This document describes how to create a managed instance group (MIG) that uses
A4X machine types. To learn more about this accelerator-optimized machine type,
see [A4X](https://docs.cloud.google.com/ai-hypercomputer/docs/evaluate-clustered-gpus.md.txt#a4x-machine).

Create a MIG if you want to manage multiple virtual machines (VMs) as a single
entity. To learn more about MIGs, see
[Managed instance groups](https://docs.cloud.google.com/compute/docs/instance-groups.md.txt#managed_instance_groups)
in the Compute Engine documentation.

To learn about other ways to create VMs or clusters, see
[Deployment options overview](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-overview.md.txt).

> [!NOTE]
> **Note:** You can also create a managed compute cluster in Cluster Director with A4X VMs to automate Virtual Private Cloud (VPC) and MRDMA network setup, topology-aware placement, GPU driver installation, and shared storage mounts. For instructions, see [Create a custom
> cluster](https://docs.cloud.google.com/cluster-director/docs/create/custom-cluster) in the Cluster Director documentation.

## Limitations

When you create a MIG with A4X VMs, consider the limitations for both the
machine type and the MIG.

### Limitations for A4X VMs

The following machine-specific limitations apply:

> [!CAUTION]
> **Caution:** The [Compute Engine Service Level Agreement (SLA)](https://cloud.google.com/compute/sla) doesn't apply to the A4X machine series.

- You don't receive [sustained
  use discounts](https://docs.cloud.google.com/compute/docs/sustained-use-discounts) or [flexible committed use](https://docs.cloud.google.com/compute/docs/instances/committed-use-discounts-overview.md.txt#spend_based) discounts for instances that use this machine type.
- You can only create instances in certain [regions and zones](https://docs.cloud.google.com/compute/docs/regions-zones/gpu-regions-zones.md.txt#view-using-table).
- You can't use Persistent Disk (regional or zonal). You can only use [Google Cloud Hyperdisk](https://docs.cloud.google.com/compute/docs/disks/hyperdisks.md.txt).
- This machine type is only available on the [NVIDIA Grace platform](https://docs.cloud.google.com/compute/docs/cpu-platforms.md.txt#arm_processors).
- Machine type changes aren't supported for A4X. To switch to or from this machine type, you must create a new instance.
- You can't run Windows operating systems on this machine type. For a list of supported Linux operating systems, review the [supported operating systems for GPU instances](https://docs.cloud.google.com/compute/docs/images/os-details.md.txt#gpu-support).
- For A4X instances, when you use `ethtool -S` to monitor GPU networking, the physical port counters that end in `_phy` don't update. This is expected behavior for instances that use the MRDMA Virtual Function (VF) architecture. For more information, see [MRDMA functions and network monitoring tools](https://docs.cloud.google.com/compute/docs/gpus/gpu-network-bandwidth.md.txt#mrdma-monitoring).
- A4X instances don't support the following:
  - [Sole-tenancy](https://docs.cloud.google.com/compute/docs/nodes/sole-tenant-nodes.md.txt)
  - [Spot VMs](https://docs.cloud.google.com/compute/docs/instances/spot.md.txt)
  - [Flex-start VMs](https://docs.cloud.google.com/compute/docs/instances/about-flex-start-vms.md.txt)
- You can't attach Hyperdisk ML disks created before February 4, 2026 to A4X machine types.

### Limitations for the MIG


When you use
A4X

machine types to create a MIG, the following
limitations apply:


- If you create a regional MIG that uses RDMA networking, then the MIG can only
  create A4X instances in the zone where you
  [configured the network profile for RDMA](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#setup-network).

- You can't configure
  [instance flexibility](https://docs.cloud.google.com/compute/docs/instance-groups/about-instance-flexibility.md.txt)
  in the MIG.

<!-- -->

- Review the [limitations for workload policies](https://docs.cloud.google.com/compute/docs/instance-groups/about-workload-policies.md.txt#limitations).

<br />

- You must use the
  [reservation-bound](https://docs.cloud.google.com/ai-hypercomputer/docs/create/review-configurations.md.txt#reservation-bound)
  provisioning model. Other provisioning models aren't supported.

- You can't use a resize request to add A4X instances to the MIG. You must
  set the target size of the MIG to add the instances.

<br />

## Before you begin

Before creating a MIG, if you haven't already done so, complete the following
steps:

1. **Choose a consumption option** : your choice of consumption option determines how you get and use GPU resources. To learn more, see [Choose a consumption option](https://docs.cloud.google.com/ai-hypercomputer/docs/consumption-models.md.txt).
2. **Obtain capacity** : the process to obtain capacity differs for each consumption option. To learn about the process to obtain capacity for your chosen consumption option, see [Capacity overview](https://docs.cloud.google.com/ai-hypercomputer/docs/obtain-capacity.md.txt).

