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Up To 10% of CD-Rs Fail Within a Few Years
Whatever you think about the likelihood that a new kind of DVDs could last for 1,000 years, this note from reader crazyeyes should give you pause about expecting current CD-Rs to be reliably readable for decades. TechARP found a failure rate near 10% for CD-Rs recorded 7 to 9 years ago, after storage in ideal conditions. On some, one or more individual files could not be recovered; others were not reliably readable on two separate drives. "In the past, hard disk drives were small (in capacity) and costly. To make up for the lack of affordable storage, many turned to CD-Rs. As it became common to store backups and personal pictures, videos, etc. on CD-Rs, the lifespan of these discs became a concern. According to manufacturers, CD-Rs should last for decades. Some even quoted an upper limit of 120 years based on accelerated aging tests! That sure is a long time, isn't it? But will CD-Rs really last that long?"
I've experienced this myself lately with a bunch of disks that were now useless. It was cheaper off brand disks that failed. The irony is at the time I got them, they were the ONLY disks I could get to work on my CD player.
So far I've had no failure with CD-R's from Sony, TDK etc... Which were the disks my CD player simply would NOT play.
i have entire 1995 to 1998 CD-R spindle's and all 400 of them still function just fine. i recently had to run trough all 400 of them, and had zero read errors. i guess my discs are possessed by some magical force, or this is just bogus.
I've had CD-Rs and DVD-Rs that I burned over a decade ago still read fine. However, those disks were verified burns where I immmediately read back the data with Nero to make sure they were ok.
There was a time when I didn't do verified burns. Those disks have a ridiculously high failure rate, but I'm betting they were bad burns in the first place. With most media I get close to a 10% failure rate on verifying the burns.
I do not fail; I succeed at finding out what does not work.
I recently tried reading a bunch of audio CD-Rs burned between 2003 to 2007. I used Exact Audio Copy on a Toshiba drive. I was able to get error-free reads from about half the disks recorded in 2003; about 3/4 of the ones from 2004, and from all the ones recorded after that. On the early ones that worked, sometimes EAC took a couple of hours to do the reads, which means it was doing a lot of retries. On the later ones, the transfers were mostly just a few minutes. On the ones that reported less than 100%, sometimes EAC spent 50-60 hours trying.
For the disks that I could not get 100% reads on from the Toshiba drive, I tried them in several other computers using a variety of programs. Mostly I was not able to get results as good as EAC on the Toshiba drive. I tried two Mac Mini's using Max and an old Mac G3 using cdparanoia from the command line, and got lots of failures. Then I tried Max on my MacBook and they all read perfectly. Go figure.
I theorize that one reason the disks had errors was that they were labeled using a Sharpie. According to the NIST report on CD-R failures (nvl.nist.gov/pub/nistpubs/jres/109/5/j95sla.pdf), this is a really, really bad idea. Since I read that report, I've been adamant about using only water-based markers on CDs and DVDs.
CD-Rs design is very flawed in that the recording layer is near the surface as opposed to being well protected in the middle, as it is in DVD-Rs.
I've had numerous CD-Rs that were well cared for get flaky after a year or so; data is usually still there, but requires use of various recovery tools.
DVD-Rs have been very reliable in comparison - never had a problem.
With that said, what I do for archival data is use two different brands of DVD-R *plus*, when possible, save two, sometimes even three, duplicate copies of the data on the same DVD-R. That way I have two to as many as six copies of the data, often including dups on the same DVD-R allowing for faster, more convenient recovery.
Ron
HD storage is incredibly cheap and like others have pointed out, we've only had 3 major interface changes in the past 20 years.
I can't read anything from my first personal 10 MB HD, either, but that never mattered. Each upgrade, transferring that to a new set of drives was trivial. I still have emails I wrote 10 years ago, not because I can read the drives. Those drives have little to no utility to me as a storage medium. I have that data because it was a 250MB HD and that takes up less space on my NAS than a single 1080p movie trailer.
In five year's time, I'm not going to be interested in reading the HDs I have now because they'll have long been transferred to the 50TB NAS type solution I'll have then.
While the GP was just joking, you CAN burn stuff to media with extra error correction of a sort. Burn it as rar files, with a certain percentage of the space devoted to par files. Redundant blocks that way - so if, say, 5% of the files are unreadable, you can reconstruct them. I suppose you could do the same thing across a series of discs, to be able to replace a bad disc.
This space available.
I'm the kind of person who usually does a fair amount of research before he leaps, and so when I first started burning CD-Rs, I did everything more or less by the book. I used quality media (Mitsui and Taiyo Yuden), quality burners (Plextor), always verified my burns, and never used any crazy high speeds. My CD-Rs have held up well in many aspects, and I've only had a few physically intact discs that went bad for no apparent reason (most of which are from what may have been a problem batch of Mitsui Silvers, burned around 2000/2001).
But no one really made it clear how physically fragile the damn things were, especially in comparison to pressed silver CDs. I kept my backups in a booklet-style binder. Yes, I know that's considered less than ideal, but these discs weren't burned solely for archival purposes -- I needed to be able to page through them efficiently. Most of them were taken out and used every so often -- say, four times a year on average, sometimes more -- and never knowingly abused.
