diff --git a/internal/admin/mrmanager/manager.go b/internal/admin/mrmanager/manager.go
index 899971816..c124327b2 100644
--- a/internal/admin/mrmanager/manager.go
+++ b/internal/admin/mrmanager/manager.go
@@ -85,14 +85,14 @@ var (
 
 type mrManager struct {
 	config
-
-	mu        sync.RWMutex
 	connector mrconnector.Connector
-
-	sfg     singleflight.Group
+	sfg       singleflight.Group
+	// mu guards two fields - dirty and updated.
+	mu      sync.RWMutex
 	dirty   bool
 	updated time.Time
-	meta    *varlogpb.MetadataDescriptor
+	// meta is a cached metadata descriptor.
+	meta *varlogpb.MetadataDescriptor
 }
 
 const (
@@ -145,9 +145,6 @@ func (mrm *mrManager) mc() (mrc.MetadataRepositoryManagementClient, error) {
 }
 
 func (mrm *mrManager) Close() error {
-	mrm.mu.Lock()
-	defer mrm.mu.Unlock()
-
 	return errors.Wrap(mrm.connector.Close(), "mrmanager")
 }
 
@@ -171,14 +168,6 @@ func (mrm *mrManager) clusterMetadata(ctx context.Context) (*varlogpb.MetadataDe
 }
 
 func (mrm *mrManager) RegisterStorageNode(ctx context.Context, storageNodeMeta *varlogpb.StorageNodeDescriptor) (err error) {
-	mrm.mu.Lock()
-	defer func() {
-		if err == nil {
-			mrm.dirty = true
-		}
-		mrm.mu.Unlock()
-	}()
-
 	cli, err := mrm.c()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -190,18 +179,11 @@ func (mrm *mrManager) RegisterStorageNode(ctx context.Context, storageNodeMeta *
 		return err
 	}
 
-	return err
+	mrm.setDirty()
+	return nil
 }
 
-func (mrm *mrManager) UnregisterStorageNode(ctx context.Context, storageNodeID types.StorageNodeID) (err error) {
-	mrm.mu.Lock()
-	defer func() {
-		if err == nil {
-			mrm.dirty = true
-		}
-		mrm.mu.Unlock()
-	}()
-
+func (mrm *mrManager) UnregisterStorageNode(ctx context.Context, storageNodeID types.StorageNodeID) error {
 	cli, err := mrm.c()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -213,18 +195,11 @@ func (mrm *mrManager) UnregisterStorageNode(ctx context.Context, storageNodeID t
 		return err
 	}
 
-	return err
+	mrm.setDirty()
+	return nil
 }
 
-func (mrm *mrManager) RegisterTopic(ctx context.Context, topicID types.TopicID) (err error) {
-	mrm.mu.Lock()
-	defer func() {
-		if err == nil {
-			mrm.dirty = true
-		}
-		mrm.mu.Unlock()
-	}()
-
+func (mrm *mrManager) RegisterTopic(ctx context.Context, topicID types.TopicID) error {
 	cli, err := mrm.c()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -236,18 +211,11 @@ func (mrm *mrManager) RegisterTopic(ctx context.Context, topicID types.TopicID)
 		return err
 	}
 
-	return err
+	mrm.setDirty()
+	return nil
 }
 
-func (mrm *mrManager) UnregisterTopic(ctx context.Context, topicID types.TopicID) (err error) {
-	mrm.mu.Lock()
-	defer func() {
-		if err == nil {
-			mrm.dirty = true
-		}
-		mrm.mu.Unlock()
-	}()
-
+func (mrm *mrManager) UnregisterTopic(ctx context.Context, topicID types.TopicID) error {
 	cli, err := mrm.c()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -259,18 +227,11 @@ func (mrm *mrManager) UnregisterTopic(ctx context.Context, topicID types.TopicID
 		return err
 	}
 
-	return err
+	mrm.setDirty()
+	return nil
 }
 
-func (mrm *mrManager) RegisterLogStream(ctx context.Context, logStreamDesc *varlogpb.LogStreamDescriptor) (err error) {
-	mrm.mu.Lock()
-	defer func() {
-		if err == nil {
-			mrm.dirty = true
-		}
-		mrm.mu.Unlock()
-	}()
-
+func (mrm *mrManager) RegisterLogStream(ctx context.Context, logStreamDesc *varlogpb.LogStreamDescriptor) error {
 	cli, err := mrm.c()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -281,18 +242,12 @@ func (mrm *mrManager) RegisterLogStream(ctx context.Context, logStreamDesc *varl
 		_ = cli.Close()
 		return err
 	}
+
+	mrm.setDirty()
 	return nil
 }
 
