CD-R's and DVD-R's are not archival ...
Eniregnat said:
After seeing the stats, I really expect to pick up any of my burned DVDs or CDs and be able to use them in 10,20,50 years. That said, I don't plan to access them every day, all day.
While your faith in CD-R's is commendable, it is just faith rather than science. How on earth can you argue with anyone that something that was only been invented 15 or 20 years ago will survive for 50?
Of course you are right that higher quality manufacturing will decrease failure, but everyone should be smart and DIVERSIFY their backup strategies.
I have a couple of CD-Rs of World Maps that I paid $400 for in 2002, and found out last week that about 20% of the data on the CD-Rs is now unreadable. I can probably hassle the vendor to replace them, as they have the original data. But CD-R's do fail.
My point about buying a fast, high capacity DVD is that smaller businesses and amateurs CAN quickly, and easily re-duplicate all their precious photos every few years. Also, my point with making multiple backups is redundancy. With multiple backups, even if some data is lost on one CD/DVD, the odds of it failing in exactly the same place on the second must be statistically lower - thus a better strategy.
If we knew before any negative event happened that it would occur, life would get a lot easier. No seat belts would be needed, there would be no plane crashes, no one would lose data. But unexpected things do happen, and data will be lost when backup CD's fail both in the medium term and especially long term.
Here's a more scientific approach (the link below is from the FbIA's website - "The Film based Imaging Association is a permanent advocacy group whose focus is on the storage and preservation of mission critical information through the use of film based imaging technology.")
"But an investigation by a Dutch personal computer magazine, PC Active, has shown that some CD-Rs are unreadable in as little as two years, because the dyes in the CD's recording layer fade. These dyes replace the aluminium "pits" of a music CD or CD-Rom, and the laser uses that layer to distinguish 0s from 1s. When the CD is written, the writing laser "burns" the dye, which becomes dark, to represent a "1" while a "0" will be left blank so that if the dye fades, there's no difference; it's just a long string of nothing to the playback laser.
So have you already lost those irreplaceable pictures you committed to the silver disc? PC Active suggests we should forget CD-Rs as a durable medium, after its own testing found some with unreadable data after just two years. "Though they looked fine from the outside, they turned out to be completely useless," wrote the technical editor Jeroen Horlings, who had tested 30 brands in 2001, left them in a dark cupboard for two years and then re-tested them in August 2003. Of the brands tested, 10 per cent showed ageing problems. And it wasn't just Horlings. After seeing the results, shocked readers contacted the magazine with their experiences.
Recordable DVDs are not off the hook either. The "dye chemicals" in write-once DVDs are similar to CD-R, though recording density and disk construction differ. "We're in the process of testing DVDs and we're sure that the same problems will occur," said Horlings, who plans to publish his findings soon."
Full article (original was in the Independent):
http://www.fbia.org/print.asp?ID=27963
