Remove legacy primary shard allocation mode based on versions (#23016)

Elasticsearch v5.0.0 uses allocation IDs to safely allocate primary shards whereas prior versions of ES used a version-based mode instead. Elasticsearch v5 still has support for version-based primary shard allocation as it needs to be able to load 2.x shards. ES v6 can drop the legacy support.

core/src/main/java/org/elasticsearch/action/admin/indices/shards/IndicesShardStoresResponse.java

@@ -22,6 +22,7 @@ package org.elasticsearch.action.admin.indices.shards;
 import com.carrotsearch.hppc.cursors.IntObjectCursor;
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
 import org.elasticsearch.ElasticsearchException;
+import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionResponse;
 import org.elasticsearch.action.ShardOperationFailedException;
 import org.elasticsearch.action.support.DefaultShardOperationFailedException;
@@ -55,7 +56,6 @@ public class IndicesShardStoresResponse extends ActionResponse implements ToXCon
      */
     public static class StoreStatus implements Streamable, ToXContent, Comparable<StoreStatus> {
         private DiscoveryNode node;
-        private long legacyVersion;
         private String allocationId;
         private Exception storeException;
         private AllocationStatus allocationStatus;
@@ -116,9 +116,8 @@ public class IndicesShardStoresResponse extends ActionResponse implements ToXCon
         private StoreStatus() {
         }
 
-        public StoreStatus(DiscoveryNode node, long legacyVersion, String allocationId, AllocationStatus allocationStatus, Exception storeException) {
+        public StoreStatus(DiscoveryNode node, String allocationId, AllocationStatus allocationStatus, Exception storeException) {
             this.node = node;
-            this.legacyVersion = legacyVersion;
             this.allocationId = allocationId;
             this.allocationStatus = allocationStatus;
             this.storeException = storeException;
@@ -131,13 +130,6 @@ public class IndicesShardStoresResponse extends ActionResponse implements ToXCon
             return node;
         }
 
-        /**
-         * Version of the store for pre-3.0 shards that have not yet been active
-         */
-        public long getLegacyVersion() {
-            return legacyVersion;
-        }
-
         /**
          * AllocationStatus id of the store, used to select the store that will be
          * used as a primary.
@@ -173,7 +165,10 @@ public class IndicesShardStoresResponse extends ActionResponse implements ToXCon
         @Override
         public void readFrom(StreamInput in) throws IOException {
             node = new DiscoveryNode(in);
-            legacyVersion = in.readLong();
+            if (in.getVersion().before(Version.V_6_0_0_alpha1_UNRELEASED)) {
+                // legacy version
+                in.readLong();
+            }
             allocationId = in.readOptionalString();
             allocationStatus = AllocationStatus.readFrom(in);
             if (in.readBoolean()) {
@@ -184,7 +179,10 @@ public class IndicesShardStoresResponse extends ActionResponse implements ToXCon
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             node.writeTo(out);
-            out.writeLong(legacyVersion);
+            if (out.getVersion().before(Version.V_6_0_0_alpha1_UNRELEASED)) {
+                // legacy version
+                out.writeLong(-1L);
+            }
             out.writeOptionalString(allocationId);
             allocationStatus.writeTo(out);
             if (storeException != null) {
@@ -198,9 +196,6 @@ public class IndicesShardStoresResponse extends ActionResponse implements ToXCon
         @Override
         public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
             node.toXContent(builder, params);
-            if (legacyVersion != ShardStateMetaData.NO_VERSION) {
-                builder.field(Fields.LEGACY_VERSION, legacyVersion);
-            }
             if (allocationId != null) {
                 builder.field(Fields.ALLOCATION_ID, allocationId);
             }
@@ -225,11 +220,7 @@ public class IndicesShardStoresResponse extends ActionResponse implements ToXCon
             } else if (allocationId == null && other.allocationId != null) {
                 return 1;
             } else if (allocationId == null && other.allocationId == null) {
-                int compare = Long.compare(other.legacyVersion, legacyVersion);
-                if (compare == 0) {
-                    return Integer.compare(allocationStatus.id, other.allocationStatus.id);
-                }
-                return compare;
+                return Integer.compare(allocationStatus.id, other.allocationStatus.id);
             } else {
                 int compare = Integer.compare(allocationStatus.id, other.allocationStatus.id);
                 if (compare == 0) {
@@ -405,7 +396,6 @@ public class IndicesShardStoresResponse extends ActionResponse implements ToXCon
         static final String FAILURES = "failures";
         static final String STORES = "stores";
         // StoreStatus fields
-        static final String LEGACY_VERSION = "legacy_version";
         static final String ALLOCATION_ID = "allocation_id";
         static final String STORE_EXCEPTION = "store_exception";
         static final String ALLOCATED = "allocation";

core/src/main/java/org/elasticsearch/action/admin/indices/shards/TransportIndicesShardStoresAction.java

@@ -180,7 +180,7 @@ public class TransportIndicesShardStoresAction extends TransportMasterNodeReadAc
                     for (NodeGatewayStartedShards response : fetchResponse.responses) {
                         if (shardExistsInNode(response)) {
                             IndicesShardStoresResponse.StoreStatus.AllocationStatus allocationStatus = getAllocationStatus(fetchResponse.shardId.getIndexName(), fetchResponse.shardId.id(), response.getNode());
-                            storeStatuses.add(new IndicesShardStoresResponse.StoreStatus(response.getNode(), response.legacyVersion(), response.allocationId(), allocationStatus, response.storeException()));
+                            storeStatuses.add(new IndicesShardStoresResponse.StoreStatus(response.getNode(), response.allocationId(), allocationStatus, response.storeException()));
                         }
                     }
                     CollectionUtil.timSort(storeStatuses);
@@ -213,7 +213,7 @@ public class TransportIndicesShardStoresAction extends TransportMasterNodeReadAc
              * A shard exists/existed in a node only if shard state file exists in the node
              */
             private boolean shardExistsInNode(final NodeGatewayStartedShards response) {
-                return response.storeException() != null || response.legacyVersion() != -1 || response.allocationId() != null;
+                return response.storeException() != null || response.allocationId() != null;
             }
 
             @Override

core/src/main/java/org/elasticsearch/cluster/metadata/MetaDataUpdateSettingsService.java

@@ -212,12 +212,6 @@ public class MetaDataUpdateSettingsService extends AbstractComponent implements
                     }
                 }
 
-                if (closeIndices.size() > 0 && closedSettings.get(IndexMetaData.SETTING_NUMBER_OF_REPLICAS) != null) {
-                    throw new IllegalArgumentException(String.format(Locale.ROOT,
-                            "Can't update [%s] on closed indices %s - can leave index in an unopenable state", IndexMetaData.SETTING_NUMBER_OF_REPLICAS,
-                            closeIndices
-                    ));
-                }
                 if (!skippedSettigns.isEmpty() && !openIndices.isEmpty()) {
                     throw new IllegalArgumentException(String.format(Locale.ROOT,
                             "Can't update non dynamic settings [%s] for open indices %s",

core/src/main/java/org/elasticsearch/cluster/routing/IndexRoutingTable.java

@@ -139,8 +139,7 @@ public class IndexRoutingTable extends AbstractDiffable<IndexRoutingTable> imple
                         "allocation set " + inSyncAllocationIds);
                 }
 
-                if (indexMetaData.getCreationVersion().onOrAfter(Version.V_5_0_0_alpha1) &&
-                    indexMetaData.isIndexUsingShadowReplicas() == false && // see #20650
+                if (indexMetaData.isIndexUsingShadowReplicas() == false && // see #20650
                     shardRouting.primary() && shardRouting.initializing() && shardRouting.relocating() == false &&
                     RecoverySource.isInitialRecovery(shardRouting.recoverySource().getType()) == false &&
                     inSyncAllocationIds.contains(shardRouting.allocationId().getId()) == false)
@@ -445,12 +444,6 @@ public class IndexRoutingTable extends AbstractDiffable<IndexRoutingTable> imple
                 if (indexMetaData.inSyncAllocationIds(shardNumber).isEmpty() == false) {
                     // we have previous valid copies for this shard. use them for recovery
                     primaryRecoverySource = StoreRecoverySource.EXISTING_STORE_INSTANCE;
-                } else if (indexMetaData.getCreationVersion().before(Version.V_5_0_0_alpha1) &&
-                    unassignedInfo.getReason() != UnassignedInfo.Reason.INDEX_CREATED // tests can create old indices
-                    ) {
-                    // the index is old and didn't maintain inSyncAllocationIds. Fall back to old behavior and require
-                    // finding existing copies
-                    primaryRecoverySource = StoreRecoverySource.EXISTING_STORE_INSTANCE;
                 } else if (indexMetaData.getMergeSourceIndex() != null) {
                     // this is a new index but the initial shards should merged from another index
                     primaryRecoverySource = LocalShardsRecoverySource.INSTANCE;

core/src/main/java/org/elasticsearch/common/settings/ClusterSettings.java

@@ -298,7 +298,6 @@ public final class ClusterSettings extends AbstractScopedSettings {
                     NetworkService.TcpSettings.TCP_CONNECT_TIMEOUT,
                     IndexSettings.QUERY_STRING_ANALYZE_WILDCARD,
                     IndexSettings.QUERY_STRING_ALLOW_LEADING_WILDCARD,
-                    PrimaryShardAllocator.NODE_INITIAL_SHARDS_SETTING,
                     ScriptService.SCRIPT_CACHE_SIZE_SETTING,
                     ScriptService.SCRIPT_CACHE_EXPIRE_SETTING,
                     ScriptService.SCRIPT_AUTO_RELOAD_ENABLED_SETTING,

core/src/main/java/org/elasticsearch/common/settings/IndexScopedSettings.java

@@ -139,7 +139,6 @@ public final class IndexScopedSettings extends AbstractScopedSettings {
         IndexModule.INDEX_QUERY_CACHE_ENABLED_SETTING,
         IndexModule.INDEX_QUERY_CACHE_EVERYTHING_SETTING,
         IndexModule.INDEX_QUERY_CACHE_TERM_QUERIES_SETTING,
-        PrimaryShardAllocator.INDEX_RECOVERY_INITIAL_SHARDS_SETTING,
         FsDirectoryService.INDEX_LOCK_FACTOR_SETTING,
         EngineConfig.INDEX_CODEC_SETTING,
         EngineConfig.INDEX_OPTIMIZE_AUTO_GENERATED_IDS,

core/src/main/java/org/elasticsearch/gateway/PrimaryShardAllocator.java

@@ -22,8 +22,6 @@ package org.elasticsearch.gateway;
 import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.message.ParameterizedMessage;
 import org.apache.logging.log4j.util.Supplier;
-import org.apache.lucene.util.CollectionUtil;
-import org.elasticsearch.Version;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.cluster.routing.RecoverySource;
@@ -37,8 +35,6 @@ import org.elasticsearch.cluster.routing.allocation.NodeAllocationResult.ShardSt
 import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
 import org.elasticsearch.cluster.routing.allocation.decider.Decision;
 import org.elasticsearch.cluster.routing.allocation.decider.Decision.Type;
-import org.elasticsearch.common.settings.Setting;
-import org.elasticsearch.common.settings.Setting.Property;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.env.ShardLockObtainFailedException;
 import org.elasticsearch.gateway.AsyncShardFetch.FetchResult;
@@ -52,7 +48,6 @@ import java.util.Comparator;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
-import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -71,34 +66,8 @@ import java.util.stream.Stream;
  */
 public abstract class PrimaryShardAllocator extends BaseGatewayShardAllocator {
 
