Even though virtualisation is now mainstream, independent software vendors' (ISVs') policies about how they license their wares in a virtual machine are still muddled and few vendors have put their virtual machine licensing terms in black and white.
Now that virtualisation is being implemented in an estimated 25% of data centres, there is no excuse for software vendors not to have a clear-cut licensing policy for virtual environments, according to Chris Wolf, senior analyst with the Burton Group.
"Servers are heading down a path toward a mobile infrastructure that's free of hardware dependencies. So when it comes to virtualisation, vendors need to be clear in their support and provide explicit licensing terms for virtualised environments," Wolf said. "It would be a favour to all of us to have licensing policies clearly stated by software vendors."
Microsoft: No licensing leadership?
While Microsoft has made many changes to its licensing in support of virtualisation, its licensing policies vary depending on the software in question, confusing users. Wolf asked the industry leader to set the tone for software licensing on virtual machines by simplifying its policies, but his request was not well received, he said.
"As an industry leader, it's very likely that if Microsoft took strong steps to simplify its OS and application licensing in support of virtualisation, many others would follow," Wolf said.
Microsoft downplays the licensing issue noted by Wolf, saying it modified its licensing policies from installation-based to instance-based, which allows customers to create virtual instance libraries (e.g., for disaster recovery, staging and deployment) without having to purchase additional licenses for non-running instances.
"Microsoft's licensing is designed specifically to encourage virtualisation scenarios and applies equally to all virtualisation products, regardless of vendor.... Licenses are designed to accommodate customers' server hardware usage scenarios," a spokesperson said. "Microsoft's instance-based licensing was specifically created to enable scenarios like the migration capabilities of Virtual Server R2, VMware's VMotion and the future Windows Server Virtualisation."
Specifically, here are some of Microsoft's licensing terms for virtual machines:
- Customers may move instances freely and as often as desired between appropriately licensed servers.
- With Windows Server 2003 R2, Enterprise Edition, customers can run one physical and four virtual instances on the licensed device.
- With Windows Server 2003 R2, Datacenter Edition, customers can run one physical and unlimited virtual instances on the licensed device.
But Microsoft's licensing is problematic for live migration (or VMotion), according to Wolf. Users often do live migrations to relocate virtual machines when doing scheduled maintenance on physical servers. Microsoft limits VM movement to once per 90 days unless you buy the Windows Server Datacenter Edition, which can be expensive. Organisations with volume licensing packages would have to purchase additional Datacenter licenses to meet Microsoft's terms, Wolf said.
A Microsoft spokesperson explains the company's position, saying, "There is some confusion about rights around the instances (or software) and the licenses themselves. Microsoft allows for relocation of virtual machines without a 90-day restriction as long as each machine on which you plan to run Microsoft software is correctly licensed. This applies to all machine virtualisation products."
Thus, according to Microsoft, if you have Standard or Enterprise Edition instead of Datacenter, live migration should not present an issue.
"If the VM is running on the same server, you don't need to reassign any licenses because the server is already licensed for the instance whether it is running physically or virtually. If the instance needs to run on a VM on a different server, [and] if that server is not already licensed for Datacenter Edition, you can reassign the physical server license to the new server running the virtual instance. For an existing license with Software Assurance coverage, the customer can acquire a "step up" to get full value for its existing investment to upgrade Standard and Enterprise licenses to Datacenter," the spokesperson explained.
According to Microsoft, the policy is consistent across both Virtual Server and Windows Server Virtualisation when it's released.
"While live migration will be deferred until a later release, both Virtual Server and the upcoming Windows Server Virtualisation will still offer migration capabilities," the spokesperson said. "Since virtualisation will be a feature of Windows Server 2008, we will be making virtualisation and its benefits available."
Software licensing made simple
Licensing doesn't have to be so confusing. For instance, companies like Novell and CA have both created simple licensing policies for running their software in virtual environments.
CA, a systems management provider, has a "buffet" style licensing policy that Wolf likes, where users purchase licenses based on physical host, not the number of virtual machines.
"Licensing should either be based on the physical machine or based on virtual machine characteristics. I think the industry can live with that - having licensing exactly the same in the virtual world as it is in the physical world. There are vendors doing that, but for the most part, software licensing is buried. It causes frustration for users attempting to virtualise, when they have to go through their apps and figure out if they are still in compliance or not," Wolf said.
On Novell SUSE Linux Enterprise 10, each physical server requires the purchase of a subscription to be activated and to receive ongoing updates and patches. That done, administrators can create an unlimited number of virtual server images in Xen or another virtualisation platform, without needing to purchase additional subscriptions for virtual images.
"For SLES 10 virtualisation deployments, licensing is simple. Just count up the number of physical servers that will run SLES 10 VMs and that's the number of licenses that are required. The total number of VMs is irrelevant," Wolf said.
A Novell spokesman said the company's simplified licensing policy was adopted to make virtualisation easy for customers and for the company.
In many cases, Wolf said, the companies that want to increase their market share, like Novell, offer the simplest licensing models.
Virtualisation providers sound off
Some companies, like Virtual Iron Software, did not want to chime in on the subject of licensing, while others had strong views to express.
VMware, virtualisation software provider, advises customers to license software within virtual machines as they would for physical hardware, so normal software policies and licensing rules apply, said Bogomil Balkansky, director of product marketing for VMware.
SWsoft, which provides its Virtuozzo virtualisation software per user for applications and per CPU for server infrastructure, pushes software vendors to be fair and flexible, said Kurt Daniel, SWsoft's marketing director.
"When parts of a server are used -- say, less than all CPUs on the server -- software companies should be flexible in allowing customers to pay for less than the whole server (if multiple CPUs)," said Daniel.
A SWsoft representative at the recent Gartner IT Infrastructure, Operations and Management Summit in Orlando said software licensing will continue to be a pain point for users until software vendors make their licensing policies clear.
Until then, users have to go to each of their software providers directly to make sure they are in compliance with licensing rules when virtualising servers.
Wolf suggests users push software vendors to spell out licensing terms. "Vendors unwilling to take the initiative to develop a virtualisation policy can be compelled to do so by the user community. RFPs are pretty powerful documents, and by including virtualisation support and licensing requirements in all RFPs, organisations will have to pressure [software vendors] to bring about change," Wolf said.