Dear Arachnes,

Susan has a good point about CD/ DVD stability.  Many of us assume that these 
are permanent media, seduced by the media hype when they first came out 
described as indestructible.

>From a recent technology review

Quote:

Commercial DVDs are expected to last more than 50 years, assuming they are 
pressed correctly on good quality media, and then stored in a cool, dark, dry 
place. Heat, humidity, handling and atmospheric pollution are all believed to 
reduce the life of optical disks, based on accelerated ageing tests, but nobody 
really knows. DVDs that are burned separately, perhaps as backups, could last 
anything from 20 years to 200 years. However, read-write (RW) discs should 
never be used for archiving: they are not as stable and many may not last 15 
years. According to a study by America's National Institute of Standards (NIST) 
and the Library of Congress, some could last only two years. There's a summary 
at The X-Lab:

http://www.tinyurl.com/yq97nf

Optical media are very variable, but Digital FAQ has published a brand media 
guide. http://www.tinyurl.com/2u48l

Endquote

The cheaper R/W discs and some of the older CD writers produced a very shallow 
burn onto the disk so their stability was very poor - anyone who has tried to 
burn a Rewritable CD and then tried it in a car CD player and found it won't 
play will have met this problem.  If you have anything precious consider 
checking that disks still read and make a second copy.

Of course old floppy disks and magnetic tape are worse still!


Regards

Louise

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