Is recorded media such as CD-R completely permanent?

October 14, 2005 7:46 AM

Does recordable media "go bad" after a while? and if it does, are there any media that is less susceptible? I am going to buy some DVD+Rs for mastering my movies to, how do I ensure that they still will work in 10 years time?

I heard a long time ago, that there is some kind of parasite that eats the dye from CD-Rs and DVD+-Rs is this true?

Have you every experienced anything like this?

I have a wallet of unbranded data DVD-Rs, sometimes they are mildly mistreated, but it seemed like they had all developed in fault manifesting as read errors.

I am going to buy some DVD+Rs for mastering my movies to, how do I ensure that they still will work in 10 years time?

What are your views on unbranded vs. branded?

posted by jwhittlestone to computers & internet (20 comments total)

CDs and DVDs don't have a shelf-life of more than 15 years at the outside.

There are other things to keep in mind besides the medium, though --

1) Will the file-format you are encoding the films as (digitally) still be readable later (10, 20, 50 years)? I suspect we will not be using .mpg in 2025...

2) Will the physical medium still be easily accessed later (10, 20, 50 years)? I suspect we will not have DVD drives in 2025... (think about how easy it is to get data off 8" or 5 1/4" disks, today)
posted by Marquis at 7:50 AM on October 14, 2005

The most practical solution is going to involve moving your data from one media to another as time progresses and media is replaced. This is the advantage of digital medial over analog - you can actually create bit-perfect copies as long as you do so before the source media is unreadable.

I still have e-mails from the beginning of my time on the internet. Of course, the original media is long gone, but I've taken the time to migrate the actual data with each upgrade.
posted by odinsdream at 7:55 AM on October 14, 2005

Great topic -- I archive a lot of perishable government data and I often wonder about this, having moved from CD-R to DVD+R. There's not much choice, though, and I don't trust hard drives for archival, so I just buy brand-name media, keep the files uncompressed, and hope for the best.
posted by rolypolyman at 8:03 AM on October 14, 2005

The most practical solution is going to involve moving your data from one media to another as time progresses and media is replaced. This is the advantage of digital medial over analog - you can actually create bit-perfect copies as long as you do so before the source media is unreadable.

Yes, but don't get mad at the media, because you'll have to do this anyhow. Or at least that will be easier than trying to find a compatible player ten years from now!
posted by mendel at 8:04 AM on October 14, 2005

My fiance has CD-Rs that he used for backups, rarely used (hidden away in sleeve, used only for emergencies). The oldest ones are 7 or 8 years old and started peeling. I haven't heard anything about burned DVDs doing this, but I suspect that it's because the media is fairly new. At least make sure to store them in a cool dry place.
Fortunately, he had copies on his computer, but he recommends keeping multiple copies (ie, on DVDs and on a RAID).
On preview, what odinsdream said.
posted by j at 8:04 AM on October 14, 2005

1) the shelf life of cds hasn't been proven yet ... i keep mine in paper envelopes in a file cabinet and haven't noticed any going bad ... i have music cds that are older than 15 years

2) there is some kind of fungus that does eat the dye on cds, but it's my understanding that this is found only in the tropics

3) it's certain you will be able to transfer your data to the next medium when it comes along ... there are sites with old apple 2 games that have been transferred to a new format and can be run on pc with an emulator

4) i use only branded cds these days ... fuji and tdk are reasonably reliable ... other brands seem to have more defects and generic cds aren't worth the frustration
posted by pyramid termite at 8:07 AM on October 14, 2005

Does recordable media "go bad" after a while? and if it does, are there any media that is less susceptible?

Yes. Apart from gross problems with decomposing adhesives or whatever (which you would hope to avoid by having any good-quality brand media), the biggest difference is the quality of the original burn. If a disc is burnt full of recoverable errors at the beginning, it's going to become unrecoverable that much more quickly, even if stored in the best conditions.

I have a wallet of unbranded data DVD-Rs, sometimes they are mildly mistreated, but it seemed like they had all developed in fault manifesting as read errors.

