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Vssadmin keeps an eye on "hidden" system snapshots

In working on this blog over the years, I’ve written repeatedly about a great open source file management project named WinDirStat. Short for Windows Directory statistics, this SourceForge project provides a nice compact tool for investigating and visualizing Windows volume layouts and contents. In working with Windows 10, however, I’ve noticed that Windows’ Volume Shadow Copies have more or less disappeared from view in that utility. In versions of Windows starting with Vista, WinDirStat has previously shown these files as Unknown when listing the contents of a boot/system drive, and has proved itself to be decent at keeping tabs on how much of a disk’s storage space is being consumed for the snapshots of disk volumes that the Volume Shadow Copy Service (which I’ll abbreviate as VSCS in future mentions, for brevity’s sake) is maintaining for Windows.

But as newer versions of Windows have appeared, the amount of disk space allocated for the VSCS has dropped, most likely in response to the increasing tendency for systems to incorporate faster but usually smaller SSDs for their boot/system drives. Whereas Vista allocated 15% of a disk’s overall storage for VSCS to use, Windows 7 took 5%,  and Windows 8 2%. Thus, I was a little surprised to see the default Windows 10 VSCS allocation increase to 4% (though this could easily reflect increasing size for most newer SSDs, which are now typically 256 GB or larger). I was also surprised to see that the Unknown file bucket in WinDirStat no longer appears in Win10 displays in the %Homedrive% listing.

Shades of D Rumsfeld: In Windows 10 the Unknown bucket is no longer known to WinDirStat.

Given that WinDirStat could no longer give me the goods on VSC storage consumption, I turned to the Windows vssadmin command inside an administrative command prompt window. Readers unfamiliar or out of practice with this command will find the Vssadmin Command Reference useful in putting its many capabilities to work. I made use of the list shadows and list shadowstorage subcommands to determine that VSC was still active and working on my boot/system drive, and that volume shadow copies were indeed still consuming disk space as this screen shot illustrates:

Note: 2.16GB of a 10 GB allocation is already in use for the two snapshots on my Build 9879 C: drive.

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