-func (mrm *mrManager) UnregisterLogStream(ctx context.Context, logStreamID types.LogStreamID) (err error) {
-	mrm.mu.Lock()
-	defer func() {
-		if err == nil {
-			mrm.dirty = true
-		}
-		mrm.mu.Unlock()
-	}()
-
+func (mrm *mrManager) UnregisterLogStream(ctx context.Context, logStreamID types.LogStreamID) error {
 	cli, err := mrm.c()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -303,18 +258,12 @@ func (mrm *mrManager) UnregisterLogStream(ctx context.Context, logStreamID types
 		_ = cli.Close()
 		return err
 	}
-	return err
-}
 
-func (mrm *mrManager) UpdateLogStream(ctx context.Context, logStreamDesc *varlogpb.LogStreamDescriptor) (err error) {
-	mrm.mu.Lock()
-	defer func() {
-		if err == nil {
-			mrm.dirty = true
-		}
-		mrm.mu.Unlock()
-	}()
+	mrm.setDirty()
+	return nil
+}
 
+func (mrm *mrManager) UpdateLogStream(ctx context.Context, logStreamDesc *varlogpb.LogStreamDescriptor) error {
 	cli, err := mrm.c()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -325,40 +274,29 @@ func (mrm *mrManager) UpdateLogStream(ctx context.Context, logStreamDesc *varlog
 		_ = cli.Close()
 		return err
 	}
-	return err
+
+	mrm.setDirty()
+	return nil
 }
 
 // It implements MetadataRepositoryManager.Seal method.
-func (mrm *mrManager) Seal(ctx context.Context, logStreamID types.LogStreamID) (lastCommittedGLSN types.GLSN, err error) {
-	mrm.mu.Lock()
-	defer func() {
-		if err == nil {
-			mrm.dirty = true
-		}
-		mrm.mu.Unlock()
-	}()
-
+func (mrm *mrManager) Seal(ctx context.Context, logStreamID types.LogStreamID) (types.GLSN, error) {
 	cli, err := mrm.c()
 	if err != nil {
 		return types.InvalidGLSN, errors.WithMessage(err, "mrmanager: not accessible")
 	}
 
-	if lastCommittedGLSN, err = cli.Seal(ctx, logStreamID); err != nil {
+	lastCommittedGLSN, err := cli.Seal(ctx, logStreamID)
+	if err != nil {
 		_ = cli.Close()
 		return types.InvalidGLSN, err
 	}
-	return lastCommittedGLSN, err
-}
 
-func (mrm *mrManager) Unseal(ctx context.Context, logStreamID types.LogStreamID) (err error) {
-	mrm.mu.Lock()
-	defer func() {
-		if err == nil {
-			mrm.dirty = true
-		}
-		mrm.mu.Unlock()
-	}()
+	mrm.setDirty()
+	return lastCommittedGLSN, nil
+}
 
+func (mrm *mrManager) Unseal(ctx context.Context, logStreamID types.LogStreamID) error {
 	cli, err := mrm.c()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -369,13 +307,12 @@ func (mrm *mrManager) Unseal(ctx context.Context, logStreamID types.LogStreamID)
 		_ = cli.Close()
 		return err
 	}
-	return err
+
+	mrm.setDirty()
+	return nil
 }
 
 func (mrm *mrManager) GetClusterInfo(ctx context.Context) (*mrpb.ClusterInfo, error) {
-	mrm.mu.RLock()
-	defer mrm.mu.RUnlock()
-
 	cli, err := mrm.mc()
 	if err != nil {
 		return nil, errors.WithMessage(err, "mrmanager: not accessible")
@@ -386,13 +323,10 @@ func (mrm *mrManager) GetClusterInfo(ctx context.Context) (*mrpb.ClusterInfo, er
 		_ = cli.Close()
 		return nil, err
 	}
-	return rsp.GetClusterInfo(), err
+	return rsp.GetClusterInfo(), nil
 }
 
 func (mrm *mrManager) AddPeer(ctx context.Context, nodeID types.NodeID, peerURL, rpcURL string) error {
-	mrm.mu.Lock()
-	defer mrm.mu.Unlock()
-
 	cli, err := mrm.mc()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -411,9 +345,6 @@ func (mrm *mrManager) AddPeer(ctx context.Context, nodeID types.NodeID, peerURL,
 }
 
 func (mrm *mrManager) RemovePeer(ctx context.Context, nodeID types.NodeID) error {
-	mrm.mu.Lock()
-	defer mrm.mu.Unlock()
-
 	cli, err := mrm.mc()
 	if err != nil {
 		return errors.WithMessage(err, "mrmanager: not accessible")
@@ -473,3 +404,9 @@ func (mrm *mrManager) StorageNode(ctx context.Context, storageNodeID types.Stora
 func (mrm *mrManager) NumberOfMR() int {
 	return mrm.connector.NumberOfMR()
 }
+
+func (mrm *mrManager) setDirty() {
+	mrm.mu.Lock()
+	mrm.dirty = true
+	mrm.mu.Unlock()
+}