Without exact information, I can tell you compression will almost always
result in longer backup times.  Significantly longer backup times.  So, if
your window is the problem, this won't help it.  If your disk stg pool is
the problem, this will help it, but at what expense?

You might even consider something very radical: move ADSM from the
mainframe to someplace else where disk (and most other things) is cheaper.

Experimentation is your best bet.  Don't be surprised by the overhead of
compression.  Nothing is free!

Kelly Lipp
Storage Solutions Specialists, Inc.
lipp AT storsol DOT com
www.storsol.com
(719) 531-5926