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Best CD or DVD Recordable Media for Longevity?
icepick72 asks: "I have recently purchased a collection of music (on CDs) for a music group that had their final tour last month. Without getting into copyright issues (I'm writing from Canada -- not that it necessarily makes a difference) I would like to know if any CD-R media on the market supports longevity. In the past Slashdot has discussed the degradation of CD/DVD media. How do I go about knowing what the good media is nowadays, and how to get a decent price on it? One company uses this foil or that foil while another uses polywatchmacallit. Looking for good suggestions, and an archived discussion on Slashdot for future reference."
Well, you could rip it to your favorite format and throw it in a spare hard drive with an external hard drive USB (or firewire) box. This should be able to hold even .WAV files (unless they released over 200 albums).
When USB begins to be phased out for something faster, simply buy whatever the newest hard drive and interface flavor-of-the-month is, and copy from the old HD to the new.
If you are really paranoid, you can just get two drives, and keep them in separate places (preferably separated by 1000 miles or more).
And if you add to that CD-R backups, then you should be prepared for anything.
"-1 Troll" is the apparently the same as "-1 I disagree with you."
It's funny how the public has grown to accept a defective product and then shrugs and says, well at least it's cheap.
It has been statistically shown that helmets increase the risk of head injury.
The NIST site that hosts the article you mentioned has some tips on specific media types, but trying to buy them in small retail quantities isn't alway easy. There's rarely any guarantee that on opening two identically packaged boxes from a media company you'll end up with identical media.
For some anecdotal info (and links to even more anecdotal info), check out the section 7 of the CD-Recordable FAQ
http://www.cdrfaq.org/
To add one more statistically questionable story to the pile, I know several recording studio techs who swear by Mitsui. They're a little more expensive than generics, but you can buy 50 or 100 disc pack from the company itself (or an official distributor) and be reasonably sure of what you're getting. I've had only good experiences with them myself.
But then I've had very few bad experiences so far with any media, and all of those have involved generics with gummy printable labels applied to them, and all were given to me by other people. (My own paranoid technique is to label disks only with a non-alcohol based felt tipped pen.)
On the other hand, if you're goal is archiving the irreplaceable (rather than just stuff that will be expensive to replace), it's hard to beat a pair of hard drives which contain flac (or, if disk space is cheaper than processor time wav) files and checksums for every file. Every year or two you plug in each drive and make sure all the files are good, and when it starts to become hard to find systems that will interface with your old drives, you transfer everything to new ones. When you can pick up a 200 gig ata drive and a USB hard drive enclosure for well under a hundred bucks, it's hard to argue against that sort of strategy. You could do the same with DVDs or even CDs, of course, but checking them becomes a manual hassle.
In any event, make two copies of everything so that if one goes bad, you are likely to have a backup. Keeping one somewhere other than your house doesn't hurt either.
Basically, you want the surroundings to be chemically inert. We always put all our DVDs and CDs in ZipLock Freezer bags, Quart size. The package says they have a "FreezeGuard Seal", which means that you can expect that all moisture is excluded.
Freezer bags have extra thick plastic, which provides good, slippery, mechanical protection, too.
If you expect to store the DVDs and CDs for a long time, put the Quart size bags inside Gallon size Freezer bags.
For extreme protection, go to a shoe store and ask them for those little packets of dessicant (moisture remover) that are in each box of shoes. They'll give them to you free. Put one in each Gallon bag. I don't put them in the inner bag because the impurities in the dessicant granules might be abrasive.
For photos, backups and other archival stuff to CD or DVD I've been adding PAR parity files. They're sort-of like RAID at a file level. Even though the initial use of .pars was for Usenet binary downloads (I think) the tools work great for any situation where partial loss of data is likely. In theory, as long as the unreadable bits of the disc are a small % of the disk, I should be able to rebuild the data. There's an article where this is tested by scratching / drawing on a CDR -- unfortunately, I don't have a bookmark. The chances are good that a disk will not go bad uniformly across the entire disk. So, the parity files should be able to recover from most scratches and a lot of bit rot.
.par files are better than making 2 copies of the same data. For example, if you're only backing up a few large files, the odds of having both copies of the file get a few bad sectors is relatively high. I suppose you could patch over unreadable bits with a hex editor or something, but I'll take a nice GUI and relatively common software anyday.