   > [!NOTE]
   > **Note:** When you request A4X Max or A4X capacity, you obtain it in the *all capacity mode*. This mode is the only supported reservation operational mode for A4X Max or A4X machine types. For more information about all capacity mode, see [Reservation operational mode](https://docs.cloud.google.com/ai-hypercomputer/docs/create/review-configurations.md.txt#reservation-operational-mode).

3. **Verify Google APIs Service Agent permissions** : when you create VMs in a MIG, Compute Engine uses the [Google APIs Service Agent](https://docs.cloud.google.com/compute/docs/access/service-accounts.md.txt#google_apis_service_agent) (`PROJECT_NUMBER@cloudservices.gserviceaccount.com`) in your project. If your instance template uses resources from another project, then verify that this service agent has the required permissions:
   - **Shared VPC** : if the VMs use a Shared VPC network, then grant the Google APIs Service Agent in the service project the [Compute Network User](https://docs.cloud.google.com/compute/docs/access/iam.md.txt#compute.networkUser) (`roles/compute.networkUser`) role on the host project or shared subnets. For more information, see [Google APIs service account as a Service Project Admin](https://docs.cloud.google.com/vpc/docs/provisioning-shared-vpc.md.txt#migs-service-accounts).
   - **Images from other projects** : if the VMs use an image from another project, then grant the Google APIs Service Agent in your project the [Compute Image User](https://docs.cloud.google.com/compute/docs/access/iam.md.txt#image_user_role) (`roles/compute.imageUser`) role on the image or the project that owns the image. For more information, see [Grant a managed instance group access to images](https://docs.cloud.google.com/compute/docs/images/managing-access-custom-images.md.txt#grant_a_managed_instance_group_access_to_images).

### Required roles


To get the permissions that
you need to create a MIG,

ask your administrator to grant you the
[Compute Instance Admin (v1)](https://docs.cloud.google.com/iam/docs/roles-permissions/compute.md.txt#compute.instanceAdmin.v1) (`roles/compute.instanceAdmin.v1`) IAM role on the project.


For more information about granting roles, see [Manage access to projects, folders, and organizations](https://docs.cloud.google.com/iam/docs/granting-changing-revoking-access.md.txt).


This predefined role contains

the permissions required to create a MIG. To see the exact permissions that are
required, expand the **Required permissions** section:


#### Required permissions

The following permissions are required to create a MIG:

- To create a MIG: `compute.instanceGroupManagers.create` on the project


You might also be able to get
these permissions
with [custom roles](https://docs.cloud.google.com/iam/docs/creating-custom-roles.md.txt) or
other [predefined roles](https://docs.cloud.google.com/iam/docs/roles-overview.md.txt#predefined).

## A4X fundamentals

An A4X cluster is organized into a hierarchy of blocks and sub-blocks to
facilitate large-scale, non-blocking network performance. Understanding this topology is key when
reserving capacity and deploying workloads.

A4X instance
:   An A4X instance is a single A4X machine type that has 4 GPUs
    attached.

Sub-block
:   A sub-block is the fundamental unit of A4X
    capacity. For A4X, a sub-block consists of 18 A4X
    instances (72 GPUs); these instances form an NVLink domain and are connected
    using a [multi-node NVLink](https://docs.nvidia.com/multi-node-nvlink-systems/mnnvl-user-guide/overview.html)
    system. You create an A4X sub-block by applying a
    workload policy that specifies a `1x72` topology.

Block
:   An A4X block is composed of 25 sub-blocks (NVLink domains), totalling up to
    450 A4X instances (1,800 GPUs). The sub-blocks are rail-aligned for efficient
    scaling. Each sub-block requires a
    MIG.
    Therefore, for a single A4X block, you can create 25
    MIGs.

The following table shows the supported topology options for A4X instances:

| Topology (`acceleratorTopology`) | Number of GPUs | Number of instances |
|---|---|---|
| `1x72` | 72 | 18 |

<br />

## Overview

Creating a MIG with the A4X machine type includes the following steps:

1. [Create VPC networks](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#setup-network)
2. [Create a workload policy](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#create-workload-policy)
3. [Create an instance template](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#specify-vm-properties)
4. [Create a MIG](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#create-mig)
5. [Install GPU drivers](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#install-drivers)
6. Optional: [Enable NVIDIA Multi-Instance GPU mode](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#multi-instance-gpu-mode)

### Create VPC networks

> [!TIP]
> **Tip:** If you are setting up a quick test, you can skip this step and specify a single NIC `--network-interface=nic-type=GVNIC` instead.

