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From: devine@shodha.enet.dec.com (Bob Devine)
Newsgroups: comp.periphs,comp.periphs.scsi,comp.multimedia,comp.misc,misc.misc,sci.electronics,comp.databases
Subject: Re: What is the life-time of magnetic tape?????
Summary: It depends...
Keywords: magnetic tape
Message-ID: <2337@shodha.enet.dec.com>
Date: 18 Jan 91 17:47:58 GMT
References: <1991Jan17.183902.24474@watdragon.waterloo.edu>
Followup-To: comp.periphs
Organization: Digital Equipment Corp. - Colorado Springs, CO.
Lines: 31

In article <1991Jan17.183902.24474@watdragon.waterloo.edu>, daford@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.  
> What is the expected life-time (i.e., you can still read what you wrote) today?

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