Matt, 

Are you running two, maybe 3 compression routines.  i.e.  once at the client, 
once at the server level (you'll see if you q devclass f=d on a sequential 
storage device) and once at the hardware level
(micro code).  

If so, have you kept check on the amount of data in your stgpool.  I say this 
because a q occ on a file space is not going to give you an accurrate 
indication of the amount of data that node/filespace
has dumped into your stgpool.  
Although the IBMers and the manuals say "don't run multiple compression 
routines", they've yet to advise on what to do if you have to run client side 
compression due to a slow network.  I can shut off
server side/devclass compression, but what about hardware compression.  Can you 
shut off compression on a 3590 tape device.  Isn't that a micro code issue.  
i.e.  you can't shut it off? 

Regards, Joe