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Re: CD Storage disks (yet again)

Subject: Re: CD Storage disks (yet again)
From: "Walter Knapp" waltknapp
Date: Sat Oct 28, 2006 9:01 am (PDT)
Posted by: "Lou Judson"  inaudio

> Replicated CDs have actual holes in the reflective medium, while CDRs
> have the reflectivity of the chemical layer changed by the laser - thus
> the reflectivity can change with time and temp and such. Sort of like
> the difference between oil painting and watercolor, in a vague way...
> or pinholes in aluminum versus sharpie dots on foil? Sorta like that...

I don't think it's holes, but pits. They are pressed just like analog
records used to be.

For my archival storage I use 3.5" optical disks. These are considered
to be about the most durable storage. They would probably be quite
common if Zip had not have been promoted for the task at a cheaper
price. Of course Zip turned out to be far less than archival. Yet
another case of a poorer technology killing a better one when people
only looked at price.

I am beginning to run a parallel copy on DVD for my digital camera
photos. And I do run a parallel copy of my audio on audio CD.

The opticals I use are in a protective case like floppy disks. I've been
using them for a very long time and have never had a disk fail.

I do not agree with the idea cited in the article quoted. Magnetic tape
storage has failed many times. NASA lost nearly all their early data by
depending on magnetic tape. I also have audio CD's I've burned that are
over 10 years old. One does have to be careful about the blanks used and
the burning technique, but they are fairly durable over this sort of
time period.


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