Wrong disk usage reported in File Explorer Windows 7

I have a weird problem in several clients on Widnows 7 x64.

Their computers show wrong disk usage.

For ecample - when viewed from explorer, C: is shown as occupying 84 GB, and when I scan all files with WinDirStat, it shows 67 GB.

Can anyone help? :)
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It may depend upon how it figures a GB. Some people call a GB
1,000,000,000 bytes
Others call it  its binary result of 1024(1k) raised to the third power

This could cause the issue.

Or: http://blogs.msdn.com/b/ntdebugging/archive/2008/07/03/ntfs-misreports-free-space.aspx
mrmutAuthor Commented:
Will try, thanks.
you can check how it reports the disk size - that will show how it calculates
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David Johnson, CD, MVPRetiredCommented:
run windirstat as an administrator you will find the missing bytes. A standard user doesn't have access to all file locations. i.e. System Volume Information.
mrmutAuthor Commented:
Yes - but the thing is that WinDirStat reports LESS bytes than explorer!

I still haven't find what is wrong with this!
and what disk size is reported??   i Always have to ask things a couple of times on EE it seems
mrmutAuthor Commented:
Explorer: 84 GB
WinDirStat: 67 GB

Difference is ~20 GB is too much

I haven't found anything suspicious, like large files etc in WinDirStat. - In it, disk useage is completely normal, and what it should be.
mrmut  -  again : what disk size is reported - and what disk model do you have ?
mrmutAuthor Commented:
OK, here you are:


Reported capacity: 104 GB

Explorer used:
85.9 GB

67.7 GB
David Johnson, CD, MVPRetiredCommented:
Showing the difference between run as administrator and run as a user

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so you have an SSD of 120 GB and windows report it as 104 GB
then it's no wonder the other figures are too low also

do the calculation sstory asked in his first post -  and tell us what you find
mrmutAuthor Commented:
The computer user is local computer administrator, and the disk size is fine, as it also contains two computer restoration hidden partitions from Lenovo.

I will, however, check results with WinDirStat run explicitly in administrator mode, and report back.

mrmutAuthor Commented:

It turned around that RRBackup folders were taking the additional space. I didn't see them with any tool, except when using TreeSize Free.

So, I deleted the old backups, and voila. The free space is back.
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