From: peter@dbaccess.com (Peter A. Castro)
Newsgroups: comp.sys.ibm.pc.rt
Subject: Trouble with RT tape drive
Summary: 6157 read/writes bad data
Keywords: RT 6157 Tape 16-bit
Date: 22 Jan 93 22:53:37 GMT
Organization: Cross Access Corp., Santa Clara, CA
X-Newsreader: TIN [version 1.1 PL8]

Hi all,
  I've got a little problem that I really don't know how to diagnose...
  hopefully someone can help me.
  We've got a PC/RT 6150 model 26, with a 6157 Streaming tape drive
  attached via a 37 pin connector to a 16 bit interface card (the
  standard one?).

  I move data to it from our other systems every two weeks, and have it
  write out the data to tape.
  Yesterday, I tried my normal dump to tape routine (tar).  The drive
  appeared to write the data out without compaint, but when I tried
  to read it back in, to verify, Tar complained that the tape had a
  directory checksum error.
  I took the tape I just wrote and tried to read it on my machine at
  home.  Result was the same, checksum error.  So, I tried dumping the
  first block off the tape to see what it contained.
  The first block contained data that looked like:

	04 61 00 65 03 2f 04 61 00 65 02 00 00 00 00 00 
 	.  a  .  e  .  /  .  a  .  e  .  .  .  .  .  .

  What it should have looked like was this:

	74 61 70 65 73 2f 74 61 70 65 32 00 00 00 00 00 
 	t  a  p  e  s  /  t  a  p  e  2

  It looks like the high 4-bits of every other byte is zero.
  I wrote a tape at home, and tried to read it on the 6157.  I had the
  same kind of results, top 4-bits of every other byte was zero...

  We have one other RT here, and I moved the tape drive and interface
  card over to it and tried to read both tapes.  I got the same
  results.
  This leads me to believe that something is wrong with the card.
  Sounds like a data buffer is grounded out...

  I also brought the RT up in diagnostics mode and had it run the System
  Test as well as the test on the drive.  It performed what I thought was
  read/write tests and said there was NO trouble!  How can that be??

  All normal operations like rewinding the tape, retensioning, skipping to
  the next tapemark, all appear to work correctly (as far as I can tell
  from the drive's actions).

  I've examined the interface card and can find no obvious damage
  indications.  I haven't opened the drive up yet, that's next.

  Has anyone experienced this kind of problem with the 6157?  Are there
  any other tests I can perform on the interface or the drive?  This
  machine is not under warrenty, or any maintainence agreement, so it's
  up to me to fix it.  Any idea where one get's replacement parts?
  Should I just give it up and toss the whole thing?

  I almost never power the machine down.  However, during that set of
  storms we had almost two weeks ago, the power was knocked out here.
  Is it likely that power-cuts would damage the tape drive?  It doesn't
  seem likely to me, but I'm fishing for ideas right now...

  Anyway, thanks for reading about my problems, and any help would be
  greatly appreciated!

  Thanks,

  --Pete
-- 
Peter A. Castro                   INTERNET: peter@dbaccess.com        // //|
c/o CROSS ACCESS CORP.            UUCP: {uunet,sgiblab}!troi!peter   // //||
2900 Gordon Avenue, Suite 100     FAX: (408) 735-0328            \\ // //=||=
Santa Clara, CA 95051-0718        TEL: (408) 735-7545             \// //  ||
Organization: User Services, Carnegie Mellon, Pittsburgh, PA