You need to look at the reclamation threshold for that pool. Once a volume is full (100%) it will stay in the full state until it is totally empty (0%) In order to help this process along, TSM provided for condensing tapes that are no longer 100% full. TSM will look at the percent reclaimable of a tape and compare it to the reclamation threshold for the pool. If the %reclaim is above the reclamation threshold, it will move all the data to a volume that is in the filling state or start writing to a scratch volume.
step 1, determine the reclamation threshold for the pool.
q stgpool {pool_name} f=d
step 2, determine if the volume is above the threshold
q vol {vol} f=d
step3, either lower the threshold to force a reclaim to start or move the data off the volume manually
update stgpool {pool_name} reclaim={%}
or
move data {vol}
-Aaron