-    private static final Function<String, String> INITIAL_SHARDS_PARSER = (value) -> {
-        switch (value) {
-            case "quorum":
-            case "quorum-1":
-            case "half":
-            case "one":
-            case "full":
-            case "full-1":
-            case "all-1":
-            case "all":
-                return value;
-            default:
-                Integer.parseInt(value); // it can be parsed that's all we care here?
-                return value;
-        }
-    };
-
-    public static final Setting<String> NODE_INITIAL_SHARDS_SETTING =
-        new Setting<>("gateway.initial_shards", (settings) -> settings.get("gateway.local.initial_shards", "quorum"), INITIAL_SHARDS_PARSER,
-            Property.Dynamic, Property.NodeScope);
-    @Deprecated
-    public static final Setting<String> INDEX_RECOVERY_INITIAL_SHARDS_SETTING =
-        new Setting<>("index.recovery.initial_shards", (settings) -> NODE_INITIAL_SHARDS_SETTING.get(settings) , INITIAL_SHARDS_PARSER,
-            Property.Dynamic, Property.IndexScope);
-
     public PrimaryShardAllocator(Settings settings) {
         super(settings);
-        logger.debug("using initial_shards [{}]", NODE_INITIAL_SHARDS_SETTING.get(settings));
     }
 
     /**
@@ -139,34 +108,13 @@ public abstract class PrimaryShardAllocator extends BaseGatewayShardAllocator {
         final boolean snapshotRestore = unassignedShard.recoverySource().getType() == RecoverySource.Type.SNAPSHOT;
         final boolean recoverOnAnyNode = recoverOnAnyNode(indexMetaData);
 
-        final NodeShardsResult nodeShardsResult;
-        final boolean enoughAllocationsFound;
-
-        if (inSyncAllocationIds.isEmpty()) {
-            assert Version.indexCreated(indexMetaData.getSettings()).before(Version.V_5_0_0_alpha1) :
-                "trying to allocate a primary with an empty in sync allocation id set, but index is new. index: "
-                    + indexMetaData.getIndex();
-            // when we load an old index (after upgrading cluster) or restore a snapshot of an old index
-            // fall back to old version-based allocation mode
-            // Note that once the shard has been active, lastActiveAllocationIds will be non-empty
-            nodeShardsResult = buildVersionBasedNodeShardsResult(unassignedShard, snapshotRestore || recoverOnAnyNode,
-                                                                 allocation.getIgnoreNodes(unassignedShard.shardId()), shardState, logger);
-            if (snapshotRestore || recoverOnAnyNode) {
-                enoughAllocationsFound = nodeShardsResult.allocationsFound > 0;
-            } else {
-                enoughAllocationsFound = isEnoughVersionBasedAllocationsFound(indexMetaData, nodeShardsResult);
-            }
-            logger.debug("[{}][{}]: version-based allocation for pre-{} index found {} allocations of {}", unassignedShard.index(),
-                         unassignedShard.id(), Version.V_5_0_0_alpha1, nodeShardsResult.allocationsFound, unassignedShard);
-        } else {
-            assert inSyncAllocationIds.isEmpty() == false;
-            // use allocation ids to select nodes
-            nodeShardsResult = buildAllocationIdBasedNodeShardsResult(unassignedShard, snapshotRestore || recoverOnAnyNode,
-                allocation.getIgnoreNodes(unassignedShard.shardId()), inSyncAllocationIds, shardState, logger);
-            enoughAllocationsFound = nodeShardsResult.orderedAllocationCandidates.size() > 0;
-            logger.debug("[{}][{}]: found {} allocation candidates of {} based on allocation ids: [{}]", unassignedShard.index(),
-                         unassignedShard.id(), nodeShardsResult.orderedAllocationCandidates.size(), unassignedShard, inSyncAllocationIds);
-        }
+        assert inSyncAllocationIds.isEmpty() == false;
+        // use in-sync allocation ids to select nodes
+        final NodeShardsResult nodeShardsResult = buildNodeShardsResult(unassignedShard, snapshotRestore || recoverOnAnyNode,
+            allocation.getIgnoreNodes(unassignedShard.shardId()), inSyncAllocationIds, shardState, logger);
+        final boolean enoughAllocationsFound = nodeShardsResult.orderedAllocationCandidates.size() > 0;
+        logger.debug("[{}][{}]: found {} allocation candidates of {} based on allocation ids: [{}]", unassignedShard.index(),
+            unassignedShard.id(), nodeShardsResult.orderedAllocationCandidates.size(), unassignedShard, inSyncAllocationIds);
 
         if (enoughAllocationsFound == false) {
             if (snapshotRestore) {
@@ -293,10 +241,10 @@ public abstract class PrimaryShardAllocator extends BaseGatewayShardAllocator {
      * inSyncAllocationIds are added to the list. Otherwise, any node that has a shard is added to the list, but
      * entries with matching allocation id are always at the front of the list.
      */
-    protected static NodeShardsResult buildAllocationIdBasedNodeShardsResult(ShardRouting shard, boolean matchAnyShard,
-                                                                             Set<String> ignoreNodes, Set<String> inSyncAllocationIds,
-                                                                             FetchResult<NodeGatewayStartedShards> shardState,
-                                                                             Logger logger) {
+    protected static NodeShardsResult buildNodeShardsResult(ShardRouting shard, boolean matchAnyShard,
+                                                            Set<String> ignoreNodes, Set<String> inSyncAllocationIds,
+                                                            FetchResult<NodeGatewayStartedShards> shardState,
+                                                            Logger logger) {
         List<NodeGatewayStartedShards> nodeShardStates = new ArrayList<>();
         int numberOfAllocationsFound = 0;
         for (NodeGatewayStartedShards nodeShardState : shardState.getData().values()) {
@@ -308,13 +256,10 @@ public abstract class PrimaryShardAllocator extends BaseGatewayShardAllocator {
             }
 
             if (nodeShardState.storeException() == null) {
-                if (allocationId == null && nodeShardState.legacyVersion() == ShardStateMetaData.NO_VERSION) {
+                if (allocationId == null) {
                     logger.trace("[{}] on node [{}] has no shard state information", shard, nodeShardState.getNode());
-                } else if (allocationId != null) {
-                    assert nodeShardState.legacyVersion() == ShardStateMetaData.NO_VERSION : "Allocation id and legacy version cannot be both present";
-                    logger.trace("[{}] on node [{}] has allocation id [{}]", shard, nodeShardState.getNode(), allocationId);
                 } else {
-                    logger.trace("[{}] on node [{}] has no allocation id, out-dated shard (shard state version: [{}])", shard, nodeShardState.getNode(), nodeShardState.legacyVersion());
+                    logger.trace("[{}] on node [{}] has allocation id [{}]", shard, nodeShardState.getNode(), allocationId);
                 }
             } else {
                 final String finalAllocationId = allocationId;
@@ -355,37 +300,6 @@ public abstract class PrimaryShardAllocator extends BaseGatewayShardAllocator {
         return new NodeShardsResult(nodeShardStates, numberOfAllocationsFound);
     }
 
-    /**
-     * used by old version-based allocation
-     */
-    private boolean isEnoughVersionBasedAllocationsFound(IndexMetaData indexMetaData, NodeShardsResult nodeShardsResult) {
-        // check if the counts meets the minimum set
-        int requiredAllocation = 1;
-        // if we restore from a repository one copy is more then enough
-        String initialShards = INDEX_RECOVERY_INITIAL_SHARDS_SETTING.get(indexMetaData.getSettings(), settings);
-        if ("quorum".equals(initialShards)) {
-            if (indexMetaData.getNumberOfReplicas() > 1) {
-                requiredAllocation = ((1 + indexMetaData.getNumberOfReplicas()) / 2) + 1;
-            }
-        } else if ("quorum-1".equals(initialShards) || "half".equals(initialShards)) {
-            if (indexMetaData.getNumberOfReplicas() > 2) {
-                requiredAllocation = ((1 + indexMetaData.getNumberOfReplicas()) / 2);
-            }
-        } else if ("one".equals(initialShards)) {
-            requiredAllocation = 1;
-        } else if ("full".equals(initialShards) || "all".equals(initialShards)) {
-            requiredAllocation = indexMetaData.getNumberOfReplicas() + 1;
-        } else if ("full-1".equals(initialShards) || "all-1".equals(initialShards)) {
-            if (indexMetaData.getNumberOfReplicas() > 1) {
-                requiredAllocation = indexMetaData.getNumberOfReplicas();
-            }
-        } else {
-            requiredAllocation = Integer.parseInt(initialShards);
-        }
-
-        return nodeShardsResult.allocationsFound >= requiredAllocation;
-    }
-
     /**
      * Split the list of node shard states into groups yes/no/throttle based on allocation deciders
      */
@@ -417,85 +331,6 @@ public abstract class PrimaryShardAllocator extends BaseGatewayShardAllocator {
                                       Collections.unmodifiableList(noNodeShards));
     }
 