Over time, the foil on quite a few of them started to flake off. Unbranded Taiyo Yudens, which are so often acclaimed, seem to be the most vulnerable -- I've had quite a few that developed holes in the foil, especially near the edge. It's a shame, because the discs read beautifully otherwise, and seem to ace most media tests. But the foil seems all too easy to damage.
(I've also lost a handful of Mitsui Silvers that way, whereas Mitsui Golds seem to have a more robust armoring on top, as do some of the 2nd tier discs I've tried -- Sony, Maxell, TDK, Memorex. Meanwhile, I've seen no evident physical damage to my DVD-Rs so far; fingers crossed.)
The "codes" on a CD-R that indicate the manufactuer are pretty much meaningless. Why? Because they are often the code assigned to the manufacturer of the stamper.
Stampers are hard to make and require a cleanroom, lots of chemicals and skilled people. After you have a stamper, you put it into a machine and any idiot can turn out CD-Rs. So plenty of manufacturers with the cleanroom facilities and the knowledgeable staff sell stampers. So you have some place like Ritek that will sell anyone stampers. Now Wong's Cheaper Discs buys up some stampers from Ritek and starts turning out discs.
Since Wong's Cheaper Discs are a few cents less than anyone else's that week, Memorex and lots of other folks buy up discs from Wong's. Sadly for Ritek, all the discs from Wong's have the manufacturer code from Ritek. Now someone from Ritek might be able to tell you that these discs were not actually made by Ritek, but it is going to take someone familiar with their processes to tell you that. It is not obvious.
So the manufacturer codes on discs are pretty useless. About the only thing you can do is buy discs from reputable manufacturers where you actually know who the manufacturer is.
I want to disagree with you, cdrguru, but with your low UID and telling username, I find myself unable to.
Instead, I'd like to ask you a question:
I had understood that, for the past many years, most CDs (whether recordable or not) were injection-molded, not stamped. Do you have any evidence or anecdotes to suggest that the primary manufacturing process for recordable media these days still involves stamping?
Kid-proof tablet..
Yes there is not a 1:1 correspondence between the code and the actual manufacturer.
BUT for people who follow the industry the codes can still be used to identify the real manufacturer, and in many cases can be used to identify people who are forging manufacturer IDs. Lots of people like to put TY02 on discs that never saw any part of Japan.
And in any case they are FAR more meaningful than the label on the box.
I used to work for a company that burned about 100 CDs a day. Half were kept as "backups" on site. The other half were shipped off to clients that were only going to use them once to transfer the days data to their server.
About 4 years later we lost a drive array and wanted to restore from the CD backup. I set one of my people to offloading the CDs to a new set of drives. Meanwhile I went to our offsite backup and copied the relevant data back to the server in a few hours. Days later my employee comes back to me and says that "most" of the CDs are coasters and the data is gone. It turns out that about 1/3rd of the CDrs either didn't burn properly in the first place, or had failed in the 2-6 years they were on a shelf.
The lesson was a simple one. The offsite backup server was faster, easier and more reliable than the CDRs. Of course, management blamed the (long since) fired employee that burned most of them. They also paid 5k$ for a brand new Mass burner / labeler, and used up nearly a week of production time getting it working and tested.
A year later the clients all moved to USB thumb drives and or FTP transfer for the data, making the fancy mass burner obsolete.
Backups are not archives. Backups are a copy of working state, such that you can restore working state if it is lost or corrupted, partially or totally.
Optical media is poorly suited to backups, for a number of reasons. Optical media backups are:
In all those cases, hard drive backups are a win. External hard drives (I won't consider internal here, but the same generally applies) are easily automated, requiring no operator intervention. External hard drives can be copied to new hard drives easily - plug in the second drive, drag and drop all files, and walk away. Hard drive backups are easily searched (assuming good software, I'll just assume you have Time Machine or equivalent). Hard drive management interfaces can report disk failures or sector entropy as soon as it happens (and external enclosures offer RAID-1 at an affordable price point now).
If you lose your backup drive(s), it's not a big deal: get a new drive, do a backup straight away. You'll have lost your recent history, which means you may be out of luck if you accidentally deleted a file yesterday, but your current data's integrity is preserved.
Archiving is a different matter. If the goal is to have highly reliable archives, again, I think hard drives offer many advantages over optical media -- do the archival work on the working system, thus letting the entire archive be backed up. Storage space is going to be your limiting factor, but hard links or delta storage can help for regular archival intervals with small deltas (eg, your SCCM repository is an archive using delta storage, you back up the repository itself, not each revision). If the goal is to have many archives, with less emphasis on reliability, optical media is probably the winner: you don't need to verify the discs regularly since individual reliability is not a key metric, and you can churn out a lot of archival entries cheaply this way. If you have massive storage requirements and massive reliability requirements, you're not doing it on a home user budget, unfortunately.
