Over the past few months I’ve been running out of space on a SAN drive in both the production and DR sites running Windows Server 2008.  (That’s one of those expensive growing pains).  We put in a request to have a LUN expanded then waited.  When we were given word that the LUN had been expanded I went into Disk Manager and rescanned the drives.  Disk Manager saw the expanded portion of the disk.  Now I needed to expand the partition.  So I right clicked the drive and chose Extend Volume.

 
(note: this screen shot for security purposes is not the actual server involved)

Now I had to sit and wait while Windows did its thing.  When it was finished Disk Manager showed a much larger disk. J 

I exited out of Disk Manager and opened My Computer only to find that Windows Explorer was not reporting new size of the disk.  After a little more searching, via Google, I came across this Microsoft article which in the More Information section talks about an undocumented command for Disk Part.

At a command prompt you need to enter the following:

C:\ > DISKPART

DISKPART> List Volume

DISKPART> select volume # (this is the number of the volume listed by the above ‘List Volume’ command)

DISKPART> extend filesystem

DISKPART> exit

Now Windows Explorer shows the new expanded size of the disk.