One of the attributes of the assembly identity is its version. Every side-by-side assembly has a unique identity. These files can be multiple versions of the same assembly or application.

It is this WinSxS folder that stores the shared components of side-by-side applications. In Windows 7 and later, there isn’t a ‘dllcache’ folder and nor can you find the ‘i386’ folder, where the system caches (like in XP) all it’s source modules. In Winsxs, the ‘backup’ folder is the largest, as can be noticed in the image below.Īgain, as can be seen in the image below, in the Winsxs folder, the ‘Other’ File types take the bulk of the space. This feature was first introduced, in Windows ME and was considered as Microsoft’s solution to the so-called ‘dll hell’ issues that plagued Windows 9x. Libraries that are being by multiple applications are stored there. Winsxs, which stands for ‘Windows Side By Side’, is Windows native assembly cache. These are actually, different versions of the same files which are being stored as different programs may require different versions. If you browse inside, you will see what looks like a lot of duplicate files, each having the same name. The WinSxS folder, stores multiple copies of dll, exe, and other system files to let multiple applications run in Windows without any compatibility problem.

Large winsxs folder