I have an issue that hard drive space appears to be going missing on my Windows Server 2012 R2 DataCentre virtual machine running Exchange 2016 CU5.

By "missing" I mean that the amount of free space as reported by explorer for the drive (20.1Gb) is wildly different from the value I get by taking total hard drive size (169Gb) minus space apparently consumed by files (81.1Gb per WinDirStat running locally as Administrator or 86.1Gb per ncdu running remotely, connected to c$ as a domain administrator)* (87.9Gb/82.9Gb).

CHKDSK when run with no arguments does report something close to what Explorer is reporting 156,252,592 KB used in 262,571 files out of a total space of 177,896,447 KB which is more space used in fewer files than the other methods were reporting.

There are no shadow copies on the disk and I'm currently struggling to understand where my space is being used or how to get any of it back.

I previously increased the size of the hard drive by 20Gb as space was running low, but this seems to have been consumed as well.

It's possible CHKDSK/Explorer are perfectly correct and that much space is being utilised but I really could do with knowing where it is being consumed so I can either free it up or at least understand why.

Can anyone offer any guidance on how I can investigate this further?

*: ncdu is reporting 350,739 items compared to WinDirStat's 347,132 - not sure what the differences are, but the two usage figures appear to be close enough.

2 Answers 2


Are you sure that its not caused by the Volume shadow copy (VSS) as reported here? It sounds like exactly as written in that article here.

So please check with:

vssadmin list shadowstorage

If you see the missing space here.

  • Yup, that'd be it then. Found 66Gb stuck in shadow copy. Thanks :)
    – Ceisc
    Jul 13, 2017 at 16:28

Found what was using all the space on my server…

For some unknown security reason 800GB of WC3 log directory contents at C:\inetpub\logs\LogFiles\ were hidden from anything that used Explorer to scan\browse the disks. Luckily good old DOS could still scan and list the directories.

Interestingly enough I have run into a SIMILAR problem with a new Exchange 2016 server. Except with the Windows\Temp directory. Some Unified Messenger logs filled the directory ( 1 TB in 2 days!!) and would not show up on a “Disk Properties” scan until the owner\security rights for the temp directory was changed to allow access.

Gotta say… It’s REALLY annoying to be browsing through folders with an Enterprise Admin account and be told that you can’t view a folder because you don’t have “Supervisor” access.

MS needs to get rid of or fix the directory access BS.

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