This closes #126
diff --git a/qa/src/main/java/org/apache/brooklyn/qa/load/SimulatedVanillaSoftwareProcessImpl.java b/qa/src/main/java/org/apache/brooklyn/qa/load/SimulatedVanillaSoftwareProcessImpl.java
index e5aea80..6b1d096 100644
--- a/qa/src/main/java/org/apache/brooklyn/qa/load/SimulatedVanillaSoftwareProcessImpl.java
+++ b/qa/src/main/java/org/apache/brooklyn/qa/load/SimulatedVanillaSoftwareProcessImpl.java
@@ -216,5 +216,14 @@
                 // no-op
             }
         }
+        
+        @Override
+        public boolean isRunning() {
+            if (Boolean.TRUE.equals(entity.getConfig(USE_SSH_MONITORING))) {
+                return super.isRunning();
+            } else {
+                return true;
+            }
+        }
     }
 }
diff --git a/qa/src/test/java/org/apache/brooklyn/qa/load/AbstractLoadTest.java b/qa/src/test/java/org/apache/brooklyn/qa/load/AbstractLoadTest.java
index c07f329..56cd756 100644
--- a/qa/src/test/java/org/apache/brooklyn/qa/load/AbstractLoadTest.java
+++ b/qa/src/test/java/org/apache/brooklyn/qa/load/AbstractLoadTest.java
@@ -161,8 +161,8 @@
         // Create management node
         persistenceDir = Files.createTempDir();
         launcher = BrooklynLauncher.newInstance()
-                .persistMode(PersistMode.CLEAN)
-                .highAvailabilityMode(HighAvailabilityMode.MASTER)
+                .persistMode(doPersistence() ? PersistMode.CLEAN : PersistMode.DISABLED)
+                .highAvailabilityMode(doPersistence() ? HighAvailabilityMode.MASTER : HighAvailabilityMode.DISABLED)
                 .persistenceDir(persistenceDir)
                 .start();
         
@@ -171,6 +171,10 @@
         
         return launcher.getServerDetails().getManagementContext();
     }
+
+    protected boolean doPersistence() {
+        return true;
+    }
     
     @Override
     protected void tearDownPlatform() {
diff --git a/qa/src/test/java/org/apache/brooklyn/qa/load/LoadWithoutPersistenceTest.java b/qa/src/test/java/org/apache/brooklyn/qa/load/LoadWithoutPersistenceTest.java
new file mode 100644
index 0000000..c69fc4f
--- /dev/null
+++ b/qa/src/test/java/org/apache/brooklyn/qa/load/LoadWithoutPersistenceTest.java
@@ -0,0 +1,65 @@
+/*
+ * 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.brooklyn.qa.load;
+
+import org.apache.brooklyn.entity.software.base.VanillaSoftwareProcess;
+import org.apache.brooklyn.util.time.Duration;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.testng.annotations.Test;
+
+import com.google.common.base.Predicates;
+import com.google.common.base.Stopwatch;
+
+public class LoadWithoutPersistenceTest extends AbstractLoadTest {
+
+    private static final Logger log = LoggerFactory.getLogger(LoadWithoutPersistenceTest.class);
+    
+    @Override
+    protected boolean doPersistence() {
+        return false;
+    }
+
+    /**
+     * Creates many SSH simulated external monitor apps, to ensure resource usage not extreme.
+     * 
+     * Long-term target is 2500 VMs under management.
+     * Until we reach that point, we can partition the load across multiple (separate) brooklyn management nodes.
+     */
+    @Test(groups="Acceptance")
+    public void testManyAppsExternallyMonitored() throws Exception {
+        // TODO Getting ssh error ("Server closed connection during identification exchange") 
+        // with only two cycles (i.e. 20 entities).
+        //
+        // The ssh activity is from `SoftwareProcessImpl.waitForEntityStart`, which calls
+        // `VanillaSoftwareProcessSshDriver.isRunning`.
+        final int TOTAL_APPS = 500; // target is 2500 VMs; each blueprint has 2 VanillaSoftwareProcess
+        final int NUM_APPS_PER_BATCH = 10;
+        Stopwatch startTime = Stopwatch.createStarted();
+        super.runLocalhostManyApps(new TestConfig(this)
+                .execSshOnStart(false) // getting ssh errors otherwise!
+                .useSshMonitoring(false) // getting ssh errors otherwise!
+                .simulateExternalMonitor(Predicates.instanceOf(VanillaSoftwareProcess.class), 5, Duration.ONE_SECOND)
+                .clusterSize(5)
+                .totalApps(TOTAL_APPS, NUM_APPS_PER_BATCH)
+                .sleepBetweenBatch(Duration.seconds(0)));
+        log.info("Created "+TOTAL_APPS+" apps in "+Duration.of(startTime));
+    }
+    
+}
diff --git a/software/network/src/test/java/org/apache/brooklyn/entity/network/bind/PrefixAndIdEnricher.java b/software/network/src/test/java/org/apache/brooklyn/entity/network/bind/PrefixAndIdEnricher.java
index cf03530..87a72e8 100644
--- a/software/network/src/test/java/org/apache/brooklyn/entity/network/bind/PrefixAndIdEnricher.java
+++ b/software/network/src/test/java/org/apache/brooklyn/entity/network/bind/PrefixAndIdEnricher.java
@@ -37,6 +37,7 @@
     public static final ConfigKey<String> PREFIX = ConfigKeys.newStringConfigKey(
             "prefixandid.prefix", "Sets SENSOR to prefix+entity id");
 
