Settings › System › Storage shows a “System & reserved” category that can be surprisingly large. It is not one thing. Some of it can shrink safely with Microsoft’s own tools; some of it should be left alone.
Hibernation file (hiberfil.sys)
Windows writes memory to this file when the PC hibernates, and Fast Startup uses it too. It is often several gigabytes. If you never hibernate, you can turn it off from an administrator command prompt. This also turns off Fast Startup.
powercfg /hibernate offPage file (pagefile.sys)
Virtual memory. Windows manages its size, and it is best left on automatic. Turning it off can make apps crash when memory runs short.
Component store (WinSxS)
WinSxS holds the components Windows needs to update and repair itself. Much of it is shared with the rest of Windows through hard links, so Explorer overstates its size. Never delete files from it by hand. Microsoft’s DISM tool can remove superseded versions safely:
Dism.exe /Online /Cleanup-Image /StartComponentCleanupWindows Update and Delivery Optimization caches
Downloaded updates and the files Windows shares with other PCs. Clear them from Settings › System › Storage › Temporary files, or with Disk Cleanup’s “Clean up system files”.
Restore points
System Restore keeps snapshots of system files. You can lower the space they use in System Properties › System Protection › Configure. Keep at least one recent restore point.
Reserved storage
Windows sets aside about 7 GB so updates always have room to install. It is there on purpose and is best left alone.
Virtual disks for WSL, Docker and Hyper-V
These .vhdx files grow as you use Linux or containers, but never shrink by themselves, even after you delete files inside them. After shutting WSL down with “wsl --shutdown”, they can be compacted with diskpart’s “compact vdisk”.
→ where Tidemark helps
Where Tidemark helps
- System lists each of these items with its real size and what it is.
- It runs Microsoft’s own tools (DISM, powercfg, Storage Sense, diskpart) in a visible window, after a Windows permission prompt.
- It never deletes system files directly.
- It compacts WSL and Docker virtual disks for you.
coming soonto the Microsoft Store
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