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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?"
According to manufacturers, CD-Rs should last for decades.
According to their marketing dept., rather.
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.
Just look at top of the line storage 30 years ago. Can you even get reliable hardware to try and read it anymore, assuming that the media was any good? Are the file formats from 30 years ago anything that you can use or even really want today?
I would say take the Rosetta Stone approach. Pick at least three types of storage and hope that in the future one would be usable.
120yers, lets start with archive rated CD-R, and use a decent recorder with a tray. Then write according to the orange book specifications.
Léa Gris
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.
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.
Though I'm not convinced many consumer hard drives have shelf lives on the same order as the optical media that some of us are backing up to. Add to that the fact that hard drive interfaces do change fairly often (some of us still have systems in the transitional period between IDE and SATA), and you could have potentially more irritating problems if you were to back up to hard drives instead.
I suspect for paranoid user it may be more cost effective to backup multiple times to CD-R rather than to a hard drive. And on top of that, if one CD of your backup set goes, you are only out 700 MB or so. If you have a series of backups on a single 100+ GB hard drive, and it fails, you may be out everything that was on that drive.
Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
CD-Rs, DVD-Rs, whatever, the burning process might have some anomalies not picked up immediate, the media is low quality, or (more likely) the laws of physics erode away at the data. This is not secret or new information, it's been known for a long time. Granted that most of my collection now has a high amount of data loss (and I've encountered several instances with corrupt data... not all that I really care about, although sometimes I do work at recovering any damage I might find, especially if it's possible to verify "corrected" files with known good checksums, or infer the original contents (with, for example, text files)), since about 2005 or 2006, I've always made recovery (http://parchive.sf.net/) discs to maintain the maximal possibility of recovering data in the future. It effectively halves the capacity of my spindles (eg, in a 100 stack, I might use 50~60 for actual files and the rest for recovery files), but it's worth it; I've already encountered quite a few cases of bad media from after the time I started making parity files, and boy am I glad for it!
Digital media are not permanent and who cares. Make more digital copies. Repeat.
dvdisaster is what I use now...both on CDs and DVDs (it also supports dual-layer)
think of it as a way to embed par2 (parity) onto a disc (it requires an ISO image that you create in your favorite authoring software, then after it's done embedding the parity in it, you can burn it)
alternately, you can create a separate recovery data which you can store on backup tapes or hard drives or on another disc, etc.
if you pay crap you get crap. i've also never really had an issue with DVD-R's besides their being more brands of burners vs 1995. i think it has more to do with the amount of quality burners vs just the poor quality of media.
Ever since the good ole days of CD-R I used to burn them to find they didn't really work after a couple of months. I actually think all optical media is like that - you burn it, should last for a few weeks after that it's hit or miss. Pressed CD's seem to last forever but not anything you burn yourself
After all it seems the only reliable storage is flash memory, preferably SLC
"Studies" like this are useless if they don't include information from the codes off the CD's (not the label on the box!) as to who the manufacturer is.
Get the Taiyo Yuden and MAM-A Gold blanks and you won't have issues like this.
Also please read the Wikipedia article on CD-ROMs, and expecially the references. You WILL end up with better burns if you do.
What a bad burner does? Burn a bad bit?
The rest are lost, or borrowed and not returned. I wouldn't trust CDs or DVDs for backups. They're not big enough now anyway.
I went through a period of backing up things on CD's, I liked the tangible backup...I stored them in those CD booklets that hold several on a page, zipped them up and put into storage. Now when I take them out, frequently they are unreadable. No physical damage, scratching, or even light exposure. Weird huh
Well, when all people buy are the cheapest brand of CD-Rs (or, in my case, the cheapest being the only thing available), and they're all manufactured by one company crapping out shoddy products (Ritek)... what do you expect? If 90% of CD-Rs adhere to substandard manufacturing techniques, I'm surprised only 10% have failed prematurely.
