I have had trouble with a C1511A knowingly for a year, and actually much
longer. When we started cross-validating our backups, sometimes a tape
which validated in a C1503B SCSI drive OK would not validate successfully
in the C1511A HP-IB. This has an implication in disaster recovery
scenarios. A tape which validated on HP-IB never failed on SCSI. The
C1511A mechanism has been changed several times, but never lasts long. Its
other trick is to throw far too much tape (between blocks?).  We have been
zealous about cleaning, and never use a tape more than 30 times (nowhere
near the 300 which is the supposed limit). The end of the story is that I
have obtained another SCSI drive and abandoned the C1511A.
 
Andrew Gosling             |  There's just two types of computer files,
Director of MIS            |  Sequential files and Inconsequential files