diff --git a/src/replica/replica.h b/src/replica/replica.h
index 9145362a44..f5baf0a92e 100644
--- a/src/replica/replica.h
+++ b/src/replica/replica.h
@@ -638,7 +638,9 @@ class replica : public serverlet<replica>, public ref_counter, public replica_ba
     bool _is_manual_emergency_checkpointing{false};
     bool _is_duplication_master{false};
     bool _is_duplication_follower{false};
-    std::atomic<bool> _is_duplication_plog_checking{false};
+    std::atomic<bool> _is_duplication_plog_checking{false}; // replica is finding some private logs
+                                                            // to load for duplication,avoid
+                                                            // unexpected plog gc
 
     // backup
     std::unique_ptr<replica_backup_manager> _backup_mgr;