Windows Server 2025: What It Means for Azure Stack HCI
Windows Server 2025 is nearly upon us, with general availability expected on November 1st. It’s been three years since Windows Server 2022, which in the fast moving world of cloud and hybrid infrastructure feels like an eternity. There’s a lot to unpack here, and while I’m not going to attempt a comprehensive feature review of the whole product, I do want to focus in on what matters specifically for Azure Stack HCI customers and those evaluating the platform.
The 24H2 Kernel
The most fundamental thing to understand is that Windows Server 2025 is built on the 24H2 kernel, the same generation as Windows 11 24H2. This matters because Azure Stack HCI’s next OS baseline will also be built on this same kernel. If you’ve been following the Azure Stack HCI release train model that I covered in my earlier post , you’ll know that the OS baseline is one component of the broader solution. The move from the 23H2 kernel to the 24H2 kernel is the next major OS shift for Azure Stack HCI, and it brings with it a substantial set of improvements.
What Matters for HCI
There are a handful of features in Windows Server 2025 that I think are particularly relevant for Azure Stack HCI customers.
Native NVMe support is probably the most impactful from a pure performance perspective. Windows Server 2025 introduces a new native NVMe storage stack that replaces the legacy StorPort based approach. For Storage Spaces Direct environments, which is what Azure Stack HCI uses under the hood, this translates directly into improved storage performance, lower latency, and better CPU efficiency. Given that storage performance is often the most scrutinised aspect of any HCI deployment, this is a big deal.
Hotpatching has been available in preview for Azure Edition VMs in Azure for a while, but Windows Server 2025 brings it closer to on-premises reality. Hotpatching allows security updates to be applied without a reboot, which for clustered environments like Azure Stack HCI means you can patch without the live migration overhead that currently accompanies every monthly update cycle. This is still maturing for on-premises scenarios, but the direction is clear and the implications for operational efficiency are significant.
SMB over QUIC improvements continue to enhance the remote access story. For Azure Stack HCI VMs that need to serve file shares to remote users without traditional VPN connectivity, this is increasingly relevant in hybrid working scenarios.
Credential Guard and improved security defaults further strengthen the security posture. Azure Stack HCI 23H2 already made great strides in security with WDAC enforcement, HVCI, and a comprehensive security baseline (as I covered in my WDAC post ). Windows Server 2025 builds on this with additional security hardening that will flow through to Azure Stack HCI’s security story.
The Licensing Angle
There’s an important licensing change to be aware of as well. With Windows Server 2025, Microsoft is introducing new options for how customers license their guest Windows Server VMs running on Azure Stack HCI. The ability to subscribe to Windows Server guest licenses through Azure, rather than needing separate on-premises licenses, simplifies the procurement story for many customers. This is especially useful for organisations who are moving to an OpEx model and want to consolidate their billing.
For Dell AX customers specifically, Dell offers options that include Windows Server 2025 guest VM licensing as part of the solution purchase, which further simplifies things. If this is relevant to your deployment, it’s worth having the conversation with your Dell account team about what’s included.
What This Means Practically
If you’re running Azure Stack HCI 23H2 today, Windows Server 2025 doesn’t change anything immediately. Your existing deployment continues to work on the 23H2 OS baseline, receiving updates through the release train model. The 24H2 based OS baseline will come as a future update option, and when it arrives, you’ll have the choice to stay on the 23H2 release train or move to the 24H2 based one, just as the release train model is designed to allow.
If you’re planning a new Azure Stack HCI deployment in the near future, it’s worth understanding the timeline. Deployments available today use the 23H2 OS baseline. The 24H2 based option is coming, and depending on your deployment timeline, you may want to plan for which baseline you’ll land on.
For those running Windows Server 2025 as guest VMs on Azure Stack HCI, the new features are available immediately. You don’t need to wait for the host OS to move to 24H2 to run Windows Server 2025 guests.
The Bigger Picture
Windows Server releases have always been markers in time for the Microsoft infrastructure ecosystem, and 2025 is no exception. What’s different this time is that for Azure Stack HCI customers, the Windows Server release is just one piece of a much larger puzzle. The OS is important, but it’s the broader solution that matters, the Arc integration, the lifecycle management, the Azure services, the OEM value that Dell brings through the AX system. Windows Server 2025 makes the foundation stronger, and that’s worth being excited about.