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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?)"
Take multiple backups and atleast have one backup on high quality CD-Rss not the 25c a piece ones.
Keep upgrading your Harddisk from time to time and backup data from old HD to new one.
for the last time people, I am "frodo from middle eaRTH", not "middle eaST".
Almost all of my no-name disks are dead after 3 years. Some of my verbatims are dead to. Hard disks at 1/gig now seems cheap compared to my dvd writer and 20c per gig disks. My bet is those optodisk-RW will be dead in two years.
treat them like a mushroom and keep them in the dark.
I have many CD-R discs that are still quite readable despite being 4-5 years old. On the other hand, I've seen a disk erase itself in less than a day when left in direct sunlight, and many disks will slowly degrade at light levels found in most human-occupied spaces.
The distributed internet backup system is anotherway for people that does not have quite as important (important for the rest of the world) data as Linus.
d ib s/
http://www.csua.berkeley.edu/~emin/source_code/
But remember, sometimes you don't miss the things that were lost after a crash... if you don't, then you are a happy person!
Evolution of Language Through The Ages: 6000 BC : ungh, grrf, booga 2000 AD : grep, awk, sed
Since it was already taking 30 seconds to feed me the page, I might as well copy what I got..
CD-Recordable discs unreadable in less than two years
Posted by Dennis on 19 August 2003 - 14:33 - Source: PC-Active
The Dutch PC-Active magazine has done an extensive CD-R quality test. For the test the magazine has taken a look at the readability of discs, thirty different CD-R brands, that were recorded twenty months ago. The results were quite shocking as a lot of the discs simply couldn't be read anymore:
Roughly translated from Dutch:
The tests showed that a number of CD-Rs had become completely unreadable while others could only be read back partially. Data that was recorded 20 months ago had become unreadable. These included discs of well known and lesser known manufacturers.
It is presumed that CD-Rs are good for at least 10 years. Some manufacturers even claim that their CD-Rs will last up to a century. From our tests it's concluded however that there is a lot of junk on the market. We came across CD-Rs that should never have been released to the market. It's completely unacceptable that CD-Rs become unusable in less than two years.
On the image you can see the exact same CD-R. On the left you see the outcome of our tests done in 2001. On the right you see the same CD-R in 2003. The colours indicate the severeness of the errors in the following order; white, green, yellow and red whereas white indicates that the disc can be read well and red indicates that it cannot be read.
For those of you who are interested, the original Dutch article can be found here and in the September issue of PC-Active. Please discuss this subject in our Media Forum.
When modding "Informative", please make sure it both has a source and IS actually informative.
The Dutch article doesn't say much more. They basically just want you to buy the magazine...
FWIW, I can't remember having a single CD-R go bad. I've had some scrathed ones which took a while to read because the reading drive slowed to a crawl, but I got the data nonetheless. I even recently found what must have been one of the first CD-Rs I've ever burned. Must have been from around '96 or '97, it had my backup copy of Duke Nukem 3D on it, among other stuff, and everything read fine (the disc was a Sony CDQ-74CN).
Did you know you can fertilize your lawn with used motor oil?
If you burn the CD at slower speeds, the laser has more time to burn better pits in the media.
You are being MICROattacked, from various angles, in a SOFT manner.
The part they translated from the online article is pretty much all the substance there is in it. The actual results and further information aren't there.
The last paragraph of that:
In the September issue of PC Active, that will be in stores on 22 August, the shocking results are described in detail. Besides the possible causes of losing data over time we also a give a number of valuable tips to preserve the data on a writeable CD for the future. On the free cd-rom there is also a program to discover the state of a cd-rom for yourself.
So the info is in the paper version, and I don't have it.
I believe posters are recognized by their sig. So I made one.
I used to work for a company in Austin, TX whose speciality was optical drives (not CDs, but WORM mostly), and one of our customers was the National Archives. This was when CD-Rs were just coming out, and the NA was interested in a cost/benefit analysis of whether or not they could replace their expensive 14" WORM systems with cheap CD-Rs.
The first thing to understand is that WORM systems, true WORM systems, not the Magnetic-Optical pseudo-WORM systems, are built on ablation of material in the disc itself. In other words, you burn holes in the disc revealing a lower layer that is reflective. In the case of most discs, and Kodak especially, they were gold on the reflective layer for long-term stability. Various tests of accelerated degradation were performed in both climate stabilized and non-stabilized situations, and at worst, the discs were stable for 100 years before any error correction was necessary.
