Create an Azure Machine Learning compute cluster

APPLIES TO: Azure CLI ml extension v2 (current) Python SDK azure-ai-ml v2 (preview)

Learn how to create and manage a compute cluster in your Azure Machine Learning workspace.

You can use Azure Machine Learning compute cluster to distribute a training or batch inference process across a cluster of CPU or GPU compute nodes in the cloud. For more information on the VM sizes that include GPUs, see GPU-optimized virtual machine sizes.

In this article, learn how to:

  • Create a compute cluster
  • Lower your compute cluster cost
  • Set up a managed identity for the cluster

Prerequisites

What is a compute cluster?

Azure Machine Learning compute cluster is a managed-compute infrastructure that allows you to easily create a single or multi-node compute. The compute cluster is a resource that can be shared with other users in your workspace. The compute scales up automatically when a job is submitted, and can be put in an Azure Virtual Network. Compute cluster supports no public IP (preview) deployment as well in virtual network. The compute executes in a containerized environment and packages your model dependencies in a Docker container.

Compute clusters can run jobs securely in a virtual network environment, without requiring enterprises to open up SSH ports. The job executes in a containerized environment and packages your model dependencies in a Docker container.

Limitations

  • Some of the scenarios listed in this document are marked as preview. Preview functionality is provided without a service level agreement, and it's not recommended for production workloads. Certain features might not be supported or might have constrained capabilities. For more information, see Supplemental Terms of Use for Microsoft Azure Previews.

  • Compute clusters can be created in a different region than your workspace. This functionality is in preview, and is only available for compute clusters, not compute instances. This preview isn't available if you're using a private endpoint-enabled workspace.

    Warning

    When using a compute cluster in a different region than your workspace or datastores, you may see increased network latency and data transfer costs. The latency and costs can occur when creating the cluster, and when running jobs on it.

  • We currently support only creation (and not updating) of clusters through ARM templates. For updating compute, we recommend using the SDK, Azure CLI or UX for now.

  • Azure Machine Learning Compute has default limits, such as the number of cores that can be allocated. For more information, see Manage and request quotas for Azure resources.

  • Azure allows you to place locks on resources, so that they can't be deleted or are read only. Do not apply resource locks to the resource group that contains your workspace. Applying a lock to the resource group that contains your workspace will prevent scaling operations for Azure ML compute clusters. For more information on locking resources, see Lock resources to prevent unexpected changes.

Tip

Clusters can generally scale up to 100 nodes as long as you have enough quota for the number of cores required. By default clusters are setup with inter-node communication enabled between the nodes of the cluster to support MPI jobs for example. However you can scale your clusters to 1000s of nodes by simply raising a support ticket, and requesting to allow list your subscription, or workspace, or a specific cluster for disabling inter-node communication.

Create

Time estimate: Approximately 5 minutes.

Azure Machine Learning Compute can be reused across runs. The compute can be shared with other users in the workspace and is retained between runs, automatically scaling nodes up or down based on the number of runs submitted, and the max_nodes set on your cluster. The min_nodes setting controls the minimum nodes available.

The dedicated cores per region per VM family quota and total regional quota, which applies to compute cluster creation, is unified and shared with Azure Machine Learning training compute instance quota.

Important

To avoid charges when no jobs are running, set the minimum nodes to 0. This setting allows Azure Machine Learning to de-allocate the nodes when they aren't in use. Any value larger than 0 will keep that number of nodes running, even if they are not in use.

The compute autoscales down to zero nodes when it isn't used. Dedicated VMs are created to run your jobs as needed.

To create a persistent Azure Machine Learning Compute resource in Python, specify the size and max_instances properties. Azure Machine Learning then uses smart defaults for the other properties.

  • size*: The VM family of the nodes created by Azure Machine Learning Compute.
  • *max_instances: The max number of nodes to autoscale up to when you run a job on Azure Machine Learning Compute.

APPLIES TO: Python SDK azure-ai-ml v2 (preview)

from azure.ai.ml.entities import AmlCompute

cluster_basic = AmlCompute(
    name="basic-example",
    type="amlcompute",
    size="STANDARD_DS3_v2",
    location="westus",
    min_instances=0,
    max_instances=2,
    idle_time_before_scale_down=120,
)
ml_client.begin_create_or_update(cluster_basic)

You can also configure several advanced properties when you create Azure Machine Learning Compute. The properties allow you to create a persistent cluster of fixed size, or within an existing Azure Virtual Network in your subscription. See the AmlCompute class for details.

Warning

When setting the location parameter, if it is a different region than your workspace or datastores you may see increased network latency and data transfer costs. The latency and costs can occur when creating the cluster, and when running jobs on it.

Lower your compute cluster cost

You may also choose to use low-priority VMs to run some or all of your workloads. These VMs don't have guaranteed availability and may be preempted while in use. You'll have to restart a preempted job.

Use any of these ways to specify a low-priority VM:

APPLIES TO: Python SDK azureml v1

from azure.ai.ml.entities import AmlCompute

cluster_low_pri = AmlCompute(
    name="low-pri-example",
    size="STANDARD_DS3_v2",
    min_instances=0,
    max_instances=2,
    idle_time_before_scale_down=120,
    tier="low_priority",
)
ml_client.begin_create_or_update(cluster_low_pri)

Set up managed identity

For information on how to configure a managed identity with your compute cluster, see Set up authentication between Azure Machine Learning and other services.

Troubleshooting

There's a chance that some users who created their Azure Machine Learning workspace from the Azure portal before the GA release might not be able to create AmlCompute in that workspace. You can either raise a support request against the service or create a new workspace through the portal or the SDK to unblock yourself immediately.

Stuck at resizing

If your Azure Machine Learning compute cluster appears stuck at resizing (0 -> 0) for the node state, this may be caused by Azure resource locks.

Azure allows you to place locks on resources, so that they cannot be deleted or are read only. Locking a resource can lead to unexpected results. Some operations that don't seem to modify the resource actually require actions that are blocked by the lock.

With Azure Machine Learning, applying a delete lock to the resource group for your workspace will prevent scaling operations for Azure ML compute clusters. To work around this problem we recommend removing the lock from resource group and instead applying it to individual items in the group.

Important

Do not apply the lock to the following resources:

Resource name Resource type
<GUID>-azurebatch-cloudservicenetworksecurityggroup Network security group
<GUID>-azurebatch-cloudservicepublicip Public IP address
<GUID>-azurebatch-cloudserviceloadbalancer Load balancer

These resources are used to communicate with, and perform operations such as scaling on, the compute cluster. Removing the resource lock from these resources should allow autoscaling for your compute clusters.

For more information on resource locking, see Lock resources to prevent unexpected changes.

Next steps

Use your compute cluster to: