(t, err)
+		assert.False(t, replica.hasCollection(collID))
+		assert.Zero(t, replica.getCollectionNum())
+		err = replica.removeCollection(collID)
+		assert.NoError(t, err)
+	})
+
+	t.Run("get_collection_by_id", func(t *testing.T) {
+		replica := newReplica()
+		require.False(t, replica.hasCollection(collID))
+
+		coll, err := replica.getCollectionByID(collID)
+		assert.Error(t, err)
+		assert.Nil(t, coll)
+
+		err = replica.addCollection(collID, collMetaMock.Schema)
+		require.NoError(t, err)
+		require.True(t, replica.hasCollection(collID))
+		require.Equal(t, 1, replica.getCollectionNum())
+
+		coll, err = replica.getCollectionByID(collID)
 		assert.NoError(t, err)
 		assert.NotNil(t, coll)
-		assert.Equal(t, UniqueID(0), coll.ID())
-		assert.Equal(t, "collection0", coll.Name())
-		assert.Equal(t, collMetaMock.GetSchema(), coll.Schema())
-
-		collID, err := replica.getCollectionIDByName("collection0")
-		assert.NoError(t, err)
-		assert.Equal(t, UniqueID(0), collID)
-
+		assert.Equal(t, collID, coll.GetID())
+		assert.Equal(t, collMetaMock.Schema.GetName(), coll.GetName())
+		assert.Equal(t, collMetaMock.Schema, coll.GetSchema())
 	})
-
-	t.Run("Test remove collection", func(t *testing.T) {
-		replica := newReplica()
-		err := replica.addCollection(0, collMetaMock.GetSchema())
-		require.NoError(t, err)
-
-		numsBefore := replica.getCollectionNum()
-		coll, err := replica.getCollectionByID(0)
-		require.NotNil(t, coll)
-		require.NoError(t, err)
-
-		err = replica.removeCollection(0)
-		assert.NoError(t, err)
-		numsAfter := replica.getCollectionNum()
-		assert.Equal(t, 1, numsBefore-numsAfter)
-
-		coll, err = replica.getCollectionByID(0)
-		assert.Nil(t, coll)
-		assert.Error(t, err)
-		err = replica.removeCollection(999999999)
-		assert.Error(t, err)
-	})
-
-	t.Run("Test errors", func(t *testing.T) {
-		replica := newReplica()
-		require.False(t, replica.hasCollection(0))
-		require.Equal(t, 0, replica.getCollectionNum())
-
-		coll, err := replica.getCollectionByName("Name-not-exist")
-		assert.Error(t, err)
-		assert.Nil(t, coll)
-
-		coll, err = replica.getCollectionByID(0)
-		assert.Error(t, err)
-		assert.Nil(t, coll)
-
-		collID, err := replica.getCollectionIDByName("Name-not-exist")
-		assert.Error(t, err)
-		assert.Zero(t, collID)
-
-		err = replica.removeCollection(0)
-		assert.Error(t, err)
-	})
-
 }
 
 func TestReplica_Segment(t *testing.T) {
diff --git a/internal/datanode/collection_test.go b/internal/datanode/collection_test.go
index 6f12bfd0bb..444ec65cd9 100644
--- a/internal/datanode/collection_test.go
+++ b/internal/datanode/collection_test.go
@@ -6,24 +6,41 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestCollection_newCollection(t *testing.T) {
-	collectionName := "collection0"
-	collectionID := UniqueID(1)
+func TestCollection_Group(t *testing.T) {
 	Factory := &MetaFactory{}
-	collectionMeta := Factory.CollectionMetaFactory(collectionID, collectionName)
 