-    /**
-     * Builds a list of previously started shards. If matchAnyShard is set to false, only shards with the highest shard version are added to
-     * the list. Otherwise, any existing shard is added to the list, but entries with highest version are always at the front of the list.
-     */
-    static NodeShardsResult buildVersionBasedNodeShardsResult(ShardRouting shard, boolean matchAnyShard, Set<String> ignoreNodes,
-                                                              FetchResult<NodeGatewayStartedShards> shardState, Logger logger) {
-        final List<NodeGatewayStartedShards> allocationCandidates = new ArrayList<>();
-        int numberOfAllocationsFound = 0;
-        long highestVersion = ShardStateMetaData.NO_VERSION;
-        for (NodeGatewayStartedShards nodeShardState : shardState.getData().values()) {
-            long version = nodeShardState.legacyVersion();
-            DiscoveryNode node = nodeShardState.getNode();
-
-            if (ignoreNodes.contains(node.getId())) {
-                continue;
-            }
-
-            if (nodeShardState.storeException() == null) {
-                if (version == ShardStateMetaData.NO_VERSION && nodeShardState.allocationId() == null) {
-                    logger.trace("[{}] on node [{}] has no shard state information", shard, nodeShardState.getNode());
-                } else if (version != ShardStateMetaData.NO_VERSION) {
-                    assert nodeShardState.allocationId() == null : "Allocation id and legacy version cannot be both present";
-                    logger.trace("[{}] on node [{}] has version [{}] of shard", shard, nodeShardState.getNode(), version);
-                } else {
-                    // shard was already selected in a 5.x cluster as primary for recovery, was initialized (and wrote a new state file) but
-                    // did not make it to STARTED state before the cluster crashed (otherwise list of active allocation ids would be
-                    // non-empty and allocation id - based allocation mode would be chosen).
-                    // Prefer this shard copy again.
-                    version = Long.MAX_VALUE;
-                    logger.trace("[{}] on node [{}] has allocation id [{}]", shard, nodeShardState.getNode(), nodeShardState.allocationId());
-                }
-            } else {
-                final long finalVersion = version;
-                if (nodeShardState.storeException() instanceof ShardLockObtainFailedException) {
-                    logger.trace((Supplier<?>) () -> new ParameterizedMessage("[{}] on node [{}] has version [{}] but the store can not be opened as it's locked, treating as valid shard", shard, nodeShardState.getNode(), finalVersion), nodeShardState.storeException());
-                    if (nodeShardState.allocationId() != null) {
-                        version = Long.MAX_VALUE; // shard was already selected in a 5.x cluster as primary, prefer this shard copy again.
-                    } else {
-                        version = 0L; // treat as lowest version so that this shard is the least likely to be selected as primary
-                    }
-                } else {
-                    // disregard the reported version and assign it as no version (same as shard does not exist)
-                    logger.trace((Supplier<?>) () -> new ParameterizedMessage("[{}] on node [{}] has version [{}] but the store can not be opened, treating no version", shard, nodeShardState.getNode(), finalVersion), nodeShardState.storeException());
-                    version = ShardStateMetaData.NO_VERSION;
-                }
-            }
-
-            if (version != ShardStateMetaData.NO_VERSION) {
-                numberOfAllocationsFound++;
-                // If we've found a new "best" candidate, clear the
-                // current candidates and add it
-                if (version > highestVersion) {
-                    highestVersion = version;
-                    if (matchAnyShard == false) {
-                        allocationCandidates.clear();
-                    }
-                    allocationCandidates.add(nodeShardState);
-                } else if (version == highestVersion) {
-                    // If the candidate is the same, add it to the
-                    // list, but keep the current candidate
-                    allocationCandidates.add(nodeShardState);
-                }
-            }
-        }
-        // sort array so the node with the highest version is at the beginning
-        CollectionUtil.timSort(allocationCandidates, Comparator.comparing(NodeGatewayStartedShards::legacyVersion).reversed());
-
-        if (logger.isTraceEnabled()) {
-            StringBuilder sb = new StringBuilder("[");
-            for (NodeGatewayStartedShards n : allocationCandidates) {
-                sb.append("[").append(n.getNode().getName()).append("]").append(" -> ").append(n.legacyVersion()).append(", ");
-            }
-            sb.append("]");
-            logger.trace("{} candidates for allocation: {}", shard, sb.toString());
-        }
-
-        return new NodeShardsResult(Collections.unmodifiableList(allocationCandidates), numberOfAllocationsFound);
-    }
-
     /**
      * Return {@code true} if the index is configured to allow shards to be
      * recovered on any node

core/src/main/java/org/elasticsearch/gateway/TransportNodesListGatewayStartedShards.java

@@ -22,6 +22,7 @@ package org.elasticsearch.gateway;
 import org.apache.logging.log4j.message.ParameterizedMessage;
 import org.apache.logging.log4j.util.Supplier;
 import org.elasticsearch.ElasticsearchException;
+import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.action.FailedNodeException;
 import org.elasticsearch.action.support.ActionFilters;
@@ -154,19 +155,18 @@ public class TransportNodesListGatewayStartedShards extends
                             exception);
                         String allocationId = shardStateMetaData.allocationId != null ?
                             shardStateMetaData.allocationId.getId() : null;
-                        return new NodeGatewayStartedShards(clusterService.localNode(), shardStateMetaData.legacyVersion,
-                            allocationId, shardStateMetaData.primary, exception);
+                        return new NodeGatewayStartedShards(clusterService.localNode(), allocationId, shardStateMetaData.primary,
+                            exception);
                     }
                 }
 
                 logger.debug("{} shard state info found: [{}]", shardId, shardStateMetaData);
                 String allocationId = shardStateMetaData.allocationId != null ?
                     shardStateMetaData.allocationId.getId() : null;
-                return new NodeGatewayStartedShards(clusterService.localNode(), shardStateMetaData.legacyVersion,
-                    allocationId, shardStateMetaData.primary);
+                return new NodeGatewayStartedShards(clusterService.localNode(), allocationId, shardStateMetaData.primary);
             }
             logger.trace("{} no local shard info found", shardId);
-            return new NodeGatewayStartedShards(clusterService.localNode(), ShardStateMetaData.NO_VERSION, null, false);
+            return new NodeGatewayStartedShards(clusterService.localNode(), null, false);
         } catch (Exception e) {
             throw new ElasticsearchException("failed to load started shards", e);
         }
@@ -257,7 +257,6 @@ public class TransportNodesListGatewayStartedShards extends
 
     public static class NodeGatewayStartedShards extends BaseNodeResponse {
 
-        private long legacyVersion = ShardStateMetaData.NO_VERSION; // for pre-3.0 shards that have not yet been active
         private String allocationId = null;
         private boolean primary = false;
         private Exception storeException = null;
@@ -265,23 +264,17 @@ public class TransportNodesListGatewayStartedShards extends
         public NodeGatewayStartedShards() {
         }
 
-        public NodeGatewayStartedShards(DiscoveryNode node, long legacyVersion, String allocationId, boolean primary) {
-            this(node, legacyVersion, allocationId, primary, null);
+        public NodeGatewayStartedShards(DiscoveryNode node, String allocationId, boolean primary) {
+            this(node, allocationId, primary, null);
         }
 
-        public NodeGatewayStartedShards(DiscoveryNode node, long legacyVersion, String allocationId, boolean primary,
-                                        Exception storeException) {
+        public NodeGatewayStartedShards(DiscoveryNode node, String allocationId, boolean primary, Exception storeException) {
             super(node);
-            this.legacyVersion = legacyVersion;
             this.allocationId = allocationId;
             this.primary = primary;
             this.storeException = storeException;
         }
 
-        public long legacyVersion() {
-            return this.legacyVersion;
-        }
-
         public String allocationId() {
             return this.allocationId;
         }
@@ -297,7 +290,10 @@ public class TransportNodesListGatewayStartedShards extends
         @Override
         public void readFrom(StreamInput in) throws IOException {
             super.readFrom(in);
-            legacyVersion = in.readLong();
+            if (in.getVersion().before(Version.V_6_0_0_alpha1_UNRELEASED)) {
+                // legacy version
+                in.readLong();
+            }
             allocationId = in.readOptionalString();
             primary = in.readBoolean();
             if (in.readBoolean()) {
@@ -308,7 +304,10 @@ public class TransportNodesListGatewayStartedShards extends
         @Override
         public void writeTo(StreamOutput out) throws IOException {
             super.writeTo(out);
-            out.writeLong(legacyVersion);
+            if (out.getVersion().before(Version.V_6_0_0_alpha1_UNRELEASED)) {
+                // legacy version
+                out.writeLong(-1L);
+            }
             out.writeOptionalString(allocationId);
             out.writeBoolean(primary);
             if (storeException != null) {
@@ -330,9 +329,6 @@ public class TransportNodesListGatewayStartedShards extends
 
             NodeGatewayStartedShards that = (NodeGatewayStartedShards) o;
 
-            if (legacyVersion != that.legacyVersion) {
-                return false;
-            }
             if (primary != that.primary) {
                 return false;
             }
@@ -345,8 +341,7 @@ public class TransportNodesListGatewayStartedShards extends
 
         @Override
         public int hashCode() {
-            int result = Long.hashCode(legacyVersion);
-            result = 31 * result + (allocationId != null ? allocationId.hashCode() : 0);
+            int result = (allocationId != null ? allocationId.hashCode() : 0);
             result = 31 * result + (primary ? 1 : 0);
             result = 31 * result + (storeException != null ? storeException.hashCode() : 0);
             return result;
@@ -357,8 +352,7 @@ public class TransportNodesListGatewayStartedShards extends
             StringBuilder buf = new StringBuilder();
             buf.append("NodeGatewayStartedShards[")
                .append("allocationId=").append(allocationId)
-               .append(",primary=").append(primary)
-               .append(",legacyVersion=").append(legacyVersion);
+               .append(",primary=").append(primary);
             if (storeException != null) {
                 buf.append(",storeException=").append(storeException);
             }

core/src/main/java/org/elasticsearch/index/shard/ShardStateMetaData.java

@@ -35,25 +35,17 @@ public final class ShardStateMetaData {
 
     private static final String SHARD_STATE_FILE_PREFIX = "state-";
     private static final String PRIMARY_KEY = "primary";
-    private static final String VERSION_KEY = "version";
+    private static final String VERSION_KEY = "version"; // for pre-5.0 shards that have not yet been active
     private static final String INDEX_UUID_KEY = "index_uuid";
     private static final String ALLOCATION_ID_KEY = "allocation_id";
 
-    public static final long NO_VERSION = -1L;
-
-    public final long legacyVersion; // for pre-3.0 shards that have not yet been active
     public final String indexUUID;
     public final boolean primary;
     @Nullable
     public final AllocationId allocationId; // can be null if we read from legacy format (see fromXContent and MultiDataPathUpgrader)
 
     public ShardStateMetaData(boolean primary, String indexUUID, AllocationId allocationId) {
-        this(NO_VERSION, primary, indexUUID, allocationId);
-    }
-
-    ShardStateMetaData(long legacyVersion, boolean primary, String indexUUID, AllocationId allocationId) {
         assert indexUUID != null;
-        this.legacyVersion = legacyVersion;
         this.primary = primary;
         this.indexUUID = indexUUID;
         this.allocationId = allocationId;
@@ -73,9 +65,6 @@ public final class ShardStateMetaData {
         if (primary != that.primary) {
             return false;
         }
-        if (legacyVersion != that.legacyVersion) {
-            return false;
-        }
         if (indexUUID != null ? !indexUUID.equals(that.indexUUID) : that.indexUUID != null) {
           return false;
         }
@@ -88,8 +77,7 @@ public final class ShardStateMetaData {
 
