Create a scale set using instance mix

1. Go to Virtual machine scale sets.
2. Select the Create button to go to the Create a virtual machine scale set view.
3. In the Basics tab, fill out the required fields. If the field isn't called out in the next sections, you can set the fields to what works best for your scale set.
4. Ensure that you select a region that instance mix is supported in.
5. Be sure Orchestration mode is set to Flexible.
6. In the Size section, click Select up to 5 sizes and the Select a VM size page appears.
7. Use the size picker to select up to five VM sizes. Once you select your VM sizes, click the Select button at the bottom of the page to return to the scale set Basics tab.
8. In the Allocation strategy field, select your allocation strategy.
9. If you use the Prioritized (preview) allocation strategy, the Rank size section appears below the Allocation strategy section. Select Rank priority to open the prioritization blade, where you can adjust the priority of your VM sizes.
10. You can specify other properties in subsequent tabs, or you can go to Review + create and select the Create button at the bottom of the page to start your instance mix scale set deployment.

Before using CLI commands with instance mix, be sure you're using the correct CLI version. Make sure you're using version 2.66.0 or greater.

You can use the following basic command to create a scale set using instance mix, which defaults to using the lowestPrice allocation strategy:

az vmss create \
  --name {myVMSS} \
  --resource-group {myResourceGroup} \
  --image ubuntu2204 \
  --vm-sku Mix \
  --skuprofile-vmsizes Standard_D2s_v5 Standard_D2as_v5 \
  --authentication-type ssh \
  --generate-ssh-keys

To specify the allocation strategy, use the --skuprofile-allocation-strategy parameter, like the following command:

az vmss create \
  --name {myVMSS} \
  --resource-group {myResourceGroup} \
  --image ubuntu2204 \
  --vm-sku Mix \
  --skuprofile-vmsizes Standard_D2s_v5 Standard_D2as_v5 \
  --skuprofile-allocation-strategy CapacityOptimized \
  --authentication-type ssh \
  --generate-ssh-keys

You can use the following basic command to create a scale set using instance mix using the following command, which defaults to using the lowestPrice allocation strategy:

New-AzVmss `
  -ResourceGroupName $resourceGroupName `
  -Credential $credentials `
  -VMScaleSetName $vmssName `
  -DomainNameLabel $domainNameLabel1 `
  -VMSize "Mix" `
  -SkuProfileVmSize @("Standard_D4s_v3", "Standard_D4s_v4");

To specify the allocation strategy, use the SkuProfileAllocationStrategy parameter, like the following command:

New-AzVmss `
-ResourceGroupName $resourceGroupName `
-Credential $credentials `
-VMScaleSetName $vmssName `
-DomainNameLabel $domainNameLabel1 `
-SkuProfileVmSize @("Standard_D4s_v3", "Standard_D4s_v4") `
-SkuProfileAllocationStrategy "CapacityOptimized";

To create a scale set using a scale set configuration object utilizing instance mix, use the following command:

$vmss = New-AzVmssConfig -Location $loc -SkuCapacity 2 -UpgradePolicyMode 'Manual' -EncryptionAtHost -SecurityType $stnd -SkuProfileVmSize @("Standard_D4s_v3", "Standard_D4s_v4") -SkuProfileAllocationStrategy "CapacityOptimized"`
            | Add-AzVmssNetworkInterfaceConfiguration -Name 'test' -Primary $true -IPConfiguration $ipCfg `
            | Set-AzVmssOSProfile -ComputerNamePrefix 'test' -AdminUsername $adminUsername -AdminPassword $adminPassword `
            | Set-AzVmssStorageProfile -OsDiskCreateOption 'FromImage' -OsDiskCaching 'None' `
            -ImageReferenceOffer $imgRef.Offer -ImageReferenceSku $imgRef.Skus -ImageReferenceVersion 'latest' `
            -ImageReferencePublisher $imgRef.PublisherName;
 
$vmssResult = New-AzVmss -ResourceGroupName $resourceGroupName -Name $vmssName -VirtualMachineScaleSet $vmss

To deploy a scale set with instance mix using the REST API, make a PUT request to the following endpoint:

PUT https://management.azure.com/subscriptions/{YourSubscriptionId}/resourceGroups/{YourResourceGroupName}/providers/Microsoft.Compute/virtualMachineScaleSets/{yourScaleSetName}?api-version=2023-09-01

In the request body, set sku.name to Mix and specify the total number of VMs:

"sku": {
  "name": "Mix",
  "capacity": {TotalNumberVMs}
},

Reference your existing subnet, as follows:

"subnet": {
  "id": "/subscriptions/{YourSubscriptionId}/resourceGroups/{YourResourceGroupName}/providers/Microsoft.Network/virtualNetworks/{YourVnetName}/subnets/default"
},

Specify the skuProfile with up to five VM sizes. The following example uses three sizes and the lowestPrice allocation strategy:

"skuProfile": {
  "vmSizes": [
    { "name": "Standard_D8s_v5"},
    { "name": "Standard_D8as_v5"},
    { "name": "Standard_D8s_v4"}
  ],
  "allocationStrategy": "lowestPrice"
},

If you use the Prioritized (preview) allocation strategy, you can assign a priority ranking to each VM size. For example:

"skuProfile": {
  "vmSizes": [
    { "name": "Standard_D8s_v5", "rank": 1 },
    { "name": "Standard_D8as_v5", "rank": 2 },
    { "name": "Standard_D8s_v4", "rank": 3 }
  ],
  "allocationStrategy": "Prioritized"
},

• Replace placeholders, such as {YourSubscriptionId}, with your actual values.
• You can specify up to five VM sizes in the vmSizes array.
• The rank property is required only when using the Prioritized (preview) allocation strategy.

Tips for REST deployments:

• Ensure sku.name is set to "Mix" and that sku.tier isn't set (or is null).
• The rank property is only required for the Prioritized strategy. Ranks with lower numbers are higher priority.
• To confirm VM size availability and quota before deployment, validate the template against the target subscription and region.