Merge pull request #4266 from vespa-engine/revert-4265-revert-4241-bratseth/select-1-host-by-index

Revert "Revert "Bratseth/select 1 host by index""

18 files changed, 212 insertions, 122 deletions

diff --git a/config-model/src/main/java/com/yahoo/config/model/ApplicationConfigProducerRoot.java b/config-model/src/main/java/com/yahoo/config/model/ApplicationConfigProducerRoot.java
index 30d83a32ff9..912968747df 100644
--- a/config-model/src/main/java/com/yahoo/config/model/ApplicationConfigProducerRoot.java
+++ b/config-model/src/main/java/com/yahoo/config/model/ApplicationConfigProducerRoot.java
@@ -29,7 +29,6 @@ import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.Set;
 
 
@@ -207,7 +206,7 @@ public class ApplicationConfigProducerRoot extends AbstractConfigProducer<Abstra
         builder.vespaVersion(vespaVersion.toSerializedForm());
         for (HostResource modelHost : getHostSystem().getHosts()) {
             builder.hosts(new Hosts.Builder()
-                    .name(modelHost.getHostName())
+                    .name(modelHost.getHostname())
                     .services(getServices(modelHost))
             );
         }
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/AbstractService.java b/config-model/src/main/java/com/yahoo/vespa/model/AbstractService.java
index 659d5b65a4c..3b75be5167d 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/AbstractService.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/AbstractService.java
@@ -315,7 +315,7 @@ public abstract class AbstractService extends AbstractConfigProducer<AbstractCon
      * @return The hostname on which this service runs.
      */
     public String getHostName() {
-        return hostResource.getHostName();
+        return hostResource.getHostname();
     }
 
     /**
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/Host.java b/config-model/src/main/java/com/yahoo/vespa/model/Host.java
index e4e1e029a1a..0adfe9e4bdb 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/Host.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/Host.java
@@ -67,7 +67,7 @@ public final class Host extends AbstractConfigProducer<AbstractConfigProducer<?>
         runsConfigServer = false;
     }
 
-    public String getHostName() {
+    public String getHostname() {
         return hostname;
     }
 
@@ -77,7 +77,7 @@ public final class Host extends AbstractConfigProducer<AbstractConfigProducer<?>
 
     /** Returns the string representation of this Host object. */
     public String toString() {
-        return "host '" + getHostName() + "'";
+        return "host '" + getHostname() + "'";
     }
 
     @Override
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/HostResource.java b/config-model/src/main/java/com/yahoo/vespa/model/HostResource.java
index 5e74a2ebc8a..72309d4c266 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/HostResource.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/HostResource.java
@@ -7,7 +7,9 @@ import com.yahoo.config.provision.Flavor;
 
 import javax.annotation.Nullable;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
@@ -205,7 +207,7 @@ public class HostResource implements Comparable<HostResource> {
     }
 
     public HostInfo getHostInfo() {
-        return new HostInfo(getHostName(), services.values().stream()
+        return new HostInfo(getHostname(), services.values().stream()
                 .map(Service::getServiceInfo)
                 .collect(Collectors.toSet()));
     }
@@ -242,11 +244,11 @@ public class HostResource implements Comparable<HostResource> {
 
     @Override
     public String toString() {
-        return "host '" + host.getHostName() + "'";
+        return "host '" + host.getHostname() + "'";
     }
 
-    public String getHostName() {
-        return host.getHostName();
+    public String getHostname() {
+        return host.getHostname();
     }
 
     @Override
@@ -264,4 +266,43 @@ public class HostResource implements Comparable<HostResource> {
         return this.host.compareTo(other.host);
     }
 
+    /**
+     * Compares by the index of the primary membership, if both hosts are members in at least one cluster at this time.
+     * Compare by hostname otherwise.
+     */
+    public int comparePrimarilyByIndexTo(HostResource other) {
+        Optional<ClusterMembership> thisMembership = this.primaryClusterMembership();
+        Optional<ClusterMembership> otherMembership = other.primaryClusterMembership();
+        if (thisMembership.isPresent() && otherMembership.isPresent())
+            return Integer.compare(thisMembership.get().index(), otherMembership.get().index());
+        else
+            return this.getHostname().compareTo(other.getHostname());
+    }
+
+    /**
+     * Picks hosts by some mixture of host name and index 
+     * (where the mix of one or the other is decided by the last parameter).
+     */
+    public static List<HostResource> pickHosts(Collection<HostResource> hosts, int count, int targetHostsSelectedByIndex) {
+        targetHostsSelectedByIndex = Math.min(Math.min(targetHostsSelectedByIndex, count), hosts.size());
+
+        List<HostResource> hostsSortedByName = new ArrayList<>(hosts);
+        Collections.sort(hostsSortedByName);
+
+        List<HostResource> hostsSortedByIndex = new ArrayList<>(hosts);
+        hostsSortedByIndex.sort((a, b) -> a.comparePrimarilyByIndexTo(b));
+        return pickHosts(hostsSortedByName, hostsSortedByIndex, count, targetHostsSelectedByIndex);
+    }
+    public static List<HostResource> pickHosts(List<HostResource> hostsSelectedByName, List<HostResource> hostsSelectedByIndex, 
+                                               int count, int targetHostsSelectedByIndex) {
+        hostsSelectedByName = hostsSelectedByName.subList(0, Math.min(count - targetHostsSelectedByIndex, hostsSelectedByName.size()));
+        hostsSelectedByIndex.removeAll(hostsSelectedByName);
+        hostsSelectedByIndex = hostsSelectedByIndex.subList(0, Math.min(targetHostsSelectedByIndex, hostsSelectedByIndex.size()));
+
+        List<HostResource> finalHosts = new ArrayList<>();
+        finalHosts.addAll(hostsSelectedByName);
+        finalHosts.addAll(hostsSelectedByIndex);
+        return finalHosts;
+    }
+
 }
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/HostSystem.java b/config-model/src/main/java/com/yahoo/vespa/model/HostSystem.java
index 2db9b6acece..6ef6c208c0a 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/HostSystem.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/HostSystem.java
@@ -101,7 +101,7 @@ public class HostSystem extends AbstractConfigProducer<Host> {
     public HostResource getHost(String hostAlias) {
         HostSpec hostSpec = provisioner.allocateHost(hostAlias);
         for (HostResource resource : hostname2host.values()) {
-            if (resource.getHostName().equals(hostSpec.hostname())) {
+            if (resource.getHostname().equals(hostSpec.hostname())) {
                 hostSpec.membership().ifPresent(resource::addClusterMembership);
                 return resource;
             }
@@ -114,8 +114,8 @@ public class HostSystem extends AbstractConfigProducer<Host> {
         HostResource hostResource = new HostResource(host);
         hostResource.setFlavor(hostSpec.flavor());
         hostSpec.membership().ifPresent(hostResource::addClusterMembership);
-        hostname2host.put(host.getHostName(), hostResource);
-        log.log(DEBUG, () -> "Added new host resource for " + host.getHostName() + " with flavor " + hostResource.getFlavor());
+        hostname2host.put(host.getHostname(), hostResource);
+        log.log(DEBUG, () -> "Added new host resource for " + host.getHostname() + " with flavor " + hostResource.getFlavor());
         return hostResource;
     }
 