To set up the network for A4X machine types, create
three VPC networks for the following network interfaces:

- 2 regular VPC networks for the [gVNIC](https://docs.cloud.google.com/compute/docs/networking/using-gvnic.md.txt) network interfaces (NICs). The NICs then use these VPC networks for host-to-host communication.
- 1 VPC network with the [RoCE network profile](https://docs.cloud.google.com/vpc/docs/rdma-network-profiles.md.txt) for the CX-7 NICs when creating multiple A4X subblocks. The RoCE VPC network for VM instances must have 4 subnets, one subnet for each CX-7 NIC. These NICs use RDMA over Converged Ethernet (RoCE), providing the high-bandwidth, low-latency communication that's essential for scaling out to multiple A4X subblocks.

**Important:** For a single A4X subblock, you don't need to create a VPC network with the RoCE network profile because within a single subblock, direct GPU-to-GPU communication is handled by the multi-node NVLink.

For more information about NIC arrangement, see
[Review network bandwidth and NIC arrangement](https://docs.cloud.google.com/compute/docs/gpus/gpu-network-bandwidth.md.txt#review-network-nic).

Create the networks either manually by following the instruction guides or
automatically by using the provided script.

### Instruction guides

To create the networks, you can use the following instructions:

- To create the regular VPC networks for the gVNIC network interfaces, see [Create and manage
  Virtual Private Cloud networks](https://docs.cloud.google.com/vpc/docs/create-modify-vpc-networks).
- To create the RoCE VPC network for VM instances (`roce`), see [Create a Virtual Private Cloud network for RDMA NICs](https://docs.cloud.google.com/vpc/docs/create-vpc-network-rdma.md.txt).

For these VPC networks, set the
[maximum transmission unit (MTU)](https://docs.cloud.google.com/vpc/docs/mtu.md.txt) to a larger value.
For A4X machine types, the recommended MTU is
`8896` bytes.
To review the recommended MTU settings for other GPU machine types, see
[MTU settings for GPU machine types](https://docs.cloud.google.com/compute/docs/gpus/gpu-network-bandwidth.md.txt#mtu-gpu).

### Script

To create the networks, follow these steps.

For these VPC networks, set the
[maximum transmission unit (MTU)](https://docs.cloud.google.com/vpc/docs/mtu.md.txt) to a larger value.
For A4X machine types, the recommended MTU is
`8896` bytes.
To review the recommended MTU settings for other GPU machine types, see
[MTU settings for GPU machine types](https://docs.cloud.google.com/compute/docs/gpus/gpu-network-bandwidth.md.txt#mtu-gpu).

1.
   Use the following script to create regular VPC networks
   for the

   gVNICs.

   ```bash
       #!/bin/bash

       # Create regular VPC networks and subnets for the gVNICs
       for N in $(seq 0 1); do
         gcloud compute networks create GVNIC_NAME_PREFIX-net-$N \
           --subnet-mode=custom \
           --mtu=8896

         gcloud compute networks subnets create GVNIC_NAME_PREFIX-sub-$N \
           --network=GVNIC_NAME_PREFIX-net-$N \
           --region=REGION \
           --range=192.168.$N.0/24

         gcloud compute firewall-rules create GVNIC_NAME_PREFIX-internal-$N \
           --network=GVNIC_NAME_PREFIX-net-$N \
           --action=ALLOW \
           --rules=tcp:0-65535,udp:0-65535,icmp \
           --source-ranges=192.168.0.0/16
       done

       # Create SSH firewall rules
       gcloud compute firewall-rules create GVNIC_NAME_PREFIX-ssh \
         --network=GVNIC_NAME_PREFIX-net-0 \
         --action=ALLOW \
         --rules=tcp:22 \
         --source-ranges=IP_RANGE

       # Assumes that an external IP is only created for vNIC 0
       gcloud compute firewall-rules create GVNIC_NAME_PREFIX-allow-ping-net-0 \
         --network=GVNIC_NAME_PREFIX-net-0 \
         --action=ALLOW \
         --rules=icmp \
         --source-ranges=IP_RANGE


         
   ```
2. If you require multiple A4X subblocks, use the following
   script to create the

   RoCE VPC network for VM instances (`roce`) and subnets for the four CX-7 NICs on each A4X
   instance.

