Windows Release Channels Explained

Semi Annual Channel vs Long Term Service Channel

Windows Release Channels Overview

At 2017’s Ignite conference Microsoft announced they would be shifting to a two Windows Release Channels model and introduced the Semi-annual Channel (SAC).  This new channel permits rapid adoption of new feature sets and capabilities in the Windows OS and enables Microsoft to remain agile in today’s rapid pace environments.  The traditional release model will continue and is now referred to as the Long Term Servicing Channel (LTSC).

Windows Version System Explained

An understanding of the Windows version system will help you understand the new Windows release channels.

Lets start by taking a look at a typical Server 2016 Long Term Servicing Channel version:
10.0.1607.14393.1794
Lets break this down to understand the components:

MajorMinorVersionBuildRevision
1001607143931794
Primary release number
ie Server 2016
Used for cadence upgrades
ie 2016R2
Semi-annual version release indicationThis typically only changes with major build releases – ie TP2 to TP3 to RTM or with a Service Pack. As MS has gotten away from Service Packs you will generally only see this number change in early release cycles. This number will normally stay the same once the OS is in General Availability release.Cumulative Update (CU) indication – ie patch level of device (windows updates)

With that break down we can look at the version of the next semi-annual release:
10.0.1709.16278.310

Here we can see that this semi annual release is still:
Server 2016 – and not a cadence update (not a R2 release) – a new semi annual version release – new build # – current patch level

Looking to the future with LTSC
We may or may not get a 2016R2. If we do it may look something like this:
10.1.800.13721.300
If instead we go to Server 2019, it may look something like this:
12.0.987.12139.410

You can reference a list of known Windows versions and releases here: Windows Version Numbers

Semi-annual vs Long Term Service Channel

Semi-annual Channel (SAC)Long Term Service Channel (LTSC)
“I need to innovate rapidly. The new Semi-annual Channel gives me early access to the newest OS innovation”“I need predictability. The traditional LTSC Channel is the best choice for me.”
Release twice a year (spring and fall)Release ever 2-3 years
18 months of mainstream production support5 years mainstream support + 5 years extended support
Available via Software Assurance or AzureAvailable through all channels
Name = Windows Server version
ex 10.0.1709.16278.310
Name = Windows Server (Year)
ex Server 2016

How it works

Windows Release Channels:

  • Semi-annual channel releases will occur every 6 months and will be supported for 18 months.
  • Long Term Servicing Channel will continue to see releases ever 2-3 years with 5 years mainstream support with extended support options.
Microsoft Windows Release Channel breakdown
MS Ignite – Servicing Channel breakdown

This is a pretty straight-forward release cadence but there are a few things to keep in mind:

  • At this time there is no capability to move between the SAC and the LTSC.  So, if you load devices with a SAC release, they can only be upgraded to future SAC releases.  You will no longer be able to engage the LTSC.
    • Likewise there is no capability to go from LTSC to SAC.  If SAC releases some new functionality that you would love to take advantage of, your LTSC devices can’t do so without a re-load.
  • SAC only has 18 months of support. This is something you have to keep in mind. Microsoft will be expecting those devices to be updated within 18 months, preferably sooner.

Semi-annual release is agile

They aren’t kidding.
The semi annual release enables MS to make rapid sweeping changes to the OS in response to customer input and current technical challenges.
For instance, in the first Semi-Annual release (1709) – MS has removed Hyperconvered storage capability by removing Storage Spaces Direct Features.

“Storage Spaces Direct is not included in Windows Server, version 1709. If you call Enable-ClusterStorageSpacesDirect or its alias Enable-ClusterS2D, on a server running Windows Server, version 1709, you will receive an error with the message “The requested operation is not supported”.

This was done because MS felt that the feature needed more work. They have committed to re-adding the feature back into the next semi-annual release cycle which will come out 6 months from now.

Additionally, if deciding to engage the 1709 SAC release you may notice another component missing: The GUI.

1709 has no native GUI support with only a Server Core version available in this SAC release.  For some of us that have long transitioned to Server Core, this isn’t a big deal – but for others – may be a blocker.

With SAC, MS now has a lot of agility to adjust the OS as they deem fit. If Active Directory is having some issues for example, MS has the ability to remove that capability in a Semi-annual release and work towards improving it for a future release.
In the example of Storage Space Direct, that feature remains in 1607 (LTSC) but will not be present in 1709 (SAC).

What are your thoughts on the new Windows Release Channels? Which one will you be using in your environment? Feel free to comment below.

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