Nutanix ROBO, Edge, and Tactical – Design – Part 3 – Licensing

December 16, 2020|Design, ROBO

Here are the things that I am going to cover in this design series. As each blog is written, I will update the links below to the other pages. The idea here is to create a live design book that can be referenced and updated for different types of use cases. This first one is ROBO.

  • Use cases
  • Node types
  • Licensing
  • Sizing
  • Edge
  • Mobile
  • Tactical Data Centers
  • Management
  • Provisioning
  • Hypervisors
  • Single and dual node
  • Networking
  • Bandwidth
  • Replication
  • SD-WAN
  • NFV
  • VDI
  • Re-use existing hardware
  • Re-use existing storage
  • Backup
  • Cost
  • Competitive outlook
  • Risks
  • External factors, (radiation, heat, water, etc.)
  • Designing for each use case


This article is not only about Nutanix licensing, but also software licensing in general. A general rule with software licensing is that customers want to get as much functionality as possible to meet their requirements, and pay as little as possible. Software vendors would like to make as much money of their customers as possible, while still providing value. Some models for licensing are:

One price, perpetual version license.

You buy it once and you own that version with updates, forever. You buy version 1.0 of a software and have access to all updates of the 1.x series. However, you will need to rebuy the software at version 2.0 to get new features.

Multiple feature tier prices, perpetual version license.

You buy it once and you own that version and tier with updates, forever. Feature sets may be labeled like bronze, silver, gold, or standard, advanced, enterprise, etc. If you buy version 1.0 bronze, you can pay the difference to go to 1.0 silver / gold. However if you want 2.0 silver, you need to rebuy the whole thing from scratch. 

All features, All you can eat, perpetual version license.

This license let you use the software as much as you want and make use of all the available features. This may be referred to as an ELA (Enterprise Licensing Agreement).

 In some cases, you may get a post-paid bill depending on which of the features you use and the quantity of deployed instances. This is called a true-up

The above licensing models are conducive to capex purchases that are performed every few years, depending on the software release cycle. As long as the software meets the demand of the user and updates are provided then there is little incentive to purchase a new version, unless additional features warrant the expense. One way for software vendors to increase sales for customers that do not want to buy the new version, is to sell support for a term. For instance if version 1.x is out and so is 2.x, then perhaps the customer does not want to buy 2.0 yet. So they will pay the software vendor a percentage of the purchase price to receive technical support and software updates for the 1.x series until it is end of life. This ends up being cheaper than a purchase of the 2.0 version, but only delays the capex expense. In the interim, the software vendor gets residual revenue, which is known as the “long tail”.

Another software licensing model is called subscription based licensing. There are a few different versions of this, but the two I will discuss are restrictive and non-restrictive. These aren’t necessarily the exact terms, but they convey the idea.

Restrictive subscription licensing

When the license term expires, all software functionality stops. Think of 30-day trial software, then extend that for longer terms.

Non-restrictive subscription licensing.

When the license term expires, all features and functions remain, but updates are no longer provided. Some software has separate support and subscription costs, so you may have one expire and the other one not. For instance, if your support expires, but not your subscription, then you can keep getting updates but no help with any issues. If your subscription expires, but not your support, then you cannot update your software, but you can get assistance on issues from the software vendor. They may tell you that you “need to update”, which would be code for “renew your subscription”. 

Nutanix licensing

Alright now that you have a bit of a foundation in a non-exhaustive list of comparative software licensing models, I’ll describe how Nutanix does licensing and support.

Nutanix offers tiered non-restrictive subscription licensing with integrated support. So there is just one price for licensing and support for a period of time. You can get licensing for 1-5 year terms, but will get the best bang for your buck on a 1-3-year contract. After your term is up, you can still use the software, but you can’t get updates or create support tickets. Renew your subscription and you get the latest version, updates and support again. 

As long as you have an active subscription, you can update to the latest version.

Now we look at the software tiers and how this all relates to ROBO environments.

Core AOS provides hyperconverged functionality and management with Prism. The tiers for AOS are Starter, Pro, and Ultimate. See here for a functionality comparison.

There are also tiers for Prism (also called Starter, Pro, Ultimate). Prism Starter comes at no additional cost to all AOS versions. It allows for multi-cluster management and health monitoring and troubleshooting. Prism Pro adds operational insights, planning and automation. Prism Ultimate adds service level insights for applications, cost metering and chargeback.

License metering

The cost of license depends on how it is metered. Nutanix has a few ways to do this, even though the license tiers may be the same. 

  • Capacity Based Licensing (CBL) will look at the total cluster capacity of SSD (in TiB) and the total core count. For example, lets look at a 3-node cluster with the following individual node specs.

2 x 12-core CPUs (24 cores per node)

2 x 1.92TB SSDs (3.84TB or 3.49TiB – )

So the licensing cost for the 3-node cluster would be 11TiB SSD and 72 cores.

  • Per VM licensing, which is sometimes referred to as ROBO licensing, is a defined cost based on the number of VMs on the cluster. The amount of resources is not measured. This works well in situations where you required only a few VMs and want to give them the maximum resources possible.  One limitation of this is that you are only allowed a maximum of 32GB of RAM per VM. This limitation stops things like massive databases running on that licensing.
  • VDI core licensing will use concurrent users as a measure of metering. This allows for a linear cost based on users and not infrastructure resources. Another benefit is that you can have license mobility between sites, depending on where your users are. A 2-site architecture with 200 concurrent users and active / passive failover, can have 200 x VDI core licenses at site 1 and 1 x VDI core license at site 2. In the process of a DR event, you would then reallocate 199 licenses from site 1 to site 2. This allows a very cost effective licensing for DR capability of VDI environments. VDI core could be applied to Citrix, VMware Horizon, Nutanix Frame, or any other VDI solution.

Here is a link to the Nutanix Licensing Guide