DVD burning is still, alas, a black art, and you'll need to try different brands (and + vs. -) to find which are most effective with your equipment. At least Lite-On and Plextor and possibly other drives have burn quality checking tools available. These are not definitive by a long shot but should give a general idea how well the medium has burnt.

Unbranded DVD-Rs from the usual suspect manufacturers behind the no-name distributors (Princo et al) are typically death for any burner. You'll be lucky to get a disc burnt within the DVD error limit specification at all, let alone anything you can read in 10 years' time. These cheap discs are the perfect WORN medium for completely unimportant backups.

(Write-once, read-never.)

I am going to buy some DVD+Rs for mastering my movies to, how do I ensure that they still will work in 10 years time?

Store them digitally on two different kinds of medium. Optical+hard disc copy is good.
posted by BobInce at 8:23 AM on October 14, 2005

I hear a lot about corporations still using tapes to back up their data. Is this just inertia, or are tapes really that much better than everything else?
posted by danb at 8:29 AM on October 14, 2005

OK, I ran your question by a government archivist and here's what she said:

Buy two different high quality brands of disks and acid-free paper sleeves (important that they are acid free). Using two different machines burn two copies on the disks (you'll end up with 4 copies). Store the disks in a dry, climate controlled and dark (again she said that it is important that it stay very dark).

She says it would be better to use CD-R but DVD-R will do for this. For loooooooooong term storage she says tape drives and pdf-a is the way to go, but that won't help in your case either.
posted by Pollomacho at 8:31 AM on October 14, 2005

Related: is there any easy way to write parity/error correction to a CD or DVD? Like say a person was willing to give up an 1/8 of the CD to parity bits has someone implemented a parity WORM filesystem?
posted by Mitheral at 8:38 AM on October 14, 2005

check the forums at cdfreaks.com, there is a lot of good information there about media and recorders.

the general consensus seems to be that BenQ and Pioneer make the best burners, and the best DVD-R media is made by Taiyo Yuden.

there is a tool called "nero cd/dvd speed" which can check the raw error rate on a CD or DVD, recorable or otherwise. its available here. unfortunately its windows only, and my experiments indicate that it wont work under vmware. its a good idea to burn a test disc when you get new media to see how compatible it is with your recorder. not all recorders can report these errors, and even if you have a compatible recorder, you may have to upgrade your firmware to get the error rates.

for DVDs, the short story seems to be that peak PI errors below 280 and peak PI failures less than 32 indicates a "good" burn, but you will see on the cdfreaks.com fora that many burner/media combos are capable of many, many fewer errors, like peak PI failures of 2, which rivals pressed media.

there doesnt seem to be a consensus about whether DVD-R or DVD+R is superior.

humidity and UV light seem to be the #1 killers of recordable media. there was a really interesting NIST report about recordable CD/DVD longevity here[pdf], but they did not identify the exact brands of discs they used. one of them was extraordinarily stable.
posted by joeblough at 8:46 AM on October 14, 2005 [1 favorite]

mitheral: perhaps you could use a PAR archive to get some redundancy on your disc. sometimes i burn the same file multiple times to a disc just for good measure.
posted by joeblough at 8:49 AM on October 14, 2005

Buy high quality media. There really is a difference. Unfortunately "name brand" doesn't help a lot, as the big brands like Maxell, Memorex, etc., just get their discs from the handfull of manufacturers that actually make discs, of which many are crap. Taiyo Yuden is the best of the makers of affordable media, and the major brands have used their discs on and off. If you're in a store shopping for media, look for "Made in Japan" on the package and you've got a set of TYs. Look at the FujiFilm media first, as they use TY media the most often. If you don't want to bother rifling through all the packages in the media aisle of your local electronics store (the sales guys always stop and ask if I need help...), you can buy them online from a store that specializes in media like RIMA or Meritline. Because TY discs are so desired, there are a lot of fakes out there, so be careful. Both of these resellers have a good reputation among, er, "media enthusiasts."

A step above TY in both reliability and price is MAM-A, short for Mitsui Advanced Media - America. They're one of the few makers still making gold archival media.

A great place for CD/DVD media information overload is the forum at CD freaks. The guys there are nuts.

