Can you not copy the unloaded database over a network, using ftp or nfs etc.
If not, can you download the file to a windows machine (if you use ftp, transfer in binary mode.) Copy to dvd? and upload to the HP either through the same windows machine, or directly from the CD/dvd
The tape block sizes are probably different for a start. The encoding could be different. The tape drives may be incompatible even if the media is supposedly interchangeable.