Back in May, Microsoft announced that Windows Server would be joining the Windows Insider Program. Late last night, the first preview release of Windows Server was published.

The biggest areas of improvement in the new build are around virtualization and containers. The preview allows exposing more of the underlying hardware capabilities to virtual machines, with support for virtualized non-volatile memory and virtualized power/battery status. For both containers and virtual machines, networking capabilities have been enhanced to enable a wider range of virtual network capabilities with greater performance.

The focus on containerization has also seen the Nano Server deployment of Windows Server change. Presently, Nano Server is still a full operating system, but with the Redstone 3 release of Windows later this year, that's going to change. It's going to be a strictly container-only deployment. Upgrading and maintaining Nano Server will be done through updating the container image. This has enabled Microsoft to strip down the Nano Server installation. It no longer requires, for example, the Windows servicing stack. Because it's upgraded simply by replacing the image, Nano Server no longer needs to use Windows Update itself. The result is a 70 percent reduction in the image's footprint.

As ever with an insider build, there is a range of known bugs and issues, including some blue screen errors around volume management (though Microsoft insists that there's no data loss risk) and some incompatibilities with certain unspecified processors.

In terms of pure participation levels, the Windows 10 Insider Program has been a big success; it has more users than any traditional Windows beta, and new builds are delivered more frequently. Microsoft is still working to ensure that the Insider Program provides more thorough, directed testing with periodic "bug bashes" that focus usage on particular areas.

Whether the same appetite for end-user involvement exists for Windows Server is less clear. The containerized Nano Server is, at least, easy to deploy and experiment with. But testing, for example, a Windows cluster is more involved and will require much greater effort from IT departments. As the release nears completion, we'd expect it to become more palatable to administrators who want to get an early start on preparing for the latest Windows features and capabilities. But in these early days, the known bugs and potential instability make the Server Insider Program feel like a bit of a niche offering.