diff --git a/plugin/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java b/plugin/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java
index 1c73460e59d..8901ada643a 100644
--- a/plugin/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java
+++ b/plugin/src/main/java/org/elasticsearch/xpack/ml/MachineLearning.java
@@ -124,13 +124,13 @@ import org.elasticsearch.xpack.ml.rest.validate.RestValidateDetectorAction;
 import org.elasticsearch.xpack.ml.rest.validate.RestValidateJobConfigAction;
 import org.elasticsearch.xpack.persistent.CompletionPersistentTaskAction;
 import org.elasticsearch.xpack.persistent.PersistentTaskParams;
-import org.elasticsearch.xpack.persistent.StartPersistentTaskAction;
 import org.elasticsearch.xpack.persistent.PersistentTasksClusterService;
 import org.elasticsearch.xpack.persistent.PersistentTasksCustomMetaData;
 import org.elasticsearch.xpack.persistent.PersistentTasksExecutorRegistry;
 import org.elasticsearch.xpack.persistent.PersistentTasksNodeService;
 import org.elasticsearch.xpack.persistent.PersistentTasksService;
 import org.elasticsearch.xpack.persistent.RemovePersistentTaskAction;
+import org.elasticsearch.xpack.persistent.StartPersistentTaskAction;
 import org.elasticsearch.xpack.persistent.UpdatePersistentTaskStatusAction;
 import org.elasticsearch.xpack.security.InternalClient;
 
@@ -155,6 +155,7 @@ public class MachineLearning implements ActionPlugin {
             Setting.boolSetting("xpack.ml.autodetect_process", true, Property.NodeScope);
     public static final Setting<Boolean> ML_ENABLED =
             Setting.boolSetting("node.ml", XPackSettings.MACHINE_LEARNING_ENABLED, Setting.Property.NodeScope);
+    public static final String ML_ENABLED_NODE_ATTR = "ml.enabled";
     public static final Setting<Integer> CONCURRENT_JOB_ALLOCATIONS =
             Setting.intSetting("xpack.ml.node_concurrent_job_allocations", 2, 0, Property.Dynamic, Property.NodeScope);
 
@@ -198,9 +199,7 @@ public class MachineLearning implements ActionPlugin {
         Settings.Builder additionalSettings = Settings.builder();
         Boolean allocationEnabled = ML_ENABLED.get(settings);
         if (allocationEnabled != null && allocationEnabled) {
-            // Copy max_running_jobs setting to node attribute, so that we use this information when assigning job tasks to nodes:
-            additionalSettings.put("node.attr." + AutodetectProcessManager.MAX_RUNNING_JOBS_PER_NODE.getKey(),
-                    AutodetectProcessManager.MAX_RUNNING_JOBS_PER_NODE.get(settings));
+            additionalSettings.put("node.attr." + ML_ENABLED_NODE_ATTR, "true");
         }
         return additionalSettings.build();
     }
diff --git a/plugin/src/main/java/org/elasticsearch/xpack/ml/action/OpenJobAction.java b/plugin/src/main/java/org/elasticsearch/xpack/ml/action/OpenJobAction.java
index ca94ce6bc1e..5e3fd5f6559 100644
--- a/plugin/src/main/java/org/elasticsearch/xpack/ml/action/OpenJobAction.java
+++ b/plugin/src/main/java/org/elasticsearch/xpack/ml/action/OpenJobAction.java
@@ -378,6 +378,7 @@ public class OpenJobAction extends Action<OpenJobAction.Request, OpenJobAction.R
         private final AutodetectProcessManager autodetectProcessManager;
         private final XPackLicenseState licenseState;
 
+        private final int maxNumberOfOpenJobs;
         private volatile int maxConcurrentJobAllocations;
 
         public OpenJobPersistentTasksExecutor(Settings settings, XPackLicenseState licenseState,
@@ -385,6 +386,7 @@ public class OpenJobAction extends Action<OpenJobAction.Request, OpenJobAction.R
             super(settings, NAME, ThreadPool.Names.MANAGEMENT);
             this.licenseState = licenseState;
             this.autodetectProcessManager = autodetectProcessManager;
+            this.maxNumberOfOpenJobs = AutodetectProcessManager.MAX_RUNNING_JOBS_PER_NODE.get(settings);
             this.maxConcurrentJobAllocations = MachineLearning.CONCURRENT_JOB_ALLOCATIONS.get(settings);
             clusterService.getClusterSettings()
                     .addSettingsUpdateConsumer(MachineLearning.CONCURRENT_JOB_ALLOCATIONS, this::setMaxConcurrentJobAllocations);
@@ -392,7 +394,7 @@ public class OpenJobAction extends Action<OpenJobAction.Request, OpenJobAction.R
 
