Create a Windows VM from a specialized disk by using PowerShell

Applies to: ✔️ Windows VMs

Create a new VM by attaching a specialized managed disk as the OS disk. A specialized disk is a copy of a virtual hard disk (VHD) from an existing VM that contains the user accounts, applications, and other state data from your original VM.

You have several options:

• Use an existing managed disk. This option is useful if you have a VM that isn't working correctly. You can delete the VM and then reuse the managed disk to create a new VM.
• Upload a VHD
• Copy an existing Azure VM by using snapshots

You can also use the Azure portal to create a new VM from a specialized VHD.

This article shows you how to use managed disks. If you have a legacy deployment that requires using a storage account, see Create a VM from a specialized VHD in a storage account.

Important

When you use a specialized disk to create a new VM, the new VM retains the computer name of the original VM. Other computer-specific information (e.g. CMID) is also kept and, in some cases, this duplicate information could cause issues. When copying a VM, be aware of what types of computer-specific information your applications rely on.
Thus, don't use a specialized disk if you want to create multiple VMs. Instead, for larger deployments, create an image and then use that image to create multiple VMs.

We recommend that you limit the number of concurrent deployments to 20 VMs from a single VHD or snapshot.

Option 1: Use an existing disk

If you had a VM that you deleted and you want to reuse the OS disk to create a new VM, use Get-AzDisk.

$resourceGroupName = 'myResourceGroup'
$osDiskName = 'myOsDisk'
$osDisk = Get-AzDisk `
-ResourceGroupName $resourceGroupName `
-DiskName $osDiskName

You can now attach this disk as the OS disk to a new VM.

Option 2: Upload a specialized VHD

You can upload the VHD from a specialized VM created with an on-premises virtualization tool, like Hyper-V, or a VM exported from another cloud.

Prepare the VM

Use the VHD as-is to create a new VM.

• Prepare a Windows VHD to upload to Azure. Do not generalize the VM by using Sysprep.
• Remove any guest virtualization tools and agents that are installed on the VM (such as VMware tools).
• Make sure the VM is configured to get the IP address and DNS settings from DHCP. This ensures that the server obtains an IP address within the virtual network when it starts up.

Upload the VHD

You can now upload a VHD straight into a managed disk. For instructions, see Upload a VHD to Azure using Azure PowerShell.

Option 3: Copy an existing Azure VM

You can create a copy of a VM that uses managed disks by taking a snapshot of the VM, and then by using that snapshot to create a new managed disk and a new VM.

If you want to copy an existing VM to another region, you might want to use azcopy to create a copy of a disk in another region.

Take a snapshot of the OS disk

You can take a snapshot of an entire VM (including all disks) or of just a single disk. The following steps show you how to take a snapshot of just the OS disk of your VM with the New-AzSnapshot cmdlet.

First, set some parameters.

$resourceGroupName = 'myResourceGroup' 
$vmName = 'myVM'
$location = 'westus' 
$snapshotName = 'mySnapshot'  

Get the VM object.

$vm = Get-AzVM -Name $vmName `
   -ResourceGroupName $resourceGroupName

Get the OS disk name.

$disk = Get-AzDisk -ResourceGroupName $resourceGroupName `
  -DiskName $vm.StorageProfile.OsDisk.Name

Create the snapshot configuration.

$snapshotConfig =  New-AzSnapshotConfig `
  -SourceUri $disk.Id `
  -OsType Windows `
  -CreateOption Copy `
  -Location $location 

Take the snapshot.

$snapShot = New-AzSnapshot `
   -Snapshot $snapshotConfig `
   -SnapshotName $snapshotName `
   -ResourceGroupName $resourceGroupName

To use this snapshot to create a VM that needs to be high-performing, add the parameter -AccountType Premium_LRS to the New-AzSnapshotConfig command. This parameter creates the snapshot so that it's stored as a Premium Managed Disk. Premium Managed Disks are more expensive than Standard, so be sure you'll need Premium before using this parameter.

Create a new disk from the snapshot

Create a managed disk from the snapshot by using New-AzDisk. This example uses myOSDisk for the disk name.

Create a new resource group for the new VM.

$destinationResourceGroup = 'myDestinationResourceGroup'
New-AzResourceGroup -Location $location `
   -Name $destinationResourceGroup

Set the OS disk name.

$osDiskName = 'myOsDisk'

Create the managed disk.