   **Important:** If your deployment consists of only a single A4X subblock, you can skip this step.

   ```bash
       #!/bin/bash

       # List and make sure network profiles exist in the machine type's zone
       gcloud compute network-profiles list --filter "location.name=ZONE"

       # Create network for RDMA NICs
       gcloud compute networks create RDMA_NAME_PREFIX-mrdma \
         --network-profile=ZONE-vpc-roce \
         --subnet-mode custom \
         --mtu=8896

       # Create subnets
       for N in $(seq 0 3); do
         gcloud compute networks subnets create RDMA_NAME_PREFIX-mrdma-sub-$N \
           --network=RDMA_NAME_PREFIX-mrdma \
           --region=REGION \
           --range=192.168.$((N+2)).0/24 # offset to avoid overlap with gVNICs
       done


         
   ```
3. Replace the following:
   - `GVNIC_NAME_PREFIX`: the custom name prefix to use for the regular VPC networks and subnets for the gVNICs.
   - `RDMA_NAME_PREFIX`: the custom name prefix to use for the RoCE VPC network for VM instances (`roce`) and subnets for the CX-7 NICs.
   - `ZONE`: specify a zone in which the machine type that you want to use is available, such as `us-central1-a`. For information about regions, see [GPU availability by regions and zones](https://docs.cloud.google.com/compute/docs/regions-zones/gpu-regions-zones.md.txt#view-using-table).
   - `REGION`: the region where you want to create the subnets. This region must correspond to the zone specified. For example, if your zone is `us-central1-a`, then your region is `us-central1`.
   - `IP_RANGE`: the IP range to use for the [SSH firewall rules](https://docs.cloud.google.com/compute/docs/connect/ssh-best-practices/network-access.md.txt#use-firewall-policies).
4. Optional: To verify that the VPC network resources are created successfully, check the network settings in the Google Cloud console:
   1. In the Google Cloud console, go to the **VPC networks** page.

      [Go to VPC networks](https://console.cloud.google.com/networking/networks/list)
   2. Search the list for the networks that you created in the previous step.
   3. To view the subnets, firewall rules, and other network settings, click the name of the network.

### Create an instance template

Specify the VM properties for a MIG by creating an instance template.

To create an instance template, select one of the following options.
The following commands also set the access scope for your instances. To simplify permissions management, Google recommends that you set the access scope on an instance to `cloud-platform` access and then use IAM roles to define what services the instance can access. For more information, see [Scopes best practice](https://docs.cloud.google.com/compute/docs/access/service-accounts.md.txt#scopes_best_practice).

### gcloud


To create a regional instance template, use the [`gcloud compute instance-templates create` command](https://docs.cloud.google.com/sdk/gcloud/reference/compute/instance-templates/create.md.txt).
**Important:** The following example uses the networking setup for multiple sub-blocks. If
you're creating only a single A4X sub-block and you only created the
gVNIC network in the [Create VPC networks](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#setup-network) step, then remove the
four RDMA subnets
indicated by the `MRDMA` NIC type from the example.

A4X instances support the following
[types of reservations](https://docs.cloud.google.com/compute/docs/instances/choose-reservation-type.md.txt):

- Future reservations for capacity blocks
- Future reservations in calendar mode

To consume these types of reservations, an instance must use the
*reservation-bound provisioning model*. For example, use the following creation parameters.

```
gcloud compute instance-templates create INSTANCE_TEMPLATE_NAME \
    --machine-type=a4x-highgpu-4g \
    --image-family=IMAGE_FAMILY \
    --image-project=IMAGE_PROJECT \
    --instance-template-region=REGION \
    --boot-disk-type=hyperdisk-balanced \
    --boot-disk-size=DISK_SIZE \
    --scopes=cloud-platform \
    --network-interface=nic-type=GVNIC,network=GVNIC_NAME_PREFIX-net-0,subnet=GVNIC_NAME_PREFIX-sub-0 \
    --network-interface=nic-type=GVNIC,network=GVNIC_NAME_PREFIX-net-1,subnet=GVNIC_NAME_PREFIX-sub-1,no-address 
    --network-interface=nic-type=MRDMA,network=RDMA_NAME_PREFIX-mrdma,subnet=RDMA_NAME_PREFIX-mrdma-sub-0,no-address \
    --network-interface=nic-type=MRDMA,network=RDMA_NAME_PREFIX-mrdma,subnet=RDMA_NAME_PREFIX-mrdma-sub-1,no-address \
    --network-interface=nic-type=MRDMA,network=RDMA_NAME_PREFIX-mrdma,subnet=RDMA_NAME_PREFIX-mrdma-sub-2,no-address \
    --network-interface=nic-type=MRDMA,network=RDMA_NAME_PREFIX-mrdma,subnet=RDMA_NAME_PREFIX-mrdma-sub-3,no-address \
    --reservation-affinity=specific \
    --reservation=RESERVATION \
    --provisioning-model=RESERVATION_BOUND \
    --instance-termination-action=DELETE \
    --maintenance-policy=TERMINATE \
    --restart-on-failure
```

Replace the following:

- `INSTANCE_TEMPLATE_NAME`: the name of the instance template.
- `IMAGE_FAMILY`: the image family of the OS image that you want to use. For a list of all supported operating systems, see [Supported operating systems](https://docs.cloud.google.com/compute/docs/images/os-details.md.txt#gpu-support).

