Brief

Licensing Microsoft Windows Server 2003 R2 to Run with Virtualization Technologies

VMwareESX Server, VMware VMotion, SWsoft Virtuozzo, and Microsoft System Center Virtualization Machine Manager

May 2007

Corporate Academic

Open License Open License Value  Select License  Academic Select  Enterprise Agreement

Summary

In this document, we discuss how the Microsoft® Windows Server® 2003 R2 operating system and other Microsoft server products are licensed when used with virtualization technologies VMware ESX Server, VMware VMotion, SWsoft Virtuozzo, and Microsoft System Center Virtual Machine Manager. In addition, we also compare costs, both between different Windows Server editions and between the different virtualization technologies.

Summary

Introduction to Licensing Virtualization Technologies

Understanding Virtualization Rights

Rights for Windows Server 2003 R2 Standard Edition, Enterprise Edition, and Datacenter Edition

Determining the Most Cost-Effective Edition of Windows Server

Considerations for Clustering, Failing Over, and Moving Instances

Client Access Licenses (CALs) and External Connectors (ECs)

Licensing for Virtualization Technologies

Licensing for VMware ESX

Licensing for VMware VMotion and Microsoft System Center Virtual Machine Manager

Licensing for SWsoft Virtuozzo

Comparing ESX Server, Virtuozzo, and Microsoft Virtual Server

Additional Resources

Introduction to Licensing Virtualization Technologies

With the growing prevalence of virtualization technologies, many customers ask how they license Windows Server products with thesetechnologies. Although seemingly complex, licensing in this case is actually quite simple. Before delving into licensing details and examples, however, it is useful to review some basic licensing concepts to better understand how they apply in virtualized scenarios.

To run Microsoft server software on a server, you must first assign the server a license. By assigning this license, you are designating a server to run an instance of Microsoft server software. In addition, you have the right to run as many instances on that server as the software allows—regardless of what kind of operating system environment (OSE) is present.

There are two types of OSEs: physical and virtual. A physical OSE is configured to run directly on a physical hardware system and can be physical and/or virtual. A virtual OSE is configured to run on a virtual—or otherwise emulated—hardware system. This distinction is vital to understanding how to license virtualization technologies; regardless of the type, each instance running requires a license.

To better understand the difference between physical and virtual OSEs, consider the following: Windows Server 2003 R2 Standard Edition permits one running instance at a time, while Enterprise Edition permits up to five—one instance running in a physical operating system environment and four instances running in a virtual OSE. If you choose to run five instances at a time under the Enterprise Edition license, the instance of the software running in the physical OSE may only be used to run hardware virtualization software and software to manage and service OSEs on the licensed server.

Please note that you need separate licenses for OSEs that include all or part of an operating system or that include all or part of a virtual instance and enable separate machine identity or separate administrative rights.

Understanding Virtualization Rights

The first step to understanding how to license virtualization technologies is to determine which Windows Server edition is right for your organization based on how many physical and virtual OSEs you need. In this section, we describe the number of OSEs each edition permits and the benefits of each. We also list other licensing considerations you may take into account.

Rights for Windows Server 2003 R2 Standard Edition, Enterprise Edition, and Datacenter Edition

When licensing Windows Server products, you should carefully consider the server’s peak capacity because it must have licenses equal to or exceeding the number of running instances. For example, if you have one Windows Server 2003 R2 Standard Edition license assigned to a server, the server may not run a second instance of the software at the same time. If, for any reason, you need to run a second instance, you must assign the server a second license.

The following outlines the maximum number of running instances each Windows Server 2003 R2 edition permits:

Product / Maximum Permitted Running Instances in a Virtual OSE per License / Application in Virtualized Environments
Windows Server 2003 R2 Standard Edition / One* / A single Standard Edition license server permits you to run one instance of the software in either a physical or virtual OSE on that server. You need to assign a Standard Edition license for each running instance (in which case you may want to choose a higher level edition).
Windows Server 2003 R2 Enterprise Edition / Four / An Enterprise Edition license grants the right to run one Enterprise server in one physical OSE and up to four simultaneous virtual OSEs. If you run all five permitted instances at the same time, the instance of the server software running in the physical OSE may only be used to run hardware virtualization software and software to manage and service the OSEs on the server.
Windows Server 2003 R2 Datacenter Edition / Unlimited / When Datacenter Edition is licensed for every physical processor in a server, the server may run in both the physical OSE and in an unlimited number of Windows Server instances in virtual OSEs.
Windows Server 2003 Web Edition / One* / A single Web Edition license server permits you to run one instance of the software in either a physical or virtual OSE on that server. You need to assign a Web Edition license for each running instance (in which case you may want to choose a higher level edition).