Magnetic storage is still best. Unlike optical media, magnetic material can be digitally refreshed without consuming additional resources (burning a new CD-R). Sigh.
There's error correction on CDs, the problem is that a 'bad' burner could produce a disk which is correctable to the proper data, but later on as some material degrades, will become unreadable, as opposed to simply requiring some error correction.
There used to be some brands that the firmware would show stats of that, however there haven't for a number of years, barring a few firmware hacks. (Amusing having to hack the firmware to get information that used to be semi-common.)
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.
So just what are the "ideal conditions" for storage of optical disks?
And, while I'm asking questions, has anyone ever experimented with submerging disks in (water | mineral oil | etc) to see if that would reduce long-term degradation? If we're talking 5 years or more I wouldn't mind drying/cleaning them to get my data.
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
...is the venerable 5.25" floppy disk, circa pre-1985. My Apple // disks from that time are still readable. It takes rather a long time to back up my 1TB WD "Green" HD onto the Apple //GS I have networked to my main machine, but hey, backups are important! :)
I burn thousands of CDs and DVDs per week and here are some tips
- use pro grade media from Taiyo Yuden (Made in Japan) or Falcon (Made in UAE). Verbatim still makes some good media but you have to know what to look for (Datalife Plus) because they also buy cheap media and rebrand it.
- burn cd-r at 16 or 24x. 32x is ok for short-term use. Even the best discs will fail if you burn at maximum speed.
- burn dvd-r at 8x
- if you must burn dvd-r at 16x, test your quality regularly for signs of failure.
how to test the quality:
- Plextor made good drives bundled with Plextools testing software but they are no longer making their own drives. For a replacement to Plextools, see Opti Drive Control at cdspeed2000.com
I have had CD-Rs fail within weeks after perfect verifies. You should expect a lot less than the given times in "normal conditions".
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
In addition to everything else, consider burning two copies. If you aren't using archival-quality media, use two different types* of CD or DVD on two different drives.
Even better, go for 3 and copy your disks every 5-10 years. As a bonus, when you re-copy you can stop to think "do I need to update the file formats of any files on this disk."
*Be careful, do different brands doesn't mean two different manufacturers or even two different dye-technologies.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
Punched cards or punched tape using something stronger than ordinary paper is very good for long-term storage. In ideal conditions it can last millennia.
If that's not good enough, non-organic inks on cave walls and cut indentations in stone can last even longer if protected.
OT: "It's been 4 minutes since you last successfully posted a comment" WTF? When did /. start limiting you to 1 comment every 4 minutes?
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
Comment removed based on user account deletion
What a bad burner does? Burn a bad bit?
The problem is that things in the physical world are rarely binary. Sure, an "on" might be the laser bounces back and an "off" is where the laser passes through. But what's the quality of the holes made and what to their boundaries look like. I'm guessing that the light reflected back is never 100% and the light that goes through is never 0%, but rather there are fuzzy boundaries. If the laser that does the burning doesn't do a good job on the boundaries between 1's and 0's then after some degradation in the material, a reading laser might have trouble figuring out if 50% should be a 1 or 0.
How on earth can something be prooven to last a thousand years if it hasn't been around that long? Only the gullible or stupid would believe such a claim. Reburnning often is the only way to be sure
(Except if you're dealing with Aliens in which case just nuke 'em from space - that's the other way to be sure)
Watch those corners
TFA mentions that there were various brands that exhibited failures, but this ultimately tells us nothing. CD-R branding is completely meaningless. What matters is the material/dye composition and the OEM, and the author did not control for this criteria.
What you are most likely to find is that discs made from early materials are more prone to failure, as are discs from disreputable OEMs. These are the relevant facts for quality, and the lack of understanding about what determines the quality of a CD-R is what leads to popular myths, my favorite being the one about writing slowly to have a better or longer-lasting copy. If you have to do that, it means your burner and/or media is junk, and you are merely performing the voodoo that is necessary to make sub-specification parts work. A quality burner and media will write at 100% speed and it will be just as good as writing it at 2X or 4X or whatever other number people care to pull out of their collective ass.
