SUMMARY: Exabyte tape and reliability

From: Doug Neuhauser (doug@seismo.gps.caltech.edu)
Date: Tue Mar 12 1991 - 20:12:31 CST


I had asked for user experiences with the new(er) Sony QG-112M
series 8 mm tapes for use with Exabytes.

I have been using the Sony P6-120MP tapes for the last year or so, based on
both vendors and other users recommendations. However, I have found over
that time 2 or 3 tapes that were written sucessfully but produced hard read
errors when later reading the tapes. I tried reading them on all 5 of my
drives, and each reported the same hard read error.

I have been using the Sony P6-120MP tapes for the last year or so, based on
both vendors and other users recommendations. However, I have found over
that time 2 or 3 tapes that were written sucessfully but produced hard read
errors when later reading the tapes. I tried reading them on all 5 of my
drives, and each reported the same hard read error.

I should have noted that my tapes and tape drives are in a "computer room
environment, with controlled temperature and humidity. In addition, I use
the Exabyte cleaning tapes every month, or more often if problems arise.

------------------------------------------------------------------------

Responses were:

1. Mike McCann was faced with the same problem, and switched to Sony
P6-120HG tapes. They are Sony's Metal High Grage tape, used by Delta
Microsystems, and can be found for about $6 each.

2. Don Kindred suggested that reading or writing a tape other than at room
temperature could cause the problem I described due to tape expansion or
contraction. In addition, humidity was suggested as a possible problem.

3. Ed Arnold had no particular experience with the high-priced tapes, but
pointed out that either Consumer Reports or Consumer's Digest did a review of
high-grade vs. standard grade video cassettes during the past year. The
conclusion was that the "high-grade" cassettes are a clever trick to
separate people from a lot of money with almost no benefit.
[NOTE: No mention whether this review was for video or digital data.]

4. Bill Eshleman used the P6-120MP tapes and have had only one read error
on a pool of 20 tapes used for the last 2.5 years. He found, though,
that another drive on campus would not read his tapes, but would read its own
tapes. Suggested that the drive may be going bad, out of alignment, or
needs cleaning.

5. George Goble says he is using the P6-120MP tape with not problems of
this type. He states:

> "When did you purchase your Exabyte drives? If before Aug '90, you are
> probably seeing the "offset bug", where temp and humidity change make it
> "appear" there are unrecovered errors on a tape. It is due to
> expansion/contraction of the media. Drives after that have the fix
> incorporated in the F/W. We are the ones who first saw this a year or so
> before the Aug '90 cutover.. Exabyte fixed it in 2 weeks or so, but for
> about a year would not incorporate the changes in the production drives. If
> your drives are pre-aug '90 build date, you can contact Jim Werder @
> Exabyte, to work out getting a set of F/W to fix this (303-447-7269). Let
> me know what happens.."

6. Jim Wills works for a vendor who sell's Exabytes. He states:
> "We just tested the QG-112M and found it to be unsatfactory. We found
> that the Sony P6-120 and the P6-120HG work just fine. We talked to an
> Engineer from Exabyte, and he told us that Sony makes their tapes especially
> for the drive.(Their specs). The performace of the tape is better, but just
> slightly."

7. John Macallister says he too has had many failures with P120 tapes. On
the other hand they use P90 tapes without any trouble at all. All SONY.

Thanks to:
        mmccann@eng.clemson.edu (Mike McCann)
        kindred@rooster.acn.purdue.edu (Don Kindred)
        era@niwot.scd.ucar.EDU (Ed Arnold)
        "Bill Eshleman" <wde@water.agen.ufl.edu>
        ghg@ecn.purdue.edu (George Goble)
        jt@deltam.com (jim wills)
        MACALLSTR@vax1.physics.oxford.ac.uk (John Macallister)
----------------------------------------------------------------------------
Doug Neuhauser Div. of Geological and Planetary Sciences
doug@seismo.gps.caltech.edu California Institute of Technology
818-356-3993 MS 252-21, Pasadena, CA 91125



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