What is Windows as a Service?

As Windows 10 releases move forward, the concept of “Windows as a Service” is important to understand.

“Windows as a Service” is not a licensing change, rather it is Microsoft managing expectations on the regular updates required to maintain support.

The below charts summaries the Windows as a Service concept for the “semi annual channel” based on Microsoft’s target of two releases per year, March and September (this is one of two servicing channels, the other being the Long Terms Servicing channel which is described at the end of this post).

The key points compare to previous releases of Windows are:

  • “Feature updates” will be released twice per year, in March and September.
  • New versions of Windows will thus be released in March or September
  • After an initial beta feedback period from Insiders, a public version will be released as a Current Branch (CB). This should be used for limited pilot testing within an organisation. Together with the twice a year release, this reflects the new naming that will be used of this release, “Semi annual” or “pilot”.
  • After 4 months, the Current Branch for Business (CBB) will be released and is intended to be suitable for full deploying within an organisation. Microsoft will be renaming this the “semi annual (broad)”.
  • The total support for a given Window version will be 18 months (CB release to CBB retirement). However, see next point on CB retirement.
  • Importantly, the CB release will no longer be supported shortly after the CBB release – indications are there will be 60 days from CBB release before the CB is not supported. “Not supported” will mean no more updates, but really this is a consequence of cumulative updates – see the next point.
  • Monthly “quality updates” are cumulative and include both security and non-security fixes. This means that administrators cannot selectively choose updates to install. It also means that security updates cannot be separated from non-security fixes.

The objective of releasing and retiring versions twice a year is to have an operating system that continually improves through incremental updates. This is in contrast to historic approaches of having a major OS upgrade every few years.

At any point in time, Microsoft has the objective of supporting only two CBB release, and one CB release. This is only possible if new releases also trigger retirements.

The below charts shows two version releases and two retirements per year. Note that it is a CBB release that triggers the retirement of a N-2 version.

To see a chart of historical and forecast Windows 10 release and retirement dates see the blog post.

Lastly, for completeness, the below chart identifies Windows 10 Long Term Servicing Branch (LTSB). This is only available on Enterprise support contracts, and is only intended for machines that should not be updated such as ATMs or shop floor computers.

Windows 10 LTSB will be supported for 10 years, 5 years of feature and security fixes (mainstream support), and then 5 years of security fixes only (extended support).

Microsoft expects to release an LTSB version every two or three years. To date two version have been released, in July 2015 and then August 2016. The next LTSB release is expected in 2019.

The chart identifies a key limitation in that LTSB is only supported on the chip generation current at release. While this restriction may be relaxed, it effectively means that LTSB will result in multiple versions of Windows LTSB in an organisation as each new LTSB release will be tied to the chip generation of the day. This reality acknowledges that ordering hardware with previous chip generations will not be possible over the 10 year life span of Windows 10 LTSB. Thus, LTSB really should be a last resort servicing channel.