Originally posted by Confused I was very sorry to hear about Ron's Western Digital 500 gig external hard-drive crapping out recently, but that kind of perfectly illustrates my point about the inherent fragility of such electro-mechanical devices. Trust me when I say that I'm in no way complacent about the longevity of either CD-R's or DVD's as a 100% long-term archival medium and to be fair I never actually claimed that they were.
What I actually said was:
"probably still the most secure & cheapest method of archiving".
However, one has to start somewhere. As many of us are all too aware, both transparencies and prints can fade alarmingly if exposed to strong sunlight for lengthy periods, as I believe can the recorded surface of both CD-R's & DVD's, which is why I initially said "correctly stored".
Incidentally, many professional recording studios have recently found to their cost that certain brands of open-reel archival master-tape are quite fragile and often liable to shed alarming amounts of ferrous oxide when replayed nowadays, so photographers aren't entirely alone in this respect.
Best regards
Richard
Richard, CDs have a average lifespan of perhaps 10 years under optimum storage conditions, but many will fail earlier on (I speak from experience). DVDs are not that much better. This is a well-researched problems, because it affects not only the marginal photography community, but large archives, corporate and governmental users even more.
I myself use DVD-R as backup media, but write three sets and store them in different locations. Even yet I have unreadable DVDs from time to time, but thanks to my multiple sets, I could always find at least one working copy and rebuild my backupsets. But the backbone of my archive is hard disc-based. The nice thing is, that even if a hard drive fails, it can be replaced and no data are lost. I do not even need to search for my copies, as the system rebuilds itself.
The problems with magnetic tape have long been known. There were large batches of tape manufactured even back in the 1970s (BASF had some problems then) for VCRs and reel-to-reel machines, where the magnetic coating simply fell off after only a handful of years. It was a disaster and many live recordings (tv mainly) of that time have been lost, due to that problem.
Today we still have inferior tapes out there, which have a tendency to get sticky and the tape binds together, which makes it impossible to play, without destroying it. But there are (luckily) also cures, which at least enable a single playback to make a copy on another media, in most cases.
BUT there is one big difference between modern digital media and old analogue recordings: If you have a high level of bit-failures and noise on a digital medium the whole information is lost. If you have the same amount of dropouts and noise on an analogue medium, you usually can still recognize the contents (though of poor quality) - so the information is still valuable and useable.
Ben