@@ -136,16 +136,16 @@ public class HostSystem extends AbstractConfigProducer<Host> {
             retAllocatedHosts.put(host, spec.membership().orElse(null));
             if (! host.getFlavor().isPresent()) {
                 host.setFlavor(spec.flavor());
-                log.log(DEBUG, () -> "Host resource " + host.getHostName() + " had no flavor, setting to " + spec.flavor());
+                log.log(DEBUG, () -> "Host resource " + host.getHostname() + " had no flavor, setting to " + spec.flavor());
             }
         }
-        retAllocatedHosts.keySet().forEach(host -> log.log(DEBUG, () -> "Allocated host " + host.getHostName() + " with flavor " + host.getFlavor()));
+        retAllocatedHosts.keySet().forEach(host -> log.log(DEBUG, () -> "Allocated host " + host.getHostname() + " with flavor " + host.getFlavor()));
         return retAllocatedHosts;
     }
 
     private Optional<HostResource> getExistingHost(HostSpec key) {
         List<HostResource> hosts = hostname2host.values().stream()
-                .filter(resource -> resource.getHostName().equals(key.hostname()))
+                .filter(resource -> resource.getHostname().equals(key.hostname()))
                 .collect(Collectors.toList());
         if (hosts.isEmpty()) {
             return Optional.empty();
@@ -156,12 +156,12 @@ public class HostSystem extends AbstractConfigProducer<Host> {
     }
 
     public void addBoundHost(HostResource host) {
-        hostname2host.put(host.getHostName(), host);
+        hostname2host.put(host.getHostname(), host);
     }
 
     Set<HostSpec> getHostSpecs() {
         return getHosts().stream()
-                .map(host -> new HostSpec(host.getHostName(), Collections.emptyList(),
+                .map(host -> new HostSpec(host.getHostname(), Collections.emptyList(),
                                           host.getFlavor(), host.primaryClusterMembership()))
                 .collect(Collectors.toCollection(LinkedHashSet::new));
     }
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/admin/Admin.java b/config-model/src/main/java/com/yahoo/vespa/model/admin/Admin.java
index d892d70e0de..59b7388f5bb 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/admin/Admin.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/admin/Admin.java
@@ -1,22 +1,26 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.vespa.model.admin;
 
-import com.yahoo.cloud.config.log.LogdConfig;
+import com.yahoo.cloud.config.SlobroksConfig;
 import com.yahoo.cloud.config.ZookeepersConfig;
+import com.yahoo.cloud.config.log.LogdConfig;
 import com.yahoo.config.model.api.ConfigServerSpec;
 import com.yahoo.config.model.deploy.DeployProperties;
 import com.yahoo.config.model.producer.AbstractConfigProducer;
-import com.yahoo.cloud.config.SlobroksConfig;
 import com.yahoo.config.provision.ApplicationId;
 import com.yahoo.config.provision.Zone;
-import com.yahoo.vespa.model.*;
+import com.yahoo.vespa.model.AbstractService;
+import com.yahoo.vespa.model.ConfigProxy;
+import com.yahoo.vespa.model.ConfigSentinel;
+import com.yahoo.vespa.model.HostResource;
+import com.yahoo.vespa.model.Logd;
 import com.yahoo.vespa.model.admin.monitoring.MetricsConsumer;
 import com.yahoo.vespa.model.admin.monitoring.Monitoring;
 import com.yahoo.vespa.model.admin.monitoring.builder.Metrics;
 import com.yahoo.vespa.model.container.ContainerCluster;
 import com.yahoo.vespa.model.filedistribution.DummyFileDistributionConfigProducer;
-import com.yahoo.vespa.model.filedistribution.FileDistributionConfigProvider;
 import com.yahoo.vespa.model.filedistribution.FileDistributionConfigProducer;
+import com.yahoo.vespa.model.filedistribution.FileDistributionConfigProvider;
 import com.yahoo.vespa.model.filedistribution.FileDistributor;
 import com.yahoo.vespa.model.filedistribution.FileDistributorService;
 
@@ -26,8 +30,6 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
-import com.yahoo.vespa.model.HostResource;
-
 /**
  * This is the admin pseudo-plugin of the Vespa model, responsible for
  * creating all admin services.
@@ -223,12 +225,12 @@ public class Admin extends AbstractConfigProducer implements Serializable {
         if (fileDistribution.getOptions().disableFiledistributor()) {
             DummyFileDistributionConfigProducer dummyFileDistributionConfigProducer =
                     new DummyFileDistributionConfigProducer(fileDistribution,
-                                                            host.getHost().getHostName(),
+                                                            host.getHost().getHostname(),
                                                             configProvider);
             fileDistribution.addFileDistributionConfigProducer(host.getHost(), dummyFileDistributionConfigProducer);
         } else {
             FileDistributorService fds = new FileDistributorService(fileDistribution,
-                                                                    host.getHost().getHostName(),
+                                                                    host.getHost().getHostname(),
                                                                     configProvider);
             fds.setHostResource(host);
             fds.initService();
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminV4Builder.java b/config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminV4Builder.java
index a7a785cea43..1f7c1ba676c 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminV4Builder.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminV4Builder.java
@@ -19,6 +19,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 /**
  * Builds the admin model from a version 4 XML tag, or as a default when an admin 3 tag or no admin tag is used.
@@ -119,12 +120,11 @@ public class DomAdminV4Builder extends DomAdminBuilderBase {
 
