diff --git a/docs/clusterdefinition.md b/docs/clusterdefinition.md
index 6467f944a2..d00492a137 100644
--- a/docs/clusterdefinition.md
+++ b/docs/clusterdefinition.md
@@ -41,6 +41,7 @@ Here are the valid values for the orchestrator types:
 |enableRbac|no|Enable [Kubernetes RBAC](https://kubernetes.io/docs/admin/authorization/rbac/) (boolean - default == true) |
 |enableAggregatedAPIs|no|Enable [Kubernetes Aggregated APIs](https://kubernetes.io/docs/concepts/api-extension/apiserver-aggregation/).This is required by [Service Catalog](https://github.com/kubernetes-incubator/service-catalog/blob/master/README.md). (boolean - default == false) |
 |enableDataEncryptionAtRest|no|Enable [kuberetes data encryption at rest](https://kubernetes.io/docs/tasks/administer-cluster/encrypt-data/).This is currently an alpha feature. (boolean - default == false) |
+|etcdDiskSizeGB|no|Size in GB to assign to etcd data volume. Defaults (if no user value provided) are: 256 GB for clusters up to 3 nodes; 512 GB for clusters with between 4 and 10 nodes; 1024 GB for clusters with between 11 and 20 nodes; and 2048 GB for clusters with more than 20 nodes|
 |privateCluster|no|Build a cluster without public addresses assigned. See `privateClusters` [below](#feat-private-cluster).|
 |maxPods|no|The maximum number of pods per node. The minimum valid value, necessary for running kube-system pods, is 5. Default value is 30 when networkPolicy equals azure, 110 otherwise.|
 |gcHighThreshold|no|Sets the --image-gc-high-threshold value on the kublet configuration. Default is 85. [See kubelet Garbage Collection](https://kubernetes.io/docs/concepts/cluster-administration/kubelet-garbage-collection/) |
diff --git a/pkg/acsengine/const.go b/pkg/acsengine/const.go
index 0f40f07dc0..3849f5deb6 100644
--- a/pkg/acsengine/const.go
+++ b/pkg/acsengine/const.go
@@ -105,7 +105,13 @@ const (
 	// DefaultEtcdVersion specifies the default etcd version to install
 	DefaultEtcdVersion = "3.2.16"
 	// DefaultEtcdDiskSize specifies the default size for Kubernetes master etcd disk volumes in GB
-	DefaultEtcdDiskSize = "128"
+	DefaultEtcdDiskSize = "256"
+	// DefaultEtcdDiskSizeGT3Nodes = size for Kubernetes master etcd disk volumes in GB if > 3 nodes
+	DefaultEtcdDiskSizeGT3Nodes = "512"
+	// DefaultEtcdDiskSizeGT10Nodes = size for Kubernetes master etcd disk volumes in GB if > 10 nodes
+	DefaultEtcdDiskSizeGT10Nodes = "1024"
+	// DefaultEtcdDiskSizeGT20Nodes = size for Kubernetes master etcd disk volumes in GB if > 20 nodes
+	DefaultEtcdDiskSizeGT20Nodes = "2048"
 	// DefaultReschedulerAddonName is the name of the rescheduler addon deployment
 	DefaultReschedulerAddonName = "rescheduler"
 	// DefaultMetricsServerAddonName is the name of the kubernetes Metrics server addon deployment
diff --git a/pkg/acsengine/defaults.go b/pkg/acsengine/defaults.go
index 5e49bfefd4..43a5ca4722 100644
--- a/pkg/acsengine/defaults.go
+++ b/pkg/acsengine/defaults.go
@@ -446,7 +446,16 @@ func setOrchestratorDefaults(cs *api.ContainerService) {
 		}
 
 		if "" == a.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB {
-			a.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB = DefaultEtcdDiskSize
+			switch {
+			case a.TotalNodes() > 20:
+				a.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB = DefaultEtcdDiskSizeGT20Nodes
+			case a.TotalNodes() > 10:
+				a.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB = DefaultEtcdDiskSizeGT10Nodes
+			case a.TotalNodes() > 3:
+				a.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB = DefaultEtcdDiskSizeGT3Nodes
+			default:
+				a.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB = DefaultEtcdDiskSize
+			}
 		}
 
 		if a.OrchestratorProfile.KubernetesConfig.PrivateJumpboxProvision() && a.OrchestratorProfile.KubernetesConfig.PrivateCluster.JumpboxProfile.OSDiskSizeGB == 0 {
diff --git a/pkg/acsengine/defaults_test.go b/pkg/acsengine/defaults_test.go
index 951f1e5d73..69d0c310c2 100644
--- a/pkg/acsengine/defaults_test.go
+++ b/pkg/acsengine/defaults_test.go
@@ -326,6 +326,63 @@ func TestKubeletFeatureGatesEnsureMasterAndAgentConfigUsedFor1_6_0(t *testing.T)
 	}
 }
 