We decided to perform the same kind of evaluation of CD-Rs, and found that brand varied greatly. The best were stable for 3-4 years, the worst only 6-8 months if the climate changed dramatically. In addition, UV exposure had a radical impact on the life-span of the disc. Further research found out that the problem was the natural instability of the organic dyes that were used in the disc layers.
Basically, if the disc wasn't perfectly sealed (look at the work done in the referenced article, and how it starts at the edges), oxygen would get in and react with the dye, which would change it's characteristics relatively quickly. It doesn't take much before the dye structure collapses, and data becomes unreadable after a short period. While I suspect the dyes have gotten better over time, they're still organic last I knew, and still subject to degradation by contact with air. Quality control is the only thing that will get you anything here, and I suspect even the best dye-based discs can't make it past 20 years unless exposure to UV is totally eliminated.
What Kodak had developed was what they called "Century Discs", which were basically scaled down WORM discs, but in CD-ROM format. They were gold inside, non-reactive, and well made. They did, however, require a very expensive writer because they needed more power than a CD-R drive could ever hope to provide to force the burn away the spots. They were, however, readable in a normal drive.
That's just my experience, but everytime I've seen an organization talking about "archiving" on CD-R, I have issues with it. It's fine for "backup," where the data cycle is shorter, but true archival purposes (for example, financial data), it won't cut it. You either need to use WORM, or tape. Tape is, however, subject to problems over the cycles as well, witness the failing properties of 9-track tapes written by NASA in the 1970s (heard first hand, not sure where to find it written up). Linear-write systems are better than helical.
Just a few thoughts, but this is not an easy issue. You have to understand what you're storing, and how long it has to be readable before you consider an actual medium for storage.
Guess it's too much effort to read the article.
The CD-Rs were stored in a humidity controlled closet away from light sources. Still most of the CD-Rs were unreadable in under two years. Clearly storage conditions are not a factor.
actually, I was going through my legally obtained mpeg-4 backup CDs earlier this week, and found a number of Discs had irrecoverable errors on them, despite having been kept at room temperature, in cd sleeves, and having no scratches. The longevity of cheap to medium grade CD media is not nearly as high as you'd think.
I found this very old dupe: http://slashdot.org/article.pl?sid=04/04/22/165825 1&tid=
I suggest you get a little cozier with your browser configuration options...
In Capitalist America, bank robs you!
As others have noted, the technologies used in the media are never printed on the packaging. Furthe, like many commodity items, the wrapper has nothing to do with who actually made the media. One spindle of Brand Y disks can be made by Manufacturer A, and the spindle twice its size, with the same labelling, also from Brand Y- will be made by Manufacturer Z. It is extremely difficult to be an educated consumer under these conditions.
It happens in lots of other places- gasolene is not "made" by Mobil; Mobil, Hess, Shell, Sunoco etc contract to area distributors. The distributors buy from whoever is the cheapest or distributes to their area; they slosh-mix any company-specific additives, if any, on the way to the station. Milk? Guess what- federal law requires that the bottling plant's registration number be printed on every bottle of milk. Next time you're in the store, notice how the brand name and generic store brand milk have the same prefix on that stamped number? Notice the brand name milk is pretty expensive compared to the store brand stuff? Dirty little secret of the milk industry, in plain view.
When I need CD-R/DVD-R media, I don't want to have to spend an hour sitting on some webforum reading posts to find out what the most reliable media looks like this week and where to buy it. I want to walk into a store, see "gold type cyno-whatever", see it's $2 more for a spindle of 20 than the other stuff, and walk out.
Though I'm sure there is collusion among manufacturers at the moment, it's only a matter of time before one manufacturer realizes they can market their product based on media type/chemistry thanks to this report educating buyers (the major PC mags will probably pick this up in an issue or two).
What bugs me is how bad my DVD-R disks SMELL. I have to hold the spindle at arm's length when I open the cakebox, and leave the room until the disk is done, because it reeks. I want to know what the hell makes it smell so bad...or, then again, maybe I don't...