Determining the Most Cost-Effective Edition of Windows Server

The most cost-effective edition of Windows Server for your specific virtualization needs depends on the number of instances per processor that can run on the server. (Please note that Enterprise Edition and Datacenter Edition may offer the ability to add instances, along with offering clustering and other functionality not available in Standard Edition).

  • Standard Edition is the most cost-effective if you want to run up to three simultaneous instances in a virtual OSE on the server.
  • Enterprise Edition is the most cost-effective if you want to run four simultaneous instances in a virtual OSE per processor. Enterprise Edition is licensed by server—not per processor. But more than one Enterprise Edition license may be assigned to a server to have the rights to run more than four instances of Windows Server. For example, one license for Enterprise Edition for a one-processor server running four instances of Windows Server in a virtual OSE is slightly less expensive than one Datacenter Edition processor license. And two licenses for Enterprise Edition for a two-processor server running eight instances of Windows Server in a virtual OSE is slightly less expensive than two-processor licenses for Datacenter Edition.
  • Datacenter Edition is most cost-effective for running more than four instances per processor. At four instances per processor, Datacenter Edition is slightly more expensive than Enterprise Edition, but provides room to add instances in a virtual OSE on the server at no additional cost.

Figure 1: The Windows Server Virtualization Calculator is a tool that can help you determine the number of Windows Server licenses and estimated cost by edition for your virtualization scenarios to find the most cost-effective edition. It is available at: .[1]

Considerations for Clustering, Failing Over, and Moving Instances

Higher availability and dynamic datacenters often need to run the same workload on two servers simultaneously or run a workload on a primary server, but periodically move it to a second server in the case of failure, load balancing, patching, or planned downtime.

In both scenarios, regardless of whether the workloads are running in physical or virtual OSEs, each server must have the appropriate number of licenses assigned to it prior to it being used to run workload, regardless of whether you plan to:

  • Always run on a single server.
  • Run in parallel on the server as a backup when the primary server fails.
  • Run the workload if the primary server is down.
  • Load balance when the primary server has high use.
  • Only run the workload during maintenance.

Figures 2, 3, and 4 demonstrate three examples that are properly licensed.

Figure 2: The servers are clustered, each licensed with Windows Server (WS) and both running the same workload in parallel.

Figure 3: The servers are clustered, each licensed with Windows Server (WS) and both running the same virtualized workload in parallel.

Figure 4: Both servers are licensed with Windows Server (WS). The workload is moved from the first server to the second server.

Client Access Licenses (CALs) and External Connectors (ECs)

Most Microsoft servers require Client Access Licenses (CALs) and have an optional external connector (EC). The CAL and EC requirements are the same for both physical and virtual OSEs.CALs are required for each device or user that accesses an instance of server software directly or indirectly. You do not need CALs for up to two devices or users to access your instances as long as they are only administering them.

In addition, Windows Server 2003 R2 Standard Edition, Enterprise Edition, and Datacenter Edition do not require CALs or ECs for users or devices that access your software instances through the Internet without being authenticated or otherwise individually identified through any means. CALs and ECs cannot be reassigned on a short-term basis.

Users and devices licensed with a CAL can access any instances (physical and virtual) running on any physical server. Outside of the exceptions above, each physical server that requires external user access must be assigned an EC. Each EC permits external users to access any instance running on a server whether it be in a physical or virtual OSE. You do not need additional ECs for each virtual instance on a physical server.

Please note that multiplexing hardware, software, or connections does not reduce the number of CALs required to access servers.

Licensing for Virtualization Technologies

Once you understand how to license Windows Server products according to how many instances you need to run, you can learn about the specific licensing requirements of various virtualization technologies. In addition to providing specific details and scenarios for each, we also compare overall licensing costs.

Licensing for VMware ESX

If a server is running VMware ESX as a virtualization technology, Windows Server is not deployed as a host operating system in the physical OSE. However, a license is still required for every instance running in a virtual OSE.

If you have assigned a single license of Windows Server Standard Edition to the server running ESX, then you may run one instance at a time of Windows Server Standard Edition.If you have assigned a single license of Windows Server Enterprise Edition to the server running ESX, then you may run up to four instances at a time of Windows Server. You may not run a fifth instance under the same Enterprise Edition license because that right requires that the fifth instance be running hardware virtualization software and software managing and servicing the OSEs on the server. However, Datacenter Edition permits unlimited running of instances in virtual OSEs.

