Change the availability set for a VM by using Azure PowerShell

  • How-to

Applies to: ✔️ Linux VMs ✔️ Windows VMs

The following steps describe how to change the availability set of a virtual machine (VM) by using Azure PowerShell. You can add a VM to an availability set only when you're creating the VM. To change the availability set, you need to delete and then re-create the VM.

This article was last tested on February 12, 2019 by using the Az PowerShell module version 1.2.0.

Warning

This is just an example. In some cases, you'll need to update it for your specific deployment.

Make sure the disks are set to detach as the delete option. If they're set to delete, update the VMs before you delete the VMs.

If your VM is attached to a load balancer, you need to update the script to handle that case.

Some extensions might also need to be reinstalled after you finish this process.

If your VM uses hybrid benefits, you need to update the example to enable hybrid benefits on the new VM.

Prerequisites

None

Change the availability set

The following script provides an example of gathering the required information, deleting the original VM, and then re-creating it in a new availability set:

  # Set variables
      $resourceGroup = "myResourceGroup"
      $vmName = "myVM"
      $newAvailSetName = "myAvailabilitySet"

  # Get the details of the VM to be moved to the availability set
      $originalVM = Get-AzVM `
        -ResourceGroupName $resourceGroup `
        -Name $vmName

  # Create a new availability set if it doesn't exist
      $availSet = Get-AzAvailabilitySet `
        -ResourceGroupName $resourceGroup `
        -Name $newAvailSetName `
        -ErrorAction Ignore
      if (-Not $availSet) {
      $availSet = New-AzAvailabilitySet `
        -Location $originalVM.Location `
        -Name $newAvailSetName `
        -ResourceGroupName $resourceGroup `
        -PlatformFaultDomainCount 2 `
        -PlatformUpdateDomainCount 2 `
        -Sku Aligned
      }

  # Remove the original VM
      Remove-AzVM -ResourceGroupName $resourceGroup -Name $vmName

  # Create the basic configuration for the replacement VM.
      $newVM = New-AzVMConfig `
        -VMName $originalVM.Name `
        -VMSize $originalVM.HardwareProfile.VmSize `
        -AvailabilitySetId $availSet.Id
  
  # For a Linux VM, change the last parameter from -Windows to -Linux
      Set-AzVMOSDisk `
        -VM $newVM -CreateOption Attach `
        -ManagedDiskId $originalVM.StorageProfile.OsDisk.ManagedDisk.Id `
        -Name $originalVM.StorageProfile.OsDisk.Name `
        -Windows

  # Add data disks
      foreach ($disk in $originalVM.StorageProfile.DataDisks) { 
      Add-AzVMDataDisk -VM $newVM `
        -Name $disk.Name `
        -ManagedDiskId $disk.ManagedDisk.Id `
        -Caching $disk.Caching `
        -Lun $disk.Lun `
        -DiskSizeInGB $disk.DiskSizeGB `
        -CreateOption Attach
      }
      
  # Add NICs and keep the same NICs as primary; keep the private IP too, if it exists
      foreach ($nic in $originalVM.NetworkProfile.NetworkInterfaces) {	
      if ($nic.Primary -eq "True")
      {
              Add-AzVMNetworkInterface `
                -VM $newVM `
                -Id $nic.Id -Primary
                }
            else
                {
                  Add-AzVMNetworkInterface `
                  -VM $newVM `
                  -Id $nic.Id 
                  }
        }

  # Re-create the VM
      New-AzVM `
        -ResourceGroupName $resourceGroup `
        -Location $originalVM.Location `
        -VM $newVM `
        -DisableBginfoExtension

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