Posted by: Ed Tittel
I’ve written repeatedly about a great, free SourceForge utility called WinDirStat for this blog over the years. But just this morning, I learned something about the program I didn’t know — namely that applying “run as administrator” when using this tool sheds additional light on where files that WinDirStat labels as “Unknown” come from. I’ll show two screen caps to illustrate what this can mean in stark fashion:
Left/above shows a huge yellow unknown area; right/below shows a much smaller area of the same hue.
The first screenshot was generated by running WinDirStat directly from the Start menu, but I created the second one for the same drive after launching the program using the right-click “Run as administrator option.” The differences between the two screenshots show that elevated privilege for the program provides more insight into Windows System information available from the System Volume Information data to administrators but not to other users (even if they, like the account used to generate both screenshots, are members of the “Administrators” or “Local Administrators” groups). I had been wondering about the huge allocation to Unknown for this drive, and discovered this technique by Googling “large unknown file WinDirStat.” In turn, this led me to a sequence of user forum posts that mentioned the difference in passing, while explaining how to reduce the size of such allocations to other users (I was already aware of using VSSADMIN to reduce shadow copy storage, and had checked — and reduced — those allocations already).
The upshot was that I was able to see that around 72 of the 90 GB that showed up as “Unknown” in the first screen cap, could actually be attributed to image and other files in the WindowsImageBackup holdings, as shown in the second screen cap. In that screen cap, the “true Unknown” — namely the volume shadow copy files — resolved to under 12 GB, entirely in keeping with the allocation that I’d made (and double-checked) using VSSADMIN. It all goes to show that some problems in Windows aren’t necessarily problems at all. Rather, they’re a matter of assessing circumstances from the proper perspective! A valuable insight for me, and I hope for some of you readers as well.