I have written hundreds of CD-Rs myself, and the only archival failures I've had have been due to cheap media -- and those tend to fail fairly quickly, it doesn't really take 9 or 10 years, and there's a pretty good chance that the bad discs in TFA died a long time ago, shortly after burn, but he's only gotten around to checking them now. Some of the cheap discs in my collection actually started turning color, as after a couple of years there was a visible gradient going from the outside towards the inside. If you can see the physical degradation of the disc then you know the data doesn't really have a chance.
As always, backing up doesn't mean making one copy and then putting it somewhere forever until it's needed. Backing up means making copies on a periodic basis. If you wait 9 or 10 years between backups, you might as well have kept your data on the hard drive the whole time.
I used-to make 2 CDs of every ISO, until I figured out how best to utilize PAR2.
PAR2 calculates parity information on a set of files, and writes out a file which can be used in the event that any of the files is damaged. This is quite similar to RAID-5, but PAR2 is more robust, and works on any files, not just equally sized hard drives.
Though it's no help on DVDs, CDs work GREAT with PAR2, because of their two different methods of recording. Mode 1, as all regular files are stored, reduces the amount of space available by about 12.5%, using that space for additional error correction data. Audio CDs, and Video CDs, where a single bit error isn't nearly as critical, are recorded in Mode 2, with substantially reduced error correction, but about 100MBs more usable space available.
PAR2 is similarly resilient to errors, so it can safely be used with Mode 2. This allows much more space for the parity information, and the opportunity to be safe against, and correct, respectively more damage to a disk.
Specifically, I recomend a 4-disk parity set. You fill 3 CDs full of data, and tell PAR2 to calculate 37% recovery data on those files. The first 33.334% allows you to RECOVER THE DATA FROM ONE COMPLETELY LOST CD, no matter which of the 3 it is. That still leaves you with a margin of 3.667%, so those two CDs you DO have, can have a few bad sectors as well, and all the data from the lost CD, as well as undamaged versions of the files on the two lightly damaged CDs can be recovered. Alternatively, if you DON'T lose an entire CD, all three (4 actually) CDs can have numerous bad sectors, in any distribution, up to a total of 37% of all the discs, and pristine data can still be recovered.
The method to do all this is quite simple. Just run the par2create command, telling it to create 37% recovery information. Then take the resulting BASENAME.Par2+??????? file, and create a CUE file, describing a CD with a single track across the whole CD, with the PAR2 file as the supposed audio data. eg.:
Now, any CD recording software that understands CUE files will happily record this to disc. On Unix systems, you can choose cdrecord, or cdrdao.
Now, like regular audio CDs and Video CDs, you can't just use or copy this data off the disc like a normal file on a CD. There are programs for converting VCDs into regular files, something like dat2mpeg, but I prefer a more generalized tool that can do the job:
mplayer vcd://2 -dumpstream -dumpfile par2.bin
You'll note that checksums of the file and the data on disk don't quite match... This is because, in mode2, data MUST be padded to the block size. PAR2 files are fine with it, and the padding is silently discarded.
Something like DD_RESCUE to copy the (normal) files off the other CDs, in the event of damage, is probably necessary as well. Then, once you've got 3CDs worth of data (eg. 700MB CDs x 3 = 2100MBytes) you can run par2recover and all with be repaired, like magic.
The only footnote being that calculating the parity information isn't fast, so this method is probably slower than just recording 2 copies of every CD. Also, if you lose more than 37% of the data across all the discs, the error-free originals can't be recovered. However, I consider it more reliable than duplicate discs, if only because the odds of an error on the same sector of two discs (or one disc lost, and the backup with a few errors), seems more likely than 37% of the discs being damaged beyond hope. And as an added bonus, you save 1/3rd on your CD-R purchases.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
I go and reinstall windows on my dad's machine. I use an nLited burnt CD I made(HP made CD) and it won't even boot. Tried a linux recovery CD(same maker of CD), would not boot. Somehow, out of the 6 tries I was able to get the XP install CD to boot. It did. Failed about halfway, asking for the file "ASMS", which didn't exist(but a folder did).
