diff --git a/apps/emqx/src/emqx_persistent_message.erl b/apps/emqx/src/emqx_persistent_message.erl
index 50e25e0be..30ebe7417 100644
--- a/apps/emqx/src/emqx_persistent_message.erl
+++ b/apps/emqx/src/emqx_persistent_message.erl
@@ -54,12 +54,14 @@ is_persistence_enabled() ->
 storage_backend() ->
     storage_backend(emqx_config:get([session_persistence, storage])).
 
-storage_backend(#{builtin := #{enable := true}}) ->
+storage_backend(#{
+    builtin := #{enable := true, n_shards := NShards, replication_factor := ReplicationFactor}
+}) ->
     #{
         backend => builtin,
         storage => {emqx_ds_storage_bitfield_lts, #{}},
-        n_shards => 16,
-        replication_factor => 3
+        n_shards => NShards,
+        replication_factor => ReplicationFactor
     }.
 
 %%--------------------------------------------------------------------
diff --git a/apps/emqx/src/emqx_schema.erl b/apps/emqx/src/emqx_schema.erl
index 1e6db805b..8e401a442 100644
--- a/apps/emqx/src/emqx_schema.erl
+++ b/apps/emqx/src/emqx_schema.erl
@@ -341,22 +341,6 @@ fields("persistent_session_store") ->
                     importance => ?IMPORTANCE_HIDDEN
                 }
             )},
-        {"n_shards",
-            sc(
-                pos_integer(),
-                #{
-                    default => 16,
-                    importance => ?IMPORTANCE_HIDDEN
-                }
-            )},
-        {"replication_factor",
-            sc(
-                pos_integer(),
-                #{
-                    default => 3,
-                    importance => ?IMPORTANCE_HIDDEN
-                }
-            )},
         {"on_disc",
             sc(
                 boolean(),
@@ -1807,6 +1791,22 @@ fields("session_storage_backend_builtin") ->
                     desc => ?DESC(session_storage_backend_enable),
                     default => true
                 }
+            )},
+        {"n_shards",
+            sc(
+                pos_integer(),
+                #{
+                    desc => ?DESC(session_builtin_n_shards),
+                    default => 16
+                }
+            )},
+        {"replication_factor",
+            sc(
+                pos_integer(),
+                #{
+                    default => 3,
+                    importance => ?IMPORTANCE_HIDDEN
+                }
             )}
     ].
 
diff --git a/rel/i18n/emqx_schema.hocon b/rel/i18n/emqx_schema.hocon
index d12f6a2d1..389a1f91b 100644
--- a/rel/i18n/emqx_schema.hocon
+++ b/rel/i18n/emqx_schema.hocon
@@ -1565,6 +1565,9 @@ session_persistence_storage.desc:
 session_storage_backend_enable.desc:
 """Enable this backend."""
 
+session_builtin_n_shards.desc:
+"""Number of shards used for storing the messages."""
+
 session_storage_backend_builtin.desc:
 """Builtin session storage backend utilizing embedded RocksDB key-value store."""