# Create a NodeClass
**Important**
You must start with 0 nodes in your instance group and let Karpenter handle the autoscaling. If you start with more than 0 nodes, Karpenter will scale them down to 0.
A node class (`NodeClass`) defines infrastructure-level settings that apply to groups of nodes in your Amazon EKS cluster, including network configuration, storage settings, and resource tagging. A `HyperPodNodeClass` is a custom `NodeClass` that maps to pre-created instance groups in SageMaker HyperPod, defining constraints around which instance types and Availability Zones are supported for Karpenter's autoscaling decisions.
**Considerations for creating a node class**
+ You can specify up to 10 instance groups in a `NodeClass`.
+ Instance groups that use `InstanceRequirements` (flexible instance groups) can contain multiple instance types within a single instance group. This simplifies your `NodeClass` configuration because you can reference fewer instance groups to cover the same set of instance types and Availability Zones. For example, instead of creating 6 instance groups (3 instance types × 2 AZs), you can create a single flexible instance group that covers all combinations. Note that `InstanceType` and `InstanceRequirements` are mutually exclusive—you must specify one or the other for each instance group.
+ When using GPU partitioning with MIG (Multi-Instance GPU), Karpenter can automatically provision nodes with MIG-enabled instance groups. Ensure your instance groups include MIG-supported instance types (ml.p4d.24xlarge, ml.p5.48xlarge, or ml.p5e/p5en.48xlarge) and configure the appropriate MIG labels during cluster creation. For more information about configuring GPU partitioning, see [Using GPU partitions in Amazon SageMaker HyperPod](sagemaker-hyperpod-eks-gpu-partitioning.md).
+ If custom labels are applied to instance groups, you can view them in the `desiredLabels` field when querying the `HyperpodNodeClass` status. This includes MIG configuration labels such as `nvidia.com/mig.config`. When incoming jobs request MIG resources, Karpenter will automatically scale instances with the appropriate MIG labels applied.
+ If you choose to delete an instance group, we recommend removing it from your `NodeClass` before deleting it from your HyperPod cluster. If an instance group is deleted while it is used in a `NodeClass`, the `NodeClass` will be marked as not `Ready` for provisioning and won't be used for subsequent scaling operations until the instance group is removed from `NodeClass`.
+ When you remove instance groups from a `NodeClass`, Karpenter will detect a drift on the nodes that were managed by Karpenter in the instance group(s) and disrupt the nodes based on your disruption budget controls.
+ Subnets used by the instance group should belong to the same AZ. Subnets are specified either using `OverrideVpcConfig` at the instance group level or the cluster level. `VpcConfig` is used by default.
+ Only on-demand capacity is supported at this time. Instance groups with Training plan or reserved capacity are not supported.
+ Instance groups with `DeepHealthChecks (DHC)` are not supported. This is because a DHC takes around 60-90 minutes to complete and pods will remain in pending state during that time which can cause over-provisioning.
The following steps cover how to create a `NodeClass`.
1. Create a YAML file (for example, nodeclass.yaml) with your `NodeClass` configuration.
1. Apply the configuration to your cluster using kubectl.
1. Reference the `NodeClass` in your `NodePool` configuration.
1. Here's a sample `NodeClass` that uses a ml.c5.xlarge and ml.c5.4xlarge instance types:
```
apiVersion: karpenter.sagemaker.amazonaws.com/v1
kind: HyperpodNodeClass
metadata:
name: sample-nc
spec:
instanceGroups:
# name of InstanceGroup in HyperPod cluster. InstanceGroup needs to pre-created
# MaxItems: 10
- auto-c5-xaz1
- auto-c5-4xaz2
```
1. Apply the configuration:
```
kubectl apply -f nodeclass.yaml
```
1. Monitor the NodeClass status to ensure the Ready condition in status is set to True:
```
kubectl get hyperpodnodeclass sample-nc -o yaml
```
```
apiVersion: karpenter.sagemaker.amazonaws.com/v1
kind: HyperpodNodeClass
metadata:
creationTimestamp: ""
name: sample-nc
uid:
spec:
instanceGroups:
- auto-c5-az1
- auto-c5-4xaz2
status:
conditions:
// true when all IGs in the spec are present in SageMaker cluster, false otherwise
- lastTransitionTime: ""
message: ""
observedGeneration: 3
reason: InstanceGroupReady
status: "True"
type: InstanceGroupReady
// true if subnets of IGs are discoverable, false otherwise
- lastTransitionTime: ""
message: ""
observedGeneration: 3
reason: SubnetsReady
status: "True"
type: SubnetsReady
// true when all dependent resources are Ready [InstanceGroup, Subnets]
- lastTransitionTime: ""
message: ""
observedGeneration: 3
reason: Ready
status: "True"
type: Ready
instanceGroups:
- desiredLabels:
- key:
value:
- key: nvidia.com/mig.config
value: all-1g.5gb
instanceTypes:
- ml.c5.xlarge
name: auto-c5-az1
subnets:
- id:
zone:
zoneId:
- instanceTypes:
- ml.c5.4xlarge
name: auto-c5-4xaz2
subnets:
- id:
zone:
zoneId:
# Flexible instance group with multiple instance types
- instanceTypes:
- ml.p5.48xlarge
- ml.p4d.24xlarge
- ml.g6.48xlarge
name: inference-workers
subnets:
- id:
zone:
zoneId:
- id:
zone:
zoneId:
```