Index: modeshape-repository/src/main/java/org/modeshape/repository/ModeShapeEngine.java
===================================================================
--- modeshape-repository/src/main/java/org/modeshape/repository/ModeShapeEngine.java	(revision 1998)
+++ modeshape-repository/src/main/java/org/modeshape/repository/ModeShapeEngine.java	(working copy)
@@ -76,6 +76,7 @@ import org.modeshape.repository.sequencer.SequencingService;
 public class ModeShapeEngine {
 
     public static final String CONFIGURATION_REPOSITORY_NAME = "dna:configuration";
+    protected static final Logger LOGGER = Logger.getLogger(ModeShapeEngine.class);
 
     protected final ModeShapeConfiguration.ConfigurationDefinition configuration;
     private final ConfigurationScanner scanner;
@@ -88,7 +89,6 @@ public class ModeShapeEngine {
     private final ClusteringService clusteringService;
     private final MimeTypeDetectors detectors;
     private final String engineId = UUID.randomUUID().toString();
-    private static final Logger LOGGER = Logger.getLogger(ModeShapeEngine.class);
 
     protected ModeShapeEngine( ExecutionContext context,
                                ModeShapeConfiguration.ConfigurationDefinition configuration ) {
@@ -446,8 +446,9 @@ public class ModeShapeEngine {
                     classname = CLUSTERED_OBSERVATION_BUS_CLASSNAME;
                 }
                 if (clusterName == null || clusterName.trim().length() == 0) {
-                    problems.addError(RepositoryI18n.clusteringConfigurationRequiresClusterName);
-                    return null;
+                    LOGGER.warn(RepositoryI18n.clusteringConfigurationRequiresClusterName);
+                    problems.addWarning(RepositoryI18n.clusteringConfigurationRequiresClusterName);
+                    return null; // Signifies no clustering
                 }
 
                 Map<String, Object> properties = new HashMap<String, Object>();
Index: modeshape-repository/src/main/resources/org/modeshape/repository/RepositoryI18n.properties
===================================================================
--- modeshape-repository/src/main/resources/org/modeshape/repository/RepositoryI18n.properties	(revision 1998)
+++ modeshape-repository/src/main/resources/org/modeshape/repository/RepositoryI18n.properties	(working copy)
@@ -43,7 +43,7 @@ errorFindingPropertyNameInPropertyRemovedEvent = Error finding the name of the r
 repositoryServiceName = Repository Service
 
 clusteringServiceName = Clustering Service
-clusteringConfigurationRequiresClusterName = Clustering configuration requires a non-blank 'clusterName' attribute
+clusteringConfigurationRequiresClusterName = Clustering configuration requires a non-blank 'clusterName' attribute. ModeShape instance will run in a local (non-clustered) mode.
 unableToRegisterObserverOnUnstartedClusteringService = Unable to register an observer until the clustering service is started
 unableToUnregisterObserverOnUnstartedClusteringService = Unable to unregister an observer until the clustering service is started
 unableToNotifyObserversOnUnstartedClusteringService = Unable to notify observers until the clustering service is started
Index: pom.xml
===================================================================
--- pom.xml	(revision 1998)
+++ pom.xml	(working copy)
@@ -199,6 +199,11 @@
 	<profiles>
 		<profile>
 			<id>preferIpv4</id>
+      <activation>
+        <property>
+          <name>!preferIpv6</name>
+        </property>
+      </activation>
 			<properties>
 				<jgroups.preferIpv4>true</jgroups.preferIpv4>
 				<jgroups.preferIpv6>false</jgroups.preferIpv6>