Virtualisation saves money on hardware and quietly changes what you owe on software. Small changes to a cluster — a host added, a VM allowed to move — can move a licence position by a large amount. Here are the questions to ask before you build, and what can now be tracked automatically.
Server virtualisation is mature, well understood and almost universal. It saves hardware spend, floor space, power and time, which is why practically every large organisation runs it somewhere.
It also changes what you owe on software, and that part is routinely overlooked. Unless you understand the implications and can see your licence position as the environment moves, you can end up paying more in additional licences — and in settlements, if a vendor finds the shortfall first — than you ever saved by virtualising.
Most publishers licence physical and virtual environments differently. The specifics vary enormously, but one theme is consistent across all of them: small changes to the virtual environment can have a large effect on what you are required to hold.
The two usual triggers are:
Converting a physical machine to a virtual one is not a like-for-like move in licensing terms. It changes the basis on which the product is counted, and the only place to find out how is your own agreement.
Maintenance matters too. Several publishers make specific rights conditional on active maintenance or Software Assurance — Microsoft’s licence mobility rights for server applications within a farm are the example most organisations meet first. Whether that applies to you depends on the product and the agreement you signed, so it is worth confirming rather than assuming.
In an audit you may be asked to demonstrate that a workload has not moved somewhere that would have made additional hosts licensable. Assertion will not do it; you need the record.
Oracle in particular documents what it recognises as hard and soft partitioning, and the distinction decides whether you can legitimately limit a workload to a subset of a cluster or whether the whole cluster counts. Understanding which side of that line your configuration falls on is not optional if you run Oracle on VMware.
What ships today. This is the question the original version of this article left with the reader, and it no longer needs to be. CerteroX ITAM and CerteroX SAM connect directly to the virtualisation layer — VMware, Microsoft Hyper-V, Citrix XenServer, IBM HMC, Oracle VM, Red Hat oVirt and Nutanix — so host, cluster and guest relationships are inventoried rather than described. On top of that:
Cluster design is usually settled on capacity, resilience and cost of hardware. The licensing consequence arrives months later as a surprise.
Knowing the effect on the specific products you intend to run turns that into an input rather than an outcome. Sometimes it argues for a smaller, dedicated cluster. Sometimes it argues for pinning a workload. Occasionally it argues for not virtualising a particular product at all. All three are cheaper decided at design time.
Spinning up another OSE is a two-minute operation and can be a five-figure one. The obvious example is Windows Server: do you have the CALs, and are you licensing by core across every physical core in the host, with the minimums the product terms impose?
Windows Server has been licensed per physical core since Windows Server 2016, not per processor. If your mental model of this predates that change — and many do, because the change is old enough to have been absorbed without ever being re-examined — it is worth re-checking your cluster maths from scratch.
Development and test workloads often carry different rights, but the conditions attached to them are strict and vary by publisher — who may use them, on what, and whether any production data may touch them. Treating a cluster as “just dev” without checking those conditions is one of the more common findings in an audit.
CerteroX SAM handles this with the Exclude From Licensing workflow for MSDN, development, training and second-use devices, so those machines are inventoried and visible but do not distort the position — and the exclusion is recorded, with an audit trail, rather than applied silently.
SQL Server can be licensed several ways in a virtual environment — per virtual core on the guests, or per physical core on the host with virtualisation rights, with the answer depending on density, edition and whether you hold Software Assurance. The right choice is genuinely organisation-specific, and the difference between the best and worst option on a busy cluster is large.
You cannot make that comparison without knowing your actual density: how many guests, how many virtual cores, on how many physical cores, running which editions. That is an inventory question before it is a licensing question.
Virtualisation did not make licensing harder because publishers made the rules more complicated. It made licensing harder because it decoupled the software from the hardware, and almost every licence metric ever written counts hardware.
That means your licence position is now a function of a configuration that changes continuously, often automatically, and frequently without anyone thinking about licensing at the moment it changes. A position calculated once a year is a position that was correct once a year.
The answer is to compute it continuously against live inventory from the hypervisor, rather than reconstructing it from memory when a letter arrives.
To see a virtual cluster modelled against the publisher rules that actually apply to it, book a demo.
Other posts covering the same ground.
Locking an application down at user level does not make you compliant with a per-device licence. In a Citrix or RDS environment, one user with access can cost you a licence for every device in the organisation.
A third-party summary of a vendor can be wrong, and it stays wrong for as long as people read it. The case for checking a vendor's facts at source — and the current, sourced record for Certero.
An audit is won or lost on the quality of your inventory long before the letter arrives. Six ways data goes wrong, and what it takes to have the answer already in hand.
Everything argued above is checkable. Name the publisher, the billing account or the platform you would argue with, and the session is built around it — the reasoning attached, not a summary slide.
No gated download at the end of it.