  > [!TIP]
  > **Tip:** We recommend using [accelerator OS images](https://docs.cloud.google.com/ai-hypercomputer/docs/images.md.txt#accelerator-os-images) for AI-optimized workloads. Unless you have unique GPU driver requirements, these images install all required GPU drivers automatically. For more information about GPU driver requirements, see [Install GPU drivers](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#install-drivers) in this document.

- `IMAGE_PROJECT`: the project ID of the OS image.
- `REGION`: the region where you want to create the instance template. Specify a region in which the machine type that you want to use is available. For information about regions, see [GPU availability by regions and zones](https://docs.cloud.google.com/compute/docs/gpus/gpu-regions-zones#view-using-table).
- `DISK_SIZE`: the size of the boot disk in GB. For more information, see either [Google Cloud Hyperdisk size limits](https://docs.cloud.google.com/compute/docs/disks/hyperdisks.md.txt#size-limits) or [Persistent Disk size limits](https://docs.cloud.google.com/compute/docs/disks/resize-persistent-disk.md.txt#size_limits) based on the type of disk.
- `GVNIC_NAME_PREFIX`: the name prefix that you specified when creating the standard VPC networks and subnets that use gVNIC NICs.
- `RDMA_NAME_PREFIX`: the name prefix that you specified when creating the VPC networks and subnets that use RDMA NICs.
- `RESERVATION`: the reservation name, a block, or a subblock within a reservation. To get the reservation name or the available blocks, see [View reserved capacity](https://docs.cloud.google.com/ai-hypercomputer/docs/view-reserved-capacity.md.txt). Based on your requirements for instance placement, choose one of the following:
  - To create A4X instances on any single block:

    ```
        projects/RESERVATION_OWNER_PROJECT_ID/reservations/RESERVATION_NAME
        
    ```
  - To create A4X instances on a specific block:

    ```
        projects/RESERVATION_OWNER_PROJECT_ID/reservations/RESERVATION_NAME/reservationBlocks/RESERVATION_BLOCK_NAME
        
    ```
  - To create A4X instances in a specific subblock:

    ```
        projects/RESERVATION_OWNER_PROJECT_ID/reservations/RESERVATION_NAME/reservationBlocks/RESERVATION_BLOCK_NAME/reservationSubBlocks/RESERVATION_SUBBLOCK_NAME
        
    ```

  > [!TIP]
  > **Tip:** If the reservation exists in the current project, then you can omit `projects/RESERVATION_OWNER_PROJECT_ID/reservations/` from the `RESERVATION` value.

<br />

### REST


To create a regional instance template, make a `POST` request to the
[`regionInstanceTemplates.insert` method](https://docs.cloud.google.com/compute/docs/reference/rest/v1/regionInstanceTemplates/insert.md.txt).
**Important:** The following example uses the networking setup for multiple sub-blocks. If
you're creating only a single A4X sub-block and you only created the
gVNIC network in the [Create VPC networks](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#setup-network) step, then remove the
four RDMA subnets
indicated by the `MRDMA` NIC type from the example.

A4X instances support the following
[types of reservations](https://docs.cloud.google.com/compute/docs/instances/choose-reservation-type.md.txt):

