I have a couple of cluster nodes that I failed to size the C: drive adequately and began to run out of disk space. No problem! They’re all virtual machines, so I just need to expand the disks and away I go! Well, I’ve run into this situation several times since my lab has a lot of machines that I’ve upgraded over the years and while 15 - 25 GB volumes were fine prior to Windows 2008, it just doesn’t get it now and I like to use 40 GB volumes. That said, I’ve seen several cases where the virtual disks grow correctly and show up in the OS correctly, but when you try and use the Windows 2008 disk extend feature then you get this error from Logical Disk Manager, “The parameter is incorrect.”

What’s worse is that the Logical Disk Manager sees the volume as 40 GB, while the file system still only recognizes it as the original size. See the diagram below where I’ve laid a Windows Explorer view of the C: file system over the (supposed) 40 GB volume after extending the volume. Weird huh? What’s worse is that reboots don’t correct the issue. LDM is firm in it’s belief that this volume is now 40 GB and the File System doesn’t seem to care.

Here’s the work around that I’ve found to correct this situation. Go back into Logical Disk Manager (Disk Management in Server Manager) and Shrink the offending volume by 1 MB. After a minute or so, this will revert the volume back to it’s original size.

Now you can choose to extend it again and all will be right with the world. Notice in the screen shot below that both the volume and the file system now agree on the correct sizing.

Hope this helps!