An instance of an Azure role or Azure VM comprises several virtual disks (VHDs) deployed into a virtual machine. For Windows OS, this VHD must be an NTFS-formatted, fixed-size VHD. The VHD can be created directly as a page blob or uploaded like any other page blob.

The Disk Management snap-in for the Microsoft Management Console (MMC) can be used to create and format a VHD on a local system. Once attached to the local system, files can be copied to or created on the filesystem of the VHD, just as they can be created on any hard drive. The VHD can then be detached from the local system and uploaded as a page blob to the Azure Blob service.

A page blob, which might have a maximum size of 1 TB, comprises a sequence of 512-byte pages. All writes to a page blob must be aligned with a page boundary. There is no charge for an empty page in a page blob. There is no need to upload empty pages in the VHD, which means that bandwidth need not be wasted uploading empty...