     @Override
     public int hashCode() {
-        int result = Long.hashCode(legacyVersion);
-        result = 31 * result + (indexUUID != null ? indexUUID.hashCode() : 0);
+        int result = (indexUUID != null ? indexUUID.hashCode() : 0);
         result = 31 * result + (allocationId != null ? allocationId.hashCode() : 0);
         result = 31 * result + (primary ? 1 : 0);
         return result;
@@ -97,7 +85,7 @@ public final class ShardStateMetaData {
 
     @Override
     public String toString() {
-        return "version [" + legacyVersion + "], primary [" + primary + "], allocation [" + allocationId + "]";
+        return "primary [" + primary + "], allocation [" + allocationId + "]";
     }
 
     public static final MetaDataStateFormat<ShardStateMetaData> FORMAT = new MetaDataStateFormat<ShardStateMetaData>(XContentType.SMILE, SHARD_STATE_FILE_PREFIX) {
@@ -111,7 +99,6 @@ public final class ShardStateMetaData {
 
         @Override
         public void toXContent(XContentBuilder builder, ShardStateMetaData shardStateMetaData) throws IOException {
-            builder.field(VERSION_KEY, shardStateMetaData.legacyVersion);
             builder.field(PRIMARY_KEY, shardStateMetaData.primary);
             builder.field(INDEX_UUID_KEY, shardStateMetaData.indexUUID);
             if (shardStateMetaData.allocationId != null) {
@@ -125,7 +112,6 @@ public final class ShardStateMetaData {
             if (token == null) {
                 return null;
             }
-            long version = NO_VERSION;
             Boolean primary = null;
             String currentFieldName = null;
             String indexUUID = IndexMetaData.INDEX_UUID_NA_VALUE;
@@ -134,12 +120,12 @@ public final class ShardStateMetaData {
                 if (token == XContentParser.Token.FIELD_NAME) {
                     currentFieldName = parser.currentName();
                 } else if (token.isValue()) {
-                    if (VERSION_KEY.equals(currentFieldName)) {
-                        version = parser.longValue();
-                    } else if (PRIMARY_KEY.equals(currentFieldName)) {
+                    if (PRIMARY_KEY.equals(currentFieldName)) {
                         primary = parser.booleanValue();
                     } else if (INDEX_UUID_KEY.equals(currentFieldName)) {
                         indexUUID = parser.text();
+                    } else if (VERSION_KEY.equals(currentFieldName)) {
+                        // ES versions before 6.0 wrote this for legacy reasons, just ignore for now and remove in 7.0
                     } else {
                         throw new CorruptStateException("unexpected field in shard state [" + currentFieldName + "]");
                     }
@@ -156,7 +142,7 @@ public final class ShardStateMetaData {
             if (primary == null) {
                 throw new CorruptStateException("missing value for [primary] in shard state");
             }
-            return new ShardStateMetaData(version, primary, indexUUID, allocationId);
+            return new ShardStateMetaData(primary, indexUUID, allocationId);
         }
     };
 }

core/src/test/java/org/elasticsearch/action/admin/indices/shards/IndicesShardStoreRequestIT.java

@@ -194,10 +194,8 @@ public class IndicesShardStoreRequestIT extends ESIntegTestCase {
             for (IndicesShardStoresResponse.StoreStatus status : shardStatus.value) {
                 if (corruptedShardIDMap.containsKey(shardStatus.key)
                         && corruptedShardIDMap.get(shardStatus.key).contains(status.getNode().getName())) {
-                    assertThat(status.getLegacyVersion(), greaterThanOrEqualTo(0L));
                     assertThat(status.getStoreException(), notNullValue());
                 } else {
-                    assertThat(status.getLegacyVersion(), greaterThanOrEqualTo(0L));
                     assertNull(status.getStoreException());
                 }
             }

core/src/test/java/org/elasticsearch/action/admin/indices/shards/IndicesShardStoreResponseTests.java

@@ -56,9 +56,9 @@ public class IndicesShardStoreResponseTests extends ESTestCase {
         DiscoveryNode node1 = new DiscoveryNode("node1", buildNewFakeTransportAddress(), emptyMap(), emptySet(), Version.CURRENT);
         DiscoveryNode node2 = new DiscoveryNode("node2", buildNewFakeTransportAddress(), emptyMap(), emptySet(), Version.CURRENT);
         List<IndicesShardStoresResponse.StoreStatus> storeStatusList = new ArrayList<>();
-        storeStatusList.add(new IndicesShardStoresResponse.StoreStatus(node1, 3, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.PRIMARY, null));
-        storeStatusList.add(new IndicesShardStoresResponse.StoreStatus(node2, ShardStateMetaData.NO_VERSION, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, null));
-        storeStatusList.add(new IndicesShardStoresResponse.StoreStatus(node1, ShardStateMetaData.NO_VERSION, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.UNUSED, new IOException("corrupted")));
+        storeStatusList.add(new IndicesShardStoresResponse.StoreStatus(node1, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.PRIMARY, null));
+        storeStatusList.add(new IndicesShardStoresResponse.StoreStatus(node2, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, null));
+        storeStatusList.add(new IndicesShardStoresResponse.StoreStatus(node1, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.UNUSED, new IOException("corrupted")));
         storeStatuses.put(0, storeStatusList);
         storeStatuses.put(1, storeStatusList);
         ImmutableOpenIntMap<List<IndicesShardStoresResponse.StoreStatus>> storesMap = storeStatuses.build();
@@ -99,16 +99,7 @@ public class IndicesShardStoreResponseTests extends ESTestCase {
                     for (int i = 0; i < stores.size(); i++) {
                         HashMap storeInfo = ((HashMap) stores.get(i));
                         IndicesShardStoresResponse.StoreStatus storeStatus = storeStatusList.get(i);
-                        boolean eitherLegacyVersionOrAllocationIdSet = false;
-                        if (storeInfo.containsKey("legacy_version")) {
-                            assertThat(((int) storeInfo.get("legacy_version")), equalTo(((int) storeStatus.getLegacyVersion())));
-                            eitherLegacyVersionOrAllocationIdSet = true;
-                        }
-                        if (storeInfo.containsKey("allocation_id")) {
-                            assertThat(((String) storeInfo.get("allocation_id")), equalTo((storeStatus.getAllocationId())));
-                            eitherLegacyVersionOrAllocationIdSet = true;
-                        }
-                        assertThat(eitherLegacyVersionOrAllocationIdSet, equalTo(true));
+                        assertThat(((String) storeInfo.get("allocation_id")), equalTo((storeStatus.getAllocationId())));
                         assertThat(storeInfo.containsKey("allocation"), equalTo(true));
                         assertThat(((String) storeInfo.get("allocation")), equalTo(storeStatus.getAllocationStatus().value()));
                         assertThat(storeInfo.containsKey(storeStatus.getNode().getId()), equalTo(true));
@@ -124,15 +115,14 @@ public class IndicesShardStoreResponseTests extends ESTestCase {
     public void testStoreStatusOrdering() throws Exception {
         DiscoveryNode node1 = new DiscoveryNode("node1", buildNewFakeTransportAddress(), emptyMap(), emptySet(), Version.CURRENT);
         List<IndicesShardStoresResponse.StoreStatus> orderedStoreStatuses = new ArrayList<>();
-        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, ShardStateMetaData.NO_VERSION, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.PRIMARY, null));
-        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, ShardStateMetaData.NO_VERSION, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, null));
-        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, ShardStateMetaData.NO_VERSION, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.UNUSED, null));
-        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, 2, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.PRIMARY, null));
-        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, 1, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.PRIMARY, null));
-        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, 1, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, null));
-        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, 1, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.UNUSED, null));
-        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, ShardStateMetaData.NO_VERSION, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, new IOException("corrupted")));
-        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, 3, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, new IOException("corrupted")));
+        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.PRIMARY, null));
+        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, null));
+        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.UNUSED, null));
+        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.PRIMARY, null));
+        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, null));
+        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.UNUSED, null));
+        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, UUIDs.randomBase64UUID(), IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, new IOException("corrupted")));
+        orderedStoreStatuses.add(new IndicesShardStoresResponse.StoreStatus(node1, null, IndicesShardStoresResponse.StoreStatus.AllocationStatus.REPLICA, new IOException("corrupted")));
 
         List<IndicesShardStoresResponse.StoreStatus> storeStatuses = new ArrayList<>(orderedStoreStatuses);
         Collections.shuffle(storeStatuses, random());

core/src/test/java/org/elasticsearch/gateway/PrimaryShardAllocatorTests.java

@@ -48,7 +48,6 @@ import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.set.Sets;
 import org.elasticsearch.env.ShardLockObtainFailedException;
 import org.elasticsearch.index.shard.ShardId;
-import org.elasticsearch.index.shard.ShardStateMetaData;
 import org.elasticsearch.snapshots.Snapshot;
 import org.elasticsearch.snapshots.SnapshotId;
 import org.junit.Before;
@@ -62,7 +61,6 @@ import java.util.Map;
 import static org.elasticsearch.cluster.routing.UnassignedInfo.Reason.CLUSTER_RECOVERED;
 import static org.elasticsearch.cluster.routing.UnassignedInfo.Reason.INDEX_CREATED;
 import static org.elasticsearch.cluster.routing.UnassignedInfo.Reason.INDEX_REOPENED;
-import static org.hamcrest.Matchers.anyOf;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.lessThanOrEqualTo;
 
@@ -93,7 +91,7 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
         final RoutingAllocation allocation;
         // with old version, we can't know if a shard was allocated before or not
         allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(),
-            randomFrom(INDEX_CREATED, CLUSTER_RECOVERED, INDEX_REOPENED), Version.CURRENT);
+            randomFrom(INDEX_CREATED, CLUSTER_RECOVERED, INDEX_REOPENED));
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(false));
         assertThat(allocation.routingNodes().unassigned().size(), equalTo(1));
@@ -105,12 +103,8 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * Tests that when async fetch returns that there is no data, the shard will not be allocated.
      */
     public void testNoAsyncFetchData() {
-        final RoutingAllocation allocation;
-        if (randomBoolean()) {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.CURRENT, "allocId");
-        } else {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_1_0);
-        }
+        final RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED,
+            "allocId");
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(1));
@@ -119,17 +113,13 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
     }
 
