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How To Choose Archival CD/DVD Media
Posted by
kdawson
on Mon Dec 11, 2006 03:33 PM
from the 70-years-or-bust dept.
from the 70-years-or-bust dept.
An anonymous reader tips us to an article by Patrick McFarland, the well-known Free Software Magazine author, going into great detail on CD/DVD media. McFarland covers the history of these media from CDs through recordable DVDs, explaining the various formats and their strengths and drawbacks. The heart of the article is an essay on the DVD-R vs. DVD+R recording standards, leading to McFarland's recommendation for which media he buys for archival storage. Spoiler: it's Taiyo Yuden DVD+R all the way. From the article: "Unlike pressed CDs/DVDs, 'burnt' CDs/DVDs can eventually 'fade,' due to five things that affect the quality of CD media: sealing method, reflective layer, organic dye makeup, where it was manufactured, and your storage practices (please keep all media out of direct sunlight, in a nice cool dry dark place, in acid-free plastic containers; this will triple the lifetime of any media)."
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Moo (Score:5, Funny)
How apropos.
'slashdotters' can eventually fade due to five things that affect the quality of slashdot comments:
I'm Surprised (Score:3, Interesting)
Patrick got his bits wrong... (Score:2, Informative)
Re:I'm Surprised (Score:5, Informative)
All current forms of optical storage share the same problem that will limit their reliable life span. This problem will effect different media design types over different periods of time, but 20 years is a good average before you will start to see bit rot. How ever ALL optical media, regardless of being commercialy pressed or being consumer grade CD/DVD-R, will eventualy suffer bit rot for the exact same reasons. The problem is that the rate of expansion and contraction of the metal substrates that make up the innner layers and the plastics that make up the outter layers are very different. All optical media will suffer bit rot over time because of this, as what eventualy happens is the metal substrate inside the plastic protective layers gets warped and ripples start to form in the surface. This of course starts to alter the smooth/pit reflection encoding of data on the disc and ruins the data.
Again, different types of optical media design will last longer than others. Yes, commercialy pressed CD/DVDs will last longer than consumer grade CD/DVD-R media on average. How ever none of these formats have the reliability and shelf life of magnetic backup tapes! Espeically newer formats like AIT, SAIT, and LTO (and VXA isn't too bad either, awesome pricing on smaller VXA auto loaders). So if you are looking for reliable long term archiving CD and DVD are NOT what you want to use! You want to use tapes. How ever, you can use CD or DVD if you keep in mind that this format has a shorter shelf life and you plan a migration of that data to a new removable media format say 10 years out from now. You have to do the same thing with tapes too, as eventualy formats become old enough that it gets hard to find tape drives that will read your backups. And yes there is still a limit to the shelf life of backup tapes, as over time the magnetic signals encoded in the tape start to transfer between layers due to the tape layers being tightly wound around each other on the take up spool. How ever, even with that in mind, tapes provide a much longer useful life span for archiving data. And beyond having a longer shelf life tapes have several other advantages. They have much larger capacities than CD/DVD media, so you don't have to sit there rotating tons of discs to restore a large archive. And in many cases newer tape formats have much faster transfer rates than CD/DVD (granted they cannot do random I/O, but burning CD/DVD isn't a random I/O process either). Any one who has serious data to protect shouldn't be using CD/DVD for backup. This is more of a cheap low end consumer approach for those who cannot dish out $1000+ for a good tape drive.
Those who still have the wool pulled over theirs eyes and still think CD/DVDs are a long term storage platform need only look to those of us who have very old CDs and laser discs for proof to the contrary. I know plenty of people who bought some of the first pressings of CD albums back in the early 80s, and many of their earlier CDs are now suffering bit rot. This is even more prevelant on laser disc, probably because of the much larger surface area being affected. Many laser disc owners are fully aware of the problem of optical media bit rot. In many cases the bit rot gets bad enough that you can visualy see the distortions on the reflective surface.
Bottom line, if you value your data then use backup tapes! That's what that technology was invented for! CD/DVD-R is more of a short term backup option, best for cheap short term archiving or transporting of data. I use CD/DVD-R for regular backups of the documents on some of my workstations. But when it comes to our servers and our customer's servers it's AIT or LTO tape drives all the way!! Use the right tool for the job!!
Parent
He forgot the most important one... (Score:5, Funny)
Re:He forgot the most important one... (Score:4, Informative)
Parent
Re: (Score:3, Funny)
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Wanring: Happy Fun CD may install a rootkit on your system if it feels threatened.
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Bummer (Score:4, Interesting)
Re:Bummer (Score:4, Interesting)
Parent
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Of course, I expect the requisite *woosh* response to my own post, but at least be kind and explain what I've missed when you do.
Safety in Numbers (Score:4, Interesting)
Why not just burn a few copies of the archive to a bunch of DVD sets? The DVDs will get defects, but shuffling the chunks across the discs just a little will probably ensure that the random distribution of specific defects will not hit every copy of a given bit, against the odds a low defect rate will produce.
