Windows Server 2008 r2 reports wrong hard drive free space

Question

I have Windows Server 2008 R2 installed onto a Virtual Machine on ESXi 5.0.0. When I originally created the VM, I gave the C: drive 350 GB of hard drive space, and I made it thin provisioned.

Today, I started getting errors from Microsoft Exchange saying that it was out of hard drive space. I looked into the issue, and Windows reports that I only have 10.1 GB free of 349 GB. I downloaded an old version of SpaceMonger, and it records the same numbers. The problem is, I can only find about 15 GB of files on the hard drive. I made sure hidden folders were visible before I checked. Also, even though SpaceMonger says that only 10.1 GB are free out of 349 GB, the visual representation shows that the free space is almost half of the drive. It just doesn't add up...

I figured it was an issue with thin provisioning, so I shut down the server and changed it to thick provisioning. After restarting the VM, the problem persists. I looked into Disk Management, but I didn't see anything wrong there...

Also, I ran DiskAnalyzerPro, which shows that the used space on the hard drive is only 16.16 GB, there are 10.01 GB free, and the total drive capacity is 349.90 GB. Again, it doesn't add up. I suspect ESXi, but I don't know what to do about it.

Solution

A friend pointed me in the right direction. I figured out that the issue was permissions. This site helped me out:

NTFS Misreports Free Space?

Because the username doesn't have access to Microsoft Exchange's mailbox store directory, windows did not report any of the files inside that directory. Needless to say, the Mailbox store is huge.

As far as I can tell, the issue had nothing to do with thin provisioning.