For many years, Linux and Windows Server have peacefully coexisted in data centers, so it is not a surprise to find the same repartition into cloud providers’ multitenant infrastructures.
Nothing new from a licensing perspective, considering that it was already possible to BYOS (Bring Your Own Subscription) on Azure. However, Microsoft announced a new Hybrid Use Benefit for some Linux subscriptions on Azure. So, what’s new?
BYOS vs Hybrid Use Benefit
The traditional BYOS model on Azure had three major pitfalls:
• It requires you to create your Virtual Machine from specific images, prefixed BYOS, so Microsoft can invoice you only the compute costs and not the software-related costs.
• You must still configure your OS manually with your subscriptions to update it properly.
• Last but not least, you cannot change the licensing model of your VM because it’s linked to the OS image.
The same process was used before for SQL Server to invoice only compute costs to customers using licenses with License Mobility through Software Assurance. They used BYOL pre-fixed images to avoid software costs being associated to their VMs.
Hybrid Use Benefit mechanism is the same as we already know for Windows Server. It uses the “License Type” attribute of a virtual machine. It means that you can change this property at any moment from PAYG to AHUB and the other way around when you want, and without any downtime. In fact, you will not use AHUB but RHEL_BYOS or SELS_BYOS, depending on the type of subscription you want to use (Red Hat or Suse). You can do it into your portal, or through command line az vm create/update.
Is this a real benefit? Yes
Of course, because you are no longer locked into a payment model. Microsoft gives a relevant example of a Test environment based on pay as you go VMs that you can change to Hybrid Use Benefit license type when you go live. It gives the opportunity to leverage your existing subscriptions only when you’re certain to use fully the virtual machines. And you still have the possibility to revert at any moment.
It also requires you to have subscriptions to Red Hat Cloud Access Program / SUSE Public Cloud Program as prerequisites. And using Hybrid Use Benefit is the perfect way to have a look into your license usage from a publisher perspective, because you are declaring it at multiple places.
In addition, with flexibility also comes risks. You will have to track and monitor your Azure subscription usages to be sure to stay compliant. Take care of double usage on-premise/on-line, license reassignment rules, etc.
A new paradigm
Yes, it is, whether you want to admit it or not. Because bringing your OS in the cloud forces you to change the way you are used to thinking, as far as software licensing is concerned.
You were used to physical servers to deal with your OS licensing scope. You now must consider individual virtual machines licensing, with all the virtualization specificities, especially flexibility.
By Mathieu Dufetelle, December 21, 2020