Attach a data disk to a Windows VM using PowerShell

This article shows you how to attach both new and existing disks to a Windows virtual machine using PowerShell. If your VM uses managed disks, you can attach additional managed data disks. You can also attach unmanaged data disks to a VM that uses unmanaged disks in a storage account.

Before you do this, review these tips:

• The size of the virtual machine controls how many data disks you can attach. For details, see Sizes for virtual machines.
• To use Premium storage, you'll need a Premium Storage enabled VM size like the DS-series or GS-series virtual machine. You can use disks from both Premium and Standard storage accounts with these virtual machines. Premium storage is available in certain regions. For details, see Premium Storage: High-Performance Storage for Azure Virtual Machine Workloads.

Before you begin

If you use PowerShell, make sure that you have the latest version of the AzureRM.Compute PowerShell module. Run the following command to install it.

Install-Module AzureRM.Compute -RequiredVersion 2.6.0

For more information, see Azure PowerShell Versioning.

Add an empty data disk to a virtual machine

This example shows how to add an empty data disk to an existing virtual machine.

Using managed disks

$rgName = 'myResourceGroup'
$vmName = 'myVM'
$location = 'West Central US' 
$storageType = 'PremiumLRS'
$dataDiskName = $vmName + '_datadisk1'

$diskConfig = New-AzureRmDiskConfig -AccountType $storageType -Location $location -CreateOption Empty -DiskSizeGB 128

$dataDisk1 = New-AzureRmDisk -DiskName $dataDiskName -Disk $diskConfig -ResourceGroupName $rgName

$vm = Get-AzureRmVM -Name $vmName -ResourceGroupName $rgName 

$vm = Add-AzureRmVMDataDisk -VM $vm -Name $dataDiskName -CreateOption Attach -ManagedDiskId $dataDisk1.Id -Lun 1

Update-AzureRmVM -VM $vm -ResourceGroupName $rgName

Using unmanaged disks in a storage account

    $vm = Get-AzureRmVM -ResourceGroupName $rgName -Name $vmName
    Add-AzureRmVMDataDisk -VM $vm -Name "disk-name" -VhdUri "https://mystore1.blob.core.windows.net/vhds/datadisk1.vhd" -LUN 0 -Caching ReadWrite -DiskSizeinGB 1 -CreateOption Empty
    Update-AzureRmVM -ResourceGroupName $rgName -VM $vm

Initialize the disk

After you add an empty disk, you need to initialize it. To initialize the disk, you can log in to a VM and use disk management. If you enabled WinRM and a certificate on the VM when you created it, you can use remote PowerShell to initialize the disk. You can also use a custom script extension:

    $location = "location-name"
    $scriptName = "script-name"
    $fileName = "script-file-name"
    Set-AzureRmVMCustomScriptExtension -ResourceGroupName $rgName -Location $locName -VMName $vmName -Name $scriptName -TypeHandlerVersion "1.4" -StorageAccountName "mystore1" -StorageAccountKey "primary-key" -FileName $fileName -ContainerName "scripts"

The script file can contain something like this code to initialize the disks:

    $disks = Get-Disk | Where partitionstyle -eq 'raw' | sort number

    $letters = 70..89 | ForEach-Object { [char]$_ }
    $count = 0
    $labels = "data1","data2"

    foreach ($disk in $disks) {
        $driveLetter = $letters[$count].ToString()
        $disk | 
        Initialize-Disk -PartitionStyle MBR -PassThru |
        New-Partition -UseMaximumSize -DriveLetter $driveLetter |
        Format-Volume -FileSystem NTFS -NewFileSystemLabel $labels[$count] -Confirm:$false -Force
    $count++
    }

Attach an existing data disk to a VM

You can also attach an existing VHD as a managed data disk to a virtual machine.

Using managed disks

$rgName = 'myRG'
$vmName = 'ContosoMdPir3'
$location = 'West Central US' 
$storageType = 'PremiumLRS'
$dataDiskName = $vmName + '_datadisk2'
$dataVhdUri = 'https://mystorageaccount.blob.core.windows.net/vhds/managed_data_disk.vhd' 

$diskConfig = New-AzureRmDiskConfig -AccountType $storageType -Location $location -CreateOption Import -SourceUri $dataVhdUri -DiskSizeGB 128

$dataDisk2 = New-AzureRmDisk -DiskName $dataDiskName -Disk $diskConfig -ResourceGroupName $rgName

$vm = Get-AzureRmVM -Name $vmName -ResourceGroupName $rgName 

$vm = Add-AzureRmVMDataDisk -VM $vm -Name $dataDiskName -CreateOption Attach -ManagedDiskId $dataDisk2.Id -Lun 2

Update-AzureRmVM -VM $vm -ResourceGroupName $rgName

Next steps

Create a snapshot.