OK, so I decided to try the defrag again after I got the free space back up to 30%. It's been running for 12+ hours, and my free space dropped down to 10% fre (80gb). I paused the defrag, then tried the same cleanmgr (twice) and the space is not freed up. I am thinking it might be the CHKDSK /F that recovered the space, but I can't run that because I only paused the defrag and CHKDSK says that something else is using the drive and I do not want to let it dismount it.
I read the stuff about 4k cluster sizes (which is what the drive has) but is there a way to fix that without destroying the contents of the drive? I think the big problem I have is a 180gb Win7 data migration file on the disk, it was what I used for transferring data from my old machine to this one. I'd rather not delete it. I probably have space on another drive to move it off the external drive so the defrag can run, and then I could put it back, but that will probably take a while to copy back and forth.
They claim on the MS page that there is a user defined limit to the size of these shadow copy files. Any idea how to set the limit so it's low?
Oh, and I am only at 38% complete, and my number of fragments has gone from 1815 at analysis to 2931 now.