# Launch an Amazon EMR Cluster with multiple primary nodes
This topic provides configuration details and examples for launching an Amazon EMR cluster with multiple primary nodes.
**Note**
Amazon EMR automatically enables termination protection for all clusters that have multiple primary nodes, and overrides any auto-termination settings that you supply when you create the cluster. To shut down a cluster with multiple primary nodes, you must first modify the cluster attributes to disable termination protection. For instructions, see [Terminate an Amazon EMR Cluster with multiple primary nodes](#emr-plan-ha-launch-terminate).
## Prerequisites
+ You can launch an Amazon EMR cluster with multiple primary nodes in both public and private VPC subnets. **EC2-Classic** is not supported. To launch an Amazon EMR cluster with multiple primary nodes in a public subnet, you must enable the instances in this subnet to receive a public IP address by selecting **Auto-assign IPv4** in the console or running the following command. Replace *22XXXX01* with your subnet ID.
```
aws ec2 modify-subnet-attribute --subnet-id subnet-22XXXX01 --map-public-ip-on-launch
```
+ To run Hive, Hue, or Oozie on an Amazon EMR cluster with multiple primary nodes, you must create an external metastore. For more information, see [Configuring an external metastore for Hive](https://docs.aws.amazon.com/emr/latest/ReleaseGuide/emr-metastore-external-hive.html), [Using Hue with a remote database in Amazon RDS](https://docs.aws.amazon.com/emr/latest/ReleaseGuide/hue-rds.html), or [Apache Oozie](https://docs.aws.amazon.com/emr/latest/ReleaseGuide/emr-oozie.html).
+ To use Kerberos authentication in your cluster, you must configure an external KDC. For more information, see [Configuring Kerberos on Amazon Amazon EMR](https://docs.aws.amazon.com/emr/latest/ManagementGuide/emr-kerberos-configure.html).
## Launch an Amazon EMR Cluster with multiple primary nodes
You can launch a cluster with multiple primary nodes when you use instance groups or instance fleets. When you use *instance groups* with multiple primary nodes, you must specify an instance count value of `3` for the primary node instance group. When you use *instance fleets* with multiple primary nodes, you must specify the `TargetOnDemandCapacity` of `3`, `TargetSpotCapacity` of `0` for the primary instance fleet, and `WeightedCapacity` of `1` for each instance type that you configure for the primary fleet.
The following examples demonstrate how to launch the cluster using the default AMI or a custom AMI with both instance groups and instance fleets:
**Note**
You must specify the subnet ID when you launch an Amazon EMR cluster with multiple primary nodes using the AWS CLI. Replace *22XXXX01* and *22XXXX02 *with your subnet ID in the following examples.
------
#### [ Default AMI, instance groups ]
**Example – Launching an Amazon EMR instance group cluster with multiple primary nodes using a default AMI**
```
aws emr create-cluster \
--name "ha-cluster" \
--release-label emr-6.15.0 \
--instance-groups InstanceGroupType=MASTER,InstanceCount=3,InstanceType=m5.xlarge InstanceGroupType=CORE,InstanceCount=4,InstanceType=m5.xlarge \
--ec2-attributes KeyName=ec2_key_pair_name,InstanceProfile=EMR_EC2_DefaultRole,SubnetId=subnet-22XXXX01 \
--service-role EMR_DefaultRole \
--applications Name=Hadoop Name=Spark
```
------
#### [ Default AMI, instance fleets ]
**Example – Launching an Amazon EMR instance fleet cluster with multiple primary nodes using a default AMI**
```
aws emr create-cluster \
--name "ha-cluster" \
--release-label emr-6.15.0 \
--instance-fleets '[
{
"InstanceFleetType": "MASTER",