Please help metamoderate.
Mitsui licensed the process to Kodak, and still sells the Gold/Silver CD-Rs under either the Mitsui or MAM-A trade names.
Older discussion: Say Goodbye To Your CD-Rs In Two Years?
afterdawn had a discussion on CD-R brands a while back. In short, go with Taiyo Yuden. And to identify Taiyo Yuden?
heres a document that may help: http://www.memorex.com/downloads/whitepapers/Refer ence%20Guide%20for%20Optical%20Media%209-9.pdf
page 24+ has some info on the different dyes and reflective layers.
Believe me, if they've got it , they'll print it on the box for you - it's not like you can get many other differentiating features in CD's.
:-)
Kodak Gold Ulitma CD's were a silver / gold alloy. I've still got a few from my first burner... they're 5 years old now and still (apparently) ok.
Here's a FAQ about data life of kodak CD's. Accelerated aging at 80 degrees C and 80% RH seems a bit tough
You are in a twisty maze of processor lines, all alike.
There is a lot of hype here.
I design a certain type of reliability test equipment for a living. The tests performed by NIST are not standard length, they took much longer than industry standards for determining reliability.
The shortest test was 450 hours, most reliability testing takes around one week, NIST took at least twice as long for their tests, and up to two months for some tests.
Occasionally researchers will run longer tests (one ran a two year test on our equipment), but companies need information quickly.
Bottom line: the NIST data is to be taken seriously.
Sig is on vacation
http://www.cdmediaworld.com/hardware/cdrom/cd_dye. shtml
see also the WSJ article, in PDF form
http://www.mitsuicdr.com/technology/WSJ.com%20-%20 Portals.pdf
Note (in the "well, duh" dept): if you google or froogle for phthalocyanine cd, you can find plenty of sources, since these are advertising points.... [Now including convenient links]
"It is a greater offense to steal men's labor, than their clothes"
Useful info on a few of the manufacturers, thx. But seriously, are you really attempting to describe the performance of a digital storage medium with terms used to describe the way the stored data sounds? "bright", "good and neutral", "richer, 'tube' toned"?
The terms you use correlate to accuracy of reproduction of various frequency of audio. Audio stored on a CD (I"m not talking about CD with mp3 files on it) is stored as a sequence of samples... that is to say strictly as a time-domain function.
I can't think of any possible way that the performance of the medium could have an effect on the sound of the audio that could be remotely described by the terms you've used.
I have to wonder how true the results of Alcohol 120 really are though. (Note that I've not used it, so I can't really say).
From the CD-Recordable FAQ:
"Two components that many users of these programs always take as gospel are Media Manufacturer and Dye Data. These two readings are next to worthless.
The reason for this is that many CD-R manufacturers (like CD- Recordable.com) purchase their stampers (the nickel die that all CD-R substrates are molded from) from 3rd party sources. These 3rd party sources (either other disc manufacturers, or mastering houses) encode the data that these 'Identification' programs read, at the time that the original glass master is encoded. The 'Manufacturer' information that is encoded is usually the name of the company that made the master. Since stampers made from that master will be sold to disc manufacturers the world over, all of discs that those manufacturers produce from those stampers will contain the same 'Manufacturer' information. Information which is obviously quite erroneous and irrelevant. Very seldom will the 'manufacturer' information encoded on a CD-R actually tell you anything other than who made the original master. [...]
The second piece of data (the dye type) is also dubious. Because most master/stamper configurations are designed to be matched to specific dye types (Phthalocyanine, Cyanine, Azo, Etc), the 'Dye' information that is encoded when the master is produced indicates the type of dye that the master was designed for. This of course, does not assure that the manufacturer that buys and uses this stamper will be using it with the dye that it has been designed for. It is quite possible that a stamper/dye combination is used by a CD-R manufacturer that contradicts the 'dye' information encoded on the master. Therefore that information becomes as potentially misleading as the 'Manufacturer' data discussed earlier."
The only reliable piece of information in the "ATIP" region is the disc length. See section (2-38) for further remarks."
-- Joe
isn't that a little bit dangerous as music CD players don't care about errors nearly as much as data CDs? hence one type of copy protection being to intentionally fuck the CD up so a computer can't read it but many CD players will.
