It's been my experience that "differential" SCSI drives as well as terminators are clearly marked as being such.
Best Regards,
Paul
-----Original Message----- This sounds remarkably similar to the symptoms I saw when I accidentally plugged a single-ended (i.e, non-differential) DLT4000 into our F740. I removed the drive after I noticed it was hanging at a similar point to where yours was, and all was well. I've since had a wide differential DLT7000 on the F740 working without any problems.
As to how to test the tape drives; no idea. `Check with your vendor'?