Licensing for VMware VMotion and Microsoft System Center Virtual Machine Manager

VMotion, System Center Virtual Machine Manager, and Windows Server Clustering all move instances of virtual OSEs between physical servers. However, the licenses remain with the physical server to which they are assigned. When an instance is moved to a new physical server, the new server must have the appropriate licenses.

With a few exceptions, described in the box to the side regarding PUR, software licenses may only be reassigned to new hardware after 90 days. However, the dynamic movement of virtual OSEs between licensed servers is not restricted in any way. As long as the servers are licensed—and are not running more instances simultaneously—you are free to use VMotion and System Center Virtual Machine Manager to move virtualized instances between licensed servers at will.

Figure 5: If each server has four licenses for Windows Server 2003 R2 Standard Edition and the second server is already running three instances of Windows Server 2003 R2 Standard Edition in a virtual OSE, then VMotion or System Center Virtual Machine Manager (Windows Server Clustering Services, scripting, or manual administration) may move one (Example A) instance of Standard Edition from the first server to the second server.But it may not move a second instance (Example B above), because moving the second instance would cause the second server to become underlicensed.

The following scenarios demonstrate how to properly license three dual-processor servers to use with VMotion and System Center Virtual Machine Manager to move instances between the three servers. The first scenario (Figure 6) shows the “standard” running state of the three servers where the three servers are each licensed with four licenses of Windows Server 2003 R2 Standard Edition and are running four instances of Windows Server 2003 R2 Standard Edition in a virtual OSE.

The second, third, and fourth scenarios (Figures 7, 8, and 9) show the VMotion or System Center Virtual Machine Manager moving two instances from the first server to the second server and the remaining two instances to the third server. In the second scenario (Figure 7), the second and third servers are under-licensed. The third and fourth scenarios (Figures 8 and 9) show two options to properly license the migration of instances of Windows Server.

Figure 6: The three servers are properly licensed to run four instances of Windows Server, because they are each licensed with four licenses of Windows Server 2003 R2 Standard Edition.

Figure 7: The instances of Windows Server running in a virtual OSE may not be moved from the first server to the second or third server, because the second and third servers are each licensed with four instances of Windows Server and are already running four instances of Windows Server before the attempted migration.

Figure 8: Two of the instances of Windows Server may be moved from the first server to the second, and the remaining two instances may be moved from the first server to the third; the second and third servers each have six licenses and were only running four instances of Windows Server prior to the migration.

Figure 9: Instead of licensing the servers with enough Windows Server 2003 R2 Standard Edition licenses to meet the largest number of simultaneously running instances of Windows Server, the processors in the servers could be licensed with Windows Server 2003 R2 Datacenter Edition to allow an unlimited number of instances of Windows Server to run simultaneously in virtual OSEs. Because each server has two processors, two Windows Server 2003 R2 Datacenter Edition licenses are required for each server. Windows Server 2003 R2 Datacenter Edition licensing provides the flexibility to move instances of Windows Server without concern about maintaining license compliance.

Licensing for SWsoft Virtuozzo

On a single physical server, SWsoft Virtuozzo software creates running instances of Windows Server in virtual OSEs that run on top of Windows Server. These running instances—also referred to as a “silo,” “isolated partition,” or “VE” (Virtualized Environment)—act as the host operating system. They share the same kernel of the host Windows Server operating system, but have isolated registry settings, operating system libraries, operating system processes, and application software. These virtual OSEs also enable separate machine identity or administration rights.

As with other virtualization technologies, each physical and virtual running instance of Windows Server requires a Windows Server license. But because every instance shares the same kernel as the host operating system, Virtuozzo is technically unable to run more than one edition of Windows Server on the physical server. As a result, you must choose a single edition when using Virtuozzo for both physical and virtual OSEs.

Furthermore, all instances are exposed to all physical processors in the server. For example, the instances on a two-processor server would each have two virtual processors, and the instances on a four-processor server would each have four virtual processors. This distinction is important for Microsoft server applications that are licensed on a “per processor” licensing model, such as Microsoft SQL Server™ 2005 and Microsoft BizTalk™ Server 2006. Finally, it is important to note that because Virtuozzo instances share the same kernel, you cannot take advantage of “downgrade” rights.