I can talk about enterprise-class storage and backup solutions if you like, running into the hundreds of thousands in capex, millions in aggregate in opex, but it might interest you to know that despite all this money thrown around on backup systems, we still run cheap USB drives attached to laptops and desktops, because it gets a user back up and running in their original configuration in half a day if their system fails and needs replacing (and frankly, I don't want to waste our enterprise storage on terabytes of staff music and photo libraries :-)
Back in the earlier days of CDR, a "high speed recorder" was recording at a whopping 4x or so. As drive recording speeds increased, the CDRs rated for those higher speeds had to become more responsive to the laser hitting it for a shorter period of time. How do you accomplish that? One big way was spreading the dye out in a thinner layer. That's likely to have a negative effect on longevity.
is what it takes to get the maximum lifespan from your archives. This means not buying the cheapest shit you can for your important data. Instead the only one who meets the entire specification is Verbatim media. Sure it's not the cheapest when it comes to media but in the long run, it's certainly cheaper then buying whatever happens to be on sale at best buy and if your data is important, then spend the extra money for quality media, which is exactly what Verbatim is.
In my normal useage, I now only buy Verbatim for anything that I need to ensure is archived for any length of time. Otherwise for a quick and dirty backup, I'm now using an external drive then burned to Verbatim media for longterm storage. For those cheap and rapidly changing ISO images, the cheap disks are sufficient (things like FC/Ubunta/Kubunta and other Linux Distro's) In fact, I've found that buying Verbatim Rewritable media has become the cheapest solution for the many test images I burn due to the quality of the material. I'm still operating on my first batch of 10 Verbatim DVD/RW disks (now pushing 5 yrs) because they've lasted through so many rewrite cycles. I've also used cheap disks and the damn things have gone to crap in just a few months.
Mod me up/Mod me down: I wont frown as I've no crown
Back in 1994 or 1995, a whole bunch of us got into the PlayStation mod chip scene which naturally included a need to make burned game copies. This was right at the advent of home CD burning and burner drives were hundreds of dollars and ran at 1x or maybe 2x and were usually SCSI. It was FAR from the drop-and-go way we do disc burning now. Aside from getting it to work at all, another major issue we had was finding affordable blank media. $5-10 a disc was not uncommon, and failed burns were also not uncommon: these were the days of 1mb buffers and Windows 95 and klunky software that barely worked. We didn't have Nero or anything like drives with underrun protection. You could coaster a ton of media easy because the wind was blowing the wrong way, it seemed. So we were always looking for a way to get media cheap. Sam's Club came to the rescue with 10-packs of Verbatim CD-Rs for $10. A buck a disk. These days, that's a ripoff. In THOSE days, however, this was practically a steal. And the discs mostly burned fine and the PSX liked them. A perfect match. All the PSX game copy people jumped into Verbatim. I remember one friend who had 5 100-disc binders of copies and those were just the ones he kept. Another guy had bookcases full of discs in jewel boxes. Almost all Verbatim. Dozens of us locally went for that brand like crazy. We thought we had it made. This went on for a year or so before the problems started. Also, we ran out of good PSX games to trade at the same time. But we still had older good games. But problems happened. Previously known-good discs started going bad. Visually, we saw pits and spots appearing that looked kinda like craters or maybe mold. Sometimes spots, sometimes half a disc at a time. The problem was flaws in the dyes. Other discs delaminated -the cyan data layer actually flaked off the polycarbonate. Mostly we saw the rot and it hit discs stored in binders, in the original jewel boxes or not ever burned. It didn't matter how the discs were stored. It didn't matter how they were recorded or if they were ever played or how long they were played. Eventually nearly 90% of the Verbatim discs failed. The other 10% escaped only because we quit looking out of disgust. In short, several thousand game copies got wiped out by this failing media. Now there's the moral argument that what we were doing was wrong and we got punished in a way and that could be kinda acceptable if it was only game copies that died. But we also lost other fully legitimate burns. The product made no distinction. The product was crap. Why, who knows. I do know I won't ever use Verbatim for anything at this point. There's no trust or faith. I have used other brands of media all along and most of those from the same era are still good to go. TDK, 3M, Memorex, Sony, even some CompUSA-branded media still works fine. Cheap computer flea market media sucked too. Go figure. Mostly, bad media was rare unless you hit a product that was just inherently worse than another. Lessons were learned from this: don't trust media for permanent storage. A CD-R that dies is 640 or 700MB down the drain. Stings but you go on. A failed DVD is 4.5GB in the trash. Ouch. That hurts a lot more. Worse for DVD DL. That brings us to BluRay. 50GB a disc? I am not trusting THAT ever. And the one beyond BD that offers 500GB? No freaking way. ONE dead disc should not wipe out 50 or 500GB of data. Disc burning is not stable and secure and reliable enough to trust at that level and we as users and consumers should refuse to accept it. What else can we do? I don't know. But clearly burned media is not the answer.
Sig for hire.
As DJ I used to store all my vinyl on CD as backup. I've once used my cd's for over a year in hard-dj-labor and most of them did survive although I might add:
--- I am known for the ones who want to find me on the net. Is that a privacy risk or a privilege? One might wonder..