-	collection := newCollection(collectionMeta.ID, collectionMeta.Schema)
-	assert.Equal(t, collection.Name(), collectionName)
-	assert.Equal(t, collection.ID(), collectionID)
-}
-
-func TestCollection_deleteCollection(t *testing.T) {
-	collectionName := "collection0"
-	collectionID := UniqueID(1)
-	Factory := &MetaFactory{}
-	collectionMeta := Factory.CollectionMetaFactory(collectionID, collectionName)
-
-	collection := newCollection(collectionMeta.ID, collectionMeta.Schema)
-	assert.Equal(t, collection.Name(), collectionName)
-	assert.Equal(t, collection.ID(), collectionID)
+	collName := "collection0"
+	collID := UniqueID(1)
+	collMeta := Factory.CollectionMetaFactory(collID, collName)
+
+	t.Run("new_collection_nil_schema", func(t *testing.T) {
+		coll, err := newCollection(collID, nil)
+		assert.Error(t, err)
+		assert.Nil(t, coll)
+	})
+
+	t.Run("new_collection_right_schema", func(t *testing.T) {
+		coll, err := newCollection(collID, collMeta.Schema)
+		assert.NoError(t, err)
+		assert.NotNil(t, coll)
+		assert.Equal(t, collName, coll.GetName())
+		assert.Equal(t, collID, coll.GetID())
+		assert.Equal(t, collMeta.Schema, coll.GetSchema())
+		assert.Equal(t, *collMeta.Schema, *coll.GetSchema())
+	})
+
+	t.Run("getters", func(t *testing.T) {
+		coll := new(Collection)
+		assert.Empty(t, coll.GetName())
+		assert.Empty(t, coll.GetID())
+		assert.Empty(t, coll.GetSchema())
+
+		coll, err := newCollection(collID, collMeta.Schema)
+		assert.NoError(t, err)
+		assert.Equal(t, collName, coll.GetName())
+		assert.Equal(t, collID, coll.GetID())
+		assert.Equal(t, collMeta.Schema, coll.GetSchema())
+		assert.Equal(t, *collMeta.Schema, *coll.GetSchema())
+	})
+
 }
diff --git a/internal/datanode/data_node.go b/internal/datanode/data_node.go
index b86f64e08a..b97e15db5d 100644
--- a/internal/datanode/data_node.go
+++ b/internal/datanode/data_node.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"sync/atomic"
 	"time"
 
 	"github.com/zilliztech/milvus-distributed/internal/errors"
@@ -56,7 +57,7 @@ type (
 		cancel  context.CancelFunc
 		NodeID  UniqueID
 		Role    string
-		State   internalpb2.StateCode
+		State   atomic.Value // internalpb2.StateCode_INITIALIZING
 		watchDm chan struct{}
 
 		dataSyncService *dataSyncService
@@ -66,7 +67,7 @@ type (
 		dataService   DataServiceInterface
 
 		flushChan chan *flushMsg
-		replica   collectionReplica
+		replica   Replica
 
 		closer io.Closer
 	}
@@ -81,7 +82,6 @@ func NewDataNode(ctx context.Context) *DataNode {
 		cancel:  cancel2,
 		NodeID:  Params.NodeID, // GOOSE TODO: How to init
 		Role:    typeutil.DataNodeRole,
-		State:   internalpb2.StateCode_INITIALIZING, // GOOSE TODO: atomic
 		watchDm: make(chan struct{}),
 
 		dataSyncService: nil,
@@ -91,6 +91,8 @@ func NewDataNode(ctx context.Context) *DataNode {
 		replica:         nil,
 	}
 
+	node.State.Store(internalpb2.StateCode_INITIALIZING)
+
 	return node
 }
 
@@ -156,10 +158,7 @@ func (node *DataNode) Init() error {
 
 	}
 
-	var replica collectionReplica = &collectionReplicaImpl{
-		collections: make([]*Collection, 0),
-		segments:    make([]*Segment, 0),
-	}
+	replica := newReplica()
 
 	var alloc allocator = newAllocatorImpl(node.masterService)
 
@@ -178,7 +177,7 @@ func (node *DataNode) Init() error {
 func (node *DataNode) Start() error {
 	node.metaService.init()
 	go node.dataSyncService.start()
-	node.State = internalpb2.StateCode_HEALTHY
+	node.State.Store(internalpb2.StateCode_HEALTHY)
 	return nil
 }
 
@@ -189,7 +188,7 @@ func (node *DataNode) WatchDmChannels(in *datapb.WatchDmChannelRequest) (*common
 
 	switch {
 
-	case node.State != internalpb2.StateCode_INITIALIZING:
+	case node.State.Load() != internalpb2.StateCode_INITIALIZING:
 		status.Reason = fmt.Sprintf("DataNode %d not initializing!", node.NodeID)
 		return status, errors.New(status.GetReason())
 
