What file is this and where can I find it? While checking the contents of my hard drive using the WinDirStar program, I found a file that cannot be opened in Windows Explorer and with which I cannot perform any operations. Please tell me what kind of file this is, whether it is important for the operating system to work, and whether it can be safely deleted after determining its location.
WinDirStat displays “Unknown” files or space that actually represents system folders to which the program doesn’t have access due to permission restrictions, such as the “System Volume Information” folder. This folder is located in the root of each drive and contains critical data essential for Windows to function, including system restore points, search indexes, and volume shadow copy services. Deleting this folder is strongly discouraged as it can disrupt system operation.
Contents
- What is the “Unknown” file in WinDirStat?
- Where is this file located?
- Content and purpose of the folder
- Why can’t WinDirStat and Explorer access it?
- Safe investigation methods
- Can this file be deleted?
- Alternative tools for disk analysis
What is the “Unknown” file in WinDirStat?
“Unknown” in WinDirStat is not a single file, but a category for data that the program cannot access due to permission restrictions. Most often, this is the “System Volume Information” system folder, which exists in the root of each drive in the Windows system.
As explained in WinDirStat sources, WinDirStat encounters limitations when trying to access protected system areas. These limitations are related to NTFS security settings, which are specifically designed to prevent unauthorized access to critically important system data.
Where is this file located?
The “System Volume Information” folder is located in the root of each drive in your system:
C:\System Volume InformationD:\System Volume InformationE:\System Volume Information(for other drives)
If you’re using external drives, they may also contain this folder. According to Microsoft data, on drives formatted with the NTFS file system, access rights to this folder are configured so that even administrators cannot access it through normal methods.
Content and purpose of the folder
The “System Volume Information” folder contains several types of critically important data:
- System restore points - allow rolling back the system to a previous state
- Indexing databases - speed up file searches in Windows Search
- Volume shadow copy data - necessary for backup functionality
- NTFS disk quota settings - manage volume limitations for users
- File deduplication databases - used in server versions of Windows
As noted in the Woshub article, deletion or corruption of these files can lead to loss of system functionality, inability to restore, and reduced performance.
Why can’t WinDirStat and Explorer access it?
The main reason for inaccessibility is NTFS access restrictions. As explained in research, on NTFS drives, this folder is protected with special permissions that:
- Prohibit access to all users, including administrators
- Prevent reading, writing, and deleting of contents
- Require special methods for temporarily changing rights
WinDirStat, like Windows Explorer, operates in the context of the current user and inherits Windows security limitations. Even when run as administrator, the program cannot bypass these restrictions without special permission configuration.
Safe investigation methods
Although direct access to the contents is restricted, there are safe investigation methods:
Running as administrator
Run WinDirStat with administrator privileges. As mentioned in Reddit sources, this may partially increase the amount of data the program can read.
Using specialized tools
Tools like TreeSize Free when run as administrator may show more information. According to the Seven Forums forum, TreeSize uses a service running as SYSTEM, which allows it to bypass some limitations.
Command line for temporary access
For temporary access to the folder, you can use the commands:
takeown /f "C:\System Volume Information"
icacls "C:\System Volume Information" /grant %username%:F
However, as warned by Woshub, this may disrupt system operation and requires subsequent restoration of default rights.
Can this file be deleted?
Strongly not recommended to delete the “System Volume Information” folder or its contents. Reasons:
- Critical importance for the system - without it, Windows won’t be able to perform restore operations, searches, and backups
- Risk of data loss - deleting restore points may make it impossible to roll back to previous system states
- Disruption of functionality - many Windows components depend on data in this folder
As explained by experts at Winhelponline, attempts at deletion can lead to serious system errors and the need for Windows reinstallation.
Alternative tools for disk analysis
If you need accurate disk space distribution, use alternative tools:
- TreeSize Free - shows more system data when run as administrator
- WinDirStat (updated version) - improved support for system folders
- WizTree - fast alternative with similar functionality
- CCleaner - tool for cleaning system junk with safe options
As noted in Tom’s Hardware discussions, these tools can provide more accurate information about disk space without risking system integrity.
Sources
- WinDirStat Blog - Unknown Space Issues
- Super User - WinDirStat Shows Unknown Space
- Reddit - What is Unknown in WinDirStat
- Windows OS Hub - System Volume Information Access
- Microsoft Dev Blog - System Volume Information Permissions
- HowToGeek - System Volume Information Folder
- Seven Forums - Disk Space Analysis
- Winhelponline - System Volume Information Overview
Conclusion
The “Unknown” file in WinDirStat is not a single file, but the “System Volume Information” system folder containing critical data for Windows to function. It’s located in the root of each drive and protected by special NTFS access permissions.
- Do not attempt to delete this folder - it will lead to serious system problems
- For safe disk space analysis use specialized tools like TreeSize Free or WizTree
- If temporary access is needed use the command line cautiously and restore original rights afterward
- Regular system maintenance with safe tools will help avoid accumulation of system junk without risking important data
If you’re concerned about large amounts of “Unknown” space, turn to tools that can show the actual reasons for its usage, and clean only those files that are safe to delete.