46

I recently noticed that one of my external hard drive seems to be missing a lot of space. It was recommended that I try WinDirStat, as it could help identify how much space each file was taking up. This is the result:

http://i.imgur.com/KU0Yia7.png

As you can see, there is about 244.7GB "unknown" usage.

Doing a bit of research online, the most common suggestion was (a) Recycle Bin and (b) System Volume Information.

(a) As you can see, empty. To double check, I ran Disk Cleanup. It confirmed that it was empty. (Note that a new file appeared by the time I took this screenshot, but it's only 129 Bytes.)

(b) Harder to tell. However, according to various forums, the most common reason for System Volume Information to grow large is due to System Restore Files. I had a look, and it is definitely turned off for this drive, as seen here:

http://i.imgur.com/JZ49qrC.png

What else could be causing this issue? It is an enormous amount of storage to have gone missing!

DavidPostill
  • 162,382
BSnapZ
  • 563

6 Answers6

29

Running Windirstat as Administrator will reveal most of this. In some cases it can be system protection files, corrupt files, old installers, or in my case, the Recycle Bin.

Per the Windirstat Propaganda Blog,

https://blog.windirstat.net/20061013/unknown-space/

This mysterious item is just the difference between what Windows reports as the free space on the volume minus size of the files WDS can access. Please note the part WDS can access! This is the important point here. WDS cannot access the files under System Volume Information on all the (NTFS?) drives, so it cannot sum up the sizes of these items. And by the way, we have had reports of up to 30 GB of “” space.

The root of the problem is permissions, apparently.

J E Carter II
  • 436
17

Instead of windirstat you should use TreeSizeFree.

enter image description here

Run it as admin, so that TreeSizeFree shows all hidden/system files.

magicandre1981
  • 99,606
3

In my case it's the Windows search file, Windows.edb, in: \ProgramData\Microsoft\Search\Data\Applications\Windows.

Lll Fff
  • 31
2

This might be of interest, or not.

I run WinDirStat (NOT as admin) and get 7.3GB unknown. Program Files 1.7GB. When I run it as admin I get 5.2 and 3.2GB respectively. There are other differences too but I won't muddy the water by posting all of them.

It's definitely a permissions issue for me. For example the difference in Program files is the WindowsApps directory. I changed the owner from Unable to display... to ....\users and WinDirStat sees it in either mode (no admin/admin).

Same for SystemVolumeInformation, despite not being able to change owner for all items. Found all but 0.6GB of unknown space. Some of the remainder is in ProgramData and small amounts in other places e.g. Config.Msi.

I am not so concerned as to spend time hunting through the whole drive and changing premissions but I now understand the differences. Hope this helps.

mwfearnley
  • 7,889
KeefyW
  • 21
  • 3
2

For others facing this same question, you might want to check the VSS settings to be sure the amount reserved for shadow copies is not consuming too much space. (ie right click the drive in windows explorer and choose "Configure Shadow Copies")

KenO
  • 21
2

Important to know is how WinDirStat works and what this "unknown" means. For example: you have a drive of 256GB. You run WinDirStat and it will scan all the files it has access to. Let's say you run it as a normal user. That user has no permissions to 'see' all the files. If the list WinDirStat can see as that user can see 200GB, there will be 56GB unknown. It is logical that the administrator can see more files compared to a normal user. There are situations where the administrator still could only see a limited amount of GB's.

For example:

  • Previous versions of files
  • Shadow copies
  • Filesystem errors (ex: not reclaimed free space - run "chkdsk c: /F" and reboot to fix this)
  • ...
phulstaert
  • 31