Scott,
I handle offsite copy and migration through several ADMIN scripts.  In the first
script  I trigger offsite copy with the number of processes dependent on how
much data is in the storage pool.  I set the wait parameter to yes. Once the
offsite copy is finished I start the migrate process by lowering the pool
thresholds with the wait parm is set to no.  The last thing this script does  is
add a schedule entry to run a second admin script in a couple of hours.

The second script checks to see if migration is running and if it is, it resets
the schedule entry to try in 20 minutes and ends.  Once the script starts and
migration is complete, the thresholds are reset to the high water marks. and
then I run my DB backups.  When those are complete I trigger space reclaimation
for the onsite tape pool.  The second script ends by adding a schedule entry to
start the third script in four hours.

The third script resets the onsite reclaim threshold to 100%, then checks to see
if reclaim is still running.  If it is the script resets the schedule to retry
in 15 minutes and ends. If onsite reclaim is finished, then it triggers offsite
reclaim and adds a schedule entry to reset the offsite reclaim to 100% which
runs in 30 minutes.

If you are interested in copies of the scripts, let me know and I send your way.

Happy New Year!
Steve