The amount of used space on a Hard Drive does not match the used space in Disk Management

Scenario:  We were getting alerted that the mount points (1 TB drives) on Exchange were getting low on free disk space.  During investigation, we noticed that there was an inconsistency with the size of the files and folders on the drive versus what Disk Management was showing.

Cause:  Shadow Copies must have been enabled at some point, and there was a shadow copy of another mount point on the mount point I was investigating.  (Open Disk Management –>Right click the drive and go to Properties –> Go to the Shadow Copies Tab and scroll down the list of Hard Drives)

Solution:

From a command prompt, enter the following:

Diskshadow

Delete Shadows All

When you look at the disk space now,  the shadow copy was removed and the space is now showing correctly.