I had the same "processing window" problems.  We have, in general, 2 start
times for our backups.  21:00 and 04:00.  I've been able to copy to a
copypool around 02:00 because the 21:00 backups are pretty much completed.
That 02:00-04:00 gives me enough time to usually complete the copypool.
Since the server is on the mainframe, I needed those tape mounts (12) to
have allocated the cart drives before the 03:00 mainframe backups are
scheduled.  When the copypool operation hasn't finished yet, there weren't
any noticeable slowdowns in the 04:00 backups (but I really wasn't
specifically looking).  I've also never monitored the ADSM task to see how
badly it gets hit with concurrent, different processes.

Dave Sanders
Sr. Technical Consultant
MassMutual / The Blue Chip Company
1295 State St, E060, Springfield, MA 01111
413-744-5095