- Future reservations for capacity blocks
- Future reservations in calendar mode

To consume these types of reservations, an instance must use the
*reservation-bound provisioning model*. For example, use the following creation parameters.

```
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION/instanceTemplates
{
  "name": "INSTANCE_TEMPLATE_NAME",
  "properties": {
    "machineType": "a4x-highgpu-4g",
    "disks": [
      {
        "boot": true,
        "initializeParams": {
          "diskSizeGb": "DISK_SIZE",
          "diskType": "hyperdisk-balanced",
          "sourceImage": "projects/IMAGE_PROJECT/global/images/family/IMAGE_FAMILY"
        },
        "mode": "READ_WRITE",
        "type": "PERSISTENT"
      }
    ],
    "serviceAccounts": [
      {
        "email": "default",
        "scopes": [
          "https://www.googleapis.com/auth/cloud-platform"
        ]
      }
    ],
    "networkInterfaces": [
      {
        "accessConfigs": [
          {
            "name": "external-nat",
            "type": "ONE_TO_ONE_NAT"
          }
        ],
        "network": "projects/NETWORK_PROJECT_ID/global/networks/GVNIC_NAME_PREFIX-net-0",
        "nicType": "GVNIC",
        "subnetwork": "projects/NETWORK_PROJECT_ID/region/REGION/subnetworks/GVNIC_NAME_PREFIX-sub-0"
      },
      {
        "network": "projects/NETWORK_PROJECT_ID/global/networks/GVNIC_NAME_PREFIX-net-1",
        "nicType": "GVNIC",
        "subnetwork": "projects/NETWORK_PROJECT_ID/region/REGION/subnetworks/GVNIC_NAME_PREFIX-sub-1"
      },
      {
        "network": "projects/NETWORK_PROJECT_ID/global/networks/RDMA_NAME_PREFIX-mrdma",
        "nicType": "MRDMA",
        "subnetwork": "projects/NETWORK_PROJECT_ID/region/REGION/subnetworks/RDMA_NAME_PREFIX-mrdma-sub-0"
      },
      {
        "network": "projects/NETWORK_PROJECT_ID/global/networks/RDMA_NAME_PREFIX-mrdma",
        "nicType": "MRDMA",
        "subnetwork": "projects/NETWORK_PROJECT_ID/region/REGION/subnetworks/RDMA_NAME_PREFIX-mrdma-sub-1"
      },
      {
        "network": "projects/NETWORK_PROJECT_ID/global/networks/RDMA_NAME_PREFIX-mrdma",
        "nicType": "MRDMA",
        "subnetwork": "projects/NETWORK_PROJECT_ID/region/REGION/subnetworks/RDMA_NAME_PREFIX-mrdma-sub-2"
      },
      {
        "network": "projects/NETWORK_PROJECT_ID/global/networks/RDMA_NAME_PREFIX-mrdma",
        "nicType": "MRDMA",
        "subnetwork": "projects/NETWORK_PROJECT_ID/region/REGION/subnetworks/RDMA_NAME_PREFIX-mrdma-sub-3"
      }
    ],
    "reservationAffinity": {
        "consumeReservationType": "SPECIFIC_RESERVATION",
        "key": "compute.googleapis.com/reservation-name",
        "values": [
          "RESERVATION"
        ]
      },
    "scheduling": {
        "provisioningModel": "RESERVATION_BOUND",
        "instanceTerminationAction": "DELETE",
        "onHostMaintenance": "TERMINATE",
        "automaticRestart": true
      }
  }
}
```

Replace the following:

- `INSTANCE_TEMPLATE_NAME`: the name of the instance template.
- `IMAGE_FAMILY`: the image family of the OS image that you want to use. For a list of all supported operating systems, see [Supported operating systems](https://docs.cloud.google.com/compute/docs/images/os-details.md.txt#gpu-support).

  > [!TIP]
  > **Tip:** We recommend using [accelerator OS images](https://docs.cloud.google.com/ai-hypercomputer/docs/images.md.txt#accelerator-os-images) for AI-optimized workloads. Unless you have unique GPU driver requirements, these images install all required GPU drivers automatically. For more information about GPU driver requirements, see [Install GPU drivers](https://docs.cloud.google.com/ai-hypercomputer/docs/create/create-mig-with-a4x.md.txt#install-drivers) in this document.

- `IMAGE_PROJECT`: the project ID of the OS image.
- `REGION`: the region where you want to create the instance template. Specify a region in which the machine type that you want to use is available. For information about regions, see [GPU availability by regions and zones](https://docs.cloud.google.com/compute/docs/gpus/gpu-regions-zones#view-using-table).
- `DISK_SIZE`: the size of the boot disk in GB. For more information, see either [Google Cloud Hyperdisk size limits](https://docs.cloud.google.com/compute/docs/disks/hyperdisks.md.txt#size-limits) or [Persistent Disk size limits](https://docs.cloud.google.com/compute/docs/disks/resize-persistent-disk.md.txt#size_limits) based on the type of disk.
- `NETWORK_PROJECT_ID`: the project ID of the network.
- `GVNIC_NAME_PREFIX`: the name prefix that you specified when creating the standard VPC networks and subnets that use gVNIC NICs.
- `REGION`: the region of the subnetwork.
- `RDMA_NAME_PREFIX`: the name prefix that you specified when creating the VPC networks and subnets that use RDMA NICs.
- `RESERVATION`: the reservation name, a block, or a subblock within a reservation. To get the reservation name or the available blocks, see [View reserved capacity](https://docs.cloud.google.com/ai-hypercomputer/docs/view-reserved-capacity.md.txt). Based on your requirements for instance placement, choose one of the following:
  - To create A4X instances on any single block:

