CDs perishable?

Discussion in 'Beyond the Basics' started by Christie Photo, Feb 17, 2005.

  1. Christie Photo

    Christie Photo No longer a newbie, moving up!

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    Well.. I know I'm several years behind the curve, but I made the jump to digital about 18 months back. Now I'm troubled by the thought that my images now have a substantialy shorter shelf life.

    I think about how I can make a print from a 100-year-old negative. And, if the neg is starting to degrade, I can still get some sort of image.

    I've been storing my work on CDs and wonder if when the file starts to degrade, can it be read at all? And that's IF there's still equipment to read CDs in 20 or 30 years!

    Has anyone done the research on this?

    Thanks!

    -Pete Christie
     
  2. Rogue Monk

    Rogue Monk TPF Noob!

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    I know that cheaper CDs can fail faster than the better quality ones. I haven't experienced a CD failure yet. But I do keep the most important stuff backed up to a couple places.

    I believe the recommendation is to always burn two disks. One is used, and one is locked away. Disk media (even DVD-Rs) is relatively cheap nowadays.

    I tend to keep an active copy on my HD and a storage copy on disk. In the near future, I plan on purchasing a decent size external drive for images too.

    I also keep multiple file formats (NEF, DNG, JPG). I've only just started using Adobe's DNG. It seems like a strong contender for an opensource RAW format. Guess we'll see.

    A quick aside...Nasa has huge amounts of information from the voyager missions stored in archive. But they have no way of reading the data as any machine that could be used has long since been dismantled and the engineers that built them are either dead or one foot in the grave.

    This will become more of an issue as people realize disks aren't forever (one good scratch will end a disk) and harddrives alone aren't reliable (a head crash or decent size magnet can finish that).

    I'm interested to hear how others archive for the future.
     
  3. Johnathan

    Johnathan TPF Noob!

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    It has been debated for a while now how long CD's will last, and how long we'll be using them. This article says that they may last anywhere from 50-200 years. It's just hard to guess.

    But, that shouldn't steer you away from using CD's. One good thing about storing your photos on a digital media is that there is not picture information lost by transferring the data. So when the next big thing after CD's come around (blue ray discs, anybody?), you can easily copy all of your CDs over to that new disc/drive/whatever with no fear of losing photo quality. You can't backup a film negative without fear of degredation.
     
  4. Unimaxium

    Unimaxium TPF Noob!

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    That's why I like to use to both film and digital; digital is more convenient, but film is more durable. All it takes to irrevocably destroy a digital image is a bad enough scratch on a CD, or even just a magnet too close to a hard drive. Since digital images rely on each bit of data, if some of them go missing then the computer freaks out and doesn't know how to open the file. There's also the issue of format. Some day CDs are likely to go the way that floppy drives are going now, eventually to disappear to the land of betamax and 8-track tapes. With film, like you said, the image is still somewhat present, and can still be used even if part of it is destrpyed in some way. And as long as you have light-sensitive paper and can obtain or build an enlarger, you can still get a print. However, there is the issue of quality loss as you reproduce the image over and over. Eventually, the quality will degrade and the image will not be so good. If you try to make a copy of it, some information on the film will inevetably be lost in the transfer due to the theory of entropy. But if you have a digital file, as long as you can keep copying it to newer mediums before the one it's currently on degrades, the file will never degrade, and can maintain the exact same quality for an indefinite period of time.
     
  5. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    There have been a few articles about this. CDs are not the 100 year storage media that some people think they are. Particularly the one that we burn ourselves.

    First, there are different qualities but there is not really any standard for labeling...so it's quite hard to tell which are good and which are bad. Storage is important, direct sunlight can ruin the disks fairly easily.

    Another problem that I have heard is that disks burned by one machine, may have trouble being read by another machine. So if you got a new CD drive or a new compuer...you may have trouble. Of course, the problems are mostly likely far and few between. If you are careful about it...CDs should be a very good way to archive your digital files.

    Of course negatives are quite delicate themselves...so don't think they are really that much more reliable than digital files for long term storage. If you take the same amount of care with the CDs, as you would with negatives...CD's should last a long time.

