Windows groups several unrelated kinds of storage under System & reserved. Memory-management files, hibernation, restore points, component files, update data, and reserved storage have different purposes and need different Windows tools.
Use the scan to separate the categories
Scan the Windows drive and open SizeTrend's Overview pane. System-managed space identifies files such as pagefile.sys, hiberfil.sys, and swapfile.sys. Other Overview rows identify the Windows component store, previous Windows installation, downloaded update data, and system restore or snapshot storage.
The displayed allocation explains where the drive went. It is not a promise that the same amount can be removed. SizeTrend keeps these entries separate from ordinary files because deleting them directly can break Windows, applications, updates, or recovery.
Pagefile and hibernation files have active jobs
pagefile.sys supports Windows memory management, crash dumps, and workloads that need more committed memory than physical RAM alone can provide. hiberfil.sys supports hibernation and related startup behavior. Their sizes often track installed memory and system configuration.
Do not delete either file in Explorer. Change hibernation or virtual-memory settings only when you understand the lost capability and performance consequences. SizeTrend reports the files and leaves their management to Windows.
WinSxS is not an ordinary duplicate folder
The Windows component store contains components, shared hard-linked files, and update rollback data. A folder scan can therefore overstate what is independently removable, and the entire displayed size is not free space waiting to be reclaimed.
SizeTrend uses Microsoft's supported DISM StartComponentCleanup operation when component cleanup is appropriate. It never deletes files from WinSxS directly and does not use the irreversible ResetBase option.
System Volume Information protects recovery data
System Volume Information can contain restore points, shadow copies, search metadata, and other protected volume data. SizeTrend reports the scan-backed folder allocation but does not assume that all of it is removable.
Use Windows System Protection or the recovery settings opened by SizeTrend to review storage and available restore points. Removing every recovery point to solve a temporary space shortage can leave you without a useful rollback when the next update or driver fails.
Let Windows clean update and reserved storage
Delivery Optimization, downloaded Windows Update content, previous Windows installations, and reserved storage are managed by Windows. SizeTrend can identify the relevant locations or open the supported cleanup path without deleting update metadata by hand.
Microsoft's Windows Storage settings guide explains the current System & reserved, Storage Sense, and Cleanup recommendations controls.
Refresh after Windows finishes
Windows cleanup can continue after the visible operation closes, and some protected files remain in use until a restart. Refresh the SizeTrend scan afterward and compare the before-and-after allocation instead of assuming that every reported byte should disappear.
If System & reserved grows repeatedly, save a scan and compare it later. That separates a one-time Windows update from an ongoing restore-point, dump-file, update-cache, or virtual-memory pattern.
Measure Windows-managed storage before changing it.
SizeTrend identifies the category, then sends cleanup back through the Windows tool that owns it.