So, bad Cd? I fire up a virtual machine, and install XP in the machine and it works flawlessly.
I go back to my dad's machine & eventually try my legit store-bought XP install CD, and it continued to install. I burn a CD of my dad's backed up data(again, an HP cd), and it reads just fine on my machine I burned it from, won't read at all on my dad's system.
Wow, I'm lucky.
What it is? Burn a bad bit?
They could be stored in perfect places as far as the atmosphere conditions go, but the CD itself may be in horrible condition. If the condition is too bad, how's it supposed to function?
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.
Just broadcast your illegal movies and ugly photos toward a large, massive body so that the signals intersect with the earth again later after traveling along space-time geodesics. You can use Sagittarius A* (black hole at the center of the galaxy) for this, but you have to remember to be there to record your 50,000 year old backup once it arrives, because it's not like the hole is your bitch.
I only record the first 1K of the disk - if I ever need the back-up, I make the 1K file available on a torrent. The *IAA then takes me to court, where they present me, with what they assure me is a completely accurate copy of the file - This allows an entire collection to be stored on a single DVD. It also provides for off-site storage. Retrieval time can be a bit lengthy however, and costs involved can seem excessive. Sometimes only the file name is required for the *IAA to present we with a complete copy. So I must give them credit for being able to extract the entire contents of a file, from nothing more than a filename. Must be that DMA they speak of so often.
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.)
This is crap. Seriously, has anyone here ACTUALLY had a CDR not work unless it was scratched to hell and back?
Seriously....
I am open source, and Linux baby!
Every time I have used a CD-R it was only as a temporary storage option (as in to take big photo files to Costco or aforementioned Officemax) until DVD-R prices came to be pretty much equal or lesser. We have all know CD-R's have high fail rates, freaking ZIP dives have better life spans (I think, I have nothing to back that up with - just fuzzy memory from back in the "old days").
6.8SPC TR of 550, l xwind at 6, drift rt at 26" drops 77". AT has 503 ft-lbs at 1403 fps. FT 0.86
CDs already write way more redundant information than simple parity. In fact, the Reed-Solomon codes they use can perfectly recover errors where 4000 consecutive bits are obliterated (say, by a centimeter-long scratch). It's interesting stuff for sure.
That said, writing extra redundant data can't hurt, except for the loss in storage space.
Which brands are the best to use? And how can we tell since each company use some other brands.?
Ant(Dude) @ Quality Foraged Links (AQFL.net) & The Ant Farm (antfarm.ma.cx / antfarm.home.dhs.org).
I found that burning CD-RWs twice (quick delete and then burn again identically with bit for bit) all but wiped out problems I'd had with rewritables.
After logging in slashdot still does not take you back to the page you were on. It's been that way for 20 years.
(Throw a coin. If it's heads, read the P.S. first. Lucky you.)
I remember a large-scale test with pretty much all CD-Rs and CD-RWs on the market back in (around) 2000 (I think).
They used a climate chamber with all the effects of nature, amplified so much, that they could simulate 10 years of normal daylight, humidity, etc.
The blue and green materials died first. (I think blue was much worse than green, but only for some models.) After an average of 3-4 years! The original golden material survived better, but not much.
Only CD-RWs could even come close to 20 years, because they had to be manufactured better, and use other materials.
I also remember that our very first CD-Rs, burned on a huge rented SCSI burner, at 13 DM a piece, were unreadable right when we took them out of the archive one year later. Which was still better than those 50% who never survived the first burning at all.