     /** Returns the count first containers in the current model having isRetired set to the given value */
     private List<HostResource> sortedContainerHostsFrom(ContainerModel model, int count, boolean retired) {
-        List<HostResource> hosts = new ArrayList<>();
-        for (Container container : model.getCluster().getContainers())
-            if (retired == container.isRetired())
-                hosts.add(container.getHostResource());
-        Collections.sort(hosts);
-        return hosts.subList(0, Math.min(count, hosts.size()));
+        List<HostResource> hosts = model.getCluster().getContainers().stream()
+                                                                     .filter(container -> retired == container.isRetired())
+                                                                     .map(Container::getHostResource)
+                                                                     .collect(Collectors.toList());
+        return HostResource.pickHosts(hosts, count, 1);
     }
 
     private void createLogserver(Admin admin, Collection<HostResource> hosts) {
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/content/cluster/ContentCluster.java b/config-model/src/main/java/com/yahoo/vespa/model/content/cluster/ContentCluster.java
index 7654fbc217b..db849d0ae50 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/content/cluster/ContentCluster.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/content/cluster/ContentCluster.java
@@ -328,9 +328,11 @@ public class ContentCluster extends AbstractConfigProducer implements StorDistri
         }
 
         private List<HostResource> drawControllerHosts(int count, StorageGroup rootGroup, Collection<ContainerModel> containers) {
-            List<HostResource> hosts = drawContentHostsRecursively(count, rootGroup);
+            List<HostResource> hostsByName = drawContentHostsRecursively(count, false, rootGroup);
+            List<HostResource> hostsByIndex = drawContentHostsRecursively(count, true, rootGroup);
             // if (hosts.size() < count) // supply with containers TODO: Currently disabled due to leading to topology change problems
             //     hosts.addAll(drawContainerHosts(count - hosts.size(), containers, new HashSet<>(hosts)));
+            List<HostResource> hosts = HostResource.pickHosts(hostsByName, hostsByIndex, count, 1);
             if (hosts.size() % 2 == 0) // ZK clusters of even sizes are less available (even in the size=2 case)
                 hosts = hosts.subList(0, hosts.size()-1);
             return hosts;
@@ -357,7 +359,7 @@ public class ContentCluster extends AbstractConfigProducer implements StorDistri
             // have one cluster controller
             List<HostResource> uniqueHostsWithoutClusterController = allHosts.stream()
                     .filter(h -> ! usedHosts.contains(h))
-                    .filter(h -> ! hostHasClusterController(h.getHostName(), allHosts))
+                    .filter(h -> ! hostHasClusterController(h.getHostname(), allHosts))
                     .distinct()
                     .collect(Collectors.toList());
 
@@ -381,7 +383,7 @@ public class ContentCluster extends AbstractConfigProducer implements StorDistri
         /** Returns whether any host having the given hostname has a cluster controller */
         private boolean hostHasClusterController(String hostname, List<HostResource> hosts) {
             for (HostResource host : hosts) {
-                if ( ! host.getHostName().equals(hostname)) continue;
+                if ( ! host.getHostname().equals(hostname)) continue;
 
                 if (hasClusterController(host))
                     return true;
@@ -403,20 +405,24 @@ public class ContentCluster extends AbstractConfigProducer implements StorDistri
          */
         // Note: This method cannot be changed to draw different nodes without ensuring that it will draw nodes
         //       which overlaps with previously drawn nodes as this will prevent rolling upgrade
-        private List<HostResource> drawContentHostsRecursively(int count, StorageGroup group) {
+        private List<HostResource> drawContentHostsRecursively(int count, boolean byIndex, StorageGroup group) {
             Set<HostResource> hosts = new HashSet<>();
             if (group.getNodes().isEmpty()) {
                 int hostsPerSubgroup = (int)Math.ceil((double)count / group.getSubgroups().size());
                 for (StorageGroup subgroup : group.getSubgroups())
-                    hosts.addAll(drawContentHostsRecursively(hostsPerSubgroup, subgroup));
+                    hosts.addAll(drawContentHostsRecursively(hostsPerSubgroup, byIndex, subgroup));
             }
             else {
                 hosts.addAll(group.getNodes().stream()
-                    .filter(node -> ! node.isRetired()) // Avoid retired controllers to avoid surprises on expiry
-                    .map(StorageNode::getHostResource).collect(Collectors.toList()));
+                     .filter(node -> ! node.isRetired()) // Avoid retired controllers to avoid surprises on expiry
+                     .map(StorageNode::getHostResource).collect(Collectors.toList()));
             }
+
             List<HostResource> sortedHosts = new ArrayList<>(hosts);
-            Collections.sort(sortedHosts);
+            if (byIndex)
+                sortedHosts.sort((a, b) -> (a.comparePrimarilyByIndexTo(b)));
+            else // by name
+                Collections.sort(sortedHosts);
             sortedHosts = sortedHosts.subList(0, Math.min(count, hosts.size()));
             return sortedHosts;
         }
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/filedistribution/FileDistributionConfigProvider.java b/config-model/src/main/java/com/yahoo/vespa/model/filedistribution/FileDistributionConfigProvider.java
index 33cc581c3a8..a78eb1f74f9 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/filedistribution/FileDistributionConfigProvider.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/filedistribution/FileDistributionConfigProvider.java
@@ -33,14 +33,14 @@ public class FileDistributionConfigProvider {
         fileDistributionOptions.getConfig(builder);
         builder.torrentport(FileDistributorService.BASEPORT + 1);
         builder.stateport(FileDistributorService.BASEPORT + 2);
-        builder.hostname(host.getHostName());
+        builder.hostname(host.getHostname());
         builder.filedbpath(FileDistribution.getDefaultFileDBPath().toString());
     }
 