         @Override
         public Assignment getAssignment(Request request, ClusterState clusterState) {
-            return selectLeastLoadedMlNode(request.getJobId(), clusterState, maxConcurrentJobAllocations, logger);
+            return selectLeastLoadedMlNode(request.getJobId(), clusterState, maxConcurrentJobAllocations, maxNumberOfOpenJobs, logger);
         }
 
         @Override
@@ -403,7 +405,8 @@ public class OpenJobAction extends Action<OpenJobAction.Request, OpenJobAction.R
                 MlMetadata mlMetadata = clusterState.metaData().custom(MlMetadata.TYPE);
                 PersistentTasksCustomMetaData tasks = clusterState.getMetaData().custom(PersistentTasksCustomMetaData.TYPE);
                 OpenJobAction.validate(request.getJobId(), mlMetadata, tasks);
-                Assignment assignment = selectLeastLoadedMlNode(request.getJobId(), clusterState, maxConcurrentJobAllocations, logger);
+                Assignment assignment = selectLeastLoadedMlNode(request.getJobId(), clusterState, maxConcurrentJobAllocations,
+                        maxNumberOfOpenJobs, logger);
                 if (assignment.getExecutorNode() == null) {
                     String msg = "Could not open job because no suitable nodes were found, allocation explanation ["
                             + assignment.getExplanation() + "]";
@@ -456,7 +459,7 @@ public class OpenJobAction extends Action<OpenJobAction.Request, OpenJobAction.R
     }
 
     static Assignment selectLeastLoadedMlNode(String jobId, ClusterState clusterState, int maxConcurrentJobAllocations,
-                                              Logger logger) {
+                                              long maxNumberOfOpenJobs, Logger logger) {
         List<String> unavailableIndices = verifyIndicesPrimaryShardsAreActive(jobId, clusterState);
         if (unavailableIndices.size() != 0) {
             String reason = "Not opening job [" + jobId + "], because not all primary shards are active for the following indices [" +
@@ -471,8 +474,8 @@ public class OpenJobAction extends Action<OpenJobAction.Request, OpenJobAction.R
         PersistentTasksCustomMetaData persistentTasks = clusterState.getMetaData().custom(PersistentTasksCustomMetaData.TYPE);
         for (DiscoveryNode node : clusterState.getNodes()) {
             Map<String, String> nodeAttributes = node.getAttributes();
-            String maxNumberOfOpenJobsStr = nodeAttributes.get(AutodetectProcessManager.MAX_RUNNING_JOBS_PER_NODE.getKey());
-            if (maxNumberOfOpenJobsStr == null) {
+            String enabled = nodeAttributes.get(MachineLearning.ML_ENABLED_NODE_ATTR);
+            if (Boolean.valueOf(enabled) == false) {
                 String reason = "Not opening job [" + jobId + "] on node [" + node + "], because this node isn't a ml node.";
                 logger.trace(reason);
                 reasons.add(reason);
@@ -504,7 +507,6 @@ public class OpenJobAction extends Action<OpenJobAction.Request, OpenJobAction.R
                 continue;
             }
 
-            long maxNumberOfOpenJobs = Long.parseLong(maxNumberOfOpenJobsStr);
             long available = maxNumberOfOpenJobs - numberOfAssignedJobs;
             if (available == 0) {
                 String reason = "Not opening job [" + jobId + "] on node [" + node + "], because this node is full. " +
diff --git a/plugin/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/AutodetectProcessManager.java b/plugin/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/AutodetectProcessManager.java
index 9b8e2e53ae0..b983518dc32 100644
--- a/plugin/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/AutodetectProcessManager.java
+++ b/plugin/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/AutodetectProcessManager.java
@@ -77,6 +77,10 @@ public class AutodetectProcessManager extends AbstractComponent {
     // and if we know that then we can prior to assigning a job to a node fail based on the
     // available resources on that node: https://github.com/elastic/x-pack-elasticsearch/issues/546
     // Note: on small instances on cloud, this setting will be set to: 1
+
+    // WARNING: This setting cannot be made DYNAMIC, because it is tied to several threadpools
+    // and a threadpool's size can't be changed at runtime.
+    // See MachineLearning#getExecutorBuilders(...)
     public static final Setting<Integer> MAX_RUNNING_JOBS_PER_NODE =
             Setting.intSetting("max_running_jobs", 10, 1, 512, Setting.Property.NodeScope);
 
