rememberingEntities with ddata mode, #22154

* one Replicator per configured role
* log LMDB directory at startup
* clarify the imporantce of the LMDB directory
* use more than one key to support many entities

akka-docs/rst/scala/distributed-data.rst

@@ -463,7 +463,9 @@ works with any type that has a registered Akka serializer. This is how such an s
 look like for the ``TwoPhaseSet``:
 
 .. includecode:: code/docs/ddata/protobuf/TwoPhaseSetSerializer2.scala#serializer
-  
+
+.. _ddata_durable_scala:
+
 Durable Storage
 ---------------
 
@@ -499,6 +501,12 @@ The location of the files for the data is configured with::
   #    a directory.
   akka.cluster.distributed-data.durable.lmdb.dir = "ddata"
 
+When running in production you may want to configure the directory to a specific
+path (alt 2), since the default directory contains the remote port of the
+actor system to make the name unique. If using a dynamically assigned 
+port (0) it will be different each time and the previously stored data 
+will not be loaded.
+
 Making the data durable has of course a performance cost. By default, each update is flushed
 to disk before the ``UpdateSuccess`` reply is sent. For better performance, but with the risk of losing 
 the last writes if the JVM crashes, you can enable write behind mode. Changes are then accumulated during