     public void getConfig(FiledistributorrpcConfig.Builder builder) {
         // If disabled config proxy should act as file distributor, so use config proxy port
         int port = (fileDistributionOptions.disableFiledistributor()) ? ConfigProxy.BASEPORT : FileDistributorService.BASEPORT;
-        builder.connectionspec("tcp/" + host.getHostName() + ":" + port);
+        builder.connectionspec("tcp/" + host.getHostname() + ":" + port);
     }
 
     public void getConfig(FilereferencesConfig.Builder builder) {
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/filedistribution/FileDistributor.java b/config-model/src/main/java/com/yahoo/vespa/model/filedistribution/FileDistributor.java
index 8fcece3aa80..f3aad88a446 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/filedistribution/FileDistributor.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/filedistribution/FileDistributor.java
@@ -78,7 +78,7 @@ public class FileDistributor {
     }
 
     public Set<String> getTargetHostnames() {
-        return getTargetHosts().stream().map(Host::getHostName).collect(Collectors.toSet());
+        return getTargetHosts().stream().map(Host::getHostname).collect(Collectors.toSet());
     }
 
     /** Returns the host which is the source of the files */
@@ -94,9 +94,9 @@ public class FileDistributor {
     public void sendDeployedFiles(FileDistribution dbHandler) {
         String fileSourceHost = fileSourceHost();
         for (Host host : getTargetHosts()) {
-            if ( ! host.getHostName().equals(fileSourceHost)) {
-                dbHandler.sendDeployedFiles(host.getHostName(), filesToSendToHost(host));
-                dbHandler.startDownload(host.getHostName(), filesToSendToHost(host));
+            if ( ! host.getHostname().equals(fileSourceHost)) {
+                dbHandler.sendDeployedFiles(host.getHostname(), filesToSendToHost(host));
+                dbHandler.startDownload(host.getHostname(), filesToSendToHost(host));
             }
         }
         dbHandler.sendDeployedFiles(fileSourceHost, allFilesToSend());
@@ -108,5 +108,5 @@ public class FileDistributor {
     public void reloadDeployFileDistributor(FileDistribution dbHandler) {
         dbHandler.reloadDeployFileDistributor();
     }
-    
+
 }
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/search/Dispatch.java b/config-model/src/main/java/com/yahoo/vespa/model/search/Dispatch.java
index 789c5562d9c..87146447dd1 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/search/Dispatch.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/search/Dispatch.java
@@ -96,7 +96,7 @@ public class Dispatch extends AbstractService implements SearchInterface,
     public int getMaxThreads() { return 500*2; }
 
     public String getHostname() {
-        return getHost().getHostName();
+        return getHost().getHostname();
     }
 
     @Override
@@ -105,7 +105,7 @@ public class Dispatch extends AbstractService implements SearchInterface,
     }
 
     public String getDispatcherConnectSpec() {
-        return "tcp/" + getHost().getHostName() + ":" + getDispatchPort();
+        return "tcp/" + getHost().getHostname() + ":" + getDispatchPort();
     }
 
     public DispatchGroup getDispatchGroup() {
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/search/IndexedSearchCluster.java b/config-model/src/main/java/com/yahoo/vespa/model/search/IndexedSearchCluster.java
index 8d7d289b99f..4925b88e608 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/search/IndexedSearchCluster.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/search/IndexedSearchCluster.java
@@ -200,7 +200,7 @@ public abstract class IndexedSearchCluster extends SearchCluster
             String containerClusterName = containerCluster.getName();
             log.log(LogLevel.DEBUG, "Adding tld with index " + containerIndex + " for content cluster " + this.getClusterName() +
                                     ", container cluster " + containerClusterName + " (container id " + containerSubId +
-                                    ") on host " + container.getHostResource().getHostName());
+                                    ") on host " + container.getHostResource().getHostname());
             rootDispatch.addDispatcher(createTld(tldParent, container.getHostResource(), containerClusterName, containerIndex));
         }
     }
diff --git a/config-model/src/main/java/com/yahoo/vespa/model/search/SearchNode.java b/config-model/src/main/java/com/yahoo/vespa/model/search/SearchNode.java
index 819d5904c25..8420a1f4b91 100644
--- a/config-model/src/main/java/com/yahoo/vespa/model/search/SearchNode.java
+++ b/config-model/src/main/java/com/yahoo/vespa/model/search/SearchNode.java
@@ -183,7 +183,7 @@ public class SearchNode extends AbstractService implements
      * @return The connection string.
      */
     public String getDispatcherConnectSpec() {
-        return "tcp/" + getHost().getHostName() + ":" + getDispatchPort();
+        return "tcp/" + getHost().getHostname() + ":" + getDispatchPort();
     }
 