     /**
-     * Tests when the node returns that no data was found for it ({@link ShardStateMetaData#NO_VERSION} for version and null for allocation id),
+     * Tests when the node returns that no data was found for it (null for allocation id),
      * it will be moved to ignore unassigned.
      */
     public void testNoAllocationFound() {
-        final RoutingAllocation allocation;
-        if (randomBoolean()) {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.CURRENT, "allocId");
-        } else {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_1_0);
-        }
-        testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, null, randomBoolean());
+        final RoutingAllocation allocation =
+            routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, "allocId");
+        testAllocator.addData(node1, null, randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(1));
@@ -141,8 +131,8 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * Tests when the node returns data with a shard allocation id that does not match active allocation ids, it will be moved to ignore unassigned.
      */
     public void testNoMatchingAllocationIdFound() {
-        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.CURRENT, "id2");
-        testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, "id1", randomBoolean());
+        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, "id2");
+        testAllocator.addData(node1, "id1", randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(1));
@@ -150,34 +140,13 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
         assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
     }
 
-    /**
-     * Tests that when there is a node to allocate the shard to, and there are no active allocation ids, it will be allocated to it.
-     * This is the case when we have old shards from pre-3.0 days.
-     */
-    public void testNoActiveAllocationIds() {
-        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_1_1);
-        testAllocator.addData(node1, 1, null, randomBoolean());
-        testAllocator.allocateUnassigned(allocation);
-        assertThat(allocation.routingNodesChanged(), equalTo(true));
-        assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).size(), equalTo(1));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).currentNodeId(), equalTo(node1.getId()));
-        assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
-    }
-
     /**
      * Tests when the node returns that no data was found for it, it will be moved to ignore unassigned.
      */
     public void testStoreException() {
-        final RoutingAllocation allocation;
-        if (randomBoolean()) {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED,
-                randomFrom(Version.V_2_0_0, Version.CURRENT), "allocId1");
-            testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, "allocId1", randomBoolean(), new CorruptIndexException("test", "test"));
-        } else {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_1_1);
-            testAllocator.addData(node1, 3, null, randomBoolean(), new CorruptIndexException("test", "test"));
-        }
+        final RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED,
+            "allocId1");
+        testAllocator.addData(node1, "allocId1", randomBoolean(), new CorruptIndexException("test", "test"));
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(1));
@@ -189,26 +158,16 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * Tests that when the node returns a ShardLockObtainFailedException, it will be considered as a valid shard copy
      */
     public void testShardLockObtainFailedException() {
-        final RoutingAllocation allocation;
-        boolean useAllocationIds = randomBoolean();
-        if (useAllocationIds) {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED,
-                randomFrom(Version.V_2_0_0, Version.CURRENT), "allocId1");
-            testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, "allocId1", randomBoolean(),
-                new ShardLockObtainFailedException(shardId, "test"));
-        } else {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_1_1);
-            testAllocator.addData(node1, 3, null, randomBoolean(), new ShardLockObtainFailedException(shardId, "test"));
-        }
+        final RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED,
+            "allocId1");
+        testAllocator.addData(node1, "allocId1", randomBoolean(), new ShardLockObtainFailedException(shardId, "test"));
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
         assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).size(), equalTo(1));
         assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).currentNodeId(), equalTo(node1.getId()));
-        if (useAllocationIds) {
-            // check that allocation id is reused
-            assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).allocationId().getId(), equalTo("allocId1"));
-        }
+        // check that allocation id is reused
+        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).allocationId().getId(), equalTo("allocId1"));
         assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
     }
 
@@ -217,34 +176,20 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * select the second node as target
      */
     public void testShardLockObtainFailedExceptionPreferOtherValidCopies() {
-        final RoutingAllocation allocation;
-        boolean useAllocationIds = randomBoolean();
         String allocId1 = randomAsciiOfLength(10);
         String allocId2 = randomAsciiOfLength(10);
-        if (useAllocationIds) {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED,
-                randomFrom(Version.V_2_0_0, Version.CURRENT), allocId1, allocId2);
-            testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, allocId1, randomBoolean(),
-                new ShardLockObtainFailedException(shardId, "test"));
-            testAllocator.addData(node2, ShardStateMetaData.NO_VERSION, allocId2, randomBoolean(), null);
-        } else {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_1_1);
-            testAllocator.addData(node1, 3, null, randomBoolean(), new ShardLockObtainFailedException(shardId, "test"));
-            if (randomBoolean()) {
-                testAllocator.addData(node2, randomIntBetween(2, 4), null, randomBoolean(), null);
-            } else {
-                testAllocator.addData(node2, ShardStateMetaData.NO_VERSION, "some alloc id", randomBoolean(), null);
-            }
-        }
+        final RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED,
+            allocId1, allocId2);;
+        testAllocator.addData(node1, allocId1, randomBoolean(),
+            new ShardLockObtainFailedException(shardId, "test"));
+        testAllocator.addData(node2, allocId2, randomBoolean(), null);
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
         assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).size(), equalTo(1));
         assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).currentNodeId(), equalTo(node2.getId()));
-        if (useAllocationIds) {
-            // check that allocation id is reused
-            assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).allocationId().getId(), equalTo(allocId2));
-        }
+        // check that allocation id is reused
+        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).allocationId().getId(), equalTo(allocId2));
         assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
     }
 
@@ -252,26 +197,16 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * Tests that when there is a node to allocate the shard to, it will be allocated to it.
      */
     public void testFoundAllocationAndAllocating() {
-        final RoutingAllocation allocation;
-        boolean useAllocationIds = randomBoolean();
-        if (useAllocationIds) {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), randomFrom(CLUSTER_RECOVERED, INDEX_REOPENED),
-                randomFrom(Version.V_2_0_0, Version.CURRENT), "allocId1");
-            testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, "allocId1", randomBoolean());
-        } else {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), randomFrom(CLUSTER_RECOVERED, INDEX_REOPENED),
-                Version.V_2_2_0);
-            testAllocator.addData(node1, 3, null, randomBoolean());
-        }
+        final RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), randomFrom(CLUSTER_RECOVERED, INDEX_REOPENED),
+            "allocId1");
+        testAllocator.addData(node1, "allocId1", randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
         assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).size(), equalTo(1));
         assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).currentNodeId(), equalTo(node1.getId()));
-        if (useAllocationIds) {
-            // check that allocation id is reused
-            assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).allocationId().getId(), equalTo("allocId1"));
-        }
+        // check that allocation id is reused
+        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).allocationId().getId(), equalTo("allocId1"));
         assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
     }
 
@@ -281,13 +216,13 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * returns a YES decision for at least one of those NO nodes, then we force allocate to one of them
      */
     public void testForceAllocatePrimary() {
-        testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, "allocId1", randomBoolean());
+        testAllocator.addData(node1, "allocId1", randomBoolean());
         AllocationDeciders deciders = new AllocationDeciders(Settings.EMPTY, Arrays.asList(
             // since the deciders return a NO decision for allocating a shard (due to the guaranteed NO decision from the second decider),
             // the allocator will see if it can force assign the primary, where the decision will be YES
             new TestAllocateDecision(randomBoolean() ? Decision.YES : Decision.NO), getNoDeciderThatAllowsForceAllocate()
         ));
-        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(deciders, CLUSTER_RECOVERED, Version.CURRENT, "allocId1");
+        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(deciders, CLUSTER_RECOVERED, "allocId1");
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertTrue(allocation.routingNodes().unassigned().ignored().isEmpty());
@@ -301,7 +236,7 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * returns a NO or THROTTLE decision for a node, then we do not force allocate to that node.
      */
     public void testDontAllocateOnNoOrThrottleForceAllocationDecision() {
-        testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, "allocId1", randomBoolean());
+        testAllocator.addData(node1, "allocId1", randomBoolean());
         boolean forceDecisionNo = randomBoolean();
         AllocationDeciders deciders = new AllocationDeciders(Settings.EMPTY, Arrays.asList(
             // since both deciders here return a NO decision for allocating a shard,
@@ -310,7 +245,7 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
             new TestAllocateDecision(Decision.NO), forceDecisionNo ? getNoDeciderThatDeniesForceAllocate() :
                                                                      getNoDeciderThatThrottlesForceAllocate()
         ));
-        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(deciders, CLUSTER_RECOVERED, Version.CURRENT, "allocId1");
+        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(deciders, CLUSTER_RECOVERED, "allocId1");
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         List<ShardRouting> ignored = allocation.routingNodes().unassigned().ignored();
@@ -325,7 +260,7 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * then we do not force allocate to that node but instead throttle.
      */
     public void testDontForceAllocateOnThrottleDecision() {
-        testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, "allocId1", randomBoolean());
+        testAllocator.addData(node1, "allocId1", randomBoolean());
         AllocationDeciders deciders = new AllocationDeciders(Settings.EMPTY, Arrays.asList(
             // since we have a NO decision for allocating a shard (because the second decider returns a NO decision),
             // the allocator will see if it can force assign the primary, and in this case,
@@ -334,7 +269,7 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
             // force allocating the shard, we still THROTTLE due to the decision from TestAllocateDecision
             new TestAllocateDecision(Decision.THROTTLE), getNoDeciderThatAllowsForceAllocate()
         ));
-        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(deciders, CLUSTER_RECOVERED, Version.CURRENT, "allocId1");
+        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(deciders, CLUSTER_RECOVERED, "allocId1");
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         List<ShardRouting> ignored = allocation.routingNodes().unassigned().ignored();
@@ -350,10 +285,10 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
         String primaryAllocId = UUIDs.randomBase64UUID();
         String replicaAllocId = UUIDs.randomBase64UUID();
         RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(),
-            randomFrom(CLUSTER_RECOVERED, INDEX_REOPENED), randomFrom(Version.V_2_0_0, Version.CURRENT), primaryAllocId, replicaAllocId);
+            randomFrom(CLUSTER_RECOVERED, INDEX_REOPENED), primaryAllocId, replicaAllocId);
         boolean node1HasPrimaryShard = randomBoolean();
-        testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, node1HasPrimaryShard ? primaryAllocId : replicaAllocId, node1HasPrimaryShard);
-        testAllocator.addData(node2, ShardStateMetaData.NO_VERSION, node1HasPrimaryShard ? replicaAllocId : primaryAllocId, !node1HasPrimaryShard);
+        testAllocator.addData(node1, node1HasPrimaryShard ? primaryAllocId : replicaAllocId, node1HasPrimaryShard);
+        testAllocator.addData(node2, node1HasPrimaryShard ? replicaAllocId : primaryAllocId, !node1HasPrimaryShard);
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
@@ -368,15 +303,9 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * it will be moved to ignore unassigned until it can be allocated to.
      */
     public void testFoundAllocationButThrottlingDecider() {
-        final RoutingAllocation allocation;
-        if (randomBoolean()) {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(throttleAllocationDeciders(), CLUSTER_RECOVERED,
-                randomFrom(Version.V_2_0_0, Version.CURRENT), "allocId1");
-            testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, "allocId1", randomBoolean());
-        } else {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(throttleAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_2_0);
-            testAllocator.addData(node1, 3, null, randomBoolean());
-        }
+        final RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(throttleAllocationDeciders(), CLUSTER_RECOVERED,
+            "allocId1");
+        testAllocator.addData(node1, "allocId1", randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(1));
@@ -389,15 +318,9 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * force the allocation to it.
      */
     public void testFoundAllocationButNoDecider() {
-        final RoutingAllocation allocation;
-        if (randomBoolean()) {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(noAllocationDeciders(), CLUSTER_RECOVERED,
-                randomFrom(Version.V_2_0_0, Version.CURRENT), "allocId1");
-            testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, "allocId1", randomBoolean());
-        } else {
-            allocation = routingAllocationWithOnePrimaryNoReplicas(noAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_0_0);
-            testAllocator.addData(node1, 3, null, randomBoolean());
-        }
+        final RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(noAllocationDeciders(), CLUSTER_RECOVERED,
+            "allocId1");
+        testAllocator.addData(node1, "allocId1", randomBoolean());;
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
@@ -406,51 +329,13 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
         assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
     }
 