Everyone around me always tells me that his old CD-Rs still work, and things like that. And they do not take me seriously when I tell them of the low life-span.
But usually, they do not even take them out to try them. And if they do, they look at the directory index, and think that means that all data is OK. And even than sometimes fails.
Also, they rarely can find CD-Rs, old enough to prove me right on the spot.
But if you take those discs, transfer everything and all its data to the hard disk, and then look at what you get, usually what you're left with, looks like a shattered mirror or the output of a random number generator.
P.S.: Sorry, just watched the Watchmen again (is that a pun?), and inadvertently wrote the whole comment in Rohrschach's journal voice.
Any sufficiently advanced intelligence is indistinguishable from stupidity.
It seems to me that burn speed would have a large influence on this. Has anyone ever seen a study comparing real world lifespans of discs burnt at different speeds?
120yers, lets start with archive rated CD-R, and use a decent recorder with a tray. Then write according to the orange book specifications.
That describes my setup c. 1996 (Kodak '100-year' 'Medical-Grade' Gold, etc.) and I'm starting to see about a 10% failure rate on them. Started about 2 years ago.
I think a dozen years is a reasonable run - I was just stupid for not forward propagating earlier.
I now have my data always on at least three SATA spindles, do versioned and checksummed backups, and keep a copy in at least two physical locations. A MOAB dropped within a block of my office is my biggest worry.
With the cost of drives these days and the kind of data I keep (just a few TB's for everything), having versioned backups forever seems to be rapidly becoming cost effective. It turns out that sorting that shelf full of CD binders full of random data is the hard part.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
I've often wondered if there'd be a market for hard drives especially designed for long-term archiving.
They'd be slow-spinning, with slow transfer rates, and hold less data per square centimeter of disk surface, for the extra magnetic integrity. Some archivists wouldn't mind if they were very large, too, or even very heavy. They could be shelved in a "slow cloud" backup warehouse. They'd be "set and forget" - used once to record the data, then shelved and hopefully never used again, and only when a slow data restoration would be no hardship.
Surely there's a niche market for an odd device with specs that emphasize duration of storage, rather than the usual "faster, smaller" attributes. Until those long-awaited chalcedony drives arrive, it seems there's a niche opportunity here for a low-volume, high-margin manufacturer.
Circa 1996
Only discs to have survived >2years. Last I checked they worked. They were 13yo.
Then I binned them because CD's are rubbish in general.
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.
Don't fill completely to capacity. The media burns from the inside-out. Because it turns at constant rate
Sure, a "52x" CD-R burn job uses constant angular velocity, with effective recording speed ranging from 20x at the start to 52x at the end, because it just isn't safe to spin the disc any faster. But when I burn at one-third of the burner's rated speed or less (e.g. 16x on a 52x CD burner), I get constant linear velocity: the drive spins the disc faster when the laser is pointed at the inside tracks. The real reason you don't always want to fill a disc to capacity is that scratches and rot start to set in on the outside.
This is why I still paper tape as a backup medium. ASR33 for the win!
need I say any more?
for anyone who has suffered hard drive failures that take out the entire drive....yea....sometimes, I want a backup on disc...something that's static and unpowered and loads cheaper than tape.
Of the thousands of CDs and DVDs I've recorded over the last ~15 years, I've seen about two go bad over time. I mostly store my disks in piles, occasionally taking time to brush off the accumulated dust or Dremel cutoff wheel grit when I need to read one. So anecdotal evidence would suggest that storing disks in their cases is what kills them early. Who KNOWS what kind of chemicals are in those things?
Three words:
Made In China.
Knowing Google's lust for data collection, the Soviet Union is still alive and well inside the psyche of Sergey Brin....
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
when CD-Rs first came out, they came in several very distinct classes.. and those classes were determined by the type of ink used. iirc, blue ink was the worst with about a 1-2 year life span, green supposedly had a 2-5 year lifespan, gold were supposed to have a 20 year lifespan, and silver pressed CDs were supposed to last 100 years.
