Reliability Exabyte tapes

[Mark W. Tilden]

In article <WRPYTPB at dri.com> braun at dri.com (Kral) writes:
>In article <1991Feb27.191216.5859 at sobeco.com> sdesmara at sobeco.com (s.desmarais) writes:
>>Speaking of reliability, I'd like to know what is the reliability and the
>>durability of the exabyte media.  What will happen in 15 years when I want
>>to restore files from exabytes? (Recently, we restored a 14 years old file
>>from a 9-track tape.)
>
>My advice: you should always "check" any wound, streaming magnetic media at
>least every 24 months.  By this I mean at least rewinding the tape, but
>possibly rewriting it as well.  Otherwise, you stand the chance of the data
>bleeding onto the next layer of tape and causing parity problems.
>
Basing the lifetime of Exabyte media against it's immediate video 
counterpart means that you can expect a lifetime of at least 25 years 
or 600 play/rewinds before the tape looses the 7dB signal loss which
will result in fatal restore errors.  This does not take into account
scratches or tape folds that can be introduced to the tape by faulty
or wearing tape mechanisms (a real problem as current Exabyte units
only last approx 1000 running hours before they become tape 'hostile').
Modern 8mm tape, especially the high-metal variety used in Exabytes,
actually has very low magnetic bleedthrough in comparison to other video
formats like beta and especially VHS, because of the extreme density
and uniformity of the metal crystals, and superior seperation between
tape layers by a tape backing as thick as the magnetic media itself.
Exabyte tapes are so reliable in fact that you could hold them to 
your filing cabinet with a (appropriately sized) fridge magnet and still
be fairly sure of getting your data back (No warrenties expressed or
implied).

The biggest danger is mechanical wear or damage.  The less you play a tape,
the better off it'll be, at least until Exabyte starts using improved
Hi8 video mechanisms in their product.

So the answer is you're in pretty good shape if you back up every
two years or leave your tape on a shelf for twenty.  The biggest danger 
will be if there'll be anything to read your quaint 'tape' come the 
year 2010.  It should be safe enough until r/w diskmans come onto the 
scene.

Is all.


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Mark Tilden: _-_-_-__--__--_      /(glitch!)  M.F.C.F Hardware Design Lab.
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