+    @SuppressWarnings("serial")
     public static final ConfigKey<AttributeSensor<?>> MONITOR = ConfigKeys.newConfigKey(new TypeToken<AttributeSensor<?>>() {},
             "prefixandid.attributetomonitor", "Changes on this sensor are monitored and the prefix/id republished");
 
@@ -52,6 +53,7 @@
                 entity.sensors().set(SENSOR, getConfig(PREFIX) + entity.getId());
             }
         });
+        highlightTriggers(getConfig(MONITOR), null);
     }
 
 }
diff --git a/software/nosql/src/main/java/org/apache/brooklyn/entity/nosql/mongodb/sharding/MongoDBRouterClusterImpl.java b/software/nosql/src/main/java/org/apache/brooklyn/entity/nosql/mongodb/sharding/MongoDBRouterClusterImpl.java
index 48b501c..ccff4e2 100644
--- a/software/nosql/src/main/java/org/apache/brooklyn/entity/nosql/mongodb/sharding/MongoDBRouterClusterImpl.java
+++ b/software/nosql/src/main/java/org/apache/brooklyn/entity/nosql/mongodb/sharding/MongoDBRouterClusterImpl.java
@@ -30,12 +30,16 @@
 import org.apache.brooklyn.core.entity.trait.Startable;
 import org.apache.brooklyn.entity.group.AbstractMembershipTrackingPolicy;
 import org.apache.brooklyn.entity.group.DynamicClusterImpl;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 
 public class MongoDBRouterClusterImpl extends DynamicClusterImpl implements MongoDBRouterCluster {
 
+    private static final Logger log = LoggerFactory.getLogger(MongoDBRouterClusterImpl.class);
+    
     @Override
     public void init() {
         super.init();
@@ -56,12 +60,17 @@
     
