When moving to a virtual world, operating system (OS) and application licensing and support become more complex and less defined than in physical server environments. Organizations preparing to implement a virtual infrastructure should examine the operating systems, applications, and suites of applications in use across the organization and the impact that a virtual infrastructure may have on them. This tip covers the often-overlooked issues surrounding operating system and application licensing and vendor support in a virtualized data center.
Operating system and application licensing
While many independent software vendors (ISVs) have been slow to spell out the licensing strictures for running their software in a virtual infrastructure, some vendors have begun to set specific virtualization policies. For example, Microsoft has defined their Windows Server licensing policies for any virtualization environment (using server virtualization software from VMware, Microsoft or Xen), as follows -- the Microsoft Windows Server license will allow a specified number of active concurrent virtual operating system instances on a single hardware device -- physical server, blade, etc. -- and an unlimited number of "powered off" instances. Specifically, Windows Server Enterprise Edition allows up to four instances of Windows to run on one physical system, while Datacenter Edition allows an unlimited number of concurrent Windows virtual machines on one physical server. Microsoft has a calculator tool available online to estimate the number of licenses and costs involved in running the various editions of Windows Server in any virtualized environment - Windows Server – virtualization licensing calculation tool
Within Microsoft's application software product lines, licensing policies vary significantly by product. For example, this year Microsoft changed the licensing on SQL Server to support a license policy more in line with the Windows Server policy for Datacenter Edition. SQL Server 2005 Enterprise Edition now allows unlimited virtual instances under one licensed server.
For users moving to a virtual client approach such as VDI, the licensing issues for client software and applications (e.g. Windows/XP and Microsoft Office) also need to be considered. Since each virtual desktop currently requires its own license for the OS and application software, depending on your agreement with Microsoft, this can require purchasing retail boxed copies of Windows/XP and any other desktop applications, just to obtain the required licenses, even though the VMs will likely be installed from virtual golden images.
As for other application vendors, Oracle is holding on to its original licensing model based upon the number of physical CPUs or processor cores in a socket on the bare metal server. Even with its own announcement of Oracle/VM, Oracle is continuing this virtualization-unfriendly policy. Other ISVs tie licensing of an application to the number of virtual processors the application has access to. Others license based upon the number of processor sockets --independent of cores -- within the hardware device.
Approaches to virtualization licensing from the various application ISVs still continue to vary greatly. When you start asking your vendors about licensing and virtualization, you may find that your specific vendors still have no clear policies for this new infrastructure model. As virtualization becomes more ubiquitous through market growth of additional virtualization vendors (e.g. Citrix/Xen and Microsoft in addition to VMware) and through OEM deals including embedded hypervisors like ESX 3i and Xen OEM edition, more application ISVs will have to evolve their policies. For those that don't, virtual licensing costs may be another reason pushing users to open source.
In general, vendors also have been slow to address the support issues concerning running and supporting applications in a virtual world. (However, large enterprise customers with support contracts have been more likely to get better support, though unofficially).
Officially, Microsoft has not supported its operating systems in virtual environments other than its own. That has limited official support to Microsoft Virtual Server because that's the only Microsoft server virtualization platform shipping to date.
Therefore, Microsoft, along with other vendors, may tell you, as an average organization, that you have to replicate issues in a physical environment before they will provide support. This requires you to perform a virtual-to-physical migration, with software such as PlateSpin's PowerConvert, to migrate a virtual server to a physical server, and then request support.
Virtualization may be the final impetus needed to get vendors to face up to the need to support their products in heterogeneous environments. This will put additional strain on vendor technical support groups since they will now need to understand how the various virtualization technologies work with their own offerings and what the optimal configurations are for their applications to be able to function well.
IT organizations need to put pressure on the OS and application software ISVs to push for support of their products in a virtual world. Before moving to a virtual infrastructure, you should get explicit knowledge regarding your specific operating systems and application software ISVs' policies on supporting their software in a virtual architecture. The support (or lack thereof) from your ISVs may have a significant impact on how smoothly your virtualization implementation will go.
In response to customer demand for support for Windows running under any virtualization software, Microsoft this month announced a new Server Virtualization Validation Program, which will begin in June, 2008. It will allow virtualization vendors to self-test and validate certain technical requirements of their server virtualization software running Windows Server 2008 and prior Windows Server releases. Microsoft will then offer cooperative technical support to customers running Windows Server on validated, non-Windows server virtualization software.
Different priorities in virtual worlds
Unfortunately, there are no standards yet for licensing or support for virtual environments today. Be sure to understand your operating systems and applications vendors' licensing and support policies for running their software in virtual machines, (including any virtual concurrent licensing options). Each vendor's policies for both licensing and support in a virtual world may be different, even within their own product lines, and everything, of course, is subject to change.
Craig A. Newell is a senior consultant at Focus Consulting and has more than 15 years of experience in infrastructure, virtualization, networking, storage area networking, and blades and has managed and supported virtualization projects for major corporations and government agencies. Newell is a certified project management professional, as a certified wireless network administrator, and a certified business continuity planner and served as a technical editor for the book Blade Servers and Virtualization: Transforming Enterprise Computing While Cutting Costs.