Windows 10 Express Installation Files and Delta Content for Updates

As Windows 10 cumulative updates get very big, very quickly (often in excess of 1GB a few months after any given Feature Upgrade), Microsoft started publishing express installation files for these updates in addition to the traditional full update files. Configuration Manager introduced support for Windows 10 Express Installation File updates in Current Branch 1802 hotfix KB4163547.

Express installation files are a much larger payload on the Distribution Point compared to traditional software update files, but the feature enables clients to download delta byte-ranges from these files, so each month the amount of data a client has to download is typically much smaller. Configuration Manager Current Branch can be configured to support express installation files (refer to https://docs.microsoft.com/en-us/configmgr/sum/deploy-use/manage-express-installation-files-for-windows-10-updates for more details).

With the release of Windows 10 1809, Microsoft replaced express update files with a new way of managing deltas within software updates. In Configuration Manager 1902 the Enable installation of Express installation files on clients option in Software Update Client Settings was replaced with Allow clients to download delta content when available.

Refer to Deploying software updates using Configuration Manager for an example scenario about deploying software updates using CM and how you can monitor those deployments using the Content Distribution app.

Updates, Nomad and Delivery Optimization

The Microsoft implementation of byte-range downloads in Configuration Manager integrates with Delivery Optimization (DO) on Windows 10 clients. When the CM client has been configured to use express installation files or delta content for software updates, Delivery Optimization will attempt to get the content from other DO peers. In normal circumstances, if DO is unable to fulfil a request from DO peers it will revert to the HTTP source on the Internet. However, in this scenario, when the software update is managed by CM, DO reverts to the CM client to get the content from the DP and in turn Nomad will be used to download the content. It is therefore possible that when using express updates or delta content for updates, some byte ranges may be downloaded by Nomad and some by DO.

Any byte ranges downloaded by Nomad in this scenario will be available to Nomad and DO peers, whereas byte ranges downloaded by DO will only be available to DO peers. As DO is typically more aggressive than Nomad at clearing its cache, it is likely that Nomad will fulfil more byte-range requests than Delivery Optimization if the update deployment is phased over a number of days, whereas DO could be expected to fulfil more requests when the same update is deployed to all clients at the same time. It is therefore important when enabling express installation files or delta content for software updates in Configuration Manager to ensure you have Delivery Optimization configured appropriately for your environment, even though you are using Nomad.

Download mode

The download mode option is important as this determines which devices DO considers as peers it can share content with and may result in content being downloaded over the WAN, for details about download mode refer to https://docs.microsoft.com/en-gb/windows/deployment/update/waas-delivery-optimization-reference#download-mode.

Setting	Description
Download Mode is set to 1	On Windows 10 Enterprise and Education, Download Mode is set to 1 (LAN) by default. This will allow peers within the same network (including all clients sharing a public Internet address through NAT) to share content. The default value for other editions is 3 (Internet) allowing clients to get content from other peers on the Internet.
Download Mode is set to 2 (Group)	Setting Download Mode to 2 (Group) will by default enable peers within the same AD site (or if not in a defined AS Site, the same AD Domain) to share content. You can use other methods to define the group, including DHCP Scope Option, DNS suffix or Azure AAD Tenant ID, refer to https://docs.microsoft.com/en-gb/windows/deployment/update/waas-delivery-optimization-reference#select-the-source-of-group-ids for details. If you enable the Configuration Manager Client setting Use Configuration Manager Boundary Groups for Delivery Optimization Group ID, Download Mode will be set to 2 (Group) and peers within the same CM Boundary Group can share content. In this scenario the CM client sets the Group ID on each client using a unique identifier for the CM Boundary Group that the client is in.
Download Mode to 0 (HTTP only)	You can turn off Delivery Optimization peer-to-peer content distribution by setting Download Mode to 0 (HTTP only). This will result in Nomad downloading all byte ranges, but will prevent DO from sharing other content. (e.g. Microsoft Store, Microsoft Updates outside of CM or Intune Win32 apps) with peers. We do not recommend turning off DO peer-to-peer if you are using or planning to use these Microsoft features.
Download Mode = 99 (bypass)	Do not use Download Mode = 99 (bypass). This option is only relevant on clients if you use WSUS (outside of CM) and prefer to use BranchCache rather than DO. If you are using CM and Nomad for software updates then this option is not needed and can prevent updates from successfully downloading.

Windows 10 express installation files

Nomad can download byte ranges from Windows 10 express installation files requested by the Configuration Manager client from either an on-premises DP, Microsoft Update or a Nomad peer.

Using Express installation file or delta content for updates in Configuration Manager (with or without Nomad) has the following additional limitations:

Limitation	Description
Express installation file support.	Express installation files are supported on Configuration Manager Current Branch 1802 (with hotfix KB4163547) and CB 1806 or later, and Windows 10 versions 1703, 1709 and 1803 or later. Delta content for updates is supported in CM CB 1910 onward.
Nomad does not send status messages for downloads of express installation file or delta content for updates.	Nomad does not send status messages for downloads of express installation file or delta content for updates as there is no way for Nomad to determine if all the required byte ranges have been downloaded for a given update. Nomad is simply obtaining byte ranges as they are requested and notifies the CM Content Transfer Manager as it completes each download.
Deploying updates using express installation files typically takes longer to install.	Deploying updates using express installation files typically takes a lot longer to install compared to traditional full updates as a lot of processing is required on the client to calculate what byte ranges are required. As an example, a typical Windows 10 Express CU may take over 1 hour to download over even a fast 1GBs Network connection, where a copy of the same full update would typically take only a couple of minutes.
The Install Software Updates step in an OS Deployment Task Sequence may become unresponsive.	The Install Software Updates step in an OS Deployment Task Sequence may become unresponsive for several hours. As examples, a Windows 10 "Wipe and load" Task Sequence might fall back to using full versions of the software updates after several retries and an in-place upgrade, fail to initialize the Delta download startup task and hang at a "install Software Updates" step, meaning OS Deployment task sequences, may take some additional hours than normal to complete.

Enabling express installation file and delta content for updates in Nomad.

Once you have configured CM for express installation files or delta content for updates and are comfortable that your Delivery Optimization configuration is appropriate for your network, you can enable the feature in Nomad through the CompatibilityFlags registry value on the client, setting bit 26 (0x4000000, or 67108864 in decimal).

Downloading the following type of updates is enabled by default in the Nomad client (1E Client 4.1 and later). Downloading from Microsoft Update is also enabled by default. Refer to Downloading content for CM Software Updates from Microsoft Update.

The settings are defined in CompatibilityFlags and you will need to ensure the relevant bits remain set if you are using that registry value to configure other options, as follows:

Type	Enable Nomad to download	Enable Nomad to download from Microsoft Update
Software Updates (including Windows 10 feature updates)	Always enabled	Set bit 27 (0x08000000, 134217728 in decimal)
Office 365 updates (Refer to Deploying Office 365 updates.)	Always enabled	Set bit 28 (0x10000000, 268435456 in decimal)
Windows 10 Express Installation Files and Delta Content for Updates	Set bit 26 (0x04000000, 67108864 in decimal)	Set bit 28 (0x10000000, 268435456 in decimal)

To enable all the above, then AND bits 26, 27 and 28 with whatever you have already set in CompatibilityFlags.

Please refer to Deploying software with Configuration Manager for how to configure client settings to set Nomad as a download provider for applications and software updates.