Microsoft keeps on finding approaches to improve Azure offerings for the customers. Azure Managed Disks, a new disk service launched in Feb ’17, has made the administration and scaling of Virtual Machines (VM) simpler. You can create a empty Managed Disk, or from a VHD in a storage account, or from an Image during the VM creation.
The price of Managed Disks, both Premium and Standard, depends on the provisioned disk size, which is not the same as the price of Standard Unmanaged Disks. To minimize the cost, Microsoft created lower pricing options with 32GB and 64GB Standard Managed Disk sizes. Apart from this, Microsoft have also included a set of Windows Server offerings with 30GB OS disks for Windows Server 2008R2, Windows Server 2012, Windows Server 2012R2 and Windows Server 2016 in Azure Marketplace. These smaller disk images are prepended with “[smalldisk]” in the image title on Azure Portal. For Powershell, CLI and ARM Templates, the image SKU is attached with “- smalldisk. So, in case your application don’t require large OS disk space, you would see a saving of $2.18 per VM when using 32GB Standard Managed disk as compare 127GB disk. For large deployments, this can result in significant savings.
You can also extend the OS disk by following the steps in below link.
After extended the OS Disk, sign into your Windows VM and utilize Disk Management Tool to extend the OS disk.