-    /**
-     * Tests that the highest version node is chosen for allocation.
-     */
-    public void testAllocateToTheHighestVersionOnLegacyIndex() {
-        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_0_0);
-        testAllocator.addData(node1, 10, null, randomBoolean()).addData(node2, 12, null, randomBoolean());
-        testAllocator.allocateUnassigned(allocation);
-        assertThat(allocation.routingNodesChanged(), equalTo(true));
-        assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).size(), equalTo(1));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).currentNodeId(), equalTo(node2.getId()));
-        assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
-    }
-
-    /**
-     * Tests that shard with allocation id is chosen if such a shard is available in version-based allocation mode. This happens if a shard
-     * was already selected in a 5.x cluster as primary for recovery, was initialized (and wrote a new state file) but did not make it to
-     * STARTED state before the cluster crashed (otherwise list of active allocation ids would be non-empty and allocation id - based
-     * allocation mode would be chosen).
-     */
-    public void testVersionBasedAllocationPrefersShardWithAllocationId() {
-        RoutingAllocation allocation = routingAllocationWithOnePrimaryNoReplicas(yesAllocationDeciders(), CLUSTER_RECOVERED, Version.V_2_0_0);
-        testAllocator.addData(node1, 10, null, randomBoolean());
-        testAllocator.addData(node2, ShardStateMetaData.NO_VERSION, "some allocId", randomBoolean());
-        testAllocator.addData(node3, 12, null, randomBoolean());
-        testAllocator.allocateUnassigned(allocation);
-        assertThat(allocation.routingNodesChanged(), equalTo(true));
-        assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).size(), equalTo(1));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).currentNodeId(), equalTo(node2.getId()));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).allocationId().getId(), equalTo("some allocId"));
-        assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
-    }
-
     /**
      * Tests that when restoring from a snapshot and we find a node with a shard copy and allocation
      * deciders say yes, we allocate to that node.
      */
     public void testRestore() {
-        boolean shardStateHasAllocationId = randomBoolean();
-        String allocationId = shardStateHasAllocationId ? "some allocId" : null;
-        long legacyVersion = shardStateHasAllocationId ? ShardStateMetaData.NO_VERSION : 1;
-        boolean clusterHasActiveAllocationIds = shardStateHasAllocationId ? randomBoolean() : false;
-        RoutingAllocation allocation = getRestoreRoutingAllocation(yesAllocationDeciders(), clusterHasActiveAllocationIds);
-        testAllocator.addData(node1, legacyVersion, allocationId, randomBoolean());
+        RoutingAllocation allocation = getRestoreRoutingAllocation(yesAllocationDeciders(), "allocId");
+        testAllocator.addData(node1, "some allocId", randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
@@ -463,12 +348,8 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * deciders say throttle, we add it to ignored shards.
      */
     public void testRestoreThrottle() {
-        boolean shardStateHasAllocationId = randomBoolean();
-        String allocationId = shardStateHasAllocationId ? "some allocId" : null;
-        long legacyVersion = shardStateHasAllocationId ? ShardStateMetaData.NO_VERSION : 1;
-        boolean clusterHasActiveAllocationIds = shardStateHasAllocationId ? randomBoolean() : false;
-        RoutingAllocation allocation = getRestoreRoutingAllocation(throttleAllocationDeciders(), clusterHasActiveAllocationIds);
-        testAllocator.addData(node1, legacyVersion, allocationId, randomBoolean());
+        RoutingAllocation allocation = getRestoreRoutingAllocation(throttleAllocationDeciders(), "allocId");
+        testAllocator.addData(node1, "some allocId", randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(false));
@@ -480,12 +361,8 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * deciders say no, we still allocate to that node.
      */
     public void testRestoreForcesAllocateIfShardAvailable() {
-        boolean shardStateHasAllocationId = randomBoolean();
-        String allocationId = shardStateHasAllocationId ? "some allocId" : null;
-        long legacyVersion = shardStateHasAllocationId ? ShardStateMetaData.NO_VERSION : 1;
-        boolean clusterHasActiveAllocationIds = shardStateHasAllocationId ? randomBoolean() : false;
-        RoutingAllocation allocation = getRestoreRoutingAllocation(noAllocationDeciders(), clusterHasActiveAllocationIds);
-        testAllocator.addData(node1, legacyVersion, allocationId, randomBoolean());
+        RoutingAllocation allocation = getRestoreRoutingAllocation(noAllocationDeciders(), "allocId");
+        testAllocator.addData(node1, "some allocId", randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
@@ -498,8 +375,8 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * the unassigned list to be allocated later.
      */
     public void testRestoreDoesNotAssignIfNoShardAvailable() {
-        RoutingAllocation allocation = getRestoreRoutingAllocation(yesAllocationDeciders(), randomBoolean());
-        testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, null, false);
+        RoutingAllocation allocation = getRestoreRoutingAllocation(yesAllocationDeciders(), "allocId");
+        testAllocator.addData(node1, null, false);
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(false));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
@@ -507,16 +384,15 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
         assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
     }
 
-    private RoutingAllocation getRestoreRoutingAllocation(AllocationDeciders allocationDeciders, boolean hasActiveAllocation) {
-        Version version = hasActiveAllocation ? Version.CURRENT : Version.V_2_0_0;
+    private RoutingAllocation getRestoreRoutingAllocation(AllocationDeciders allocationDeciders, String... allocIds) {
         MetaData metaData = MetaData.builder()
-            .put(IndexMetaData.builder(shardId.getIndexName()).settings(settings(version)).numberOfShards(1).numberOfReplicas(0)
-                .putInSyncAllocationIds(0, hasActiveAllocation ? Sets.newHashSet("allocId") : Collections.emptySet()))
+            .put(IndexMetaData.builder(shardId.getIndexName()).settings(settings(Version.CURRENT)).numberOfShards(1).numberOfReplicas(0)
+                .putInSyncAllocationIds(0, Sets.newHashSet(allocIds)))
             .build();
 
         final Snapshot snapshot = new Snapshot("test", new SnapshotId("test", UUIDs.randomBase64UUID()));
         RoutingTable routingTable = RoutingTable.builder()
-            .addAsRestore(metaData.index(shardId.getIndex()), new SnapshotRecoverySource(snapshot, version, shardId.getIndexName()))
+            .addAsRestore(metaData.index(shardId.getIndex()), new SnapshotRecoverySource(snapshot, Version.CURRENT, shardId.getIndexName()))
             .build();
         ClusterState state = ClusterState.builder(org.elasticsearch.cluster.ClusterName.CLUSTER_NAME_SETTING.getDefault(Settings.EMPTY))
             .metaData(metaData)
@@ -530,11 +406,8 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * deciders say yes, we allocate to that node.
      */
     public void testRecoverOnAnyNode() {
-        boolean hasActiveAllocation = randomBoolean();
-        String allocationId = hasActiveAllocation ? "allocId" : null;
-        long legacyVersion = hasActiveAllocation ? ShardStateMetaData.NO_VERSION : 1;
-        RoutingAllocation allocation = getRecoverOnAnyNodeRoutingAllocation(yesAllocationDeciders(), hasActiveAllocation);
-        testAllocator.addData(node1, legacyVersion, allocationId, randomBoolean());
+        RoutingAllocation allocation = getRecoverOnAnyNodeRoutingAllocation(yesAllocationDeciders(), "allocId");
+        testAllocator.addData(node1, "allocId", randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
@@ -547,11 +420,8 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * deciders say throttle, we add it to ignored shards.
      */
     public void testRecoverOnAnyNodeThrottle() {
-        boolean hasActiveAllocation = randomBoolean();
-        String allocationId = hasActiveAllocation ? "allocId" : null;
-        long legacyVersion = hasActiveAllocation ? ShardStateMetaData.NO_VERSION : 1;
-        RoutingAllocation allocation = getRecoverOnAnyNodeRoutingAllocation(throttleAllocationDeciders(), hasActiveAllocation);
-        testAllocator.addData(node1, legacyVersion, allocationId, randomBoolean());
+        RoutingAllocation allocation = getRecoverOnAnyNodeRoutingAllocation(throttleAllocationDeciders(), "allocId");
+        testAllocator.addData(node1, "allocId", randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(false));
@@ -563,11 +433,8 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * deciders say no, we still allocate to that node.
      */
     public void testRecoverOnAnyNodeForcesAllocateIfShardAvailable() {
-        boolean hasActiveAllocation = randomBoolean();
-        String allocationId = hasActiveAllocation ? "allocId" : null;
-        long legacyVersion = hasActiveAllocation ? ShardStateMetaData.NO_VERSION : 1;
-        RoutingAllocation allocation = getRecoverOnAnyNodeRoutingAllocation(noAllocationDeciders(), hasActiveAllocation);
-        testAllocator.addData(node1, legacyVersion, allocationId, randomBoolean());
+        RoutingAllocation allocation = getRecoverOnAnyNodeRoutingAllocation(noAllocationDeciders(), "allocId");
+        testAllocator.addData(node1, "allocId", randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(true));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
@@ -580,8 +447,8 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
      * BalancedShardAllocator assign the shard
      */
     public void testRecoverOnAnyNodeDoesNotAssignIfNoShardAvailable() {
-        RoutingAllocation allocation = getRecoverOnAnyNodeRoutingAllocation(yesAllocationDeciders(), randomBoolean());
-        testAllocator.addData(node1, ShardStateMetaData.NO_VERSION, null, randomBoolean());
+        RoutingAllocation allocation = getRecoverOnAnyNodeRoutingAllocation(yesAllocationDeciders(), "allocId");
+        testAllocator.addData(node1, null, randomBoolean());
         testAllocator.allocateUnassigned(allocation);
         assertThat(allocation.routingNodesChanged(), equalTo(false));
         assertThat(allocation.routingNodes().unassigned().ignored().isEmpty(), equalTo(true));
@@ -589,13 +456,12 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
         assertClusterHealthStatus(allocation, ClusterHealthStatus.YELLOW);
     }
 