     public int getDispatchPort() {
@@ -247,7 +247,7 @@ public class SearchNode extends AbstractService implements
             partition(getNodeSpec().partitionId()).
             clustername(getClusterName()).
             basedir(getBaseDir()).
-            tlsspec("tcp/" + getHost().getHostName() + ":" + getTransactionLogServer().getTlsPort()).
+            tlsspec("tcp/" + getHost().getHostname() + ":" + getTransactionLogServer().getTlsPort()).
             tlsconfigid(getConfigId()).
             slobrokconfigid(getClusterConfigId()).
             routingconfigid(getClusterConfigId()).
diff --git a/config-model/src/test/java/com/yahoo/config/model/provision/ModelProvisioningTest.java b/config-model/src/test/java/com/yahoo/config/model/provision/ModelProvisioningTest.java
index 63d5d37598b..6ea15788cf3 100644
--- a/config-model/src/test/java/com/yahoo/config/model/provision/ModelProvisioningTest.java
+++ b/config-model/src/test/java/com/yahoo/config/model/provision/ModelProvisioningTest.java
@@ -391,16 +391,16 @@ public class ModelProvisioningTest {
         ContainerCluster clusterControllers = cluster.getClusterControllers();
         assertEquals(3, clusterControllers.getContainers().size());
         assertEquals("bar-controllers", clusterControllers.getName());
-        assertEquals("default10", clusterControllers.getContainers().get(0).getHostName());
-        assertEquals("default13", clusterControllers.getContainers().get(1).getHostName());
-        assertEquals("default16", clusterControllers.getContainers().get(2).getHostName());
+        assertEquals("default28", clusterControllers.getContainers().get(0).getHostName());
+        assertEquals("default31", clusterControllers.getContainers().get(1).getHostName());
+        assertEquals("default54", clusterControllers.getContainers().get(2).getHostName());
         assertEquals(0, cluster.getRootGroup().getNodes().size());
         assertEquals(9, cluster.getRootGroup().getSubgroups().size());
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getIndex(), is("0"));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().size(), is(3));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getDistributionKey(), is(0));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getConfigId(), is("bar/storage/0"));
-        assertEquals("default10", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getHostName());
+        assertEquals("default54", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getHostName());
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().get(1).getDistributionKey(), is(1));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().get(1).getConfigId(), is("bar/storage/1"));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().get(2).getDistributionKey(), is(2));
@@ -409,13 +409,13 @@ public class ModelProvisioningTest {
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().size(), is(3));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getDistributionKey(), is(3));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getConfigId(), is("bar/storage/3"));
-        assertEquals("default13", cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getHostName());
+        assertEquals("default51", cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getHostName());
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(1).getDistributionKey(), is(4));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(1).getConfigId(), is("bar/storage/4"));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(2).getDistributionKey(), is(5));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(2).getConfigId(), is("bar/storage/5"));
         // ...
-        assertEquals("default16", cluster.getRootGroup().getSubgroups().get(2).getNodes().get(0).getHostName());
+        assertEquals("default48", cluster.getRootGroup().getSubgroups().get(2).getNodes().get(0).getHostName());
         // ...
         assertThat(cluster.getRootGroup().getSubgroups().get(8).getIndex(), is("8"));
         assertThat(cluster.getRootGroup().getSubgroups().get(8).getNodes().size(), is(3));
@@ -430,23 +430,23 @@ public class ModelProvisioningTest {
         clusterControllers = cluster.getClusterControllers();
         assertEquals(3, clusterControllers.getContainers().size());
         assertEquals("baz-controllers", clusterControllers.getName());
-        assertEquals("default37", clusterControllers.getContainers().get(0).getHostName());
-        assertEquals("default38", clusterControllers.getContainers().get(1).getHostName());
-        assertEquals("default39", clusterControllers.getContainers().get(2).getHostName());
+        assertEquals("default01", clusterControllers.getContainers().get(0).getHostName());
+        assertEquals("default02", clusterControllers.getContainers().get(1).getHostName());
+        assertEquals("default27", clusterControllers.getContainers().get(2).getHostName());
         assertEquals(0, cluster.getRootGroup().getNodes().size());
         assertEquals(27, cluster.getRootGroup().getSubgroups().size());
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getIndex(), is("0"));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().size(), is(1));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getDistributionKey(), is(0));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getConfigId(), is("baz/storage/0"));
-        assertEquals("default37", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getHostName());
+        assertEquals("default27", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getHostName());
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getIndex(), is("1"));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().size(), is(1));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getDistributionKey(), is(1));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getConfigId(), is("baz/storage/1"));
-        assertEquals("default38", cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getHostName());
+        assertEquals("default26", cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getHostName());
         // ...
-        assertEquals("default39", cluster.getRootGroup().getSubgroups().get(2).getNodes().get(0).getHostName());
+        assertEquals("default25", cluster.getRootGroup().getSubgroups().get(2).getNodes().get(0).getHostName());
         // ...
         assertThat(cluster.getRootGroup().getSubgroups().get(26).getIndex(), is("26"));
         assertThat(cluster.getRootGroup().getSubgroups().get(26).getNodes().size(), is(1));
@@ -483,9 +483,9 @@ public class ModelProvisioningTest {
         ContainerCluster clusterControllers = cluster.getClusterControllers();
         assertEquals(3, clusterControllers.getContainers().size());
         assertEquals("bar-controllers", clusterControllers.getName());
-        assertEquals("default10", clusterControllers.getContainers().get(0).getHostName());
-        assertEquals("default11", clusterControllers.getContainers().get(1).getHostName());
-        assertEquals("default12", clusterControllers.getContainers().get(2).getHostName());
+        assertEquals("default01", clusterControllers.getContainers().get(0).getHostName());
+        assertEquals("default02", clusterControllers.getContainers().get(1).getHostName());
+        assertEquals("default08", clusterControllers.getContainers().get(2).getHostName());
         assertEquals(0, cluster.getRootGroup().getNodes().size());
         assertEquals(8, cluster.getRootGroup().getSubgroups().size());
         assertEquals(8, cluster.distributionBits());
@@ -494,19 +494,19 @@ public class ModelProvisioningTest {
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().size(), is(1));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getDistributionKey(), is(0));
         assertThat(cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getConfigId(), is("bar/storage/0"));
-        assertEquals("default10", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getHostName());
+        assertEquals("default08", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getHostName());
         // second group
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getIndex(), is("1"));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().size(), is(1));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getDistributionKey(), is(1));
         assertThat(cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getConfigId(), is("bar/storage/1"));
-        assertEquals("default11", cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getHostName());
+        assertEquals("default07", cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getHostName());
         // ... last group
         assertThat(cluster.getRootGroup().getSubgroups().get(7).getIndex(), is("7"));
         assertThat(cluster.getRootGroup().getSubgroups().get(7).getNodes().size(), is(1));
         assertThat(cluster.getRootGroup().getSubgroups().get(7).getNodes().get(0).getDistributionKey(), is(7));
         assertThat(cluster.getRootGroup().getSubgroups().get(7).getNodes().get(0).getConfigId(), is("bar/storage/7"));
-        assertEquals("default17", cluster.getRootGroup().getSubgroups().get(7).getNodes().get(0).getHostName());
+        assertEquals("default01", cluster.getRootGroup().getSubgroups().get(7).getNodes().get(0).getHostName());
     }
 