diff --git a/plugin/src/main/java/org/elasticsearch/xpack/ml/notifications/Auditor.java b/plugin/src/main/java/org/elasticsearch/xpack/ml/notifications/Auditor.java
index a675c1686a1..dad9c1b7786 100644
--- a/plugin/src/main/java/org/elasticsearch/xpack/ml/notifications/Auditor.java
+++ b/plugin/src/main/java/org/elasticsearch/xpack/ml/notifications/Auditor.java
@@ -56,7 +56,7 @@ public class Auditor {
 
                     @Override
                     public void onFailure(Exception e) {
-                        LOGGER.error(new ParameterizedMessage("Error writing {}", new Object[]{type}, e));
+                        LOGGER.debug(new ParameterizedMessage("Error writing {}", new Object[]{type}, e));
                     }
                 });
     }
diff --git a/plugin/src/test/java/org/elasticsearch/xpack/ml/action/OpenJobActionTests.java b/plugin/src/test/java/org/elasticsearch/xpack/ml/action/OpenJobActionTests.java
index 6f528cbcbec..44c31b55ad9 100644
--- a/plugin/src/test/java/org/elasticsearch/xpack/ml/action/OpenJobActionTests.java
+++ b/plugin/src/test/java/org/elasticsearch/xpack/ml/action/OpenJobActionTests.java
@@ -25,6 +25,7 @@ import org.elasticsearch.common.transport.TransportAddress;
 import org.elasticsearch.index.Index;
 import org.elasticsearch.index.shard.ShardId;
 import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.xpack.ml.MachineLearning;
 import org.elasticsearch.xpack.ml.MlMetadata;
 import org.elasticsearch.xpack.ml.job.config.Job;
 import org.elasticsearch.xpack.ml.job.config.JobState;
@@ -44,7 +45,6 @@ import java.util.List;
 import java.util.Map;
 
 import static org.elasticsearch.xpack.ml.job.config.JobTests.buildJobBuilder;
-import static org.elasticsearch.xpack.ml.job.process.autodetect.AutodetectProcessManager.MAX_RUNNING_JOBS_PER_NODE;
 
 public class OpenJobActionTests extends ESTestCase {
 
@@ -79,7 +79,7 @@ public class OpenJobActionTests extends ESTestCase {
 
     public void testSelectLeastLoadedMlNode() {
         Map<String, String> nodeAttr = new HashMap<>();
-        nodeAttr.put(MAX_RUNNING_JOBS_PER_NODE.getKey(), "10");
+        nodeAttr.put(MachineLearning.ML_ENABLED_NODE_ATTR, "true");
         DiscoveryNodes nodes = DiscoveryNodes.builder()
                 .add(new DiscoveryNode("_node_name1", "_node_id1", new TransportAddress(InetAddress.getLoopbackAddress(), 9300),
                         nodeAttr, Collections.emptySet(), Version.CURRENT))
@@ -103,7 +103,7 @@ public class OpenJobActionTests extends ESTestCase {
         metaData.putCustom(PersistentTasksCustomMetaData.TYPE, tasks);
         cs.metaData(metaData);
         cs.routingTable(routingTable.build());
-        Assignment result = OpenJobAction.selectLeastLoadedMlNode("job_id4", cs.build(), 2, logger);
+        Assignment result = OpenJobAction.selectLeastLoadedMlNode("job_id4", cs.build(), 2, 10, logger);
         assertEquals("_node_id3", result.getExecutorNode());
     }
 
@@ -112,7 +112,7 @@ public class OpenJobActionTests extends ESTestCase {
         int maxRunningJobsPerNode = randomIntBetween(1, 100);
 
