Index: oak-run/src/main/java/org/apache/jackrabbit/oak/run/Mode.java
===================================================================
--- oak-run/src/main/java/org/apache/jackrabbit/oak/run/Mode.java	(revision 1730474)
+++ oak-run/src/main/java/org/apache/jackrabbit/oak/run/Mode.java	(working copy)
@@ -42,6 +42,7 @@
     TARMKDIFF("tarmkdiff", new FileStoreDiffCommand()),
     TARMKRECOVERY("tarmkrecovery", new FileStoreRevisionRecoveryCommand()),
     DUMPDATASTOREREFS("dumpdatastorerefs", new DumpDataStoreReferencesCommand()),
+    RESETCLUSTERID("resetclusterid", new ResetClusterIdCommand()),
     HELP("help", new HelpCommand());
 
     private final String name;
Index: oak-run/src/main/java/org/apache/jackrabbit/oak/run/ResetClusterIdCommand.java
===================================================================
--- oak-run/src/main/java/org/apache/jackrabbit/oak/run/ResetClusterIdCommand.java	(revision 0)
+++ oak-run/src/main/java/org/apache/jackrabbit/oak/run/ResetClusterIdCommand.java	(working copy)
@@ -0,0 +1,116 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.jackrabbit.oak.run;
+
+import static org.apache.jackrabbit.oak.plugins.segment.FileStoreHelper.openFileStore;
+
+import org.apache.jackrabbit.oak.api.CommitFailedException;
+import org.apache.jackrabbit.oak.api.Type;
+import org.apache.jackrabbit.oak.plugins.document.DocumentMK;
+import org.apache.jackrabbit.oak.plugins.document.DocumentNodeStore;
+import org.apache.jackrabbit.oak.plugins.identifier.ClusterRepositoryInfo;
+import org.apache.jackrabbit.oak.plugins.segment.SegmentNodeStore;
+import org.apache.jackrabbit.oak.plugins.segment.file.FileStore;
+import org.apache.jackrabbit.oak.spi.commit.CommitInfo;
+import org.apache.jackrabbit.oak.spi.commit.EmptyHook;
+import org.apache.jackrabbit.oak.spi.state.NodeBuilder;
+import org.apache.jackrabbit.oak.spi.state.NodeStore;
+
+import com.google.common.io.Closer;
+import com.mongodb.MongoClient;
+import com.mongodb.MongoClientURI;
+import com.mongodb.MongoURI;
+
+/**
+ * OFFLINE utility to delete the clusterId stored as hidden
+ * property as defined by ClusterRepositoryInfo.
+ * <p>
+ * This utility is meant to be the only mechanism to delete
+ * this id and yes, it is meant to be used offline only
+ * (as otherwise this would correspond to breaking the
+ * requirement that the clusterId be stable and persistent).
+ * <p>
+ * Target use case for this tool is to avoid duplicate 
+ * clusterIds after a repository was cloned.
+ */
+public class ResetClusterIdCommand implements Command {
+
+    private static void deleteClusterId(NodeStore store) {
+        NodeBuilder builder = store.getRoot().builder();
+        NodeBuilder clusterConfigNode = builder.getChildNode(
+                ClusterRepositoryInfo.CLUSTER_CONFIG_NODE);
+        
+        if (!clusterConfigNode.exists()) {
+            // if it doesn't exist, then there is no way to delete
+            System.out.println("clusterId was never set or already deleted.");
+            return;
+        }
+        
+        if (!clusterConfigNode.hasProperty(ClusterRepositoryInfo.CLUSTER_ID_PROP)) {
+            // the config node exists, but the clusterId not 
+            // so again, no way to delete
+            System.out.println("clusterId was never set or already deleted.");
+            return;
+        }
+        String oldClusterId = clusterConfigNode.getProperty(ClusterRepositoryInfo.CLUSTER_ID_PROP)
+                .getValue(Type.STRING);
+        clusterConfigNode.removeProperty(ClusterRepositoryInfo.CLUSTER_ID_PROP);
+        try {
+            store.merge(builder, EmptyHook.INSTANCE, CommitInfo.EMPTY);
+
+            System.out.println("clusterId deleted successfully. (old id was " + oldClusterId + ")");
+        } catch (CommitFailedException e) {
+            System.err.println("Failed to delete clusterId due to exception: "+e.getMessage());
+            e.printStackTrace();
+        }
+    }
+
+    @Override
+    public void execute(String... args) throws Exception {
+        if (args.length != 1) {
+            System.out
+                    .println("usage: resetclusterid {<path>|<mongo-uri>}");
+            System.exit(1);
+        }
+
+        Closer closer = Closer.create();
+        try {
+            NodeStore store;
+            if (args[0].startsWith(MongoURI.MONGODB_PREFIX)) {
+                MongoClientURI uri = new MongoClientURI(args[0]);
+                MongoClient client = new MongoClient(uri);
+                final DocumentNodeStore dns = new DocumentMK.Builder()
+                        .setMongoDB(client.getDB(uri.getDatabase()))
+                        .getNodeStore();
+                closer.register(Utils.asCloseable(dns));
+                store = dns;
+            } else {
+                FileStore fs = openFileStore(args[0]);
+                closer.register(Utils.asCloseable(fs));
+                store = SegmentNodeStore.newSegmentNodeStore(fs).create();
+            }
+            
+            deleteClusterId(store);
+        } catch (Throwable e) {
+            throw closer.rethrow(e);
+        } finally {
+            closer.close();
+        }
+    
+    }
+    
+}

Property changes on: oak-run/src/main/java/org/apache/jackrabbit/oak/run/ResetClusterIdCommand.java
___________________________________________________________________
Added: svn:eol-style
## -0,0 +1 ##
+native
\ No newline at end of property