@@ -206,12 +205,12 @@ func (node *DataNode) WatchDmChannels(in *datapb.WatchDmChannelRequest) (*common
 }
 
 func (node *DataNode) GetComponentStates() (*internalpb2.ComponentStates, error) {
-	log.Println("DataNode current state:", node.State)
+	log.Println("DataNode current state:", node.State.Load())
 	states := &internalpb2.ComponentStates{
 		State: &internalpb2.ComponentInfo{
 			NodeID:    Params.NodeID,
 			Role:      node.Role,
-			StateCode: node.State,
+			StateCode: node.State.Load().(internalpb2.StateCode),
 		},
 		SubcomponentStates: make([]*internalpb2.ComponentInfo, 0),
 		Status:             &commonpb.Status{ErrorCode: commonpb.ErrorCode_SUCCESS},
diff --git a/internal/datanode/data_sync_service.go b/internal/datanode/data_sync_service.go
index 4a49b79af0..0e7146dfb6 100644
--- a/internal/datanode/data_sync_service.go
+++ b/internal/datanode/data_sync_service.go
@@ -13,12 +13,12 @@ type dataSyncService struct {
 	ctx         context.Context
 	fg          *flowgraph.TimeTickedFlowGraph
 	flushChan   chan *flushMsg
-	replica     collectionReplica
+	replica     Replica
 	idAllocator allocator
 }
 
 func newDataSyncService(ctx context.Context, flushChan chan *flushMsg,
-	replica collectionReplica, alloc allocator) *dataSyncService {
+	replica Replica, alloc allocator) *dataSyncService {
 	service := &dataSyncService{
 		ctx:         ctx,
 		fg:          nil,
diff --git a/internal/datanode/flow_graph_dd_node.go b/internal/datanode/flow_graph_dd_node.go
index 30b97ab138..00afd3df98 100644
--- a/internal/datanode/flow_graph_dd_node.go
+++ b/internal/datanode/flow_graph_dd_node.go
@@ -26,7 +26,7 @@ type ddNode struct {
 
 	idAllocator allocator
 	kv          kv.Base
-	replica     collectionReplica
+	replica     Replica
 	flushMeta   *metaTable
 }
 
@@ -367,7 +367,7 @@ func (ddNode *ddNode) dropPartition(msg *msgstream.DropPartitionMsg) {
 }
 
 func newDDNode(ctx context.Context, flushMeta *metaTable,
-	inFlushCh chan *flushMsg, replica collectionReplica, alloc allocator) *ddNode {
+	inFlushCh chan *flushMsg, replica Replica, alloc allocator) *ddNode {
 	maxQueueLength := Params.FlowGraphMaxQueueLength
 	maxParallelism := Params.FlowGraphMaxParallelism
 
diff --git a/internal/datanode/flow_graph_gc_node.go b/internal/datanode/flow_graph_gc_node.go
index 765481b6b3..b5b3277876 100644
--- a/internal/datanode/flow_graph_gc_node.go
+++ b/internal/datanode/flow_graph_gc_node.go
@@ -6,7 +6,7 @@ import (
 
 type gcNode struct {
 	BaseNode
-	replica collectionReplica
+	replica Replica
 }
 
 func (gcNode *gcNode) Name() string {
@@ -38,7 +38,7 @@ func (gcNode *gcNode) Operate(in []*Msg) []*Msg {
 	return nil
 }
 
-func newGCNode(replica collectionReplica) *gcNode {
+func newGCNode(replica Replica) *gcNode {
 	maxQueueLength := Params.FlowGraphMaxQueueLength
 	maxParallelism := Params.FlowGraphMaxParallelism
 
diff --git a/internal/datanode/flow_graph_insert_buffer_node.go b/internal/datanode/flow_graph_insert_buffer_node.go
index 59a292a913..9fb4f94587 100644
--- a/internal/datanode/flow_graph_insert_buffer_node.go
+++ b/internal/datanode/flow_graph_insert_buffer_node.go
@@ -34,7 +34,7 @@ type (
 	insertBufferNode struct {
 		BaseNode
 		insertBuffer *insertBuffer
-		replica      collectionReplica
+		replica      Replica
 		flushMeta    *metaTable
 
 		minIOKV     kv.Base
@@ -417,7 +417,7 @@ func (ibNode *insertBufferNode) Operate(in []*Msg) []*Msg {
 		if ibNode.insertBuffer.full(currentSegID) {
 			log.Printf(". Insert Buffer full, auto flushing (%v) rows of data...", ibNode.insertBuffer.size(currentSegID))
 
