What drive letters should you use for your Azure VM Data Disks?

On an Azure VM the SYSTEM disk is deployed on the C: drive.

The D: drive is temporary. This means that when you shut down a VM, anything you stored on that disk in your session would be lost. This D: drive could be used for things like page files.

By default the E: drive is used for the DVD drive by Azure.

The data disks on your VM start at drive letter F: and goes up from there (G:, H:, I:, etc.). This is where you would store data files.