    ```
        projects/RESERVATION_OWNER_PROJECT_ID/reservations/RESERVATION_NAME
        
    ```
  - To create A4X instances on a specific block:

    ```
        projects/RESERVATION_OWNER_PROJECT_ID/reservations/RESERVATION_NAME/reservationBlocks/RESERVATION_BLOCK_NAME
        
    ```
  - To create A4X instances in a specific subblock:

    ```
        projects/RESERVATION_OWNER_PROJECT_ID/reservations/RESERVATION_NAME/reservationBlocks/RESERVATION_BLOCK_NAME/reservationSubBlocks/RESERVATION_SUBBLOCK_NAME
        
    ```

  > [!TIP]
  > **Tip:** If the reservation exists in the current project, then you can omit `projects/RESERVATION_OWNER_PROJECT_ID/reservations/` from the `RESERVATION` value.

<br />

### Create a MIG

When you use an A4X machine type, you must create a MIG by specifying its target
size.


To obtain a GPU topology of `1x72`, create a MIG with
18 A4X instances. When you create the MIG, apply the workload policy that specifies the `acceleratorTopology`
field. Applying the policy ensures that Compute Engine creates all 18 A4X
instances in one sub-block to use an NVLink domain.


If a sub-block lacks capacity for all 18 instances, then any
[managed instance](https://docs.cloud.google.com/compute/docs/instance-groups/working-with-managed-instances.md.txt#what_is_a_managed_instance)
that can't be created immediately will remain in `CREATING` state until capacity
becomes available. These managed instances represent the compute instances that the MIG creates
when there is capacity.


**Important:**

When you create an A4X MIG with a `1x72` topology,
Compute Engine allocates an entire 18-instance sub-block (NVLink
domain) to that MIG. If you create fewer than 18 instances, the unused
instances in that sub-block remain idle and are unavailable for other MIGs.
However, it's possible to provision these unused instances by resizing the MIG.
To maximize resource efficiency, we recommend that you create exactly 18
instances in a MIG.


When you apply a workload policy with the `acceleratorTopology` field set to
`1x72`, you cannot create more than 18 A4X instances in a MIG.
Specifying more than 18 instances causes the MIG creation to fail. To create multiple NVLink
domains, create a separate MIG for each domain and apply the same workload policy to each MIG.

<br />

To create a MIG, select one of the following options:

### gcloud


To create a MIG with a specified target size, use the
[`instance-groups managed
create` command](https://docs.cloud.google.com/sdk/gcloud/reference/compute/instance-groups/managed/create).

> [!IMPORTANT]
> **Important:** If the instance template specifies Flex-start VMs, then you must also [turn off repairs](https://docs.cloud.google.com/compute/docs/instance-groups/turn-off-vm-repairs-in-mig.md.txt) by adding the `--default-action-on-vm-failure=do-nothing` flag to the command.

Create a zonal or regional MIG as follows:

- To create a zonal MIG, use the following command:

  ```
  gcloud compute instance-groups managed create MIG_NAME \
    --template=INSTANCE_TEMPLATE_URL \
    --size=TARGET_SIZE \
    --workload-policy=WORKLOAD_POLICY_URL \
    --zone=ZONE
  ```
- To create a regional MIG, use the following command:

  ```
  gcloud compute instance-groups managed create MIG_NAME \
      --template=INSTANCE_TEMPLATE_URL \
      --size=TARGET_SIZE \
      --workload-policy=WORKLOAD_POLICY_URL \
      --region=REGION
  ```

Replace the following:

<!-- -->

- `MIG_NAME`: the name of the MIG.
- `INSTANCE_TEMPLATE_URL`: the URL of the instance template that you want to use to create instances in the MIG. The URL can contain either the [ID](https://docs.cloud.google.com/compute/docs/instance-templates/get-list-delete-instance-templates.md.txt#get_information_about_an_instance_template) or name of the instance template. Specify one of the following values:
  - For a regional instance template: `projects/PROJECT_ID/regions/REGION/instanceTemplates/INSTANCE_TEMPLATE_ID`
  - For a global instance template: `INSTANCE_TEMPLATE_ID`
- `TARGET_SIZE`: the number of instances that you want in the MIG. For the accelerator topology of `1x72`, set the target size to `18`.
- `WORKLOAD_POLICY_URL`: The URL of the workload policy---for example, `projects/example-project/regions/us-central1/resourcePolicies/example-workload-policy`.
- `ZONE`: the zone in which you want to create the MIG. Specify a zone within the workload policy's region.
- `REGION`: the region in which you want to create the MIG. Specify the same region as that of the workload policy. For a regional MIG, instead of a region, you can specify the zones in that region by using the `--zones` flag.