+func TestEtcdDiskSize(t *testing.T) {
+	mockCS := getMockBaseContainerService("1.8.10")
+	properties := mockCS.Properties
+	properties.OrchestratorProfile.OrchestratorType = "Kubernetes"
+	properties.MasterProfile.Count = 1
+	setOrchestratorDefaults(&mockCS)
+	if properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB != DefaultEtcdDiskSize {
+		t.Fatalf("EtcdDiskSizeGB did not have the expected size, got %s, expected %s",
+			properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB, DefaultEtcdDiskSize)
+	}
+
+	mockCS = getMockBaseContainerService("1.8.10")
+	properties = mockCS.Properties
+	properties.OrchestratorProfile.OrchestratorType = "Kubernetes"
+	properties.MasterProfile.Count = 5
+	setOrchestratorDefaults(&mockCS)
+	if properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB != DefaultEtcdDiskSizeGT3Nodes {
+		t.Fatalf("EtcdDiskSizeGB did not have the expected size, got %s, expected %s",
+			properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB, DefaultEtcdDiskSizeGT3Nodes)
+	}
+
+	mockCS = getMockBaseContainerService("1.8.10")
+	properties = mockCS.Properties
+	properties.OrchestratorProfile.OrchestratorType = "Kubernetes"
+	properties.MasterProfile.Count = 5
+	properties.AgentPoolProfiles[0].Count = 6
+	setOrchestratorDefaults(&mockCS)
+	if properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB != DefaultEtcdDiskSizeGT10Nodes {
+		t.Fatalf("EtcdDiskSizeGB did not have the expected size, got %s, expected %s",
+			properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB, DefaultEtcdDiskSizeGT10Nodes)
+	}
+
+	mockCS = getMockBaseContainerService("1.8.10")
+	properties = mockCS.Properties
+	properties.OrchestratorProfile.OrchestratorType = "Kubernetes"
+	properties.MasterProfile.Count = 5
+	properties.AgentPoolProfiles[0].Count = 16
+	setOrchestratorDefaults(&mockCS)
+	if properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB != DefaultEtcdDiskSizeGT20Nodes {
+		t.Fatalf("EtcdDiskSizeGB did not have the expected size, got %s, expected %s",
+			properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB, DefaultEtcdDiskSizeGT20Nodes)
+	}
+
+	mockCS = getMockBaseContainerService("1.8.10")
+	properties = mockCS.Properties
+	properties.OrchestratorProfile.OrchestratorType = "Kubernetes"
+	properties.MasterProfile.Count = 5
+	properties.AgentPoolProfiles[0].Count = 50
+	customEtcdDiskSize := "512"
+	properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB = customEtcdDiskSize
+	setOrchestratorDefaults(&mockCS)
+	if properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB != customEtcdDiskSize {
+		t.Fatalf("EtcdDiskSizeGB did not have the expected size, got %s, expected %s",
+			properties.OrchestratorProfile.KubernetesConfig.EtcdDiskSizeGB, customEtcdDiskSize)
+	}
+}
+
 func getMockAddon(name string) api.KubernetesAddon {
 	return api.KubernetesAddon{
 		Name:    name,
diff --git a/pkg/acsengine/engine.go b/pkg/acsengine/engine.go
index a141db3b1f..f33c0e9882 100644
--- a/pkg/acsengine/engine.go
+++ b/pkg/acsengine/engine.go
@@ -676,14 +676,7 @@ func getParameters(cs *api.ContainerService, isClassicMode bool, generatorCode s
 			addValue(parametersMap, "jumpboxStorageProfile", cs.Properties.OrchestratorProfile.KubernetesConfig.PrivateCluster.JumpboxProfile.StorageProfile)
 		}
 		if cs.Properties.HostedMasterProfile == nil {
-			var totalNodes int
-			if cs.Properties.MasterProfile != nil {
-				totalNodes = cs.Properties.MasterProfile.Count
-			}
-			for _, pool := range cs.Properties.AgentPoolProfiles {
-				totalNodes = totalNodes + pool.Count
-			}
-			addValue(parametersMap, "totalNodes", totalNodes)
+			addValue(parametersMap, "totalNodes", cs.Properties.TotalNodes())
 		}
 
 		if properties.OrchestratorProfile.KubernetesConfig == nil ||
diff --git a/pkg/api/types.go b/pkg/api/types.go
index dab27f4cb2..e91082563c 100644
--- a/pkg/api/types.go
+++ b/pkg/api/types.go
@@ -564,6 +564,18 @@ func (p *Properties) HasStorageAccountDisks() bool {
 	return false
 }
 
+// TotalNodes returns the total number of nodes in the cluster configuration
+func (p *Properties) TotalNodes() int {
+	var totalNodes int
+	if p.MasterProfile != nil {
+		totalNodes = p.MasterProfile.Count
+	}
+	for _, pool := range p.AgentPoolProfiles {
+		totalNodes = totalNodes + pool.Count
+	}
+	return totalNodes
+}
+
 // IsCustomVNET returns true if the customer brought their own VNET
 func (m *MasterProfile) IsCustomVNET() bool {
 	return len(m.VnetSubnetID) > 0