According to the recent Citrix Virtualisation Index white paper, over the next twelve months almost two thirds of UK companies intend to extend their current use of server virtualisation and about a third of UK CIOs will start implementing some form of desktop virtualisation.

While these numbers show a healthy adoption rate of these technologies, software licencing is the second biggest concern, behind security, for both server and desktop virtualisation, as revealed in the same Citrix survey. Software licence management is complicated enough in the physical world due to complex licence models, use rights and restrictions. With virtualisation, licence management becomes even more challenging – the virtual environment is more dynamic and there are new rights and restrictions. To fully take advantage of the cost benefits of virtualisation, CIOs should make their move into the virtualised world with their eyes open. Licencing issues are yet to be fully addressed by software publishers for both desktop and server virtualisation.

Desktop virtualisation is inherently user-centric, while traditional software licence models are typically device-based. When rolling out desktop virtualisation, there are at least three potential licence metrics that CIOs should consider: pay per device (desktop, laptop, or thin client), pay per user authorised to access the application, or pay per user who actually uses the application. Under the standard Microsoft licence model, enterprises still have to pay per computer that is used to access an application – meaning that every device that could be used for access must be licenced. However, it is generally in the interest of enterprises to be able to pay per user that actually uses the application. Not everyone who has access may use a given application, and one of the benefits of desktop virtualisation is giving users the flexibility to access applications from any PC, not just their own. Software licencing should therefore not be a hindrance to achieving this goal, and CIOs should not be afraid to demand from software vendors, alternative licencing approaches that best meet their requirements.

A further complication with device-based virtual application licencing involves the situation where one version of the software is installed on endpoint devices and another version is installed on the application server. For example, if a desktop computer has a lower version than the one installed on the server, then a licence for the server version is most likely required for that desktop device when it is used to access the virtual application. Reconciliation between local installations and software that can be accessed using the virtual desktop technology must be carefully managed.

Server virtualisation has broken the bonds of the legacy datacentre IT architecture in which a single application and a single operating system (OS) run on each server. Server virtualisation allows multiple software instances of a computing platform to run concurrently on one physical machine. These virtual machines (VM) are capable of running an operating system and a set of applications. Each VM may run a different OS – Windows, Linux, UNIX, etc., or different versions of the same OS, depending on the needs of the software applications.

There are several common server licence models that originated in the physical datacenter and add licencing complexity in virtual server environments: physical server based licences, processor (CPU or Core)-based licences; and processor value unit (PVU) licences. In all of these cases, licences are tied in some way to the underlying physical hardware such as the server itself, the processor type, number of processors, and/or the number of cores. This can be problematic from a licence compliance standpoint because the physical hardware details may be hidden from the virtual environment by the server virtualisation technology (e.g. Microsoft’s Hyper-V, VMware’s vSphere, and Citrix’s XenServer).

Further, when considering dynamic virtualisation, where running VMs can be moved from one physical host to another, CIOs should look out for mobility restrictions. Some software licences place limits on the frequency of application/OS transfers from one server to another thereby compounding the risk of compliance drift. With automatic load balancing, for example, it’s easy to violate this mobility rule and drift out of licence compliance. Even if there are no mobility restrictions, simply moving a VM to another server may require a different licence if the new server has a different number or type of processors and cores than the original server.

CIOs should ask their software vendors for virtual server based licencing with no mobility restrictions to alleviate many of these virtualised datacenter issues.

Given the current state of affairs, and short of wholesale changes to vendor licence models, adopting a next generation software asset management solution is the only way to ensure licence compliance and minimise software costs in virtual environments. Such solutions, known as Enterprise Licence Optimisation solutions, are able to reconcile the list of installed applications with software purchase data, licence types and associated conditions of use to generate a detailed licence compliance report and out-of-compliance alerts. Such tools also provide CIOs with leverage to negotiate the most economical licencing model with software publishers and perhaps even push them to change their licencing policies to make them more suitable for virtualised environments.

About the author:

Patrick Gunn, is Vice President Sales, Flexera Software