How about a pair of those archivers, which fire up every few years just to transfer the aging DVDs to fresh new ones? For another $1000, that's another 5 cycles of DVDs, 800GB per cycle. Another $1000 gets a pair of backup jukeboxes.
For higher capacities than 800GB, there are pricier pro jukeboxes, but with dual drives for the retranscription cycle (and faster restores). But the architecture is the same. Why try to make the media more reliable, when there's cheaper/easier solutions that just accept unreliable media, and move on?
Re:Safety in Numbers (Score:5, Insightful)
I think it's absolutely stupid to use a DVD jukebox. Really. Look into a NAS box with RAID.
Parent
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If you really want to be safe, have two NAS devices. One as your main one, for putting stuff on, and the other to make a backup of the NAS device. Or have the NAS backup itself to another drive. There are a numb
Re:Safety in Numbers (Score:4, Interesting)
Plus, you get a DVD reader and writer. For dealing with the DVDs (and CDs) that still distribute lots of content as a transfer medium. And for those without distributed endpoints to where they can archive data, or insufficient network bandwidth to archive all their data across the WAN frequently enough, DVDs are good and cheap offsite archive repositories. Plus you can burn DVDs that will play in every consumer player, which can connect your data to lots of people without data processing HW. HDs are a cul de sac for data, trapped within the infosystem.
DVD archiving isn't really competition to online HD storage. It's complementary, in different use cases, different user environments. There's considerable overlap in their related extremes, but there's a lot of difference that makes leaves the DVD solution worthwhile for many scenarios.
BTW, while I'm offering detailed factual analysis of HD vs DVD mass storage, don't throw in your "opinion" that "it's absolutely stupid...". Especially if you're going to offer a disagreement worth considering. Do you want to work together to figure out the real merits in a debate, or do you want to get into an obnoxious pissing contest that few other people will want to wade through? Few people worth teaching will learn anything from such unnecessary conflict. Including ourselves.
Parent
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But what happens if a DVD gets corrupt? Or scratched? Or, lost?
"Plus, you get a DVD reader and writer. For dealing with the DVDs (and CDs) that still distribute l
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I'd say that the 4.7TB that $1K will buy, along with the DVD-R burner jukebox, is more than "little bits of data". I already pointed out how to deal with
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No, you will not get "more room". You will still have 1 Terrabyte of the same data copied out over more disks, but still only 1 Terrabyte.
I agree... But where can I find some? (Score:3, Informative)
The only drawback is that you can only order them from the Internet. I do not know of any retail store who actually sells the brand outright nor do I know of any brand (like Sony, Memorex, Fujifilm) who sells rebranded Taiyo Yuden discs.
Also, the Taiyo brand is more expensive than any other brand.
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MediaSupply.com (Score:3, Informative)
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I'm told the Fuji's that are "Made in Japan" are usually Taiyo Yudens. I've gotten a pack of them at Best Buy (the country of origin isn't always the same) and they've worked well. I haven't gone the additional step of running a disc ID program on them.
Usually I just order
Inkjet Printables (Score:2)
What's a good inkjet printer for printing on printable CD/DVD media?
Re:I agree... But where can I find some? (Score:5, Informative)
Parent
The secret to spotting Taiyo Yudens (Score:5, Informative)
I've seen Taiyo Yuden CD-Rs and DVD+/-Rs in a number of retail stores under various brand names. I'm hesitant to publicize my trick, but I suppose the Slashdot community should know. Here's how to spot Taiyo Yudens quickly in the store, without checking each label for "Made in Japan":
The spindles all have a unique bottom lip. Whereas most plastic spindle coverings are the same diameter from the top of the spindle to the bottom, Taiyo Yuden cases have a "lip" on the bottom of the plastic covering that starts about an inch from the bottom. The bottom of the clear plastic covering sticks out just a bit and then recesses to the diameter of the rest of the spindle. Taiyo Yudens comes in these cases no matter how they are branded, and I have never seen a spindle of discs with this bottom lip that are not Taiyo Yuden. I guess Taiyo Yuden supplies the plastic spindles as well as the branding on top of the disc.
In any case, I have had better luck with the consistency of Taiyo Yudens than any other brand of DVD+R. I'm not sure what the case is now, since I've only been using Taiyo Yudens for the past few years, but when DVD recording was first becoming affordable, the compatibility of much DVD media with various recorders was so terrible as to be useless (and endlessly frustrating). Taiyo Yuden makes quality discs, and it's always nice to spot them in the store when there's a deal going on.
Parent
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People like stores. It's not a guessing game. (Score:3, Informative)
Why not just order them online, and know what you're getting?
Sometimes you need media immediately. Some people like to pick up media at the store. If you're going to be buying it at the store, why not get the good stuff, especially if it's the same price?
Additionally, it's not a guessing game once you know what you're looking for. If it comes in the Taiyo Yuden "That's" packaging and says "Made in Japan", it's Taiyo Yuden (unless it's a cheap imitation, which is still identifiable and not very common). People over at the media section of the CD Freaks Forum [cdfreaks.com] have
Not a concern with MY optical media (Score:3, Interesting)
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But, I really wish I still had the double sided player. It died. I still have a single one though.....
