The fastest scratch provisioning in a situation like that is to delete any Pending volumes.
Where you are constrained for tape space to reclaim volumes within the library, consider performing a Move Data to the upper disk storage pool in the hierarchy. (You can always temporarily add a spare disk to the top of the hierarchy, if you don't already have one in the hierarchy, and leave the copy group target as tape, unchanged.) You can later let the disk-held data drain down into the tape pool when you have the tape space. Richard Sims
