CD lifespans

Julian Humphries humphries at MAIL.UTEXAS.EDU
Wed Oct 30 10:21:54 CST 2002


Robin Leech wrote:
> Last year, I think, there was a long, long discussion about media for
>
saving taxonomic information, durability of those media, etc.
>
> An article in the Edmonton Journal yesterday stated that few
computer-burned CDs will last longer than 5 years. The advice was to put
all data to be saved into several different storage systems. Also
advised to resave the data onto new CDs at least every 3 years.
Interestingly, hard copy was not discussed.
>
> Robin Leech Edmonton, Alberta

It is always dangerous to trust newspapers for information relevant to
something important like this.  A longer quote:

************
"Although CD-writing technology has matured, blank CD media is still
unpredictable," said Susan Munro, owner of Edmonton based Mehco Inc., a
CD-ROM duplicating and replicating service.

Munro attributes the short CD life to poor sealing of disk edges,
allowing moisture and air to seep in and corrode the recorded digital
information.

Munro's best advice for consumers who want to be sure of the quality of
CD media they buy is stick with a good brand name and don't worry about
the higher prices. Blank CDs cost from 40 cents to one dollar each.
****************

I think the likelihood of this being reliable advice is low. MEHco has
only been in business for a year, I have little faith in Ms Munro's
estimate. We burn hundreds of CD's a year and have for several years.
If "few will last longer than 5 years" then we should be experiencing
massive failures.  That hasn't happened and I doubt it will.  BTW we use
cheap (<20 cents US) blanks and verify every image and movie on every CD
(I suspect many failures actually happen during the burn process, we
throw out a few percent of our burned disks).  Multiple copies is always
a good idea, we always burn two CD's at least, but reburning a CD every
3 years seems foolish advice.

Julian

P.S.  Actually, a little reseach indicates the 5 year span turns out to
be mostly an oft repeated urban myth, for details see:

http://www.dtic.mil/dtic/digest/digest2001-1/Nonprintmed.html

--
Julian Humphries
DigiMorph.Org
Geological Sciences
University of Texas at Austin
Austin, TX 78712
512-471-3275




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