Mine will be kept on a real Hard Disk. What I have now is a 120GB, 7,200 rpm Maxtor HD, which has never disappointed me at all.
How long have you had it, under a year? Just wait, it will die soon.
I have ~4 drives, well, 3 now... 2 WD, 2 Maxtor.
The 2 WD are both over 6 years old, not a single problem. One of the Maxtors died, and the second one I'm fussing around with corruption on an almost timely basis (once a week, on Tuesday).
ReiserFSCK can usually keep it under control, but once in awhile the corruption is so bad that files are destroyed and I have to rebuild the tree (once I had 5 100 TB files, on an 80 GB HD, fun fun). That drive is 14 months old.
All I'm saying is after ~ 10-11 months of having a Maxtor drive, it starts screwing up really badly in my experience, and if you want that data to stay for awhile, you might want to invest in a good WD drive.
Also, how do you keep everything on 120GB? I have 5 spools of CDs and one spool of DVDs, none of which the data is stored on my computer, and I hardly have room on my computer, you must not download much.
I have several old Kodak gold CDs recorded on an HP 4x burner about five years ago (about US$400 -- top of the line at the time) which have died. They were stored in an airtight plastic camera box with dessicant and rarely removed. Now the dead ones seem to have some sort of dull, milky film on the shiny surface. Cause of death is unknown. Their neighbors (the exact same gold discs in the same box) are still OK, but I am making backups while I can. You can't necessarily trust gold either :-(
Archivists make a mistake when they focus on the preservation of digital media instead of the preservation of the bits. Since bits can be copied over and over without degradation, they are potentially immortal. Academic disk-based storage systems like Oceanstore http://oceanstore.cs.berkeley.edu/ and commercial systems such as Centera and Permeon http://www.computerbanter.com/showthread.php?t=309 50 keep the bits safe using redundancy on multiple servers, geographic distribution, and continuous and automatic migration to new hardware. Just as in biology, the organism (storage cluster) lives much longer than the individual cells (servers).
Modern translations are made by experts in ancient Greek and Hebrew from the most reliable early manuscripts. They don't keep translating form past translations. What we have should match the original to 99% accuracy.
While using a flashlight on a disk may be worth doing, the results may not mean what you think they will. First, light from the flashlight is either reflected, absorbed, or transmitted. If you shine light through the disk, you can see pinholes that could be a sign of poor manufacturing or subsequent damage. It is not the absolute reflectivity of the disk that matters it is the contrast.
Imagine disk A reflects 90% of light for a one and 80% of the light for a zero. Disk B reflects 70% of the light for a 1 and 30% of the light for a zero. Disk A looks more shiny initially and even more so when data is recorded on itbut Disk B is clearly the better disk (not considering differences in aging processes) to store data on.
Now consider two new hypothetical disks. Disk C starts out with a reflectivity of 90% but ages linearly to 30% over 5 years. Disk D starts out at 70% and ages linearly to 65% over 5 years. The manufacturers engineered Disk C for good looks and Disk D for data preservation.
PHB: "can't you make the disk more shiny"
Engineer: "Yes, but it won't last as long"
PHB: "Yeah but longevity is intangible. You can't see it in the store or when you open the package when you get home"
Engineer: but eventually people will notice problems
PHB: Yeah, but we will blame it on improper storage and handling. Besides, in three years I will have milked this company for as much as I can by favoring short term quarter gains over long term growth and will have cashed out my stock option bonuses for showing quartly gains and moved on to another company.
A shiny disk might be better or it might be worse; you just can't tell.
You should try out unison which can be used for file-synchronization either locally or remote and is avaliable both for windows and unix.
I use it for synchronising my laptop and my stationary pc, and it works wonderfully for that. For a couple of years I had looked into and partly tried coda, intermezzo, openafs, etc but it always stranded on that it was complex and that the kernel had to be patched so I had more or less given up the thought until I stumbeled over unison.
When you are sure of something, you probably are wrong (search for "Unskilled and Unaware of It").
You must have missed the point of the article. They aren't all created equal. Some discs will last a lot longer than others.
You can't create a technology that's immune from crappy generic products at the bottom of the price range, particularly a media technology. Buy better stuff.
Now before I get modded down, I be to remind whoever might read this that what I am saying is FACT. - bogaboga