     @Test
@@ -538,16 +538,51 @@ public class ModelProvisioningTest {
         ContentCluster cluster = model.getContentClusters().get("bar");
         ContainerCluster clusterControllers = cluster.getClusterControllers();
         assertEquals( 8, cluster.distributionBits());
-        assertEquals("We get the closest odd numer", 5, clusterControllers.getContainers().size());
+        assertEquals("We get the closest odd number", 5, clusterControllers.getContainers().size());
         assertEquals("bar-controllers", clusterControllers.getName());
-        assertEquals("default10", clusterControllers.getContainers().get(0).getHostName());
-        assertEquals("default11", clusterControllers.getContainers().get(1).getHostName());
-        assertEquals("default13", clusterControllers.getContainers().get(2).getHostName());
-        assertEquals("default14", clusterControllers.getContainers().get(3).getHostName()); // Should be 16 for perfect distribution ...
-        assertEquals("default10", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getHostName());
-        assertEquals("default11", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(1).getHostName());
-        assertEquals("default13", cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getHostName());
-        assertEquals("default16", cluster.getRootGroup().getSubgroups().get(2).getNodes().get(0).getHostName());
+        assertEquals("default01", clusterControllers.getContainers().get(0).getHostName());
+        assertEquals("default02", clusterControllers.getContainers().get(1).getHostName());
+        assertEquals("default04", clusterControllers.getContainers().get(2).getHostName());
+        assertEquals("default05", clusterControllers.getContainers().get(3).getHostName());
+        assertEquals("default07", clusterControllers.getContainers().get(4).getHostName());
+        assertEquals("default09", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(0).getHostName());
+        assertEquals("default08", cluster.getRootGroup().getSubgroups().get(0).getNodes().get(1).getHostName());
+        assertEquals("default06", cluster.getRootGroup().getSubgroups().get(1).getNodes().get(0).getHostName());
+        assertEquals("default03", cluster.getRootGroup().getSubgroups().get(2).getNodes().get(0).getHostName());
+    }
+
+    @Test
+    public void testClusterControllersWithGroupSize2() {
+        String services =
+                "<?xml version='1.0' encoding='utf-8' ?>\n" +
+                "<services>" +
+                "  <admin version='4.0'/>" +
+                "  <container version='1.0' id='foo'>" +
+                "     <nodes count='10'/>" +
+                "  </container>" +
+                "  <content version='1.0' id='bar'>" +
+                "     <redundancy>2</redundancy>" +
+                "     <documents>" +
+                "       <document type='type1' mode='index'/>" +
+                "     </documents>" +
+                "     <nodes count='8' groups='4'/>" +
+                "  </content>" +
+                "</services>";
+
+        int numberOfHosts = 18;
+        VespaModelTester tester = new VespaModelTester();
+        tester.addHosts(numberOfHosts);
+        VespaModel model = tester.createModel(services, true);
+        assertThat(model.getRoot().getHostSystem().getHosts().size(), is(numberOfHosts));
+
+        // Check content clusters
+        ContentCluster cluster = model.getContentClusters().get("bar");
+        ContainerCluster clusterControllers = cluster.getClusterControllers();
+        assertEquals("We get the closest odd number", 3, clusterControllers.getContainers().size());
+        assertEquals("bar-controllers", clusterControllers.getName());
+        assertEquals("default01", clusterControllers.getContainers().get(0).getHostName());
+        assertEquals("default03", clusterControllers.getContainers().get(1).getHostName());
+        assertEquals("default08", clusterControllers.getContainers().get(2).getHostName());
     }
 
     @Test
@@ -604,7 +639,7 @@ public class ModelProvisioningTest {
         int numberOfHosts = 19;
         VespaModelTester tester = new VespaModelTester();
         tester.addHosts(numberOfHosts);
-        VespaModel model = tester.createModel(services, true, "default10", "default13", "default16");
+        VespaModel model = tester.createModel(services, true, "default09", "default06", "default03");
         assertThat(model.getRoot().getHostSystem().getHosts().size(), is(numberOfHosts));
 
         // Check content clusters
@@ -612,9 +647,9 @@ public class ModelProvisioningTest {
         ContainerCluster clusterControllers = cluster.getClusterControllers();
         assertEquals(3, clusterControllers.getContainers().size());
         assertEquals("bar-controllers", clusterControllers.getName());
-        assertEquals("Skipping retired default10", "default11", clusterControllers.getContainers().get(0).getHostName());
-        assertEquals("Skipping retired default13", "default14", clusterControllers.getContainers().get(1).getHostName());
-        assertEquals("Skipping retired default16", "default17", clusterControllers.getContainers().get(2).getHostName());
+        assertEquals("Skipping retired default09", "default01", clusterControllers.getContainers().get(0).getHostName());
+        assertEquals("Skipping retired default03", "default04", clusterControllers.getContainers().get(1).getHostName());
+        assertEquals("Skipping retired default06", "default08", clusterControllers.getContainers().get(2).getHostName());
     }
 
     @Test
@@ -631,15 +666,15 @@ public class ModelProvisioningTest {
         int numberOfHosts = 10;
         VespaModelTester tester = new VespaModelTester();
         tester.addHosts(numberOfHosts);
-        VespaModel model = tester.createModel(services, true, "default0");
+        VespaModel model = tester.createModel(services, true, "default09");
         assertThat(model.getRoot().getHostSystem().getHosts().size(), is(numberOfHosts));
 
         // Check slobroks clusters
         assertEquals("Includes retired node", 1+3, model.getAdmin().getSlobroks().size());
-        assertEquals("default1", model.getAdmin().getSlobroks().get(0).getHostName());
-        assertEquals("default2", model.getAdmin().getSlobroks().get(1).getHostName());
-        assertEquals("default3", model.getAdmin().getSlobroks().get(2).getHostName());
-        assertEquals("Included in addition because it is retired", "default0", model.getAdmin().getSlobroks().get(3).getHostName());
+        assertEquals("default01", model.getAdmin().getSlobroks().get(0).getHostName());
+        assertEquals("default02", model.getAdmin().getSlobroks().get(1).getHostName());
+        assertEquals("default10", model.getAdmin().getSlobroks().get(2).getHostName());
+        assertEquals("Included in addition because it is retired", "default09", model.getAdmin().getSlobroks().get(3).getHostName());
     }
 
