Author: techguy86

Because this was hard to find…

This is an old problem that in my experience seems to affect Server 2008R2 and earlier VMs.

The fix for this is an un-documented DISKPART command: EXTEND FILESYSTEM

See below for a usage example:

DISKPART> list volume

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
  Volume 0     D                      Removable     27 PB
  Volume 1     E   DATA_VOL    NTFS   Partition   2000 MB  Healthy
  Volume 2     C   Windows     NTFS   Partition   4001 MB  Healthy    System 

DISKPART> select volume 1 

DISKPART> extend filesystem

DiskPart successfully extended the file system on the volume.

DISKPART> exit


Source: https://community.spiceworks.com/t/disk-management-and-windows-explorer-show-different-sizes/681766