Azure – Expand OS Drive for Azure Virtual Machine

When you create an Azure Virtual Machine, it comes with an OS drive having a default size. The size is different for Windows and Linux machines. ~128GB and ~30GB for Windows and Linux machines respectively. The OS drive can be expanded to a maximum size of 2TB as of this writing. Use the below code to allocate space to your Azure VM’s OS drive. After executing the code, login to the virtual machine and expand (Disk Management for Windows) the drive using the newly allocated space.

Resize a Managed Disk:

## Resize OS disk size for Managed Disk

# Set Resource Group and Virtual Machine name
$resourceGroupName = 'my_resource_group_name'
$virtualMachineName = 'my_virtual_machine_name'

# Create VM reference object
$vm = Get-AzureRmVM -ResourceGroupName $resourceGroupName -Name $virtualMachineName

# Stop the Virtual Machine
Stop-AzureRmVM -ResourceGroupName $resourceGroupName -Name $virtualMachineName

# Create a reference to the Managed disk and set the size as required
$disk= Get-AzureRmDisk -ResourceGroupName $resourceGroupName -DiskName $vm.StorageProfile.OsDisk.Name
$disk.DiskSizeGB = 1023
Update-AzureRmDisk -ResourceGroupName $resourceGroupName -Disk $disk -DiskName $disk.Name

# Start the Azure Virtual Machine
Start-AzureRmVM -ResourceGroupName $resourceGroupName -Name $virtualMachineName

Resize an Unmanaged Disk:

## Resize OS disk size for Unmanaged Disk

# Set Resource Group and Virtual Machine name
$resourceGroupName = 'my-resource-group-name'
$virtualMachineName = 'my-vm-name'

# Create VM reference object
$vm = Get-AzureRmVM -ResourceGroupName $resourceGroupName -Name $virtualMachineName

# Stop the Virtual Machine
Stop-AzureRmVM -ResourceGroupName $resourceGroupName -Name $virtualMachineName

# Create a reference to the Unmanaged disk and set the size as required
$vm.StorageProfile.OSDisk.DiskSizeGB = 1023
Update-AzureRmVM -ResourceGroupName $resourceGroupName -VM $vm

# Start the Azure Virtual Machine
Start-AzureRmVM -ResourceGroupName $resourceGroupName -Name $virtualMachineName