$osDisk = New-AzDisk -DiskName $osDiskName -Disk `
    (New-AzDiskConfig  -Location $location -CreateOption Copy `
	-SourceResourceId $snapshot.Id) `
    -ResourceGroupName $destinationResourceGroup

Create the new VM

Create networking and other VM resources to be used by the new VM.

Create the subnet and virtual network

Create the virtual network and subnet for the VM.

1. Create the subnet. This example creates a subnet named mySubNet, in the resource group myDestinationResourceGroup, and sets the subnet address prefix to 10.0.0.0/24.

   $subnetName = 'mySubNet'
   $singleSubnet = New-AzVirtualNetworkSubnetConfig `
      -Name $subnetName `
      -AddressPrefix 10.0.0.0/24
   

2. Create the virtual network. This example sets the virtual network name to myVnetName, the location to West US, and the address prefix for the virtual network to 10.0.0.0/16.

   $vnetName = "myVnetName"
   $vnet = New-AzVirtualNetwork `
      -Name $vnetName -ResourceGroupName $destinationResourceGroup `
      -Location $location `
      -AddressPrefix 10.0.0.0/16 `
      -Subnet $singleSubnet
   

Create the network security group and an RDP rule

To be able to sign in to your VM with remote desktop protocol (RDP), you'll need to have a security rule that allows RDP access on port 3389. In our example, the VHD for the new VM was created from an existing specialized VM, so you can use an account that existed on the source virtual machine for RDP. This example denies RDP traffic, to be more secure. You can change -Access to Allow if you want to allow RDP access.

This example sets the network security group (NSG) name to myNsg and the RDP rule name to myRdpRule.

$nsgName = "myNsg"

$rdpRule = New-AzNetworkSecurityRuleConfig -Name myRdpRule -Description "Deny RDP" `
    -Access Deny -Protocol Tcp -Direction Inbound -Priority 110 `
    -SourceAddressPrefix Internet -SourcePortRange * `
    -DestinationAddressPrefix * -DestinationPortRange 3389
$nsg = New-AzNetworkSecurityGroup `
   -ResourceGroupName $destinationResourceGroup `
   -Location $location `
   -Name $nsgName -SecurityRules $rdpRule
	

For more information about endpoints and NSG rules, see Opening ports to a VM in Azure by using PowerShell.

Create a public IP address and NIC

To enable communication with the virtual machine in the virtual network, you'll need a public IP address and a network interface.

1. Create the public IP. In this example, the public IP address name is set to myIP.

   $ipName = "myIP"
   $pip = New-AzPublicIpAddress `
      -Name $ipName -ResourceGroupName $destinationResourceGroup `
      -Location $location `
      -AllocationMethod Dynamic
   

2. Create the NIC. In this example, the NIC name is set to myNicName.

   $nicName = "myNicName"
   $nic = New-AzNetworkInterface -Name $nicName `
      -ResourceGroupName $destinationResourceGroup `
      -Location $location -SubnetId $vnet.Subnets[0].Id `
      -PublicIpAddressId $pip.Id `
      -NetworkSecurityGroupId $nsg.Id
   

Set the VM name and size

This example sets the VM name to myVM and the VM size to Standard_A2.

$vmName = "myVM"
$vmConfig = New-AzVMConfig -VMName $vmName -VMSize "Standard_A2"

Add the NIC

$vm = Add-AzVMNetworkInterface -VM $vmConfig -Id $nic.Id

Add the OS disk

Add the OS disk to the configuration by using Set-AzVMOSDisk. This example sets the size of the disk to 128 GB and attaches the managed disk as a Windows OS disk.

$vm = Set-AzVMOSDisk -VM $vm -ManagedDiskId $osDisk.Id -StorageAccountType Standard_LRS `
    -DiskSizeInGB 128 -CreateOption Attach -Windows

Complete the VM

Create the VM by using New-AzVM with the configurations that we just created.

New-AzVM -ResourceGroupName $destinationResourceGroup -Location $location -VM $vm

If this command is successful, you'll see output like this:

RequestId IsSuccessStatusCode StatusCode ReasonPhrase
--------- ------------------- ---------- ------------
                         True         OK OK   

Verify that the VM was created

You should see the newly created VM either in the Azure portal under Browse > Virtual machines, or by using the following PowerShell commands.

$vmList = Get-AzVM -ResourceGroupName $destinationResourceGroup
$vmList.Name

Next steps

Sign in to your new virtual machine. For more information, see How to connect and log on to an Azure virtual machine running Windows.