Hi chewchewy,
Accroding to PC Guide
http://www.pcguide.com/care/care/mediaLife-c.html
Media Use and Storage Life
"A critical point to remember about media is that they are not
forever. Well, most are not anyway, and the kinds that are writeable
or rewriteable definitely have a limited life span. Magnetic media are
formed of a substrate or carrier material that is coated with a
magnetic substance that holds the data. Over a long period of time,
this material will wear and eventually errors will result. Dirt and
contaminants also build up and eventually cause problems. Also,
magnetic fields themselves tend to diminish over time.
How much time it takes for problems to occur with media depends on
many factors:
Media Type and Quality: Some types of media just last longer than
others. The method of manufacture is critical: what technique does the
manufacturer use to adhere the magnetic coating to the disk or tape?
How rigorous is the testing process? Etc.
Hygiene: If the media are kept clean and the heads of the drive are
cleaned and maintained regularly, the lifespan of the media will be
enhanced.
Storage Conditions: Disks and tapes stored in a cool, dry, clean
environment will live longer than those stored in a moist, warm dirty
one.
Use: Of course, media that are used more often will, all else being
equal, fail sooner than those that are used infrequently.
Storage Time: Time itself is a factor with magnetic media. The data on
them is stored as tiny magnetic fields in close proximity, and over
months and years these fields can tend to fade. They can also
eventually interfere with one another. The storage life of magnetic
media is not unlimited."
[edit]
"Compact Disks: One of the great advantages of the compact disk medium
is that its data is encoded physically and not magnetically, which
affords the medium much more longevity than magnetic disks or tapes.
The low-power laser used to read CDs does not affect the media when
reading it. Stamped (regular) compact disks use physical pits to
encode data and will last for many years--decades in fact, normally,
as long as they are not destroyed by heat or dirt. Recorded CDs (CD-R
disks) use different types of dyes in the recording layer. The
longevity of these disks is still a matter of some debate, but most of
what I have read suggests that they will last for many, many years as
well, as long as they are carefully protected from high temperatures."
==============================================================================
Experts Exchange
http://beta.experts-exchange.com/Hardware/Q_20675935.html
Solution Title: How Long do CDS retain data?
Author: mojo652
"Hi everyone, I was just curious if anyone could provide a definitive
answer to this question.. though it probably is based largely on the
brand of CD.
Anyhow, so how long do normal 80 min. CDs retain data for? I've been
using mostly SmartBuys, they're cheaper, so they probably last for
less time. I burn many many cds, on the order of 1000's.. and would
just like to know how long I can expect them to retain their data, and
to stay in one piece (i've noticed very few CDS peeling, maybe 1/200
just after less than 2 years) before I need to undergo some sort of
extreme backup procedure. Also, does the finalized/unfinalized status
of the CD (set when burning) have anything to do with the matter?"
scroll to "accepted answer" written in green, bottom of page:
Accepted Answer from Dalziel
Date: 07/13/2003 08:23AM PDT Accepted Answer
"If you think this is a simple question.....The lifespan of a CD-R
depends on the conditions in which it's kept, the dye used and
naturally the quality of the manufacturing process. I assume that you
know but as this is an information service I'll say it anyway. CD's
when produced in a factory have the metal layer "stamped" with the
data pattern, generally aluminium. Obviously this wouldn't work for
CD-R's etc. in the home so a "dye" system is used, involving a metal
layer generally gold or silver and a dye. When the laser in a writer
hits..."
==============================================================================
http://tingilinde.typepad.com/starstuff/2003/08/how_long_will_y.html
http://www.halfbakery.com/idea/Data-side_20scratch_20resistant_20CDs#1026937982
Google Search:
compact disk lifespan
how long will cd retain data
Best regards,
tlspiegel |
Clarification of Answer by
tlspiegel-ga
on
06 Oct 2003 20:21 PDT
Hi Paul,
A music cd you buy in the store if taken care of properly will last
forever. Because the material is 'read' by a lazer light, nothing is
touching the compact disk. They are much more durable than vinyl
records, which has to have a needle contact to play the music.
As long as you are reasonably careful you will not scratch them.
http://www.maxpatchink.com/cd-repair-info.htm
How Does a Scratch Cause Problems?
"Scratches on compact discs are not digital problems, but optical
problems. When the laser in your player hits a scratch, the refraction
causes the laser to mistrack and be unable to find the next digital
"one or zero" on the bit plane. On a music CD you will hear the
familiar repeating glitch sound as the laser is stuck looking for the
next digital bit, while on a CD-ROM, the program will freeze or be
unable to load.
Where is the Scratch?
Probably one of the most difficult problems in determining where a CD
is scratched is that CDs are just the opposite of old vinyl records.
The tracks begin on the inside of the disc rather than the outside.
Also, depending on the number of tracks on a CD, the music usually
does not "fill up" the whole disc. Therefore, outer edge scratches
would not be heard on tracks 1 or 2, but on the later tracks of a CD.
You would usually find track 1 or 2 scratches towards the center of
the disc.
Hint:
In the right reflecting light you can actually see the separations
between tracks just like on records only they are quite close
together. This only pertains to "music" CDs."
Best regards,
tlspiegel
|
