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I store all my data and the most of applications (those legally available in "portable" versions) on drive D: and only use drive C: for the Windows system and some heavily integrated applications like MS Office, Visual Studio, Adobe Reader, Flash Player etc. When I was using Windows XP, 50 GiB drive C: was more than enough. Now, as I've mitigated to Windows 7, it hardly is.

Yesterday as I've checked, 7 GiBs were free on drive C:. Then I've installed fresh Windows updates (which were just some tens of MiBs to download) and checked again: now there are only 2 GiBs free. Where have 5 GiBs gone?

PS: Don't be surprised my system installation takes actually that much: I've got Visual Studio and SQL Server with complete offline documentation library, but that doesn't explain where does free space disappear on simple Windows updates.

PPS: I use an augmented CCleaner version to clean my PC every day, so there are for sure no temporary internet files of recycle bin trash files taking the place.

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Use a tool like SpaceMonger or WinDirStat to find out. – David Schwartz Dec 17 '12 at 12:05
I would run the Cleanup Tool built into Windows. This will free some additional space. At the end of the day Windows 7 just takes more space then Windows XP an operating system nearly 14 years old. – Ramhound Dec 17 '12 at 12:34
Thanks for the recomendation to use WinDirStat, @DavidSchwartz. I've found the leak with it. It is Steam that has installed a new game to drive c: despite the fact I have configured it to put them on drive d: :-] And the second biggest folder is c:\windows\winsxs. The solution I've used with Steam is to move it to drive c: manually and replace its folder with a symlink. Now I wonder if I can do the same with winsxs... But I believe I can probably do the same with my Visual Studio offline help library which is quite big too... – Ivan Dec 17 '12 at 14:35
I would not move the winsxs folder. This is the side by side assemblies folder, which contains the entire dll library used by your computer. It is essential to even basic operation and should be maintained on the same drive as the OS itself. – Fopedush Dec 17 '12 at 15:02
up vote 6 down vote accepted

The winsxs file can not be moved/removed, windows needs it to run to store old DLL versions of files. Most tools will report the size of the windows directory incorrectly due to the fact that the winsxs folder uses hard links so the file may show up in two places but it only takes up the HD space once (Windows explorer, SpaceMonger, and WinDirStat all report this the "incorrect" way) so it is not taking up as much as you think.

SysInternal's Disk Useage can give you the "real" amount, you can have it enumerate the entire windows directory (as administrator) and it will count hard links once.

enter image description heredu included a few more files than the windows properties screen, that is why it is not exactly the same numbers for the -u switch

Adding the -u switch makes it behave like windows explorer (or 99.9% of all other programs) and the files that use hard links are counted every time it sees it. You can see that if you exclude hard linked duplicates the program is reporting 4.5 extra GB* that simply does not exist because it is being double counted.

There is one thing you can do to shrink the size if you have not done it yet, When you apply the Windows Service Packs it keeps the old files around in the event you ever need to uninstall the SP. You can remove those uninstall files and free up a chunk of space by running the following command in a administrative console (Start the console with a right click->Run As Adiministrator)

dism /online /cleanup-image /spsuperseded

This will remove those uninstall files and possibly free up several GB.

* 1 GB = 1 x 1024 x 1024 x 1024 Bytes

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You answered on your own questions. Visual studio installs huge amount of different packages, required for MVS. The other thing, is that most of MS apps makes cache for install files/updated files on your PC. Make visible all files and delete MSOCACHE in root of your C:\. Then check/google where visual studio cache files(if any exists). And after run disk cleanup, to delete all temp files. Also cleaning browser cache would give you some space

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