Clean up Winsxs on Windows 2008 R2 after SP1 install

Last year I wrote a post where I explained what the Winsxs folder was and which were the possible solutions to contain its bad habit of eating free space on your hard drive. Some days ago I have discovered that, starting from Service Pack 1, Windows 2008 R2 (... and Windows 7) finally has a built-in tool to reduce the size of the Windows Side-by-Side DLL repository and free up some GBs on your server storage. This tool is DISM.exe.

Cool news isn't it? Personally I am happy to know that someone at Microsoft has finally decided to make it possible to reclaim a few GBs on the system partition and to partially solve this major bug.

The procedure is the following:

• Install Windows Service Pack 1 then ...
• Start and elevated command prompt (run 'CMD' as administrator) and ...
• Run the DISM command, which replaces the old VSP1CLN and COMPCLN we used on previous Windows versions: DISM.exe /online /Cleanup-Image /spsuperseded
• Wait 10 minutes before the task completes ( it ends with “Service Pack Cleanup operation completed. The operation completed successfully”)

Normally you should have been able to reduce the Winsxs folder size by 1 or maybe 2 GBs, sometimes more. Saved space may vary a lot.

Just know that after using DISM you will not be able to uninstall the Service Pack 1 anymore.

Let's have a look at the used switches for DISM.exe:

• The /online switch tells DISM to work on the running OS installation
• The /spsuperseded option removes the backup files created during installation. 

Optionally you could use the /hidesp option which will remove SP1 (KB976932) from the “Installed Updates” section of Programs and Features, to ensure that users do not try to uninstall the Service Pack.

I hope this helps. Please let me know how much disk space you were able to free up using the given command.