Today I was trying to open a big .rar file when I ran into am unexpected “low disk space” warning.

What??!!?? Low space??? How the hell did I fill up all of my 200GB disk?!?!?

Further investigation led to this: there is a folder called winsxs inside the Windows directory that takes up a LOT of space (in my case it was about 12GB!). I never heard of it before, so I searched the web for more info about it, and this is what i found.

The Windows component store (C:\Windows\winsxs) directory is used during servicing operations within Windows installations. Servicing operations include, but are not limited to, Windows Update, Service Pack and hotfix installations). The component store contains all of the files needed for a Windows installation and any updates to those files are also held within the component store as they are installed.
Read the rest of the Microsoft Technet article here.

In other words, the ‘winsxs‘ folder is used to store all install and uninstall files, windows packages (not only the current version of a component, but also the previous ones) and out-of-band releases. Therefore you should expect it’s content to grow constantly through time.

But there’s something you can do to shrink it’s size and gain back some of your vital space.

If you like to work with the command line, and you have SP1 installed (required!!), you can run this command (in elevated/admin mode):

dism /online /cleanup-image /spsuperseded

In my case, it helped me reduce it from 12GB to 7GB!! Not bad, uh??