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March 2, 2017

An update on our Unified Update Platform (UUP)

Back in November, we announced the next generation of our delivery technologies called the Unified Update Platform (UUP). Windows Insiders are the first to experience UUP with Insider Preview builds. We began releasing new Insider Preview builds using UUP to Mobile devices first starting with Build 14959 in November. Then we began releasing new Insider Preview builds to PCs using UUP starting with Build 14986 in early December. I wanted to give a small update on where we are today with UUP.

As a recap, one of the biggest benefits UUP brings to our customers is a reduction in download size of build updates on PCs. We’ve converged technologies in our build and publishing systems to enable differential downloads for both PC and Mobile.

A differential download package contains only the changes that have been made since the last time you updated your device, rather than a full build. Differential download packages rely on re-using files on your current OS to reconstruct the newer OS. This could include copying files as-is that have not changed between builds, or it could involve applying “binary deltas” or “diffs” to old files to generate newer files. Differential download packages are smaller and can take a shorter amount of time to download.

For a full build, we refer to this as a canonical download package. It is a self-contained update that contains all files for the update, and does not rely on any files on your device. Canonical download packages tend to be larger in size and may take longer to download.

We are excited to begin releasing PC builds to Windows Insiders using differential download packages! As we discussed in November, as we roll out UUP in our retail release, users can expect their download size to decrease by approximately 35% when going from one major update of Windows to another. For retail users, the first time they get the UUP client code is part of the Creators Update, therefore, they will see the benefit of differential download packages when they go from the Creators Update to the next feature update of Windows.

Windows Insiders have been running the UUP bits for a while now and are already experiencing the benefits of differential packages as seen in the below.

Diff Download Graph

NOTE: Given the frequency of Insider flights, Insider build update diffs are considerably smaller (<1GB) than what we expect for retail users to experience when going from feature update to feature update.

It’s also important to note that Windows Insiders may not get a differential download packages even if we ship them. A baseline build has to be set for differential download packages and if that baseline build is newer than the build Windows Insiders are updating from (in the case where they are not on the latest flight) – they will receive a larger download.

Thank you for participating in this journey and giving us feedback to help us finalize this generational shift in the way we update Windows devices in the future!