From: utzoo!decvax!harpo!floyd!whuxlb!eisx!npoiv!houxm!ihnp4!ixn5c!inuxc!pur-ee!uiucdcs!hall
Newsgroups: net.periphs
Title: Re: ts11 FCO details - (nf)
Article-I.D.: uiucdcs.1923
Posted: Sat Apr 23 21:41:40 1983
Received: Mon Apr 25 04:55:37 1983

#R:rocks34:-16000:uiucdcs:11600003:000:2717
uiucdcs!hall    Apr 23 16:57:00 1983

I have a few comments (negative) about the Kennedy TS-11 tape drive.
We (not U of I--another place I was at) had a old DEC TU-10 and
bought the TS-11 as our second unit. Usage of both drives was
mainly for once-a-day backups and file archival. Both machines
were under service contract with regular preventive maintenance.
 (1) The failure modes of the two machines were different. The TU-10
     has a vacuum-servo system for tape positioning; when it failed,
     the machine would lose vacuum, and a few feet of tape might be
     unwound before the unit stopped. The TS-11 has tensioner arms
     used for positioning. When our tensioner arms failed, the motors
     for each reel turned in opposite directions, breaking the tape.
     Also, the capstan had a habit of catching (much like car 8-track
     tape decks) and winding up many feet of tape around the capstan,
     while crimping (destroying) the tape.
 (2) The first TS-11 we got failed diagnostics. The FE was on
     the phone to California for about 2 hours trying to figure it
     out. Eventually, they gave up and got us another drive.
 (3) Our drive was dual density 800/1600 BPI. If you tried to read a
     tape at the wrong density, it would always crash the computer.
     Discalimer: This might of been a software problem, and the system
     was not UNIX.
 (4) Oh yeh, I almost forgot a few more problems. When you rewound a
     tape, the drive often did not sense the physical beginning of the tape,
     and the reel would continue turning merrily until you shut the
     power off to the drive. The light for the photosensor was the
     problem (at least this problem was resolved).
 (5) We also had to have the R/W head assembly replaced I believe.
 (6) The tensioner arm adjustment was extremely picky. The arms would
     bottom out (like car shocks) if rereads were necessary due to
     tape errors. This surely stretches the tape.
 (7) TS-11 did not handle the EOT correctly. Evidently, a different
     error code must have been returned to the software. The standard
     backup software from DEC worked on the TU-10 but returned a read
     error when EOT was reached on the TS-11; it was still workable
     since the backup software just gave up (at the right time) after
     so many retries.

Conclusion:  I'd avoid the TS-11 if possible. I wasn't going to post
  this, but the few testiminials I've seen in favor of the unit made
  it necessary. In general, I'd like to stick with vacuum-tape units.
  Even if tensioner arms work correctly, the tension they exert on the
  tape tends to STRETCH it. Vacuum units do not have this problem.
Enough already,
--John R. Hall, University of Illinois, (...pur-ee!uiucdcs!hall)