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Subject: Magnetic tape longevity

Magnetic tape longevity

From: Walter Henry <whenry>
Date: Sunday, January 27, 1991
The following discussion took place recently in comp.misc.  It has been
lifted without the knowledge or permission of the authors and has been
edited very slightly for format.

 Article 11584 of comp.misc:
 From: henry [at] zoo__toronto__edu (Henry Spencer)
 Subject: Re: What is the life-time of magnetic tape?????
 Date: 17 Jan 91
 Organization: U of Toronto Zoology
  In article <1991Jan17.183902.24474 [at] watdragon__waterloo__edu>
     daford [at] watdragon__waterloo__edu (Daniel Ford) writes:
 >I have an old reference that states that the life-time of well cared
 >for magnetic tape is about 2 years.
 >Is that the current state of affairs for magnetic tape? What is the
 >expected life-time (i.e., you can still read what you wrote) today?

 We restore off backups that old now and then, and see few problems.
 Tapes ten years old normally remain readable, although we pay attention
 to cleaning the tape heads afterward.

 If the Space Shuttle was the answer,| Henry Spencer at U of Toronto Zoology
 what was the question?              |  henry [at] zoo__toronto__edu   utzoo!henry

 Article 11590 of comp.misc:
 From: dafuller [at] sequent__UUCP (David Fuller)
 Subject: Re: What is the life-time of magnetic tape?????
 Date: 18 Jan 91
 Organization: Sequent Computer Systems, Inc
  My recommendations are that you need to commit to the information
 value of the stuff you're recording before you record it.  I recommend
 that you either use a tape that's been thru a verifier or use a new
 tape that has been recorded end to end and rewinded a few times to weed
 out DOAs and shed spare oxide.

  Most important - storage environment.  If the environment changes
 radically, reread the tape.  Store tapes with the tape path VERTICAL.
 If you store tapes horizontally, the tape pack may slump over time and
 you'll have a hell of a time reading them.

 Dave Fuller
 Sequent Computer Systems  Think of this as the hyper-signature.
 (708) 318-0050 (humans)  It means all things to all people.
 dafuller [at] sequent__com

 Article 11593 of comp.misc:
 From: buckland [at] cheddar__ucs__ubc__ca (Tony Buckland)
 Subject: Re: What is the life-time of magnetic tape?????
 Date: 18 Jan 91
 Organization: Computing Services, University of British Columbia
  I have been using tapes for about two decades, and do some consulting
  on their use.  I advise people to think of tapes as reliable for five
  to ten years, and to mount them at least twice a year to optimize
  their tensioning.  I have had only two tapes actually go bye-bye on
  me, in neither case with the loss (due to unrecoverable read errors)
  of more than a record or two, and I have several tapes which have
  lasted far beyond the five-to-ten-year range.  So I'd recommend as a
  conservative policy:

   (1) always have a backup tape, i.e. a pair of tapes with identical
      contents for every collection of data.

   (2) keep them hanging vertically (to avoid edge damage) in a
      dust-free environment with controlled temperature and humidity.

   (3) at least mount and check them every six months.

   (4) be alert for recoverable read errors, and if they recur or seem
      to be increasing, replace the tape.

   (5) if you're a belt-and-suspenders man, or whatever the gender-free
      equivalent is, replace any tape more than ten years old.

 Article 11595 of comp.misc:
 From: devine [at] shodha__enet__dec__com (Bob Devine)
 Subject: Re: What is the life-time of magnetic tape?????
 Summary: It depends...
 Date: 18 Jan 91
 Organization: Digital Equipment Corp. - Colorado Springs, CO.
  There are many factors in how long a tape is usable :

   0. Quality of new tape

      - a cheap tape is no savings

      - check quality measurements like number of errors when new, how
       the tape did on peel adhesion test for oxide break-down, and how
       it complies with ANSI spec X3.40-1981 (defines the minimal
       physical properties of an acceptable tape)

      - tapes are back-coated to reduce static build-up but such tapes
       the coating causes slippage and leaves a residue on the drive

   1. environment of storage

      - extreme temp swings are bad

      - contamination (fingerprints, dust, used on dirty drives, etc)

      - rough handling by operators

   2. number of uses

      - tapes can last fine through up to 500 uses if handled correctly

      - should retention and clean often (but don't clean too often
       because it results in extra wear)

      - start/stop drives are harsher on tapes than streamers just
       because of the jerkiness causes stretching

 Soooo, if tapes are handled well and stored properly, they should last
 two to five years.  The only sure gauge of tape reliability is the
 number of errors a tape generates -- a couple dozen recoverable errors
 is acceptable, hundreds of errors mean it is new tape time.

 Bob Devine

                  Conservation DistList Instance 4:40
                 Distributed: Sunday, January 27, 1991
                        Message Id: cdl-4-40-003
Received on Sunday, 27 January, 1991

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