Integrate 'Relabel Scratch' command with Fujitsu Eternus vJuke virtual libraries

Fujitsu Eternus VTLs are well known in several customer's ISP environments. Main difference to other VTLs is the ability to stack logical volumes on physical tapes in the backend.
Data written to the VTL is stored in a tape volume cache (TVC) on virtual volumes first and is moved to physical tape as new data is ingested. If data needs to be restored, the logical volume is requested from the hierarchy and has to be retrieved from physical tape if not present in the TVC. This recall might take some time dependent on the size of the logical volume and the availability of physical tape drives in the backend.
This retrieve occurs even when a scratch mount request is performed, because ISP doesn't ask explicitly for a scratch volume but asks for a volume to be mounted in a tape drive, forcing the system to recall data which will be overwritten as soon as the logical volume is successfully retrieved from the physical volume.
Fujitsu provides an API which allows the user to delete (or 'scratch') a volume which isn't required any more, thus to prevent unnecessary data movement within the storage hierarchy during a scratch mount.
Eternus vJuke libraries are a library emulation which can be treated as a SCSI library or a VTL, both types allow the 'relabel scratch' option. Issuing this command to a Eternus vJuke library currently forces the library to recall the data from tape which is then overwritten immediately. The recall lasts some 3 or more minutes and could be avoided by integrating this API call into the library command set.