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Choose a VM size and image for compute nodes in an Azure Batch pool

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When you select a node size for an Azure Batch pool, you can choose from almost all the VM sizes available in Azure. Azure offers a range of sizes for Linux and Windows VMs for different workloads.

Supported VM series and sizes

Pools in Virtual Machine configuration

Batch pools in the Virtual Machine configuration support almost all VM sizes available in Azure. The supported VM sizes in a region can be obtained via the Batch Management API. You can use one of the following methods to return a list of VM sizes supported by Batch in a region:

For example, using the Azure CLI, you can obtain the list of skus for a particular Azure region with the following command:

az batch location list-skus --location <azure-region>

Tip

Avoid VM SKUs/families with impending Batch support end of life (EOL) dates. These dates can be discovered via the ListSupportedVirtualMachineSkus API, PowerShell, or Azure CLI. For more information, see the Batch best practices guide regarding Batch pool VM SKU selection.

Using Generation 2 VM Images

Some VM series, such as FX and Mv2, can only be used with generation 2 VM images. Generation 2 VM images are specified like any VM image, using the sku property of the imageReference configuration; the sku strings have a suffix such as -g2 or -gen2. To get a list of VM images supported by Batch, including generation 2 images, use the 'list supported images' API, PowerShell, or Azure CLI.

Size considerations

  • Application requirements - Consider the characteristics and requirements of the application run on the nodes. Aspects like whether the application is multithreaded and how much memory it consumes can help determine the most suitable and cost-effective node size. For multi-instance MPI workloads or CUDA applications, consider specialized HPC or GPU-enabled VM sizes, respectively. For more information, see Use RDMA-capable or GPU-enabled instances in Batch pools.

  • Tasks per node - It's typical to select a node size assuming one task runs on a node at a time. However, it might be advantageous to have multiple tasks (and therefore multiple application instances) run in parallel on compute nodes during job execution. In this case, it's common to choose a multicore node size to accommodate the increased demand of parallel task execution.

  • Load levels for different tasks - All of the nodes in a pool are the same size. If you intend to run applications with differing system requirements and/or load levels, we recommend that you use separate pools.

  • Region availability - A VM series or size might not be available in the regions where you create your Batch accounts. To check that a size is available, see Products available by region.

  • Quotas - The cores quotas in your Batch account can limit the number of nodes of a given size you can add to a Batch pool. When needed, you can request a quota increase.

Supported VM images

Use one of the following APIs to return a list of Windows and Linux VM images currently supported by Batch, including the node agent SKU IDs for each image:

For example, using the Azure CLI, you can obtain the list of supported VM images with the following command:

az batch pool supported-images list

Images that have a verificationType of verified undergo regular interoperability validation testing with the Batch service by the Azure Batch team. The verified designation doesn't mean that every possible application or usage scenario is validated, but that functionality exposed by the Batch API such as executing tasks, mounting a supported virtual filesystem, etc. are regularly tested as part of release processes. Images that have a verificationType of unverified don't undergo regular validation testing but were initially verified to boot on Azure Batch compute nodes and transition to an idle compute node state. Support for unverified images isn't guaranteed.

Tip

Avoid images with impending Batch support end of life (EOL) dates. These dates can be discovered via the ListSupportedImages API, PowerShell, or Azure CLI. For more information, see the Batch best practices guide regarding Batch pool VM image selection.

Tip

The value of the AZ_BATCH_NODE_ROOT_DIR compute node environment variable is dependent upon if the VM has a local temporary disk or not. See Batch root directory location for more information.

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