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Microsoft Server Licenses in VMware and Hyper-V

When virtualising Microsoft server software, such as SQL Server, one question often arises: "How do I handle licensing?" It's a valid question, especially when you're working in environments where virtual machine mobility is enabled.

Note: you can also watch the video below, but please know that it was recorded before Microsoft introduced the Flexible Virtualisation Benefit for Windows Server. So please ensure that you also read this entire article for up-to-date information.

The 90-days rule

By default, Microsoft licenses are assigned to a host for 90 days. That means that any virtual machines running on that host can't move to another host until the 90 days have expired, or you will become non-compliant. 

This can be a problem if you're using VMware's Distributed Resource Scheduler (DRS) or Hyper-V's VM mobility. These features allow virtual machines to move between hosts in order to balance resources and optimise performance. But if a virtual machine running a licensed piece of software moves to another host, the license can't move with it.

So, what's the solution? Software Assurance.

Software Assurance is a subscription add-on to Microsoft licenses that provides additional perks. One of them – License Mobility in Server Farms – allows the licenses to travel between hosts.

With Software Assurance, even if a virtual machine running a licensed piece of software moves to another host, the license can move with it. This effectively overrides the 90-day rule and allows you to take full advantage of virtual machine mobility.

Subscription Microsoft CSP licenses also have this benefit.

What about Windows Server? Can its licenses move?

It's worth noting that Windows Server doesn't have License Mobility. And until October 2022, Windows Server licenses had to remain assigned to a host for at least 90 days. Software Assurance did not affect it.

However, in October 2022, Microsoft gave Windows Server the so-called Flexible Virtualisation Benefit. Like License Mobility, it also requires Software Assurance or a CSP subscription. And like License Mobility, it overrides the 90-day rule.

Talk to a Microsoft Licensing expert

Virtualising Microsoft server software can be a bit tricky when it comes to licensing. Still, with some planning and the right tools, you can take full advantage of virtual machine mobility without breaking the rules. 

If you have any doubts, please let us know using the form below. We don't sell licenses, so our advice is truly impartial.