-    private RoutingAllocation getRecoverOnAnyNodeRoutingAllocation(AllocationDeciders allocationDeciders, boolean hasActiveAllocation) {
-        Version version = hasActiveAllocation ? Version.CURRENT : Version.V_2_0_0;
+    private RoutingAllocation getRecoverOnAnyNodeRoutingAllocation(AllocationDeciders allocationDeciders, String... allocIds) {
         MetaData metaData = MetaData.builder()
-            .put(IndexMetaData.builder(shardId.getIndexName()).settings(settings(version)
+            .put(IndexMetaData.builder(shardId.getIndexName()).settings(settings(Version.CURRENT)
                 .put(IndexMetaData.SETTING_SHARED_FILESYSTEM, true)
                 .put(IndexMetaData.SETTING_SHARED_FS_ALLOW_RECOVERY_ON_ANY_NODE, true))
-                .numberOfShards(1).numberOfReplicas(0).putInSyncAllocationIds(0, hasActiveAllocation ? Sets.newHashSet("allocId") : Collections.emptySet()))
+                .numberOfShards(1).numberOfReplicas(0).putInSyncAllocationIds(0, Sets.newHashSet(allocIds)))
             .build();
 
         RoutingTable routingTable = RoutingTable.builder()
@@ -608,99 +474,10 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
         return new RoutingAllocation(allocationDeciders, new RoutingNodes(state, false), state, null, System.nanoTime(), false);
     }
 
-    /**
-     * Tests that only when enough copies of the shard exists we are going to allocate it. This test
-     * verifies that with same version (1), and quorum allocation.
-     */
-    public void testEnoughCopiesFoundForAllocationOnLegacyIndex() {
-        MetaData metaData = MetaData.builder()
-                .put(IndexMetaData.builder(shardId.getIndexName()).settings(settings(Version.V_2_0_0)).numberOfShards(1).numberOfReplicas(2))
-                .build();
-        RoutingTable routingTable = RoutingTable.builder()
-                .addAsRecovery(metaData.index(shardId.getIndex()))
-                .build();
-        ClusterState state = ClusterState.builder(org.elasticsearch.cluster.ClusterName.CLUSTER_NAME_SETTING.getDefault(Settings.EMPTY))
-                .metaData(metaData)
-                .routingTable(routingTable)
-                .nodes(DiscoveryNodes.builder().add(node1).add(node2).add(node3)).build();
-
-        RoutingAllocation allocation = new RoutingAllocation(yesAllocationDeciders(), new RoutingNodes(state, false), state, null, System.nanoTime(), false);
-        testAllocator.allocateUnassigned(allocation);
-        assertThat(allocation.routingNodesChanged(), equalTo(true));
-        assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(1));
-        assertThat(allocation.routingNodes().unassigned().ignored().get(0).shardId(), equalTo(shardId));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.UNASSIGNED).size(), equalTo(2)); // replicas
-        assertClusterHealthStatus(allocation, ClusterHealthStatus.RED);
-
-        testAllocator.addData(node1, 1, null, randomBoolean());
-        allocation = new RoutingAllocation(yesAllocationDeciders(), new RoutingNodes(state, false), state, null, System.nanoTime(), false);
-        testAllocator.allocateUnassigned(allocation);
-        assertThat(allocation.routingNodesChanged(), equalTo(true));
-        assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(1));
-        assertThat(allocation.routingNodes().unassigned().ignored().get(0).shardId(), equalTo(shardId));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.UNASSIGNED).size(), equalTo(2)); // replicas
-        assertClusterHealthStatus(allocation, ClusterHealthStatus.RED);
-
-        testAllocator.addData(node2, 1, null, randomBoolean());
-        allocation = new RoutingAllocation(yesAllocationDeciders(), new RoutingNodes(state, false), state, null, System.nanoTime(), false);
-        testAllocator.allocateUnassigned(allocation);
-        assertThat(allocation.routingNodesChanged(), equalTo(true));
-        assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(0));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.UNASSIGNED).size(), equalTo(2)); // replicas
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).size(), equalTo(1));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).currentNodeId(), anyOf(equalTo(node2.getId()), equalTo(node1.getId())));
-        assertClusterHealthStatus(allocation, ClusterHealthStatus.RED);
-    }
-
-    /**
-     * Tests that only when enough copies of the shard exists we are going to allocate it. This test
-     * verifies that even with different version, we treat different versions as a copy, and count them.
-     */
-    public void testEnoughCopiesFoundForAllocationOnLegacyIndexWithDifferentVersion() {
-        MetaData metaData = MetaData.builder()
-                .put(IndexMetaData.builder(shardId.getIndexName()).settings(settings(Version.V_2_0_0)).numberOfShards(1).numberOfReplicas(2))
-                .build();
-        RoutingTable routingTable = RoutingTable.builder()
-                .addAsRecovery(metaData.index(shardId.getIndex()))
-                .build();
-        ClusterState state = ClusterState.builder(org.elasticsearch.cluster.ClusterName.CLUSTER_NAME_SETTING.getDefault(Settings.EMPTY))
-                .metaData(metaData)
-                .routingTable(routingTable)
-                .nodes(DiscoveryNodes.builder().add(node1).add(node2).add(node3)).build();
-
-        RoutingAllocation allocation = new RoutingAllocation(yesAllocationDeciders(), new RoutingNodes(state, false), state, null, System.nanoTime(), false);
-        testAllocator.allocateUnassigned(allocation);
-        assertThat(allocation.routingNodesChanged(), equalTo(true));
-        assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(1));
-        assertThat(allocation.routingNodes().unassigned().ignored().get(0).shardId(), equalTo(shardId));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.UNASSIGNED).size(), equalTo(2)); // replicas
-        assertClusterHealthStatus(allocation, ClusterHealthStatus.RED);
-
-        testAllocator.addData(node1, 1, null, randomBoolean());
-        allocation = new RoutingAllocation(yesAllocationDeciders(), new RoutingNodes(state, false), state, null, System.nanoTime(), false);
-        testAllocator.allocateUnassigned(allocation);
-        assertThat(allocation.routingNodesChanged(), equalTo(true));
-        assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(1));
-        assertThat(allocation.routingNodes().unassigned().ignored().get(0).shardId(), equalTo(shardId));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.UNASSIGNED).size(), equalTo(2)); // replicas
-        assertClusterHealthStatus(allocation, ClusterHealthStatus.RED);
-
-        testAllocator.addData(node2, 2, null, randomBoolean());
-        allocation = new RoutingAllocation(yesAllocationDeciders(), new RoutingNodes(state, false), state, null, System.nanoTime(), false);
-        testAllocator.allocateUnassigned(allocation);
-        assertThat(allocation.routingNodesChanged(), equalTo(true));
-        assertThat(allocation.routingNodes().unassigned().ignored().size(), equalTo(0));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.UNASSIGNED).size(), equalTo(2)); // replicas
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).size(), equalTo(1));
-        assertThat(allocation.routingNodes().shardsWithState(ShardRoutingState.INITIALIZING).get(0).currentNodeId(), equalTo(node2.getId()));
-        assertClusterHealthStatus(allocation, ClusterHealthStatus.RED);
-    }
-
-    private RoutingAllocation routingAllocationWithOnePrimaryNoReplicas(AllocationDeciders deciders,
-                                                                        UnassignedInfo.Reason reason, Version version,
+    private RoutingAllocation routingAllocationWithOnePrimaryNoReplicas(AllocationDeciders deciders, UnassignedInfo.Reason reason,
                                                                         String... activeAllocationIds) {
         MetaData metaData = MetaData.builder()
-                .put(IndexMetaData.builder(shardId.getIndexName()).settings(settings(version))
+                .put(IndexMetaData.builder(shardId.getIndexName()).settings(settings(Version.CURRENT))
                     .numberOfShards(1).numberOfReplicas(0).putInSyncAllocationIds(shardId.id(), Sets.newHashSet(activeAllocationIds)))
                 .build();
         RoutingTable.Builder routingTableBuilder = RoutingTable.builder();
@@ -773,15 +550,15 @@ public class PrimaryShardAllocatorTests extends ESAllocationTestCase {
             return this;
         }
 
-        public TestAllocator addData(DiscoveryNode node, long version, String allocationId, boolean primary) {
-            return addData(node, version, allocationId, primary, null);
+        public TestAllocator addData(DiscoveryNode node, String allocationId, boolean primary) {
+            return addData(node, allocationId, primary, null);
         }
 
-        public TestAllocator addData(DiscoveryNode node, long version, String allocationId, boolean primary, @Nullable Exception storeException) {
+        public TestAllocator addData(DiscoveryNode node, String allocationId, boolean primary, @Nullable Exception storeException) {
             if (data == null) {
                 data = new HashMap<>();
             }
-            data.put(node, new TransportNodesListGatewayStartedShards.NodeGatewayStartedShards(node, version, allocationId, primary, storeException));
+            data.put(node, new TransportNodesListGatewayStartedShards.NodeGatewayStartedShards(node, allocationId, primary, storeException));
             return this;
         }
 

core/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java

@@ -158,20 +158,19 @@ public class IndexShardTests extends IndexShardTestCase {
     public void testWriteShardState() throws Exception {
         try (NodeEnvironment env = newNodeEnvironment()) {
             ShardId id = new ShardId("foo", "fooUUID", 1);
-            long version = between(1, Integer.MAX_VALUE / 2);
             boolean primary = randomBoolean();
             AllocationId allocationId = randomBoolean() ? null : randomAllocationId();
-            ShardStateMetaData state1 = new ShardStateMetaData(version, primary, "fooUUID", allocationId);
+            ShardStateMetaData state1 = new ShardStateMetaData(primary, "fooUUID", allocationId);
             write(state1, env.availableShardPaths(id));
             ShardStateMetaData shardStateMetaData = load(logger, env.availableShardPaths(id));
             assertEquals(shardStateMetaData, state1);
 
