In side-by-side, Windows stores multiple versions of a DLL in the %systemroot%\WinSxS directory, and loads them on demand.
When the operating system loads the application and detects the presence of a manifest, the operating system DLL loader is directed to the version of the DLL corresponding to that listed in the manifest.
On Windows Vista and later, sxstrace.exe can help to diagnose failures in the starting of applications due to SxS misconfiguration.
From Vista onward, the Windows operating system uses WinSxS for its core components.
[8] Because of its elevated importance, from Vista onward the winsxs directory is owned by the Trusted Installer service SID.
[10] Windows 7 includes Windows AIK tool Deployment Image Servicing and Management (DISM) which can remove files used by superseded OS updates using the Trusted Installer worker service, without the need to reboot or take down the system;[11] post-SP1 updates add Windows Update cleanup to the Disk Cleanup tool (cleanmgr.exe)[12] and the downloadable System Update Readiness tool (CheckSUR)[13] which can repair components store errors and replace corrupt or missing OS files with known good versions.
Windows 8 integrates repair capability to the DISM tool which is now able to copy valid OS files from Windows Update or an offline WIM image, as well as reset the component store to only contain the latest versions of OS components.
[18] DIR and Explorer fail to check for hard links, and so may count the same file multiple times, adding incorrectly to the perceived disk usage.
The disk usage reported by these two programs is as if each hard link is an actual file.
[19] Since Windows 8.1, the DISM tool can be used to analyze the component store and report its actual size.