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NIST Releases Study Of CD/DVD Longevity
dirkin writes "The National Institute of Standards and Technology has released a preliminary study of the potential lifespan of CD-Rs and DVD-Rs. The PDF study is here. A good starting point for deciding what type of media to purchase to keep those backups and photos kicking around longer. (You DID buy the silver/gold alloy phthalocyanine CDs, didn't you?)"
the speed in which the CDR is burned sometimes it makes a difference, for the highest reliability I think 1x is the best.
Just do what I do : buy a rack, install in front of your machine (under the DVD or CD-RW or somewhere) and back up all your important data (or your entire harddrive) to a separate harddisk. Prices on smaller models (40-60 gigs) aren't all that steep, and most people I know have trouble just filling up their 'small' 20 or 30 gig drives. A spare 60 gigger rackdisk will keep you satifsied for a long time... Alternatively you could also just buy an external fire-wire or USB harddisk, although I don't really have all that much experience with those kind of devices.
Simply buy twice the number of drives you need, and do an rsync between the two sets now and again. For added safety, get a friend with broadband and store the second box there. Then you are safe from fire, theft, drive crashes etc, with minimal effort to keep the backup up to date.
I've got a whole load of burned CD's that I created up to about 5 years ago.. and on varying quality of media, and a lot of them aren't any problem.
I suppose storage is the key thing, keep them in a dark cool place will help them last just that bit longer (unless you have a case of those little bugs that like eating the data layer).
Although they are of a similar tech, what about DVD recordable disks? I've got plenty of those now... but if I keep doing what i've been doing over the years and backup my backups onto newer media then I'm not too worried.
Just my $0.02
Are you local? There's nothing for you here!
Or, rather literally translated into English: "Our sample shows that there is a lot of junk on the market. We have found cd-rs that should never have been for sale. Possibly it concerns rejected batches." Which suggests to me that the correct heading of this article should be: CD-Rs are like everything else: you get what you pay for.
Back in the eighties, when regular CD's were first introduced that could be read by a standard computer (pc, mac, etc), the discs were fairly thick, and consisted of (iirc) from top down:
disc label
protective coating
data layer (usually pressed)
protective coating
Then at the end of the eighties, I don't recall exactly what year, but it was adopted by various cd makers till eventually all, the price of CD's dropped dramatically, almost in half.
The reason for this was the fact that the top protective layer was removed from the manufacturing process, leaving just the thin disc label and it's material to protect the data layer, barely.
I want to clarify that I'm talking about regular PRESSED cd's manufactured in bulk, and not dye layered ones, but the point is the same in both cases. By removing the top protective layer, it allowed manufacturing of CD's to drop in price dramatically.
I'm positive there have been other cost cutting measures used for dye layer CD's that the manufacturers have adopted over the years, such as cheper dyes that are affected faster due to exposure to sunlight, and so on.
It's not just about scratches or dye, but about the overall picture here. The manufacturers WANT to have built in obselesance. This gives them a nice steady flow of income when one has to contually burn his media archive every 2 years.
Food for thought anyhow. I thought I'd post about what I saw in the eighties, in case it was relevant.
user@host$ diff
used to include a study of glove compartment temperature cycles for their high end discs...
"Win treats sysadmins better than users. Mac treats users better than sysadmins. Linux treats everyone like sysadmins."
You DID buy the silver/gold alloy phthalocyanine CDs, didn't you?
No, I've not ever ran across them, and it's not like they print the reflective layer and dye compositions on the side of the package. Mine are always green-ish.
(fp?)
"Alcohol, Tobacco, Firearms, and Explosives" should be a convenience store, not a government agency.
that buying cheap crappy CD-Rs meant that your data died faster, but I had no idea how the degredation worked. What about the "armored" DVD-Rs from places like Datawrite? They're supposedly almost impossible to destroy. How well do they stand up?
I wish they would test the Memorex black cd's. If you scratch the non-readable side of them, they are actually gold. I've been using these for the past year or two. The price is good on them, and I've had no problems.
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The trouble with this approach is the same as the trouble with preserving old videotape material, something I used to be involved in.
;)
I worked for a museum that preserved such materials, and always wanted to establish a program not just to copy older videotape to newer analog formats (which already existed) but to copy and RE-copy those digital tapes on a two-year cyclical program; the digital data wouldn't degrade during the transfer, and by essentially replacing the media containing the data on a regular basis, we'd have a good chance of saving the material long-term.
I never got approval for a simple reason: tape stock is expensive, staff is expensive, and coordination of such an effort requires diligence. Similarly, you could use CD-R/DVD-R to back up your material and re-burn the discs on an ongoing rotation, but most people don't have that kind of discipline even if they have the money.
For me personally, I've found the best approach is to maintain the data on a redundant RAID array, with occasional backup to DVD-R. This way, the data itself will outlive the death of individual local drives, while the DVD-R only needs to serve as a short-term disaster-recovery solution.
Of course, once my critical dataset gets large enough to require more than a few DVD-Rs, I'll probably get lazy...aren't we about due for a new format by now?
DVD media should do better than CD, if only because the data layer is completely encapsulated, as opposed to covered in thin lacquer like CDRs. This assumes, of course, that the edges are similarly well sealed. Looking at my (DataWrite 8x plain white printable) DVD+Rs, that seems to be the case - the data layer stops about 1mm short of the edge of the disc.