Re: Where has all the space gone on our DD2500 ???
The numbers you get for "filesys show compression /mtree" or "filesys show compression /mtree/file.ext" will be the values from the moment the files were ingested, not in real-time.
This is because everything shares physical space in the background.
Because of that, what you see in "filesys show compression" with no folders/mtrees/files specified is the "truth" as it is at the moment you run it. As you expire, run snapshots, etc, the aggregate usage will change from the original usage.