Here’s an easy “Don’t panic!” situation.

You’ve got a VHD file.  You’ve adjusted it to allow more space in the “Edit Disk”.   When you go into Server 2008 / 2008R2 and Extend the free space in DiskMgmt you get some confusion.

The DiskMgmt utility shows the Correct number but the File system shows the old number.  Rebooting does fix it either!

So… before you go running to the Datacenter cursing the gods, try this.

Odds are, the server was a high usage thing with Big files (Like Exchange or SQL etc etc)

Before you reboot, make sure anything that can cause it to “Get busy” is switched to Manual (Sql Instance, Exchange Datastore) and reboot.  Do this in the safest manner of course.

Down the server again and adjust the space a bit larger (Any amount, 1 gb or 20 gb) and then power the machine up again.  

Now that the computer is running in a say “Less frantic” state try re-extending the partition.  Odds are it’ll work this time. 

I ran into this and I’m presuming it’s a case of the Partition table was updated but the File Allocation wasn’t.   I’m not sure on the DEEP details but here’s what worked for me

Maybe it’ll help you out.

”The Energized Tech”