Live Optics | OS Licensing by Cluster

Windows and some variations of Linux can dictate operating systems licenses by the number of potential Cores or Sockets.

For Windows, the minimum number of cores that can be licensed on a machine are 16 and would require a Datacenter license. In a three-node cluster, this would mean a minimum of 48 licensed cores. 

This might seem too obvious, but for that reason it is often overlooked. Here is an figure of how to read this AIR report graph and put it to use towards saving licensing fees in your environment.

Overtime people create new VMs and might not consider the licensing impact associated with where they place that VM. This can create an almost "Operating Systems Fragmentation" like effect.

Consider this scenario:

In this environment there are two clusters. Each cluster is consisted of three nodes. Each node has a two-socket/four cores per socket hardware spec.

Example A (left graph):

Here we can see that each cluster is hosting approximately 50% licensable Linux and 50% licensable Windows Operating Systems.

The net effect is that each Operating System could cause an over licensing scenario whereby two clusters need Windows licensing instead of one. In a true-up scenario, this could be subject to heavy unforeseen fees.

Example B (right graph):

When concentrating all licensable operating systems to a single cluster, the net effect is that it is possible to reduce licensing overhead to only one cluster, thus reducing licensing overhead by 50% (and perhaps 50% associated with two different operating system vendors).  

The larger the environment, the more potential for operating system licensing fragmentation and the greater the value of emphasizing the disbursement of operating systems between clusters

Here is another before and after way to look at this to drive the point home. 

In reality this might force the assumption that all VMs are equal and swapping a VM from one cluster to another is an even trade; rarely the case. There are many other factors like function, location, and failover that factor into VM placement and licensing requirements.

While creating 100% homogenous clusters to an OS might not always be achievable, it is still worth paying attention to as licensing is expensive and any recuperation of overage is pure benefit.

If you have any questions, please reach out to Live Optics Support at liveoptics.support@dell.com.