Plus, I feel that
Although, to be perfectly honest, I just don't rely on CDR or DVDR. I keep a copy of all stuff on a hard drive too. DVD's go offsite, HD stays at home.
Use RE-Writables, not WORM.
RW discs:
*blanking aneals metal-layer in disc
*burning quick-melts spots of metal in disc, so they freeze quickly to different crystallization than the annealed "normal"
*reading means reading the changes in reflectivity that occur ( or differences in polarization, in magneto-optical, IIRC ) in the METAL reflecting the laser-beam.
Write Once discs:
*new disc is "blank"
*laser "burns" organic-dye in writing,
*reading-laser "sees" the diff between burnt and non-burnt as less-transparent vs more-transparent, and the reflective-layer behind-it means that this is usable binary encoding. . . ( beam goes through organic-dye twice and then is read, or perhaps gets-eaten by the burnt dye and then its absence is read. . . )
*organic-dye decays
IF you care about archival, you then store complete versions of your files,
with checksums and ECC on RW discs.
IF you are using organic-dye write-once discs, then you are basing your ability-to-recover your stuff based on Estimates & Marketing Claims(tm). ..
Cheerses
IPTables enhancement Fail2Ban bans cracker-login's
Well, there's what banks do with their optical media, which is have the glass master stored in a safe deposit box. A glass master for a DVD costs about $1000 , CD costs about $700. (Googled from http://www.cddvdking.com/ ).
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Barring that, you can buy TDK professional media ( http://www.tdk.com/professional/ )
Also, googling for Archival CDR reveals a review on the subject by photo.net at http://www.photo.net/mjohnston/column53/, which leads to the $3-a-disk Archival stuff here. http://store.mam-a-store.com/standard---archive-g
Hope this helps.
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I have quite a lot of data (>800GB and growing) I want to keep for at least twenty years, on a budget. Currently, I am using DVD-R.
.PAR2 files, is created by QuickPAR and other tools. Basically, with parity data, if some of your actual data becomes corrupt, you can recover it. I usually create 5% parity data, which means that if 5% of my data becomes corrupt I can still recover it. If 6% becomes corrupt, I'm stuffed. So, for very important stuff, I use 10% or even 25% parity data. Remember to burn the parity data to a different disc, preferably stored in a different place to the disc with the actual data on it.
I only use Taiyo Yuden DVD-Rs, with a Pioneer 108 DVD-RW drive. Taiyo Yuden invented the original CD-R, and are the only company that still makes discs in Japan. Their discs have excellent quality dye, and provide good quality burns.
When determining how to burn discs, some experimentation is needed. Try different speeds. I have found that a 12x burn gives better quality (i.e. fewer errors, no burn is perfect) than 8x on Taiyo Yuden 8x discs with my burner, but other drives may be different. Try using tools like Nero CD-DVD Speed and DVDInfo to check the number of errors, and that your drive can read the discs at maximum speed all the way to the end. Take a look at the CD Freaks forums, particularly the media tests sub-forum for more info: http://club.cdfreaks.com/
I always create parity data. Parity data, in the form of
A note about PAR2 files and DVDs. If your DVD becomes unreadable, i.e. you can't see the filesystem, rip it as an ISO image file. Use a tool that can skip errors, like ISOBuster. Then, use the PAR2 files to try and recover data from it. PAR2 is clever enough to find useful data blocks inside the ISO.
Don't use anything silly like multi-session discs, and make sure your PC can keep up with your burner so that you don't need to rely on "just-link" or whatever they call it. Make sure you verify data after burning (Nero can do this automatically).
Store the discs in a cool, dry place. If you are on a budget, metal "flight case" boxes with CD wallet style holders are a good bet if you keep them in a cupboard out of the light. Don't use flexible wallets. If you have the money, there are commercial storage systems designed for very old books which would probably work well.
Also, be sure to check discs every few years. I generally test a sample of my discs once a year. If any of them show signs of degrading, such as no longer being able to read at maximum speed or high error rates, I re-copy them. My oldest Taiyo Yuden discs are now four and a half years old, and only one (which I may have mishandled) has started to fail so far.
If you are really paranoid, you could keep the parity data on magnetic tape or hard disc. The advantage of only keeping parity data on these more expensive mediums is that it's usually only 5-10% the size of the actual data, which keeps costs down.
const int one = 65536; (Silvermoon, Texture.cs)
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