How Windows 11 makes updates so much smaller

To encourage everybody to replace each month, Microsoft discovered a option to make replace packages smaller to obtain—and less complicated for organizations that handle updates themselves.


Picture: Shutterstock/Den Rise

For the previous few years, Microsoft has been progressively decreasing the dimensions of the obtain for the month-to-month Patch Tuesday replace. Meaning financial savings for Microsoft on the storage and community bandwidth wanted to distribute patches and it means smaller, sooner downloads for customers who could also be working from house on sluggish broadband (or not wanting to make use of up as a lot of their month-to-month information allowance on LTE-connected laptops).

For those who’re working from house, your broadband connection is perhaps quick—but when your PC is managed and it’s essential to get updates over a company VPN, smaller updates scale back the site visitors on an usually overloaded community.

With Home windows 11, replace packages are 40% smaller than for Home windows 10. That is not as a result of there is not a lot to replace on a brand new OS (Home windows 11 can be a characteristic replace for Home windows 10) however as a result of the updates are packaged in a different way.


Home windows Replace packages are smaller and cleverer on Home windows 11.

Accumulating completely different updates

Again in 2018, Microsoft made the month-to-month package deal of Home windows updates smaller by altering how cumulative updates labored. Updates change system information that get safety enhancements or new options; as an alternative of getting a complete new copy of the file, you simply get a delta or “differential”—what adjustments within the file.

SEE: Home windows 11 cheat sheet: Every thing it’s essential to know (free PDF) (TechRepublic)

Earlier than model 1809 of Home windows 10, Specific cumulative updates included all of the adjustments made to a system file because the final main launch of Home windows, in case you’d skipped a month of updates someplace alongside the way in which. So for Home windows 10 1803, launched in Could 2018, the August replace included a differential to go from the unique model of every file to the August replace, but in addition differentials to improve from the June and July updates. The updates bought bigger each month till a brand new Home windows model was launched.

For those who had been downloading updates instantly from the Home windows Replace service that Microsoft runs, your PC would simply get the precise information it wanted; that was known as an Specific replace. In case your group makes use of instruments just like the Home windows Server Replace Service to handle updates, your PC would nonetheless get simply the information it wants however the IT group needed to obtain and retailer the Patch Storage File (PSF for brief) with the total set of cumulative adjustments someplace earlier than they may ship that sort of on-demand replace, so many did not trouble.

From 1809 onward, what downloaded in every month-to-month replace package deal was the delta to revert the system file to the way in which it was within the unique launch and one other delta to replace it to the most recent model of the file, with all of the outdated and new patches in.

Microsoft calls these ahead and reverse differentials, and the obtain is about 10 occasions smaller than a file that has all of the cumulative updates in. However you’ve got nonetheless bought two patches for every file—one to undo earlier updates and one to ship the most recent replace. That is twice as a lot content material within the replace as you really want since you’re getting a duplicate of what must get added to the file in addition to what bought deleted every time to take you again.

SEE: A brand new Microsoft Retailer: What does it imply for you and your small business? Lots, truly (TechRepublic)

In Home windows 11, you now not get the reverse differential within the package deal, so it is smaller to obtain. As an alternative, your PC watches the directions that run to use the ahead replace and works out from them what the directions could be to take the file again to its earlier state. That is not as easy as you would possibly suppose as a result of making a single change to the meeting code can imply altering the addresses of tens of hundreds of perform calls. The MSDelta algorithm Microsoft makes use of for the differentials understands how Home windows works and remaps these addresses routinely so it does not need to retailer all these adjustments.


Though making use of an replace would possibly make adjustments to a number of perform calls, the reverse differential does not need to retailer all of them individually—simply the instruction that prompted the adjustments to ripple via the addresses of these calls.

Picture: Microsoft

It additionally provides any additional info it wants to use the directions in reverse, making the calculated reverse differential about as environment friendly as one which was programmed and included within the replace package deal. Meaning you are not buying and selling a smaller replace obtain for having your PC do extra work within the background simply to arrange for a future replace.

As with the outdated Specific updates, Home windows 11 downloads solely the information it wants every time, so when you take updates each month, your PC will not obtain the components of the cumulative replace which can be wanted on PCs that replace much less usually, making the obtain even smaller. When the 22000.132 replace for Home windows 11 got here out, when you had been updating from construct 22000.1, you’d additionally have to obtain the adjustments included within the 22000.120 replace—which modified extra information than the 22000.132 replace did. For those who hadn’t finished the primary replace, the second replace was one thing like 159MB to obtain; when you had finished the primary replace, the second obtain was almost a 3rd smaller, at round 112MB.

It is not clear whether or not there’s any technical cause Home windows 10 updates could not be slimmed down in the identical method by including the code to observe updates putting in, create the reverse differential in your PC for every replace and save that to make use of with the following month’s replace. Microsoft tells us “they don’t have something to share presently” about that risk.

SEE: The right way to set up Home windows 11 on older, unsupported PCs (TechRepublic)

Combining and slimming down updates

For those who’re utilizing WSUS to handle updates (on any model of Home windows), the Scan Cab that accommodates metadata for safety updates (so you’ll be able to scan Home windows PCs to see if they should set up any safety updates with out connecting to Home windows Replace) can also be getting smaller.

Over time, the CAB file has grown to be so massive it is laborious to distribute, so Microsoft is pruning metadata for older safety updates. From March 2022, the smaller CAB file would be the solely choice, however you can begin utilizing it now.

There are additionally some Home windows 11-specific adjustments for organizations that use WSUS and the Microsoft Replace Catalog.

Earlier this 12 months, Microsoft began distributing updates to Home windows in the identical package deal as updates to the servicing stack that applies the month-to-month cumulative updates to Home windows (generally known as Newest Cumulative Updates or LCUs). Beforehand, admins needed to know whether or not a month-to-month LCU wanted an identical servicing stack replace, know which was the proper servicing stack replace and know whether or not they might apply each updates directly or in the event that they wanted to ship the servicing stack replace first—issues Home windows Replace takes care of for business units. As of September 2021, WSUS additionally will get mixed updates for Home windows 10 1809 and Home windows Server 2019 onward).

In Home windows 11, that mixed cumulative replace now makes use of the Unified Replace Platform and the identical orchestration engine (generally known as the UUP replace agent) as Home windows Replace and Home windows Replace for Enterprise, although you are still utilizing WSUS and the Microsoft Replace Catalog. This can be a newer and extra dependable servicing stack that would ship completely different sorts of servicing packages sooner or later.

It additionally means the updates delivered by WSUS will likely be smaller and take up much less community bandwidth, as a result of as an alternative of a single CAB file in every replace package deal, there’s each a cumulative replace CAB and a PSF with the differentials in, so the replace stack can undergo the listing and obtain solely the components of the replace that PC wants.

For those who’re used to grabbing the CAB file out of the MSU replace package deal and distributing it in another method, that may now not work, so you could want to vary a few of your scripts and automations.

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