     @Test
@@ -656,16 +691,16 @@ public class ModelProvisioningTest {
         int numberOfHosts = 10;
         VespaModelTester tester = new VespaModelTester();
         tester.addHosts(numberOfHosts);
-        VespaModel model = tester.createModel(services, true, "default3", "default4");
+        VespaModel model = tester.createModel(services, true, "default09", "default08");
         assertThat(model.getRoot().getHostSystem().getHosts().size(), is(numberOfHosts));
 
         // Check slobroks clusters
         assertEquals("Includes retired node", 3+2, model.getAdmin().getSlobroks().size());
-        assertEquals("default0", model.getAdmin().getSlobroks().get(0).getHostName());
-        assertEquals("default1", model.getAdmin().getSlobroks().get(1).getHostName());
-        assertEquals("default2", model.getAdmin().getSlobroks().get(2).getHostName());
-        assertEquals("Included in addition because it is retired", "default3", model.getAdmin().getSlobroks().get(3).getHostName());
-        assertEquals("Included in addition because it is retired", "default4", model.getAdmin().getSlobroks().get(4).getHostName());
+        assertEquals("default01", model.getAdmin().getSlobroks().get(0).getHostName());
+        assertEquals("default02", model.getAdmin().getSlobroks().get(1).getHostName());
+        assertEquals("default10", model.getAdmin().getSlobroks().get(2).getHostName());
+        assertEquals("Included in addition because it is retired", "default08", model.getAdmin().getSlobroks().get(3).getHostName());
+        assertEquals("Included in addition because it is retired", "default09", model.getAdmin().getSlobroks().get(4).getHostName());
     }
 
     @Test
@@ -685,19 +720,19 @@ public class ModelProvisioningTest {
         int numberOfHosts = 13;
         VespaModelTester tester = new VespaModelTester();
         tester.addHosts(numberOfHosts);
-        VespaModel model = tester.createModel(services, true, "default0", "default10", "default11");
+        VespaModel model = tester.createModel(services, true, "default12", "default03", "default02");
         assertThat(model.getRoot().getHostSystem().getHosts().size(), is(numberOfHosts));
 
         // Check slobroks clusters
         // ... from cluster default
         assertEquals("Includes retired node", 3+3, model.getAdmin().getSlobroks().size());
-        assertEquals("default1", model.getAdmin().getSlobroks().get(0).getHostName());
-        assertEquals("default2", model.getAdmin().getSlobroks().get(1).getHostName());
-        assertEquals("Included in addition because it is retired", "default0", model.getAdmin().getSlobroks().get(2).getHostName());
+        assertEquals("default04", model.getAdmin().getSlobroks().get(0).getHostName());
+        assertEquals("default13", model.getAdmin().getSlobroks().get(1).getHostName());
+        assertEquals("Included in addition because it is retired", "default12", model.getAdmin().getSlobroks().get(2).getHostName());
         // ... from cluster bar
-        assertEquals("default12", model.getAdmin().getSlobroks().get(3).getHostName());
-        assertEquals("Included in addition because it is retired", "default10", model.getAdmin().getSlobroks().get(4).getHostName());
-        assertEquals("Included in addition because it is retired", "default11", model.getAdmin().getSlobroks().get(5).getHostName());
+        assertEquals("default01", model.getAdmin().getSlobroks().get(3).getHostName());
+        assertEquals("Included in addition because it is retired", "default02", model.getAdmin().getSlobroks().get(4).getHostName());
+        assertEquals("Included in addition because it is retired", "default03", model.getAdmin().getSlobroks().get(5).getHostName());
     }
 
     @Test
@@ -828,10 +863,10 @@ public class ModelProvisioningTest {
         ContainerCluster clusterControllers = cluster.getClusterControllers();
         assertEquals(4, clusterControllers.getContainers().size());
         assertEquals("bar-controllers", clusterControllers.getName());
-        assertEquals("default19", clusterControllers.getContainers().get(0).getHostName());
-        assertEquals("default20", clusterControllers.getContainers().get(1).getHostName());
-        assertEquals("default21", clusterControllers.getContainers().get(2).getHostName());
-        assertEquals("default22", clusterControllers.getContainers().get(3).getHostName());
+        assertEquals("default04", clusterControllers.getContainers().get(0).getHostName());
+        assertEquals("default03", clusterControllers.getContainers().get(1).getHostName());
+        assertEquals("default02", clusterControllers.getContainers().get(2).getHostName());
+        assertEquals("default01", clusterControllers.getContainers().get(3).getHostName());
     }
 
     @Test
@@ -957,7 +992,7 @@ public class ModelProvisioningTest {
         ContainerCluster clusterControllers = cluster.getClusterControllers();
         assertEquals(1, clusterControllers.getContainers().size());
         assertEquals("bar-controllers", clusterControllers.getName());
-        assertEquals("default0", clusterControllers.getContainers().get(0).getHostName());
+        assertEquals("default01", clusterControllers.getContainers().get(0).getHostName());
         assertEquals(1, cluster.redundancy().effectiveInitialRedundancy()); // Reduced from 3*3
         assertEquals(1, cluster.redundancy().effectiveFinalRedundancy()); // Reduced from 3*4
         assertEquals(1, cluster.redundancy().effectiveReadyCopies()); // Reduced from 3*3
diff --git a/config-model/src/test/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminV2BuilderTest.java b/config-model/src/test/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminV2BuilderTest.java
index 91f6dd65bda..446ceb686e8 100755
--- a/config-model/src/test/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminV2BuilderTest.java
+++ b/config-model/src/test/java/com/yahoo/vespa/model/builder/xml/dom/DomAdminV2BuilderTest.java
@@ -124,7 +124,7 @@ public class DomAdminV2BuilderTest extends DomBuilderTest {
         assertThat(admin.getClusterControllerHosts().size(), is(1));
         assertNotNull(admin.getHostSystem().getHostByHostname("test1"));
         for (Configserver configserver : admin.getConfigservers()) {
-            assertThat(configserver.getHostName(), is(not(admin.getClusterControllerHosts().get(0).getHost().getHostName())));
+            assertThat(configserver.getHostName(), is(not(admin.getClusterControllerHosts().get(0).getHost().getHostname())));
             for (Slobrok slobrok : admin.getSlobroks()) {
                     assertThat(slobrok.getHostName(), is(not(configserver.getHostName())));
             }
diff --git a/config-model/src/test/java/com/yahoo/vespa/model/builder/xml/dom/VespaDomBuilderTest.java b/config-model/src/test/java/com/yahoo/vespa/model/builder/xml/dom/VespaDomBuilderTest.java
index 51e982f8a34..77cc881e0d9 100755
--- a/config-model/src/test/java/com/yahoo/vespa/model/builder/xml/dom/VespaDomBuilderTest.java
+++ b/config-model/src/test/java/com/yahoo/vespa/model/builder/xml/dom/VespaDomBuilderTest.java
@@ -122,9 +122,9 @@ public class VespaDomBuilderTest {
         System.out.println(hostSystem);
         assertThat(hostSystem.getHosts().size(), is(1));
         HostResource host = hostSystem.getHosts().get(0);
-        assertThat(host, is(hostSystem.getHostByHostname(host.getHostName())));
+        assertThat(host, is(hostSystem.getHostByHostname(host.getHostname())));
         assertNotNull(hostSystem.getHost("node1"));
-        assertThat(hostSystem.toString(), is("host '" + host.getHostName() + "'"));
+        assertThat(hostSystem.toString(), is("host '" + host.getHostname() + "'"));
     }
 