The game changed when they started mixing the inks, and I don't know how this affects DVD-Rs as I lost interest, but I was always sure to buy the more expensive gold CD-Rs to back up my porn^H^H^H^H important documents.
No doubt the amount of CDs now being produced lowered the cost, but I'm sure that cheap mass production also affects quality adversely.
But this seriously isn't news. PAR2 has been mentioned to death, which sounds like a good thing. I've never used it myself, important docs like insurance, inland revenue stuff, and other odds and ends get copied onto several CDs. I mean, they're so cheap now, you'd be silly not to at least do that.
The reason girls and Windows users don't understand UNIX is because all the documentation is in Man files.
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.
That CDs/DVDs won't last forever was a given. That we relied on them is simply due to us considering the promised 10 years "long". Other media last longer. But is there something that will last forever?
Let's be honest here. Imagine our civilisation fails for some reason. And in a millenium or two, archeologists want to find out how we lived. What will they find? Well, of course they will find a lot of plastic bags and maybe a few cans, a couple glass bottles and some foundations of houses and churches. But anything we wrote? Any data we collected? Art? Anything at all that shows we were literate?
Aside of grave stones?
It's amazing that in almost 10 millenia of culture we didn't manage to invent anything but stone tablets to record information "forever". Nothing else will survive. Digital data fails before a century. Current paper won't survive for more than a few centuries, even if stored properly.
It's a curious mind experiment to ponder what would the average archeologist think of us if he finds some of our artifacts with no further data. Considering how most artefacts that make no immediate sense are classified as "religious" or "cultural", my guess is that we'll be considered a lot more religious than we really are, and that Pepsi is our god, and the Pepsi cultists were in heated battle with those that worship the Mountain Dew.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
Its not just the readable surface that fails. I have had a commercially printed CD shatter in my drive due to plastic fatigue. Not very nice, very loud and took the drive with it! http://tinyurl.com/m6ecgj
I do not keep my CD's in "ideal storage conditions". They are in my home, with varying temperatures and humidity. None of the more than 5 year old CD's can be read. Thus a CD-R is a null device. I threw them all out and got some shelf space back. Memory sticks nowadays have more capacity than CD-R's, even DVD's, so why bother with this unpractical and unreliable medium?
I have lost about 15% of my "backed up" movies collection on CD's and DVD's, that's more than 20 dead disks, all written at low speed, verified then kept vertical in their sleeve in a fresh place away from sunlight and *never* used again. After remaining untouched for two to five years they were completely dead. So I rushed out to buy some big hard drives, set up a mirroring file server and transferred the remaining good disks on those drives. Now I'm not going to use a CD/DVD to store anything important anymore unless at gunpoint.
CD's are for pussies. I don't use harddisks either. All my backups are done by the 20 illegal Chinese that sit in my basement remembering 0's and 1's for me. If you feed em reasonably, they last up to 80 years!
"Sarcasm is for *winners*, Alan." - Charlie Harper (Two and a Half Men)
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..
2500 CD-Rs, various brands, transferred to hard disks. 1-2% failed. Most failures were Memorex. Harddisk space is cheap enough to have two copies. They have to be spun up every few months.
CDRS that state they have recorded successfully have a substantially nonzero chance of not working IMMEDIATELY after being burned ( 10% is conservative ). Also CDRS that have been used, have likely been left sitting in grit and dust and quickly get scratched into uselessness. In my experience, CDRS that have worked at least once and have been sitting in a jacket pretty much unused, fairly reliably retain their data over at least a couple of years. YMMV.
...
I can say that CD-Rs are pretty unreliable past about 5 years. I recently tried to open some old graphics files from our CD-R archives at work, and it didn't go so well.
Everything I was trying to open recently was about 7 years old, and about half the discs wouldn't even read, or would throw errors when I tried to actually copy anything off them.
