Alongside the Windows 10 Fall Creators Update, Microsoft delivered its first feature update for Windows Server 2016 this week.

While some administrators are just starting to kick the tires, they've already noticed a few surprise omissions from that "Semi-Annual Channel" update, also known as build 1709 (for September, the ninth month, of 2017.)

First, here's a brief recap of what did make it into 1709.

As Microsoft said would happen, the Server Core container image is about 60 percent smaller, while the Nano Server container image is nearly 80 percent smaller, than they were in the original version of Windows Server 2016. Microsoft also added the promised Linux container with Hyper-V isolation support to this release.

As Microsoft officials said previously, the original Nano Server has been "deprecated" and replaced by Nano running in a container image. It seems few users were onboard with Microsoft's push to make Nano Server the smallest footprint version of Windows Server, and so a repositioning was in order. The introduction of a new Windows Server graphical management tool, known as "Project Honolulu" (in technical preview) also became part of the new grand plan.

SMB1 and guest authentication removal also made it into this release, as did a number of other compute, storage, networking and remote-desktop services updates, listed in this Microsoft Docs article.

But a couple of things were cut from 1709.

For one, the Essentials version of Windows Server 2016 is gone.Windows Server 2016 Essentials edition was a "cloud-connected" first server for small businesses with up to 25 users. Microsoft introduced the Essentials edition in October 2016.

But in the list of Windows Server installation options in Microsoft's "Getting Started" with 1709 post, there's no mention of Essentials. (Thanks to Directions on Microsoft for the heads-up.)

Windows Server 1709 is available only in Standard and Datacenter editions. (As of October 19, Windows Server 1709 also available on Azure.) It's also worth noting that those installing 1709 only get Server Core as an installation option, even though Windows Server 2016 allows both Server Core and Server with Desktop Experience installation options.

I asked Microsoft whether the company would continue to offer an Essentials version of Windows Server in the future and have not heard back.

Here's Microsoft's list of which of the new 1709 features are in Standard and which are in Datacenter:

Credit: Microsoft

In addition, Storage Spaces Direct is not in Windows Server 1709, as Microsoft acknowledges in its updated Release Notes for 1709.

Storage Spaces Direct spans Windows Server clusters and creates a bus via which the servers can see all of each other's local drives. It was introduced as a feature of Windows Serve r2016 and described by Microsoft as "the foundation for our hyper-converged platform."

I heard last month from one of my contacts that Microsoft wasn't happy with the quality of Storage Spaces Direct and thus opted to block it from being usable for all software-defined Datacenter aplications in 1709. Administrators cannot add servers running 1709 to deployments of Windows Server 2016 where Storage Spaces Direct is being used.

The next possible update to Storage Spaces Direct may be part of "Redstone 4," the update of Windows 10 client and server due to begin rolling out around April next year.

Update (October 30): Microsoft posted a Frequently Asked Questions (FAQ) blog post on 1709 on October 26 that includes some useful information for those wondering how 1709 fits in with Windows Server 2016.

The FAQ makes it clear IT pros have options: Those interested in getting new server features more quickly can opt for the Semi-Annual Channel (feature updates) which are supported for 18 months each and released twice a year. Windows Server 2016 is in the Long-Term Servicing Channel (LTSC) and will continue to be supported for 10 years with a new release out every two to three years.

Those running Server 2016 today shouldn't treat 1709 as a feature update to 2016, officials said. To move from Windows Server 2016 or earlier versions of Windows Server to 1709, users must run a clean install, as no in-place upgrades are supported. Those who want Semi-Annual Channel releases need Software Assurance for their Windows Server licenses or be willing to use the Semi-Annual Channel releases hosted on Azure or other cloud-hosted environments.

Windows Server Essentials releases will only be available in LTSC; Standard or Datacenter are the only supported editions in the Semi-Annual Channel. Also: Server Core is the only installation option support in Semi-Annual Channel (which some users are complaining about).