     private VespaModel createModel(String hosts, String services) {
diff --git a/config-model/src/test/java/com/yahoo/vespa/model/test/VespaModelTester.java b/config-model/src/test/java/com/yahoo/vespa/model/test/VespaModelTester.java
index 901bd7f55b5..b88ba0276c4 100644
--- a/config-model/src/test/java/com/yahoo/vespa/model/test/VespaModelTester.java
+++ b/config-model/src/test/java/com/yahoo/vespa/model/test/VespaModelTester.java
@@ -18,7 +18,6 @@ import com.yahoo.vespa.model.test.utils.ApplicationPackageUtils;
 import com.yahoo.vespa.model.test.utils.VespaModelCreatorWithMockPkg;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
@@ -29,7 +28,7 @@ import java.util.Optional;
  * Helper class which sets up a system with multiple hosts.
  * Usage:
  * <code>
- *     VespaModelteser teser = new VespaModelTester();
+ *     VespaModelteser tester = new VespaModelTester();
  *     tester.addHosts(count, flavor);
  *     ... add more nodes
  *     VesoaModel model = tester.createModel(servicesString);
@@ -43,7 +42,7 @@ public class VespaModelTester {
     private final ConfigModelRegistry configModelRegistry;
 
     private boolean hosted = true;
-    private Map<String, Collection<Host>> hosts = new HashMap<>();
+    private Map<String, Collection<Host>> hostsByFlavor = new HashMap<>();
 
     public VespaModelTester() {
         this(new NullConfigModelRegistry());
@@ -55,20 +54,31 @@ public class VespaModelTester {
     
     /** Adds some hosts of the 'default' flavor to this system */
     public Hosts addHosts(int count) { return addHosts("default", count); }
+
     /** Adds some hosts to this system */
     public Hosts addHosts(String flavor, int count) { 
-        List<Host> hosts = new ArrayList<>();
-        for (int i = 0; i < count; i++)
-            hosts.add(new com.yahoo.config.model.provision.Host(flavor + i));
-        this.hosts.put(flavor.isEmpty() ? "default" : flavor, hosts);
-        return new Hosts(hosts);
+        return addHosts(Optional.empty(), flavor, count);
     }
+
     public void addHosts(Flavor flavor, int count) {
+        addHosts(Optional.of(flavor), flavor.name(), count);
+    }
+
+    private Hosts addHosts(Optional<Flavor> flavor, String flavorName, int count) {
         List<Host> hosts = new ArrayList<>();
+        
         for (int i = 0; i < count; ++i) {
-            hosts.add(new Host(flavor.name() + i, ImmutableList.of(), Optional.of(flavor)));
+            // Let host names sort in the opposite order of the order the hosts are added
+            // This allows us to test index vs. name order selection when subsets of hosts are selected from a cluster
+            // (for e.g cluster controllers and slobrok nodes)
+            String hostname = String.format("%s%02d", flavorName, count - i);
+            hosts.add(new Host(hostname, ImmutableList.of(), flavor));
         }
-        this.hosts.put(flavor.name(), hosts);
+        this.hostsByFlavor.put(flavorName, hosts);
+
+        if (hosts.size() > 100)
+            throw new IllegalStateException("The host naming scheme is nameNN. To test more than 100 hosts, change to nameNNN");
+        return new Hosts(hosts);
     }
 
     /** Sets whether this sets up a model for a hosted system. Default: true */
@@ -95,7 +105,7 @@ public class VespaModelTester {
         ApplicationPackage appPkg = modelCreatorWithMockPkg.appPkg;
 
         HostProvisioner provisioner = hosted ? 
-                                      new InMemoryProvisioner(hosts, failOnOutOfCapacity, startIndexForClusters, retiredHostNames) :
+                                      new InMemoryProvisioner(hostsByFlavor, failOnOutOfCapacity, startIndexForClusters, retiredHostNames) :
                                       new SingleNodeProvisioner();
 
         DeployState deployState = new DeployState.Builder()
diff --git a/container-search/src/main/java/com/yahoo/fs4/MapEncoder.java b/container-search/src/main/java/com/yahoo/fs4/MapEncoder.java
index 2f915257938..4245f51ace8 100644
--- a/container-search/src/main/java/com/yahoo/fs4/MapEncoder.java
+++ b/container-search/src/main/java/com/yahoo/fs4/MapEncoder.java
@@ -6,13 +6,10 @@ import com.yahoo.tensor.serialization.TypedBinaryFormat;
 import com.yahoo.text.Utf8;
 
 import java.nio.ByteBuffer;
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Set;
 
 /**
  * A static utility for encoding values to the binary map representation used in fs4 packets.