"TargetOnDemandCapacity": 3,
"TargetSpotCapacity": 0,
"LaunchSpecifications": {
"OnDemandSpecification": {
"AllocationStrategy": "lowest-price"
}
},
"InstanceTypeConfigs": [
{
"WeightedCapacity": 1,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.xlarge"
},
{
"WeightedCapacity": 1,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.2xlarge"
},
{
"WeightedCapacity": 1,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.4xlarge"
}
],
"Name": "Master - 1"
},
{
"InstanceFleetType": "CORE",
"TargetOnDemandCapacity": 5,
"TargetSpotCapacity": 0,
"LaunchSpecifications": {
"OnDemandSpecification": {
"AllocationStrategy": "lowest-price"
}
},
"InstanceTypeConfigs": [
{
"WeightedCapacity": 1,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.xlarge"
},
{
"WeightedCapacity": 2,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.2xlarge"
},
{
"WeightedCapacity": 4,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.4xlarge"
}
],
"Name": "Core - 2"
}
]' \
--ec2-attributes '{"InstanceProfile":"EMR_EC2_DefaultRole","SubnetIds":["subnet-22XXXX01", "subnet-22XXXX02"]}' \
--service-role EMR_DefaultRole \
--applications Name=Hadoop Name=Spark
```
------
#### [ Custom AMI, instance groups ]
**Example – Launching an Amazon EMR instance group cluster with multiple primary nodes using a custom AMI**
```
aws emr create-cluster \
--name "custom-ami-ha-cluster" \
--release-label emr-6.15.0 \
--instance-groups InstanceGroupType=MASTER,InstanceCount=3,InstanceType=m5.xlarge InstanceGroupType=CORE,InstanceCount=4,InstanceType=m5.xlarge \
--ec2-attributes KeyName=ec2_key_pair_name,InstanceProfile=EMR_EC2_DefaultRole,SubnetId=subnet-22XXXX01 \
--service-role EMR_DefaultRole \
--applications Name=Hadoop Name=Spark \
--custom-ami-id ami-MyAmiID
```
------
#### [ Custom AMI, instance fleets ]
**Example – Launching an Amazon EMR instance fleet cluster with multiple primary nodes using a custom AMI**
```
aws emr create-cluster \
--name "ha-cluster" \
--release-label emr-6.15.0 \
--instance-fleets '[
{
"InstanceFleetType": "MASTER",
"TargetOnDemandCapacity": 3,
"TargetSpotCapacity": 0,
"LaunchSpecifications": {
"OnDemandSpecification": {
"AllocationStrategy": "lowest-price"
}
},
"InstanceTypeConfigs": [
{
"WeightedCapacity": 1,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.xlarge"
},
{
"WeightedCapacity": 1,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.2xlarge"
},
{
"WeightedCapacity": 1,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.4xlarge"
}
],
"Name": "Master - 1"
},
{
"InstanceFleetType": "CORE",
"TargetOnDemandCapacity": 5,
"TargetSpotCapacity": 0,
"LaunchSpecifications": {
"OnDemandSpecification": {
"AllocationStrategy": "lowest-price"
}
},
"InstanceTypeConfigs": [
{
"WeightedCapacity": 1,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.xlarge"
},
{
"WeightedCapacity": 2,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.2xlarge"
},
{
"WeightedCapacity": 4,
"BidPriceAsPercentageOfOnDemandPrice": 100,
"InstanceType": "m5.4xlarge"
}
],
"Name": "Core - 2"
}
]' \
--ec2-attributes '{"InstanceProfile":"EMR_EC2_DefaultRole","SubnetIds":["subnet-22XXXX01", "subnet-22XXXX02"]}' \
--service-role EMR_DefaultRole \
--applications Name=Hadoop Name=Spark \
--custom-ami-id ami-MyAmiID
```
------
## Terminate an Amazon EMR Cluster with multiple primary nodes
To terminate an Amazon EMR cluster with multiple primary nodes, you must disable termination protection before terminating the cluster, as the following example demonstrates. Replace *j-3KVTXXXXXX7UG* with your cluster ID.
```
aws emr modify-cluster-attributes --cluster-id j-3KVTXXXXXX7UG --no-termination-protected
aws emr terminate-clusters --cluster-id j-3KVTXXXXXX7UG
```