Oct 242008

!–adsense–>One of the largest changes between previous versions of Windows and Windows Vista was a move from an INF described OS to componentization.  A component in Windows is one or more binaries, a catalog file, and an XML file that describes everything about how the files should be installed. From associated registry keys and services to what kind security permissions the files should have.  Components are grouped into logical units, and these units are used to build the different Windows editions.

All of the components in the operating system are found in the WinSxS folder – in fact we call this location the component store.  Each component has a unique name that includes the version, language, and processor architecture that it was built for.  The WinSxS folder is the only location that the component is found on the system, all other instances of the files that you see on the system are “projected” by hard linking from the component store.  Let me repeat that last point – there is only one instance (or full data copy) of each version of each file in the OS, and that instance is located in the WinSxS folder.   So looked at from that perspective, the WinSxS folder is really the entirety of the whole OS, referred to as a “flat” in down-level operating systems.  This also accounts for why you will no longer be prompted for media when running operations such as System File Checker (SFC), or when installing additional features and roles.

That explains why the folder starts off big, but not why it gets larger over time – the answer to that question is servicing.   In previous versions of Windows the atomic unit of servicing was the file, in Windows Vista it’s the component.  When we update a particular binary we release a new version of the whole component, and that new version is stored alongside the original one in the component store.  The higher version of the component is projected onto the system, but the older version in the store isn’t touched.  The reason for that is the third part of why the component store gets so large.

Not every component in the component store is applicable, meaning that not every component should be projected onto the system.  For example, on systems where IIS is available but has not been installed, the IIS components are present in the store, but not projected into any location on the system where they might be used.

  If you’re familiar with how multi-branch servicing works in previous versions of Windows then it’ll make sense to you that we have a different version of the component for each distribution branch and service pack level, and that all these different versions are also stored in the WinSxS folder, even if they’re not immediately applicable.  So a single Post SP1 GDR package that contains an update to one component will end up installing four versions of that component in the WinSxS folder – double that on a 64 bit operating system for some components.

Now that you know why the store can grow to be so large, your next question is probably to ask why we don’t remove the older versions of the components.  The short answer to that is reliability.  The component store, along with other information on the system, allows us to determine at any given time what the best version of a component to project is.  That means that if you uninstall a security update we can install the next highest version on the system – we no longer have an “out of order uninstall” problem.  It also means that if you decide to install an optional feature, we don’t just choose the RTM version of the component, we’ll look to see what the highest available version on the system is.  As each component on the system changes state that may in turn trigger changes in other components, and because the relationships between all the components are described on the system we can respond to those requirements in ways that we couldn’t in previous OS versions.

The only way to safely reduce the size of the WinSxS folder is to reduce the set of possible actions that the system can take – the easiest way to do that is to remove the packages that installed the components in the first place.  This can be done by uninstalling superseded versions of packages that are on your system.  Service Pack 1 contains a binary called VSP1CLN.EXE, a tool that will make the Service Pack package permanent (not removable) on your system,  and remove the RTM versions of all superseded components.  This can only be done because by making the Service Pack permanent we can guarantee that we won’t ever need the RTM versions.

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  One Response to “What is the WINSXS directory in Windows server 2008 and Vista”

  1. Win XP
    Outlook Express 6 (OE6)
    1.There is no help associated with Video Acceleration Settings Dialog in Performance tab of Options dialog for Media Player so how users understand about function of this options and customize it for their own use?
    2.What is the function of Change default display to this taskpad view for these tree items Check box in New Taskpad View Wizard I didn’t understand by reading it’s help and when i uncheck it in Taskpad Option and then return back it is still checked and i can’t remove it’s check?.
    3.When user account is removed from MMC in Users and Groups folder it’s associated folders and
    files is not removed in addition to registry entries
    4.In Help Menu of OE6 there is a selection named Send Feedback but when i click on it and a webpage opens after a while i receive the page cannot be displayed error
    5.In User Configuration\Administrative Templates\Windows Components\Windows Explorer\Common Open File Dialog of gpedit.msc dialog there is an Item with Items displayed in Places Bar description .when i specify some folders for example My Documents and My Computer and Enable it when i click open from any program i see Three other folders with yellow Icons that there is no reason that while I just specified two Items in gpedit it puts three yellow Icons that are of no use instead of hiding the rest of icons in open dialog.This is another drawback and poor programming of few parts of windows that i mentioned
    6.There is no help associated with Enable Integrated Windows Authentication check in Internet Option
    7.Skydrive for windows live is not compatible with webdav and it is impossible using Add a Network Place Wizard to upload files to skydrive
    8.I can’t search for profiles in windows live and after it redirects to auth.bay.livestorefiles.com i receive the page cannot be displayed error message
    9. There is an option in Synchronize Newsgroup dialog of Tools menu named get messages marked for download but it is always dimmed and i don’t know what is it for and there is another option in Mark for offline menu of tools menu that is Do Not Download Message and it is always dimmed too even i select a message that is not downloaded
    10.There is a section in Internet Option with the title of When Searching and there are four options and the first option and last options are Display results, and go to the most likely site and Just go to the most likely site but whenever i search from address bar and set one either of these two options,ie just displayes the result and don’t go automatically to a selective site of ones that are listed in search window and the search bar is not being displayed automatically after i search from address bar as it written in the first option.why i don’t see the changes?
    11.They have put a checkbox named Get messages marked for download in Synchronize Newsgroup Dialog of Tools menu in OE6 when a Newsgroup is chosen in Folders pane and they even don’t know themselves what is it for and I didn’t find any help in Microsoft site and another sites about this.
    Please send this messages to another prople and important sites to know about many poor works of microsoft

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