     public static class MemberTrackingPolicy extends AbstractMembershipTrackingPolicy {
         @Override protected void onEntityEvent(EventType type, Entity member) {
+            defaultHighlightAction(type, entity);
             ((MongoDBRouterClusterImpl)super.entity).setAnyRouter();
         }
         @Override protected void onEntityRemoved(Entity member) {
+            // TODO shouldn't be invoked - remove
+            log.warn("Removal handler should be hidden by event handler", new Throwable("Trace for unexpected mongo node handler"));
             ((MongoDBRouterClusterImpl)super.entity).setAnyRouter();
         }
         @Override protected void onEntityChange(Entity member) {
+            // TODO shouldn't be invoked - remove
+            log.warn("Change handler should be hidden by event handler", new Throwable("Trace for unexpected mongo node handler"));
             ((MongoDBRouterClusterImpl)super.entity).setAnyRouter();
         }
     }
diff --git a/software/webapp/src/main/java/org/apache/brooklyn/entity/dns/AbstractGeoDnsServiceImpl.java b/software/webapp/src/main/java/org/apache/brooklyn/entity/dns/AbstractGeoDnsServiceImpl.java
index 0f96c87..d94d551 100644
--- a/software/webapp/src/main/java/org/apache/brooklyn/entity/dns/AbstractGeoDnsServiceImpl.java
+++ b/software/webapp/src/main/java/org/apache/brooklyn/entity/dns/AbstractGeoDnsServiceImpl.java
@@ -180,6 +180,7 @@
     public static class MemberTrackingPolicy extends AbstractMembershipTrackingPolicy {
         @Override
         protected void onEntityEvent(EventType type, Entity entity) {
+            defaultHighlightAction(type, entity);
             ((AbstractGeoDnsServiceImpl)super.entity).refreshGroupMembership();
         }
     }
diff --git a/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/AbstractControllerImpl.java b/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/AbstractControllerImpl.java
index c24b2bc..34c324e 100644
--- a/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/AbstractControllerImpl.java
+++ b/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/AbstractControllerImpl.java
@@ -154,6 +154,7 @@
     public static class ServerPoolMemberTrackerPolicy extends AbstractMembershipTrackingPolicy {
         @Override
         protected void onEntityEvent(EventType type, Entity entity) {
+            defaultHighlightAction(type, entity);
             // relies on policy-rebind injecting the implementation rather than the dynamic-proxy
             ((AbstractControllerImpl)super.entity).onServerPoolMemberChanged(entity);
         }
diff --git a/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/AbstractNonProvisionedControllerImpl.java b/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/AbstractNonProvisionedControllerImpl.java
index c26235a..7ad7224 100644
--- a/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/AbstractNonProvisionedControllerImpl.java
+++ b/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/AbstractNonProvisionedControllerImpl.java
@@ -51,6 +51,7 @@
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Maps;
 
+/** For use by downstream load-balancers. */
 public abstract class AbstractNonProvisionedControllerImpl extends AbstractEntity implements AbstractNonProvisionedController {
     
     private static final Logger LOG = LoggerFactory.getLogger(AbstractNonProvisionedControllerImpl.class);
@@ -66,6 +67,7 @@
 
     public static class MemberTrackingPolicy extends AbstractMembershipTrackingPolicy {
         @Override protected void onEntityEvent(EventType type, Entity member) {
+            defaultHighlightAction(type, entity);
             ((AbstractNonProvisionedControllerImpl)super.entity).onServerPoolMemberChanged(member);
         }
     }
@@ -216,6 +218,7 @@
     public static class ServerPoolMemberTrackerPolicy extends AbstractMembershipTrackingPolicy {
         @Override
         protected void onEntityEvent(EventType type, Entity entity) {
+            defaultHighlightAction(type, entity);
             // relies on policy-rebind injecting the implementation rather than the dynamic-proxy
             ((AbstractNonProvisionedControllerImpl)super.entity).onServerPoolMemberChanged(entity);
         }
diff --git a/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/nginx/NginxControllerImpl.java b/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/nginx/NginxControllerImpl.java
index 7756909..979f915 100644
--- a/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/nginx/NginxControllerImpl.java
+++ b/software/webapp/src/main/java/org/apache/brooklyn/entity/proxy/nginx/NginxControllerImpl.java
@@ -178,6 +178,7 @@
     public static class UrlMappingsMemberTrackerPolicy extends AbstractMembershipTrackingPolicy {
         @Override
         protected void onEntityEvent(EventType type, Entity entity) {
+            defaultHighlightAction(type, entity);
             // relies on policy-rebind injecting the implementation rather than the dynamic-proxy
             ((NginxControllerImpl)super.entity).updateNeeded();
         }