<br />

### REST


To create a MIG with a specified target size, make a `POST` request.

> [!IMPORTANT]
> **Important:** If the instance template specifies Flex-start VMs, then you must also [turn off repairs](https://docs.cloud.google.com/compute/docs/instance-groups/turn-off-vm-repairs-in-mig.md.txt) by adding the `"defaultActionOnFailure": "DO_NOTHING"` field to the request.

Create a zonal or regional MIG as follows:

- To create a zonal MIG, make a `POST` request to the [`instanceGroupManagers.insert` method](https://docs.cloud.google.com/compute/docs/reference/rest/v1/instanceGroupManagers/insert.md.txt).

  ```
  POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instanceGroupManagers
  {
    "versions": [
      {
        "instanceTemplate": "INSTANCE_TEMPLATE_URL"
      }
    ],
    "name": "MIG_NAME",
    "targetSize": TARGET_SIZE,
    "resourcePolicies": {
      "workloadPolicy": "WORKLOAD_POLICY_URL"
    }
  }
  ```
- To create a regional MIG, make a `POST` request to the [`regionInstanceGroupManagers.insert` method](https://docs.cloud.google.com/compute/docs/reference/rest/v1/regionInstanceGroupManagers/insert.md.txt).

  ```
    POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION/instanceGroupManagers
    {
      "name": "MIG_NAME",
      "instanceTemplate": "INSTANCE_TEMPLATE_URL",
      "targetSize": TARGET_SIZE,
      "resourcePolicies": {
        "workloadPolicy": "WORKLOAD_POLICY_URL"
      }
    }
  ```

Replace the following:

<!-- -->

- `PROJECT_ID`: the project ID.
- `ZONE`: the zone in which you want to create the MIG. Specify a zone within the workload policy's region.
- `REGION`: the region in which you want to create the MIG. Specify the same region as that of the workload policy.
- `INSTANCE_TEMPLATE_URL`: the URL of the instance template that you want to use to create instances in the MIG. The URL can contain either the [ID](https://docs.cloud.google.com/compute/docs/instance-templates/get-list-delete-instance-templates.md.txt#get_information_about_an_instance_template) or name of the instance template. Specify one of the following values:
  - For a regional instance template: `projects/PROJECT_ID/regions/REGION/instanceTemplates/INSTANCE_TEMPLATE_ID`
  - For a global instance template: `INSTANCE_TEMPLATE_ID`
- `MIG_NAME`: the name of the MIG.
- `TARGET_SIZE`: the number of instances that you want in the MIG. For the accelerator topology of `1x72`, set the target size to `18`.
- `WORKLOAD_POLICY_URL`: The URL of the workload policy---for example, `projects/example-project/regions/us-central1/resourcePolicies/example-workload-policy`.

<br />

### Install GPU drivers

After you create an instance, the instance can't use its GPUs unless the correct GPU drivers are
already installed.


If you didn't specify an [OS image that includes GPU drivers](https://docs.cloud.google.com/ai-hypercomputer/docs/images.md.txt#accelerator-os-images), then see
[Install GPU drivers](https://docs.cloud.google.com/compute/docs/gpus/install-drivers-gpu.md.txt) in the
Compute Engine documentation.

### Optional: Enable NVIDIA Multi-Instance GPU mode

> [!NOTE]
> **Note:** In this section, *MIG* refers to Multi-Instance GPU from NVIDIA, not a managed instance group.

Multi-Instance GPU (MIG) mode is a feature that you can enable for a [supported NVIDIA GPU](https://docs.nvidia.com/datacenter/tesla/mig-user-guide/latest/supported-gpus.html). After you create an instance, you can enable MIG mode on a single GPU that is attached to your machine. With MIG mode enabled, the single GPU is partitioned into as many as seven independent GPU instances. Each instance runs simultaneously, each with its own memory, cache, and streaming multiprocessors. You can then run different workloads on these GPU instances in parallel. For more information about using MIG mode, see the [Multi-Instance GPU (MIG) User Guide](https://docs.nvidia.com/datacenter/tesla/mig-user-guide/index.html#getting-started-with-mig) in the NVIDIA documentation.

## What's next?

- [View the topology of a compute instance](https://docs.cloud.google.com/ai-hypercomputer/docs/manage/instance-topology.md.txt)
- [Monitor VMs](https://docs.cloud.google.com/ai-hypercomputer/docs/monitor.md.txt)
- [Report faulty host](https://docs.cloud.google.com/ai-hypercomputer/docs/manage/report-faulty-host.md.txt)
- [Troubleshoot reservation consumption](https://docs.cloud.google.com/compute/docs/troubleshooting/troubleshooting-reservation-consumption.md.txt)