I have some disc in my studio, on the wall, and people always ask about them......
You don't get (Score:5, Funny)
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This bears repeating (Score:5, Insightful)
Repeating again and again and again:
For backups and archival you need tape backups, stored offsite. If you want something with more capacity and faster recovery, a backup server with rsync and beefy hard drives. Nothing else will do. With the time and effort you'll spend searching and writing DVD media you could have already bought and set up a file server or bought that tape drive.
Unless you're going to be taking those backups with you and using them in high volume, backing up to DVDs is simply a waste of time and space, and when you get some dreaded CRC errors you'll be crying for not having done otherwise.
sig: Cosas varias de un sysadmin argentino: http://aosinski.phpnet.us/ [phpnet.us]
Re: (Score:3, Interesting)
If you have a large organization and you're backing up terabytes+ daily, then yes with incremental. You can probably afford the $37,000+ for a TB storage solution.
A good bit of small businesses really don't have more than a couple hundred gigs that need to be backed up and the nightly stuff is probably under a gig unless you're in the media business.
Tape backup for archival is a horrible solution. You're dependant upon the media and the media player and in the case of Microsoft, the
Re: (Score:3, Insightful)
I agree when it comes to backing up, but not necessarily on the archival issue. Whenever you are planning long term archival, your best shot is a nice laser print out on acid free paper. If this is simply not possible then your second best choice will be a media which you suspect you will be able to read in the next 25 years, and in this case my money is on CD/DVD rather than on a particular type of tape.
Try getting now a days a QIC tape drive which will read
I have CDs good since 1998 (Score:5, Interesting)
Re:I have CDs good since 1998 (Score:5, Insightful)
Probably using the original dyes, then? According to the article, they are most likely to fail in 2008:
These people are talking about serious long-term archiving, not "it worked for this one guy for eight years".
No one has successfully used them as long as these people are talking about; they haven't existed that long. The lifespan claims are made from an understanding of chemistry (theory) and accelerated aging techniques (experiment).
Parent
my experience: some DVD media dies with no reason (Score:3, Interesting)
Possibly relevant, I noticed an internal pattern of small spots visible with a loupe or macro lens (on order of 10 microns in size; much larger than the data pits). You can read more about it here: http://www.bealecorner.com/trv900/DVD/Maxell-DVDR
Maxell America agreed to take back this DVD for analysis. As instructed I sent it to their Fair Lawn, NJ site. It was received Oct. 5 2006 and Maxell acknowledged receipt. They have apparently done nothing with it since, despite several emails to them in the ensuing two months.
Long term storage (Score:2, Funny)
I use DVD+/-R over CD-R for archiving. (Score:3, Interesting)
Sure, you can handle the CD-Rs carefully and avoid this problem. But wouldn't you rather use a more reliable medium in the first place?
Out of direct sunlight, cool dark place (Score:3, Funny)
Well, it's good to know that 95% of slashdotters are already following this practice by inherently storing their media close to themselves, next to their computers.
The usual vague personal testimony... (Score:5, Interesting)
Everyone says "I've never had any trouble with brand ABC," but the thing is, ABC varies depending on what you read or who you talk to. Some people insist they've never had any trouble with the cheapest generic products they buy at Staples. Some say any name brand is OK. Some say Verbatim is good. Some say to stay away from Verbatim. The more sophisticated will tell you not to use anything but phtalocy- pthalocy- pffthal- the Mitsui stuff. Others (like this guy) are partial to other dyes. Some say you're a fool to use anything but Mitsui Gold... some say they're an overpriced waste of money.
It's all authoritative sounding talk, talk, talk and no two experts say the same thing.
In reality, I don't think anyone understands very well what actually causes these disks to fail in the real world. I've had disks fail in less than two years--maybe only a couple-three in many hundreds, but certainly not zero--and I've never seen any obvious pattern as to which of them fail.
The thing that really bothers me is that drives and/or their accompanying software drivers never give you any indication of what the signal quality of a particular disk is. If they did, you could detect that a disk was deteriorating before it failed, and make a copy. As it is, they just keep silently keep correcting errors behind your back and you have no warning until there is utter, catastrophic failure.
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Have you ever heard of bait and switch? It's a deeply engrained trait in the human species. Under one set of conditions, such as not having much credibility to begin with, an organization will work very hard to establish the reputation of a product line. Then under another set of conditions--major stakeholders change chairs, new management team recruited, under a short-term cash-out-now incentive structure--all the expensive magic that made the original product good is discarded, and the newly watered do
Taiyo Yuden FAQ (Score:3, Informative)
independence (Score:3, Interesting)
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Takes way, way longer to burn a DVD that way, but it's worth it.
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Maybe not. PAR2 files store the filenames as part of the recovery data. As long as the TOC track (innermost track) isn't kaput, you can recover the data even if both the UDF and older 8.3 file tables are blitzed. If the TOC is busted, you'll have to get a professional DVD reader or go to a recovery service.
(The "how to" is over on the QuickPar forums. Basically, you rip the disk at the sector level to a pair of file