Change the size of a virtual machine

1. Open the Azure portal.
2. Open the page for the virtual machine.
3. In the left menu, select Size.
4. Pick a new size from the list of available sizes and then select Resize.

If your VM is still running and you don't see the size you want in the list, stopping the virtual machine may reveal more sizes.

To resize a VM, you need the latest Azure CLI installed and logged in to an Azure account using az sign-in.

The below script checks if the desired VM size is available before resizing. If the desired size isn't available, the script exits with an error message. If the desired size is available, the script deallocates the VM, resizes it, and starts it again. You can replace the values of resourceGroup, vm, and size with your own.

 # Set variables
resourceGroup=myResourceGroup
vm=myVM
size=Standard_DS3_v2

# Check if the desired VM size is available
if ! az vm list-vm-resize-options --resource-group $resourceGroup --name $vm --query "[].name" | grep -q $size; then
    echo "The desired VM size is not available."
    exit 1
fi

# Deallocate the VM
az vm deallocate --resource-group $resourceGroup --name $vm

# Resize the VM
az vm resize --resource-group $resourceGroup --name $vm --size $size

# Start the VM
az vm start --resource-group $resourceGroup --name $vm

Use Azure CLI to resize a VM in an availability set.

The below script sets the variables resourceGroup, vm, and size. It then checks if the desired VM size is available by using az vm list-vm-resize-options and checking if the output contains the desired size. If the desired size isn't available, the script exits with an error message. If the desired size is available, the script deallocates the VM, resizes it, and starts it again.

# Set variables
resourceGroup="myResourceGroup"
vmName="myVM"
newVmSize="<newVmSize>"
availabilitySetName="<availabilitySetName>"

# Check if the desired VM size is available
availableSizes=$(az vm list-vm-resize-options \
  --resource-group $resourceGroup \
  --name $vmName \
  --query "[].name" \
  --output tsv)
if [[ ! $availableSizes =~ $newVmSize ]]; then
  # Deallocate all VMs in the availability set
  vmIds=$(az vmss list-instances \
    --resource-group $resourceGroup \
    --name $availabilitySetName \
    --query "[].instanceId" \
    --output tsv)
  az vm deallocate \
    --ids $vmIds \
    --no-wait

  # Resize and restart the VMs in the availability set
  az vmss update \
    --resource-group $resourceGroup \
    --name $availabilitySetName \
    --set virtualMachineProfile.hardwareProfile.vmSize=$newVmSize
  az vmss start \
    --resource-group $resourceGroup \
    --name $availabilitySetName \
    --instance-ids $vmIds
  exit
fi

# Resize the VM
az vm resize \
  --resource-group $resourceGroup \
  --name $vmName \
  --size $newVmSize

Use PowerShell to resize a VM not in an availability set.

You can execute it locally on your machine. This local version of the PowerShell script includes additional steps to import the Azure module and authenticate your Azure account.

# Import the Azure module
Import-Module Az
# Login to your Azure account
Connect-AzAccount -Environment AzureChinaCloud
# Set variables
$resourceGroup = 'myResourceGroup'
$vmName = 'myVM'
$size = 'Standard_DS3_v2'
# Select the subscription
Select-AzSubscription -SubscriptionId '<subscriptionID>'
# Get the VM
$vm = Get-AzVM -ResourceGroupName $resourceGroup -Name $vmName
# Change the VM size
$vm.HardwareProfile.VmSize = $size
# Update the VM
Update-AzVM -ResourceGroupName $resourceGroup -VM $vm

Use PowerShell to resize a VM in an availability set

If the new size for a VM in an availability set isn't available on the hardware cluster currently hosting the VM, then you need to deallocate all VMs in the availability set to resize the VM. You also might need to update the size of other VMs in the availability set after one VM has been resized. To resize a VM in an availability set, run the below script. You can replace the values of $resourceGroup, $vmName, $newVmSize, and $availabilitySetName with your own.

# Set variables
$resourceGroup = "myResourceGroup"
$vmName = "myVM"
$newVmSize = "<newVmSize>"
$availabilitySetName = "<availabilitySetName>"

# Check if the desired VM size is available
$availableSizes = Get-AzVMSize `
  -ResourceGroupName $resourceGroup `
  -VMName $vmName |
  Select-Object -ExpandProperty Name
if ($availableSizes -notcontains $newVmSize) {
  # Deallocate all VMs in the availability set
  $as = Get-AzAvailabilitySet `
    -ResourceGroupName $resourceGroup `
    -Name $availabilitySetName
  $virtualMachines = $as.VirtualMachinesReferences | Get-AzResource | Get-AzVM
  $virtualMachines | Stop-AzVM -Force -NoWait

  # Resize and restart the VMs in the availability set
  $virtualMachines | Foreach-Object { $_.HardwareProfile.VmSize = $newVmSize }
  $virtualMachines | Update-AzVM
  $virtualMachines | Start-AzVM
  exit
}

# Resize the VM
$vm = Get-AzVM `
  -ResourceGroupName $resourceGroup `
  -VMName $vmName
$vm.HardwareProfile.VmSize = $newVmSize
Update-AzVM `
  -VM $vm `
  -ResourceGroupName $resourceGroup

This script sets the variables $resourceGroup, $vmName, $newVmSize, and $availabilitySetName. It then checks if the desired VM size is available by using Get-AzVMSize and checking if the output contains the desired size. If the desired size isn't available, the script deallocates all VMs in the availability set, resizes them, and starts them again. If the desired size is available, the script resizes the VM.