    You can print your digital photos on archival paper and store them properly.

    Do a search on this site...I remember a few articles and/or questions about this subject. http://www.vividlight.com/
     
  6. Johnathan

    Johnathan TPF Noob!

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    Wow, beat by seconds!

    You make some good points there, Rogue Monk. That stinks for NASA. I'm sure if they weren't having such bad money problems they could hire programmers to write something that could read their files.

    You are right that you get what you pay for with CD-Rs too. Here is someone selling archival grade CD-Rs. Also, I've been told that you should burn mission-critical files at half of what your burner is capable of to avoid errors. And always make multiple backups!

    As for file formats, I have a hard time believing that old ones will disapear. Bitmaps (.bmp) have been around since there have been pictures (as opposed to text) on computer screens. As long as you don't use an obscure format that nobody has ever heard of, you should be ok.
     
  7. photong

    photong Typo Queen

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    What if I buy a a bunch of harddrives (external types) and put all of my digital images on there (or any files for that matter). Would those files degrade or corrupt?
     
  8. Johnathan

    Johnathan TPF Noob!

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    A hard drive is a magnetic disk. It would probably actually degrade faster. On top of that, It has moving parts, which are apt to break. In other words, hard drives are pretty horrible for long term storage.
     
  9. Rob

    Rob TPF Noob!

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    Files don't degrade on their own, unfortunately the device holding them may. A file-system such as NTFS can corrupt, and media such as CDs and HDDs can physically and logically corrupt, but there is almost always a way of recovering your data. This is IMO not really the question - it more like: "what storage methods will last? "

    The MTBF (mean time between failure) of a HDD is really impressive these days, but that said you don't want to put all your eggs in one basket. Especially a basket with Microsoft at the helm.

    As has been mentioned, home-written CDs are less strongly "written to" than commercial (e.g. music) CDs, so they are going to degrade much more quickly. Also if you buy a big cheap spindle (like me) then the plastic is very very thin indeed. I've blanked a recorded CD by leaving it in sunshine in my car before, so this does not make a good "permanent" (50yr+) solution.

    Following on from the multiple HDD issue, I reckon that your cheapest, most feasible resilient option is to use a number of methods: If you have two computers networked together with enough storage capacity, back up onto both. If you have a CD/DVD burner, produce 6 monthly full archives and store them in a jewel case under similar sensible conditions to film neg.

    Tip: Although it's proper old technology, server tape drives are ultra-reliable backup devices. Get something like a 40/80Gb DLT drive (and full tape set) for free from a company who have upgraded their systems. Tapes will last indefinately if they are stored correctly and are still the off-line data backup method of choice for most big enterprise organisations. The total cost of this method is usually no more than a cheap SCSI card for your PC, and it's reasonably quick. HDDs in configurations such as SAN or NAS are so large these days that entire auto-loading tape libraries are needed to back up one storage area. As a consequence, many DAS (directly attached storage) solutions are going free as companies go down the SAN route.

    One of the methods that we sell to clients at work is network backup, where data is copied to an off-site facility. If you can rent an FTP site with "unlimited" capacity, then it may be an option to copy your files there using an incremental method. The main draw-back to network backup is that you need a line size proportional to your data - you are not going to back up 400Gb of jpgs over a 1Mbit DSL line for example.

    Hope this isn't just meaningless techno-babble!!

    Rob
     
  10. Hertz van Rental

    Hertz van Rental TPF Noob!

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    UV light will wipe a CD/DVD that you have burned yourself - so do not expose them to strong sunlight. This also raises a question about reading CD/DVD's - the more you read them in a drive the more susceptible they may become to being wiped. Re-writable CD/DVD's are certainly more delicate.
    As with anything, buy the best discs you can afford for archiving. I use Kodak.
    There is also some evidence that the plastic of the jewel case can react adversely with the plastic of the CD. Some commercial CD's produced when the technology started have already begun to decompose.
    The best course to follow is to store important CD's in low-light, temperature and humidity stable conditions using paper sleeves. Check the CD's every year and at 5 year intervals (or less) copy the CD's onto new media.
    If you have any CD's you need to access a lot, make a working copy as well as the archive copy.
     

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