         Map<String, String> nodeAttr = new HashMap<>();
-        nodeAttr.put(MAX_RUNNING_JOBS_PER_NODE.getKey(), String.valueOf(maxRunningJobsPerNode));
+        nodeAttr.put(MachineLearning.ML_ENABLED_NODE_ATTR, "true");
         DiscoveryNodes.Builder nodes = DiscoveryNodes.builder();
         PersistentTasksCustomMetaData.Builder tasksBuilder = PersistentTasksCustomMetaData.builder();
         for (int i = 0; i < numNodes; i++) {
@@ -134,7 +134,7 @@ public class OpenJobActionTests extends ESTestCase {
         metaData.putCustom(PersistentTasksCustomMetaData.TYPE, tasks);
         cs.metaData(metaData);
         cs.routingTable(routingTable.build());
-        Assignment result = OpenJobAction.selectLeastLoadedMlNode("job_id2", cs.build(), 2, logger);
+        Assignment result = OpenJobAction.selectLeastLoadedMlNode("job_id2", cs.build(), 2, maxRunningJobsPerNode, logger);
         assertNull(result.getExecutorNode());
         assertTrue(result.getExplanation().contains("because this node is full. Number of opened jobs [" + maxRunningJobsPerNode
                 + "], max_running_jobs [" + maxRunningJobsPerNode + "]"));
@@ -160,14 +160,14 @@ public class OpenJobActionTests extends ESTestCase {
         metaData.putCustom(PersistentTasksCustomMetaData.TYPE, tasks);
         cs.metaData(metaData);
         cs.routingTable(routingTable.build());
-        Assignment result = OpenJobAction.selectLeastLoadedMlNode("job_id2", cs.build(), 2, logger);
+        Assignment result = OpenJobAction.selectLeastLoadedMlNode("job_id2", cs.build(), 2, 10, logger);
         assertTrue(result.getExplanation().contains("because this node isn't a ml node"));
         assertNull(result.getExecutorNode());
     }
 
     public void testSelectLeastLoadedMlNode_maxConcurrentOpeningJobs() {
         Map<String, String> nodeAttr = new HashMap<>();
-        nodeAttr.put(MAX_RUNNING_JOBS_PER_NODE.getKey(), "10");
+        nodeAttr.put(MachineLearning.ML_ENABLED_NODE_ATTR, "true");
         DiscoveryNodes nodes = DiscoveryNodes.builder()
                 .add(new DiscoveryNode("_node_name1", "_node_id1", new TransportAddress(InetAddress.getLoopbackAddress(), 9300),
                         nodeAttr, Collections.emptySet(), Version.CURRENT))
@@ -195,7 +195,7 @@ public class OpenJobActionTests extends ESTestCase {
         csBuilder.metaData(metaData);
 
         ClusterState cs = csBuilder.build();
-        Assignment result = OpenJobAction.selectLeastLoadedMlNode("job_id6", cs, 2, logger);
+        Assignment result = OpenJobAction.selectLeastLoadedMlNode("job_id6", cs, 2, 10, logger);
         assertEquals("_node_id3", result.getExecutorNode());
 
         tasksBuilder = PersistentTasksCustomMetaData.builder(tasks);
@@ -205,7 +205,7 @@ public class OpenJobActionTests extends ESTestCase {
         csBuilder = ClusterState.builder(cs);
         csBuilder.metaData(MetaData.builder(cs.metaData()).putCustom(PersistentTasksCustomMetaData.TYPE, tasks));
         cs = csBuilder.build();
-        result = OpenJobAction.selectLeastLoadedMlNode("job_id7", cs, 2, logger);
+        result = OpenJobAction.selectLeastLoadedMlNode("job_id7", cs, 2, 10, logger);
         assertNull("no node selected, because OPENING state", result.getExecutorNode());
         assertTrue(result.getExplanation().contains("because node exceeds [2] the maximum number of jobs [2] in opening state"));
 
@@ -216,7 +216,7 @@ public class OpenJobActionTests extends ESTestCase {
         csBuilder = ClusterState.builder(cs);
         csBuilder.metaData(MetaData.builder(cs.metaData()).putCustom(PersistentTasksCustomMetaData.TYPE, tasks));
         cs = csBuilder.build();
-        result = OpenJobAction.selectLeastLoadedMlNode("job_id7", cs, 2, logger);
+        result = OpenJobAction.selectLeastLoadedMlNode("job_id7", cs, 2, 10, logger);
         assertNull("no node selected, because stale task", result.getExecutorNode());
         assertTrue(result.getExplanation().contains("because node exceeds [2] the maximum number of jobs [2] in opening state"));
 
