Virtual Machine Role in Windows Azure

The Virtual Machine (VM) role enables you to deploy a custom Windows Server image to Windows Azure. The VM role runs a virtual hard drive (VHD) image of a Windows Server 2008 R2 virtual machinethat you create on-premises and upload to Windows Azure. The creation and updating of the VHD image is managed by you, giving you full control to configure and maintain the operating system image. The VM role is currently in beta. You can request enrollment via the Windows Azure Management Portal.

There are many practical uses for the VM role.  Some common uses include:

Application installations

In certain scenarios, pre-installing your application on a VHD image saves you significant time when you need to scale. For example, an application that takes an extended amount of time to install can be installed once on a VHD image. The VHD is then easily replicated. Other useful scenarios for the VM role include application installations that require manual interaction, such as inputting text, or complex, error-prone application installations that may call for action during installation to resolve. These scenarios are not possible to execute using the alternative automated startup tasks in the web or worker role.

Application migration

The VM role can be used to migrate stateless applications that do not depend on data stored in the operating system, to Windows Azure.

Capabilities and Benefits of the VM Role

Application environment control

• The image-based management of the VM Role allows massive scale-out and easy application updating. When you use the VM role, you retain most of the benefits of automated service management (load balancing and failover) with the exception of automated OS patching.
• You get full control of the operating system image. Administrators can remotely access the virtual machine to perform maintenance and troubleshooting tasks.

Pricing and Metering for the VM Role

Pricing for the VM Role is identical to Compute.  You are charged at an hourly rate depending on the compute instance size. The Windows Azure fee for running the VM role – whether consumption or commitment based – includes the Windows Server licensing costs.

Customers may use bits obtained through volume licensing (physical or electronic) to create the image. During the beta release of the VM role, you can use the 64-bit version of Windows Server 2008 R2 for production services. Other Microsoft software acquired through an active MSDN® license or subscription can be run in the VM role for development and test purposes only. Use of any third party software in the VM role will be governed by use rights for that software. There is no requirement for Windows Server Client Access Licenses (CALs) to connect to the VM role. There is also no transfer of use rights from any existing Windows Server 2008 R2 license acquired through any other licensing program to the VM role nor are rights from the VM role transferable to any other device.

Visit MSDN to get in-depth information on the VM role.