-			err = ibNode.flushSegment(currentSegID, msg.GetPartitionID(), collection.ID())
+			err = ibNode.flushSegment(currentSegID, msg.GetPartitionID(), collection.GetID())
 			if err != nil {
 				log.Printf("flush segment (%v) fail: %v", currentSegID, err)
 			}
@@ -617,7 +617,7 @@ func (ibNode *insertBufferNode) getCollectionSchemaByID(collectionID UniqueID) (
 }
 
 func newInsertBufferNode(ctx context.Context, flushMeta *metaTable,
-	replica collectionReplica, alloc allocator) *insertBufferNode {
+	replica Replica, alloc allocator) *insertBufferNode {
 	maxQueueLength := Params.FlowGraphMaxQueueLength
 	maxParallelism := Params.FlowGraphMaxParallelism
 
diff --git a/internal/datanode/meta_service.go b/internal/datanode/meta_service.go
index 8a9561fae1..a7dab0883a 100644
--- a/internal/datanode/meta_service.go
+++ b/internal/datanode/meta_service.go
@@ -14,11 +14,11 @@ import (
 
 type metaService struct {
 	ctx          context.Context
-	replica      collectionReplica
+	replica      Replica
 	masterClient MasterServiceInterface
 }
 
-func newMetaService(ctx context.Context, replica collectionReplica, m MasterServiceInterface) *metaService {
+func newMetaService(ctx context.Context, replica Replica, m MasterServiceInterface) *metaService {
 	return &metaService{
 		ctx:          ctx,
 		replica:      replica,
diff --git a/internal/dataservice/server.go b/internal/dataservice/server.go
index 12d9b8a06e..2116478e9a 100644
--- a/internal/dataservice/server.go
+++ b/internal/dataservice/server.go
@@ -141,9 +141,9 @@ func (s *Server) Start() error {
 	if err = s.loadMetaFromMaster(); err != nil {
 		return err
 	}
+	s.startServerLoop()
 	s.waitDataNodeRegister()
 	s.cluster.WatchInsertChannels(s.insertChannels)
-	s.startServerLoop()
 	if err = s.initMsgProducer(); err != nil {
 		return err
 	}
diff --git a/internal/distributed/datanode/service.go b/internal/distributed/datanode/service.go
index 9821405c9f..aa3a06717a 100644
--- a/internal/distributed/datanode/service.go
+++ b/internal/distributed/datanode/service.go
@@ -27,8 +27,10 @@ type Server struct {
 }
 
 func New(ctx context.Context) (*Server, error) {
+	ctx1, cancel := context.WithCancel(ctx)
 	var s = &Server{
-		ctx: ctx,
+		ctx:    ctx1,
+		cancel: cancel,
 	}
 
 	s.core = dn.NewDataNode(s.ctx)
@@ -76,6 +78,7 @@ func (s *Server) Start() error {
 
 func (s *Server) Stop() error {
 	err := s.core.Stop()
+	s.cancel()
 	s.grpcServer.GracefulStop()
 	return err
 }
@@ -89,7 +92,7 @@ func (s *Server) WatchDmChannels(ctx context.Context, in *datapb.WatchDmChannelR
 }
 
 func (s *Server) FlushSegments(ctx context.Context, in *datapb.FlushSegRequest) (*commonpb.Status, error) {
-	if s.core.State != internalpb2.StateCode_HEALTHY {
+	if s.core.State.Load().(internalpb2.StateCode) != internalpb2.StateCode_HEALTHY {
 		return &commonpb.Status{
 			ErrorCode: commonpb.ErrorCode_UNEXPECTED_ERROR,
 			Reason:    "DataNode isn't healthy.",