@@ -227,7 +227,7 @@ public class OpenJobActionTests extends ESTestCase {
         csBuilder = ClusterState.builder(cs);
         csBuilder.metaData(MetaData.builder(cs.metaData()).putCustom(PersistentTasksCustomMetaData.TYPE, tasks));
         cs = csBuilder.build();
-        result = OpenJobAction.selectLeastLoadedMlNode("job_id7", cs, 2, logger);
+        result = OpenJobAction.selectLeastLoadedMlNode("job_id7", cs, 2, 10, logger);
         assertNull("no node selected, because null state", result.getExecutorNode());
         assertTrue(result.getExplanation().contains("because node exceeds [2] the maximum number of jobs [2] in opening state"));
     }
diff --git a/plugin/src/test/java/org/elasticsearch/xpack/ml/integration/BasicDistributedJobsIT.java b/plugin/src/test/java/org/elasticsearch/xpack/ml/integration/BasicDistributedJobsIT.java
index f9d558a6ce6..61218f9ca8b 100644
--- a/plugin/src/test/java/org/elasticsearch/xpack/ml/integration/BasicDistributedJobsIT.java
+++ b/plugin/src/test/java/org/elasticsearch/xpack/ml/integration/BasicDistributedJobsIT.java
@@ -41,8 +41,6 @@ import java.util.Map;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.TimeUnit;
 
-import static org.elasticsearch.xpack.ml.job.process.autodetect.AutodetectProcessManager.MAX_RUNNING_JOBS_PER_NODE;
-
 public class BasicDistributedJobsIT extends BaseMlIntegTestCase {
 
     public void testFailOverBasics() throws Exception {
@@ -173,7 +171,7 @@ public class BasicDistributedJobsIT extends BaseMlIntegTestCase {
 
             DiscoveryNode node = clusterState.nodes().resolveNode(task.getExecutorNode());
             Map<String, String> expectedNodeAttr = new HashMap<>();
-            expectedNodeAttr.put(MAX_RUNNING_JOBS_PER_NODE.getKey(), "10");
+            expectedNodeAttr.put(MachineLearning.ML_ENABLED_NODE_ATTR, "true");
             assertEquals(expectedNodeAttr, node.getAttributes());
             JobTaskStatus jobTaskStatus = (JobTaskStatus) task.getStatus();
             assertNotNull(jobTaskStatus);
@@ -379,7 +377,7 @@ public class BasicDistributedJobsIT extends BaseMlIntegTestCase {
             assertFalse(task.needsReassignment(clusterState.nodes()));
             DiscoveryNode node = clusterState.nodes().resolveNode(task.getExecutorNode());
             Map<String, String> expectedNodeAttr = new HashMap<>();
-            expectedNodeAttr.put(MAX_RUNNING_JOBS_PER_NODE.getKey(), "10");
+            expectedNodeAttr.put(MachineLearning.ML_ENABLED_NODE_ATTR, "true");
             assertEquals(expectedNodeAttr, node.getAttributes());
 
             JobTaskStatus jobTaskStatus = (JobTaskStatus) task.getStatus();
diff --git a/plugin/src/test/resources/rest-api-spec/test/ml/get_datafeed_stats.yaml b/plugin/src/test/resources/rest-api-spec/test/ml/get_datafeed_stats.yaml
index d33c449e6d3..f5fd378f390 100644
--- a/plugin/src/test/resources/rest-api-spec/test/ml/get_datafeed_stats.yaml
+++ b/plugin/src/test/resources/rest-api-spec/test/ml/get_datafeed_stats.yaml
@@ -111,7 +111,7 @@ setup:
   - match: { datafeeds.0.state: "started"}
   - is_true: datafeeds.0.node.name
   - is_true: datafeeds.0.node.transport_address
-  - match: { datafeeds.0.node.attributes.max_running_jobs: "10"}
+  - match: { datafeeds.0.node.attributes.ml\.enabled: "true"}
 
 ---
 "Test implicit get all datafeed stats given started datafeeds":
diff --git a/plugin/src/test/resources/rest-api-spec/test/ml/jobs_get_stats.yaml b/plugin/src/test/resources/rest-api-spec/test/ml/jobs_get_stats.yaml
index d4df12f7362..fcc831a021a 100644
--- a/plugin/src/test/resources/rest-api-spec/test/ml/jobs_get_stats.yaml
+++ b/plugin/src/test/resources/rest-api-spec/test/ml/jobs_get_stats.yaml
@@ -79,7 +79,7 @@ setup:
   - match: { jobs.0.state: opened }
   - is_true: jobs.0.node.name
   - is_true: jobs.0.node.transport_address
-  - match: { jobs.0.node.attributes.max_running_jobs: "10"}
+  - match: { jobs.0.node.attributes.ml\.enabled: "true"}
   - is_true: jobs.0.open_time
 
 ---