On preview: Mithereal, check out this AskMe question for something approaching what you want.
On preview 2: what joebough said.
posted by zsazsa at 8:49 AM on October 14, 2005

danb writes "are tapes really that much better than everything else?"

Tape is cheap, fast, and fairly reliable. Take my employer, we backup around 7 terabytes every night. Tape is the only thing that meets our volume needs and is cheap enough to actually use.
posted by Mitheral at 8:52 AM on October 14, 2005

There is a QuickPar forum on using it for parity while archiving CDs and DVDs.

There is also a particularly interesting thread at hydrogenaudio about the same question. It is a little long, but if I remember correctly this post in particular will at least get you up to speed on what the thinking is out there.

One problem is generating par2 blocks can be very slow. One solution for at least some really important material might be this:

1. Select data files to half fill a DVD
   
2. Create a handful of very small par2 blocks
   
3. Burn DVD with two copies of the data files in different directories, filling the DVD - don't forget to add the par2 files to the disc too!

I use that method on movies that aren't very important, but mostly the movies I download only fill half a disc anyway. Might as well use the extra space for something constructive.
posted by Chuckles at 8:56 AM on October 14, 2005

Related: is there any easy way to write parity/error correction to a CD or DVD? Like say a person was willing to give up an 1/8 of the CD to parity bits has someone implemented a parity WORM filesystem?

I'm fairly sure cdrecord on unix/linux systems can do this.
posted by odinsdream at 10:06 AM on October 14, 2005

fwiw, most CDRs that i've burned eat it in about a year without any special treatment (they're stored on spindles, which is probably bad).
posted by fishfucker at 11:49 AM on October 14, 2005

Here is a summary of my experience on this topic and what has been said already in the thread.

• Start with quality media: Taiyo Yuden, Mitsui, etc.
  
• Record at 1X speed.
  
• Avoid adhesive labels.
  
• Some people will tell you to buy a special pen for labeling because a Sharpie will damage the disc.. I personally think that's just the pen manufacturer's marketing department's propaganda trying to make you buy their special $5 pen, but you might want to anyway.
  
• Store away from direct light (especially sunlight), humidity, dust, and temperature extremes.
  
• Use an acid-free paper sleeve, or perhaps a jewel case (so that the surface of the disc is not actually touching anything.)
  
• Make multiple copies of each disc.
  
• Generate extra redundant recovery records with a program like QuickPar so that you can recover any corrupted segments.
  
• Plan to periodically refresh the copy by reading it and reburning it to a new medium. Make sure you record the md5 or sha1 hash of the original so that you can verify that there were no bit errors in the copy.
  
• If you wanted to be really paranoid, you could buy two DVDR drives of the exact same model and firmware. Use one to do the recording, and keep the other one unused to use in the future for reading. (The theory here is that since they are the same manufacturer, model, and firmware, that you maximize the chances of the drive being able to read the disc later.) Alternatively, buy two completely different DVDR drives and two completely different brands of media and record a copy of the disc using all four combinations, so that you will have the greatest chance of not having a compatibility problem.
  

posted by Rhomboid at 10:49 PM on October 14, 2005 [1 favorite]

zsazsa: Look at the FujiFilm media first, as they use TY media the most often.

Though I don't know exactly what you mean by "most often", every single box of Fujifilm media I've picked up in the last 6 months has been made in Taiwan, which means that it's not TY (made in Japan). I was just at Best Buy, saw Fujifilm DVD-R's on sale, and put them back after seeing the "made in Taiwan".

Buy name brand TY's or Verbatims (manufactured by Mitsubishi Chemical). I use this list when trying to find good quality media.
posted by exhilaration at 6:51 PM on October 15, 2005

five days later....

exhilaration: I meant that of the major media brands, the odds of seeing "Made in Japan" on a Fujifilm package is highest. I just bought TY Fujifilm 8x DVD+Rs at Best Buy a couple weeks ago, but it is getting much harder to find. I also saw some Panasonic branded media made in Japan, most likely marketed for their consumer DVD video recorders, but it was very expensive.
posted by zsazsa at 9:04 AM on October 20, 2005