-            ShardStateMetaData state2 = new ShardStateMetaData(version, primary, "fooUUID", allocationId);
+            ShardStateMetaData state2 = new ShardStateMetaData(primary, "fooUUID", allocationId);
             write(state2, env.availableShardPaths(id));
             shardStateMetaData = load(logger, env.availableShardPaths(id));
             assertEquals(shardStateMetaData, state1);
 
-            ShardStateMetaData state3 = new ShardStateMetaData(version + 1, primary, "fooUUID", allocationId);
+            ShardStateMetaData state3 = new ShardStateMetaData(primary, "fooUUID", allocationId);
             write(state3, env.availableShardPaths(id));
             shardStateMetaData = load(logger, env.availableShardPaths(id));
             assertEquals(shardStateMetaData, state3);
@@ -236,21 +235,20 @@ public class IndexShardTests extends IndexShardTestCase {
 
     public void testShardStateMetaHashCodeEquals() {
         AllocationId allocationId = randomBoolean() ? null : randomAllocationId();
-        ShardStateMetaData meta = new ShardStateMetaData(randomLong(), randomBoolean(),
+        ShardStateMetaData meta = new ShardStateMetaData(randomBoolean(),
             randomRealisticUnicodeOfCodepointLengthBetween(1, 10), allocationId);
 
-        assertEquals(meta, new ShardStateMetaData(meta.legacyVersion, meta.primary, meta.indexUUID, meta.allocationId));
+        assertEquals(meta, new ShardStateMetaData(meta.primary, meta.indexUUID, meta.allocationId));
         assertEquals(meta.hashCode(),
-            new ShardStateMetaData(meta.legacyVersion, meta.primary, meta.indexUUID, meta.allocationId).hashCode());
+            new ShardStateMetaData(meta.primary, meta.indexUUID, meta.allocationId).hashCode());
 
-        assertFalse(meta.equals(new ShardStateMetaData(meta.legacyVersion, !meta.primary, meta.indexUUID, meta.allocationId)));
-        assertFalse(meta.equals(new ShardStateMetaData(meta.legacyVersion + 1, meta.primary, meta.indexUUID, meta.allocationId)));
-        assertFalse(meta.equals(new ShardStateMetaData(meta.legacyVersion, !meta.primary, meta.indexUUID + "foo", meta.allocationId)));
-        assertFalse(meta.equals(new ShardStateMetaData(meta.legacyVersion, !meta.primary, meta.indexUUID + "foo", randomAllocationId())));
+        assertFalse(meta.equals(new ShardStateMetaData(!meta.primary, meta.indexUUID, meta.allocationId)));
+        assertFalse(meta.equals(new ShardStateMetaData(!meta.primary, meta.indexUUID + "foo", meta.allocationId)));
+        assertFalse(meta.equals(new ShardStateMetaData(!meta.primary, meta.indexUUID + "foo", randomAllocationId())));
         Set<Integer> hashCodes = new HashSet<>();
         for (int i = 0; i < 30; i++) { // just a sanity check that we impl hashcode
             allocationId = randomBoolean() ? null : randomAllocationId();
-            meta = new ShardStateMetaData(randomLong(), randomBoolean(),
+            meta = new ShardStateMetaData(randomBoolean(),
                 randomRealisticUnicodeOfCodepointLengthBetween(1, 10), allocationId);
             hashCodes.add(meta.hashCode());
         }

core/src/test/java/org/elasticsearch/index/shard/ShardPathTests.java

@@ -43,7 +43,7 @@ public class ShardPathTests extends ESTestCase {
             ShardId shardId = new ShardId("foo", "0xDEADBEEF", 0);
             Path[] paths = env.availableShardPaths(shardId);
             Path path = randomFrom(paths);
-            ShardStateMetaData.FORMAT.write(new ShardStateMetaData(2, true, "0xDEADBEEF", AllocationId.newInitializing()), path);
+            ShardStateMetaData.FORMAT.write(new ShardStateMetaData(true, "0xDEADBEEF", AllocationId.newInitializing()), path);
             ShardPath shardPath = ShardPath.loadShardPath(logger, env, shardId, IndexSettingsModule.newIndexSettings(shardId.getIndex(), settings));
             assertEquals(path, shardPath.getDataPath());
             assertEquals("0xDEADBEEF", shardPath.getShardId().getIndex().getUUID());
@@ -62,8 +62,7 @@ public class ShardPathTests extends ESTestCase {
             ShardId shardId = new ShardId("foo", indexUUID, 0);
             Path[] paths = env.availableShardPaths(shardId);
             assumeTrue("This test tests multi data.path but we only got one", paths.length > 1);
-            int id = randomIntBetween(1, 10);
-            ShardStateMetaData.FORMAT.write(new ShardStateMetaData(id, true, indexUUID, AllocationId.newInitializing()), paths);
+            ShardStateMetaData.FORMAT.write(new ShardStateMetaData(true, indexUUID, AllocationId.newInitializing()), paths);
             Exception e = expectThrows(IllegalStateException.class, () ->
                 ShardPath.loadShardPath(logger, env, shardId, IndexSettingsModule.newIndexSettings(shardId.getIndex(), settings)));
             assertThat(e.getMessage(), containsString("more than one shard state found"));
@@ -78,8 +77,7 @@ public class ShardPathTests extends ESTestCase {
             ShardId shardId = new ShardId("foo", "foobar", 0);
             Path[] paths = env.availableShardPaths(shardId);
             Path path = randomFrom(paths);
-            int id = randomIntBetween(1, 10);
-            ShardStateMetaData.FORMAT.write(new ShardStateMetaData(id, true, "0xDEADBEEF", AllocationId.newInitializing()), path);
+            ShardStateMetaData.FORMAT.write(new ShardStateMetaData(true, "0xDEADBEEF", AllocationId.newInitializing()), path);
             Exception e = expectThrows(IllegalStateException.class, () ->
                 ShardPath.loadShardPath(logger, env, shardId, IndexSettingsModule.newIndexSettings(shardId.getIndex(), settings)));
             assertThat(e.getMessage(), containsString("expected: foobar on shard path"));
@@ -131,7 +129,7 @@ public class ShardPathTests extends ESTestCase {
             ShardId shardId = new ShardId("foo", indexUUID, 0);
             Path[] paths = env.availableShardPaths(shardId);
             Path path = randomFrom(paths);
-            ShardStateMetaData.FORMAT.write(new ShardStateMetaData(2, true, indexUUID, AllocationId.newInitializing()), path);
+            ShardStateMetaData.FORMAT.write(new ShardStateMetaData(true, indexUUID, AllocationId.newInitializing()), path);
             ShardPath shardPath = ShardPath.loadShardPath(logger, env, shardId,
                 IndexSettingsModule.newIndexSettings(shardId.getIndex(), indexSettings, nodeSettings));
             boolean found = false;

core/src/test/java/org/elasticsearch/index/store/CorruptedFileIT.java

@@ -537,7 +537,6 @@ public class CorruptedFileIT extends ESIntegTestCase {
         internalCluster().ensureAtLeastNumDataNodes(2);
 
         assertAcked(prepareCreate("test").setSettings(Settings.builder()
-            .put(PrimaryShardAllocator.INDEX_RECOVERY_INITIAL_SHARDS_SETTING.getKey(), "one")
             .put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, cluster().numDataNodes() - 1)
             .put(MergePolicyConfig.INDEX_MERGE_ENABLED, false)
             .put(MockFSIndexStore.INDEX_CHECK_INDEX_ON_CLOSE_SETTING.getKey(), false) // no checkindex - we corrupt shards on purpose

core/src/test/java/org/elasticsearch/indices/settings/UpdateSettingsIT.java

@@ -191,20 +191,17 @@ public class UpdateSettingsIT extends ESIntegTestCase {
 
         client().admin().indices().prepareClose("test").execute().actionGet();
 
-        try {
-            client()
-                .admin()
-                .indices()
-                .prepareUpdateSettings("test")
-                .setSettings(Settings.builder().put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, 1))
-                .execute()
-                .actionGet();
-            fail("can't change number of replicas on a closed index");
-        } catch (IllegalArgumentException ex) {
-            assertTrue(ex.getMessage(), ex.getMessage().startsWith("Can't update [index.number_of_replicas] on closed indices [[test/"));
-            assertTrue(ex.getMessage(), ex.getMessage().endsWith("]] - can leave index in an unopenable state"));
-            // expected
-        }
+        client()
+            .admin()
+            .indices()
+            .prepareUpdateSettings("test")
+            .setSettings(Settings.builder().put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, 1))
+            .execute()
+            .actionGet();
+
+        indexMetaData = client().admin().cluster().prepareState().execute().actionGet().getState().metaData().index("test");
+        assertThat(indexMetaData.getNumberOfReplicas(), equalTo(1));
+
         client()
             .admin()
             .indices()

docs/reference/indices/shard-stores.asciidoc

@@ -52,9 +52,8 @@ The shard stores information is grouped by indices and shard ids.
                     }
                 },
                 "allocation_id": "2iNySv_OQVePRX-yaRH_lQ", <4>
-                "legacy_version": 42, <5>
-                "allocation" : "primary" | "replica" | "unused", <6>
-                "store_exception": ... <7>
+                "allocation" : "primary" | "replica" | "unused", <5>
+                "store_exception": ... <6>
             },
             ...
         ]
@@ -67,9 +66,7 @@ The shard stores information is grouped by indices and shard ids.
 <3> The node information that hosts a copy of the store, the key
     is the unique node id.
 <4> The allocation id of the store copy
-<5> The version of the store copy (available only for legacy shard copies that have
-    not yet been active in a current version of Elasticsearch)
-<6> The status of the store copy, whether it is used as a
+<5> The status of the store copy, whether it is used as a
     primary, replica or not used at all
-<7> Any exception encountered while opening the shard index or
+<6> Any exception encountered while opening the shard index or
     from earlier engine failure

test/framework/src/main/java/org/elasticsearch/test/gateway/TestGatewayAllocator.java

@@ -75,7 +75,7 @@ public class TestGatewayAllocator extends GatewayAllocator {
                     routing -> currentNodes.get(routing.currentNodeId()),
                     routing ->
                         new NodeGatewayStartedShards(
-                            currentNodes.get(routing.currentNodeId()), -1, routing.allocationId().getId(), routing.primary())));
+                            currentNodes.get(routing.currentNodeId()), routing.allocationId().getId(), routing.primary())));
 
             return new AsyncShardFetch.FetchResult<>(shardId, foundShards, Collections.emptySet(), ignoreNodes);
         }