Virtual machines use virtual hard disks (VHDs) to store their operating system (OS) and data. VHDs are also used for the images you can choose from to install an OS.
Azure provides many marketplace images to use with various versions and types of Windows Server operating systems. Marketplace images are identified by an image publisher, offer, SKU, and version.
You can add a new HDD to your VM with a few clicks, you don’t need to worry about hardware headache.