It also opened up the issue of file formats...what the hell am I going to do with an Aldus Pagemaker file from 2001? Nothing in Adobe CS3 had any idea what to do with it. I think that's what that extension was, anyway. Archiving photos and videos is pretty safe as far as file formats go. A BMP is crappy and gigantic next to a TIFF or PNG, but you can still open it.
Proprietary layout formats though...they get old faster than cheese in a hot car.
Porquoi?
I have some several CDRs that I burnt from 1994 to 1997 with a Pinnacle Micro RCD-1000. It was the first burner I can remember that was under $2000. The media was Verbatim with the gold dye. Back then they were about $12 each in packs of 10. They have been stored in CD booklets and kept in a cool, dark location.
Every one of them still reads and verifies when I use my Plextor DVD burner - I just tested them earlier this year while backing them up to a hard drive. However, only about half read without errors if I use the other DVD readers that I have, including Samsung and Asus or the other DVD burner which is a Pioneer.
Ironically, Verbatim is currently one of the best DVD-R brands. Back in the day, TDK was great as they used Taiyo Yuden, not anymore... And yes, i even had a gold verbatim cd-r develop a hole on its own (i think they used something different than Cyanide with the gold, as the bottom didn't gave the distinct green look). Thats very old before Verbatim switched to their blueish cheaper material, some of which failed one way or another anyway.
In any case Dvdisaster is a must, and the most streamlined safe way to add redundancy and recover from failure when you know its time to reburn or copy to a hopefully better storage format. There are many alternative methods using quickpar which might work, but you need a standardized (read as blocks, not necessarily in order) way to access your media, which is also identical across the various platforms dvdisaster runs on. Even if you only had .par2 files made against a disc image, i would use dvdisaster adaptive reading strategy to read what it can from the disc, but since dvdisaster can also make (and recover from) redundancy data just fine, why bother with more tools and complex steps?
Your games are not really lost as they are online anyway, but some people actually burned unrecoverable personal data that no one else has. Sure the gold layer might have lasted a hundred years, but nobody ever mentioned anything about the other materials attached to it...
Artix
Your Linux, your init.
Yea, I went to a stack of discs recently that date back to 2001-ish. Most of my archives work, but burning to the blanks causes the paint to "flake" off without error :(
So, backing up an old PC to ~ six CDRs ends with holding two discs up to the light and explaining, "see the pin-hole, that's where we lost three gigs of data". Hah, never again, but the worst part was no error.
Under the influence of Post-Cyberpunk Gonzo Journalism
I've got some CD's I burned clear back in the year 2000 that are still readable. Part of it is the media, buy cheap junk media and you get what you paid for.
But backups, true backups. I've got an external 750GB drive and I use Macrium Reflect to do full system backups once a month. It's compression takes a 160GB partition down to about 27GB.
The only thin CD-R's are used for these days is audio CD's.
As long they are not raid controlled and off-shore, this plan won't go nowhere!
--- 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..
did not want to deal with the CD cartridges. now they whine that the cds are getting scratched. SO the solution is to go to USB/SD Flash to store the movies and songs. and u not need to worry about cds skipping when you hit a bump in the road. 4gb standard 2hr movie, 900tb for EP mode plus audio and data:)
You have a point there. I don't suppose you have directions to the nearest refugee camp do you?
It is a covert DRM system that is put on the blank discs by the manufacturers. They can erase them even out of the drives :-P
one "archive", which you don't touch. one "for use", which you touch and use. If that one goes bad, re-dump it to your harddrive and burn another archive... Or, alternately, simply throw it in the burn workflow for another 2 burns.
-Clio
Karma: Bad (mostly from not giving a fuck)
Blog: http://clintjcl.wordpress.com
I have been using a combination of verified writes and dvdisaster to hold my important data. And for CDs they can not only be verified, but checked with C2 scans to see if the "correct" readback requires ECC at the sector level, or if the initial burn is successful.