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. 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. 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. 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. Each component has a unique name that includes the version, language, and processor architecture that it was built for. What is the Windows Side By Side folder? Well, that's explained pretty well here.Īll of the components in the operating system are found in the WinSxS folder – in fact we call this location the component store. I used TreeSize to check for the culprits.Īnd the primary culprit is that /winsxs or 'Windows Side-By-Side' folder. A Vista virtual machine I use only has a 10 GB virtual hard disk - and I'm worried about it running out of space over time.

Large winsxs folder