OS License Change Aids Consolidation

Microsoft has modified Windows Server 2008 licensing terms to make it less costly to use the server OS to host virtual machines (VMs) running older versions of Windows Server as well as Linux OS workloads. By eliminating a requirement that customers purchase Windows Server 2008 Client Access Licenses (CALs) in certain virtualization scenarios, the new licensing terms make Windows Server 2008 more appealing as a virtualization platform, particularly for consolidating multiple existing legacy Windows Servers. However, customers must take care in how they configure Windows Server 2008 to stay within the new guidelines.

Windows Server 2008 Client-side Licensing Requirements

The three editions of Windows Server 2008 typically used as a virtualization host—Standard, Enterprise, and Datacenter Editions—are licensed with a server/CAL model, with one (or more) server licenses required for the physical server, and a CAL required for each client user or device accessing the server.

Under the previous Windows Server 2008 licensing rules, any client accessing a VM hosted on Windows Server 2008 required a Windows Server 2008 CAL, even if the client never accessed the physical server directly, but only a VM running on it. This gave pause to customers who wanted to consolidate multiple servers, such as existing Windows 2003 servers, on Windows Server 2008 and its built-in Hyper-V virtualization technology: using the technology to host VMs required customers to upgrade all of their Windows Server CALs from Windows Server 2003 to Windows Server 2008, at a cost of about US$30 per client computer (Open Business price, the highest price a business customer would pay through a volume purchasing program).