diff --git a/internal/distributed/datanode/service.go b/internal/distributed/datanode/service.go
index 97c08469cd..63c0c53a3f 100644
--- a/internal/distributed/datanode/service.go
+++ b/internal/distributed/datanode/service.go
@@ -269,6 +269,7 @@ func (s *Server) init() error {
 	return nil
 }
 
+// start starts datanode's grpc service.
 func (s *Server) start() error {
 	if err := s.datanode.Start(); err != nil {
 		return err