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[OM] Re: Back up and storage

Subject: [OM] Re: Back up and storage
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sun, 03 Dec 2006 06:57:01 -0500
Normal (low cost) CD's are unreliable.  A normal writeable CD is a layer 
of plastic coated with a very thin layer of dye followed by a very thin 
layer of aluminum which, in turn, is coated with a layer of laquer (the 
painted label).  Pressure on the laquer layer (such as with a pen) can 
distort the aluminum recording layer underneath and destroy bits.

More insidious is that the thin laquer layer on top is not impervious to 
the atmosphere, moisture or contaminants.  Eventually the aluminum layer 
starts to oxidize (rust) or corrode and your bits go bye-bye.

It is not uncommon for CD's to last as little as a year although 2-3 
years is more likely and possibly much longer if they're stored under 
exceptionally good conditions.  The problem is that you don't know and 
you won't know until they suddenly start having read problems.

Since the fundamental problem is oxidation of aluminum the solution is 
to use gold which does not oxidize and also use a more expensive and 
more stable dye than is used in the typical cost competitive CD.  Gold 
CD's are available from MAM-A or Kodak but they're much more expensive 
than convetional CD's.  <http://www.datamediastore.com/goarqucd.html>

Gold CD's probably will last a very long time (assuming you don't write 
on the label with a pen) but the cost makes them more expensive than 
multiple external hard drives even considering that you should have two 
or three identical drives as backup.  Keep the third one off-site and 
rotate where the drives are stored.

Chuck Norcutt

Phil wrote:

> I was led to believe that the safest method of storage for my images was CD.
> The theory was that any form of magnetic storage (HD) would be less
> relaible.
> Having just read a thread on DP review, many are claiming the oposite and
> that a separate Hard drive is there preferred method and CD's are unreliable
> As all my images
> are on CD I am a little worried, what do you guys use to store you files.
> 
> Thanks
> 
> Phil
> 
> 
> 
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